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Volume 26,2021 Issue 5
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Available online:May 10, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23036
Abstract:The observational data of meteorological stations during 1980～2019 in China was used in this study, including daily precipitation, daily maximum temperature, humidity, cloud cover and wind speed. Then holiday climate index (HCI) is constructed by these meteorological elements to show holiday climatic suitability over China. The annual mean holiday comfort day (HCD) is 131.1 days over China, with a bimodal distribution throughout the year, which is more in spring and autumn while less in winter and summer. Affected by the effective temperature and wind speed, the annual mean HCD show a significant increasing trend. The bimodal distribution of HCD is more prominent caused by effective temperature, cloud cover and precipitation. The spatial distribution of annual mean HCD is not even in China, which is greater in North China, Huanghuai, Jianghuai, Xinjiang and Yunnan province than those in other regions. HCD in Tibetan is the least in China. HCD in most areas over China has an increasing trend, except for central South China and eastern Hebei province. The spatial distributions of HCD in winter, spring and autumn show increasing trends in most part of China, while decreasing trends in summer. Closely attention on the influence of climate change on holiday comfort over China is conducive to the rational development and utilization of climate resources, providing protection for the sustainable development of tourism industry.
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Available online:May 10, 2024 DOI: 10.3878/j.issn.1006-9585.2024.23114
Abstract:Based on datasets of three drought indices (i.e., the Standardized Precipitation Index, SPI-12, Standardized Precipitation Evapotranspiration Index, SPEI-12, and self-calibrated Palmer Drought Severity Index, scPDSI) for the period 1901~2020, this study investigates the long-term characteristics of drought in China over the past 120 years and then explores reasons for their inconsistency. Results indicate a significant drying trend in southwestern China, the Loess Plateau, southern Northeast China, and southern Xinjiang, while regions with significant wetting trends are located in North China, the east part of Northwest China, and the north part of Northeast. As far as drought events are concerned, both Northeast China and Northwest China are characterized by prolonged duration and higher intensity, but the drought tends to decrease in general, especially in eastern Northwest China and northern Northeast China. On the contrary, the duration and intensity of drought events increased in southern Northeast China. There are approximately 2820000km2 of land area each year that has experienced drought, and among them about 30500 km2 of land areas are threatened by extreme drought. Drought severity increases with time, with rapid growth after the mid-1990s. During the past 120 years, drought area exhibits significant interannual and decadal variabilities, with the main periods of 2~3 years and 18~22 years, respectively. In humid regions, three drought indices show good consistency, while in semi-arid and arid regions, their consistency is relatively low. In humid areas, the wet-dry variation is dominated by precipitation. In semi-arid and arid areas, besides precipitation, both temperature anomaly and soil characteristics also play an important role in drought. Therefore, more attention should be paid to the drought index selection over arid and semi-arid areas in the context of global warming.
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Available online:May 10, 2024 DOI: 10.3878/j.issn.1006-9585.2024.23126
Abstract:The performances of CMIP5 and CMIP6 Earth System models in simulating China’s terrestrial vegetation biomass were assessed based on two sets of the observation biomass carbon density data, the first to ninth (1950-2018) China Forest Resource Inventory data and a set of remote sensing land cover data. The impacts of different Land-Use Harmonization (LUH) datasets on vegetation biomass simulations of CMIP5 and CMIP6 models were further explored. Our results show that both CMIP5 and CMIP6 models overestimate China"s total vegetation carbon storage during 1995-2004 (28.0 ± 6.0 Pg C for CMIP5, 25.3 ± 7.7 Pg C for CMIP6, and the two sets of reference data are 18.1 Pg C and 18.7 Pg C respectively). The spatial distributions of vegetation carbon density as simulated in CMIP6 models are better than those in CMIP5, with improved Taylor Skill Score(TSS) values and reduced model uncertainties. During 1950-1990, China’s vegetation in CMIP5 and CMIP6 are carbon sources of ?89.4 Tg C yr-1 and ?58.2 Tg C yr-1, respectively. These carbon sources significantly increase to ?256.6 Tg C yr-1 (CMIP5) and ?171.0 Tg C yr-1(CMIP6) in the 1980s. During 1990-2014, in CMIP5 the vegetation carbon sources are much weaker (?48.1 Tg C yr-1) , while in CMIP6 those sources are changed to weak sinks (42.8 Tg C yr-1, P<0.05). The differences of China"s vegetation carbon between CMIP5 and CMIP6 are closely related to their different land change conditions. Compared to Land-Use Harmonization (LUH1) in CMIP5, the forest covers and their changes in LUH2(in CMIP6) are more consistent with China Forest Inventory data and are closer to that since 1980s. This study implies that LUH datasets used in CMIPs have large bias from China’s forest and crop trajectories over the past 65 years. More accurate land cover datasets are essential for improving the simulation of vegetation carbon in the future CMIP models.
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Available online:February 19, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23084
Abstract:Urban ventilation corridor was designed to improve urban air circulation, alleviate urban thermal environment and improve human comfort, has been widely used in cities all over the world. Based on the observation data of meteorological stations, satellite remote sensing data, basic geographic information and urban planning of Pingdingshan city, with the method of mathematical statistics, land surface temperature retrieval, geographic information systems and remote sensing techniques , we analyzed wind environment, urban heat island (UHI), green source and ventilation potential of the city, meanwhile constructed the structure of urban ventilation corridor preliminarily. The results showed that: (1) The dominate wind in Pingdingshan was mainly from northwest, northeast and south. (2) The spatial distribution of UHI was multicenter, and the intensity of UHI decreased from the central city to surrounding area. Urban green source was mainly distributed around the city, which can introduce fresh air into urban center. (3) Based on the comprehensive assessment of urban ventilation potential, urban surface roughness, sky view factor etc., the corridor system of “six main and ten secondary corridors” in Pingdingshan city was constructed.
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Wang Suyao, Shi Chune, WU Zhaoxian
Available online:February 19, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23054
Abstract:Fog and haze can transform from/to each other under such a typical evolution pattern as “heavy haze (HH) – extremely dense fog (EDF) – heavy haze”. To explore the key meteorological factors for the transformation from HH to EDF, the near-surface circulation patterns of 247 EDF and 96 HH cases in the central area of the Huaihe River Basin (HRB) at 08:00 (high-intensity period) for 40 years were objectively classified respectively, using the multi-element oblique rotation principal component analysis method, together with the ERA5 reanalysis data. Based on the results of classification, the formation mechanisms for EDF under various circulation patterns were analyzed, and the differences of meteorological conditions in the surface and boundary layer of HH and EDF with similar large-scale circulation patterns were compared. The results show that: (1) The circulation of EDF can be divided into five types, with a cold high in northwest or northeast China for each type, and a sub-synoptic system in the HRB, such as weak high, frontal or inverted trough; The studied area is located in the north (33%) or inside (19%) of the weak high, in front of the front (29%) or the invert trough (11%) or at the bottom of the cold high (7%), prevailing with southwest, south or east wind with average wind speed lower than 1.6 m/s at ground level. At 925 hPa, the study area is located in the warm ridge and low humidity area, with an average wind speed of 2 m/s. In the vertical, the relative humidity (RH) decreases rapidly with height, and to below 60% at 925hPa or 850hPa, which is conducive to the surface radiation cooling, with an average temperature decrease range larger than 3℃, forming a deep near-surface inversion, with a temperature difference of 2-4 ℃ between 975 hPa and the ground. (2) The near-surface circulation for HH can be divided into three types, which are all related to high pressure system. The study area is located in the front (56%), bottom (19%) or rear (26%) of the surface high, but there is no sub-synoptic scale system or the system is weak in the HRB. (3) The reasons for HH cannot develop into EDF include: ① insufficient water vapor source (due to northerly wind on the ground); ② low cooling range at ground level (the average lower than 3.1 ℃) with relative high wind speed (the average over 2.2 m/s). (4)The sub-synoptic scale system near the study area is the key reason for whether HH can develop into EDF. This system determines local meteorological conditions, such as whether there are light winds, significant cooling, and sufficient sources of water vapor. The inter-monthly variation and generation and disappearance time of EDF under various circulation patterns are also analyzed.
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Duan Sainan, Jiao Ruili, Wu Chenglai
Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23042
Abstract:Time series analysis methods have been developed before to identify dust weather based on pollutant concentrations, but the criteria used are subject to considerable uncertainty. Therefore, in this study, we propose an objective identification method for dust weather based on the K-means clustering method by using the hourly concentration of PM2.5 and PM10 from the environmental monitoring stations. The core idea of this method is as follows: first select the optimal number of classifications K for cluster analysis; then classify the cluster groups that show large scattering in the distribution of PM2.5 and PM10 concentrations until no further classification is needed. This method is applied to identify dust weather in Xi"an from February to April 2018. The results show that this method can effectively identify the main dust weather events. Based on this method, typical characteristics of dust weather can be obtained: the ratio of PM2.5 to PM10 concentration is less than 43.5%, and the PM10 concentration is greater than 228μg/m3, which is consistent with our knowledge that the PM10 concentration is high and mainly consists of coarse particles during the dust event. Overall, this method has a clear physical basis, and it is easy to operate, suitable for massive data processing, and promising for applications in relevant areas.
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Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23096
Abstract:Based on coherent Doppler wind lidar and ground-based conventional observational data, a typical dust weather process occurring in Hulunbuir was analyzed using machine learning and the HYSPLIT model. The study revealed that the dust event started with a sudden increase in southerly wind. Subsequently, the wind direction shifted to south-southwest, resulting in a reduction in wind speed and a weakening of dust transport. However, when the wind shifted to westerlies, the dust transport intensified again. The transport of dust ceased after a decrease in westerly wind speeds. During the dust transport period, turbulence was relatively weak, and the mixing layer height remained limited. Machine learning particle size calculations indicated PM10 dominating the early transport and both PM10 and PM2.5 showing substantial growth in the later phase. This divergence in particle sizes across different transport periods suggests a potential change in dust sources. HYSPLIT revealed that in the early phase of dust transport originated from northwestern Mongolia, passing through Xilingol League in China before reaching Hulunbuir. In the later phase, dust transport directly entered Hulunbuir from the southern regions of Russia, resulting in an escalation of dust pollution. Finally, using total mass flux analysis, it was determined that the response to dust occurred earlier in the period from the pre-dust period until the beginning, compared to ground-level particulate concentration. The total mass flux threshold for this dust event was established using box-and-whisker plot. Variations in total mass flux and the establishment of thresholds could serve as novel indicators for dust event early warning systems.
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Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23080
Abstract:In order to investigate the non-uniform distribution characteristics of the flood season precipitation and trend, this paper analyzes the temporal distribution characteristics and evolution trend of the flood season precipitation in Jinhua from 1971 to 2020 by using the dayily precipitation data combined with the ECMWF reanalysis data, and by applying the improved index of precipitation concentration and concentration period. The results show that the initial day of the precipitation concentration period during is on June 13, which coincides with the initial day of the monsoon season; Jinhua region generally has a relatively uniform temporal distribution of precipitation, but with large inter-annual variability; and There is a quasi 18-year cycle of precipitation concentration and period of concentration. In the SST field, the anomalously high SST in the east-central Pacific Ocean in the winter before the year of precipitation anomaly concentration, and then the SST difference in the east-central Pacific Ocean at the equator gradually turns into a significant negative anomaly, which suggests that the anomalously concentrated year of precipitation anomaly may occur in the decaying stage of El Ni?o. The most notable anomalies in the situation field are the strong and westerly subtropical high pressure in the western Pacific and the anomalous anticyclone in the Philippine region. Anomalous anticyclones in the Philippine region allow for strong moisture transport from the southwesterly flow along the eastern coast of China during the early summer season, an the same time causing the subtropical high pressure to strengthen and extend westward. The potential gradient between the stronger subtropical high pressure and the westerly trough can increase the transport of warm and humid air from the southwest and slow down the movement of the westerly trough ridge, in order to form a more stable circulation configuration, resulting in the emergence of sustained precipitation. And after the strong subtropical high pressure continues to extend west and lift north, the westerly wind belt system southward is blocked, the large warm high pressure of the sinking air flow will lead to persistent high temperature and drought heat weather, which will lead to an abnormal concentration of precipitation.
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YANG Dao-han, WU Jing, LI Chun-bin, LI Ying, QIN Ge-xia
Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23028
Abstract:Abstract: Soil heat flux (G) is one of key factors in affecting the surface energy balance over the Qinghai-Tibetan Plateau. The estimation and spatiotemporal distribution analysis can provide a reference for the surface energy balance in the region. In this paper, the applicability and accuracy of the model was evaluated by combining SEBAL model inversion data with observation data over the Qinghai-Tibetan Plateau from 2003 to 2018 based on the MODIS, the China regional surface meteorological element driven data set, and the 1 km all-weather surface temperature data set in Western China. We found that SEBAL model had high accuracy for inverting soil heat flux (G) over the Qinghai-Tibetan Plateau. On this basis, soil heat flux (G) value were inverted by remote-sensing data, and analyzed the spatiotemporal distribution characteristics of G in the region from 2003 to 2018. The results showed that: (1)The mean value of G showed a fluctuating downward trend in multiyear, with the maximum valley value appearing in 2011, and the maximum peak value in 2016. The mean value of G showed a fluctuating downward trend in every season, except in winter. The mean value ranges of G in different seasons showed a trend of summer > spring > autumn > winter , and the order of magnitude of fluctuation changes was consistent with former. (2)The mean value of G showed spatial distribution characteristics that the highest area in the northern Qaidam Basin and its surrounding areas, the southwestern region such as Ngari region and circumjacent areas followed, the rest of the area was mostly low in general, and with obvious spatial heterogeneity. The mean value of G in different seasons showed spatial distribution characteristics were basically consistent with former. (3)The central and southeastern areas showed an increasing trend, while the northern, western and southwestern areas showed a decreasing trend. The proportion of areas with an increasing trend was highest in winter and lowest in summer, the proportion of areas with a decreasing trend was highest in summer and lowest in winter. The results of this study demonstrated the applicability of the SEBAL model for inverting G, and enriched the studies of surface energy balance over the Qinghai-Tibetan Plateau.
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YANG Jin, ZHANG Shuangyi, WANG Hailong, NIU Fengguo, LI Donghui, YUAN Zongtao
Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.22106
Abstract:In recent years, reanalysis data are more and more used in wind energy resource assessment. In this paper, the observation data from 40 ground stations in China are used to evaluate the ground wind speed error of ERA5 and ERA5-Land reanalysis data with different resolutions. The results show that the mean Bias Error (BE) of multi-year mean wind speed of ERA5 and ERA5-Land data is 0.08 m s-1 and -0.06 m s-1 respectively, the maximum BE is 0.46 m s-1 and -0.19 m s-1 respectively, the Relative Bias Error (RBE) is 4.4% and -2.0%, and the maximum RBE is 33.0% and -10.1% respectively; The slope of the linear fitting equation of monthly mean wind speed is 0.93 and 0.97 respectively, the intercept is 0.29 m s-1 and 0.02 m s-1 respectively, and the correlation coefficient is 0.98 and 0.99 respectively; The mean Root Mean Square Error (RMSE) of monthly mean wind speed is 0.17 m s-1 and 0.14 m s-1 respectively, the maximum RMSE is 0.49 m s-1 and 0.22 m s-1 respectively, the Relative Root Mean Square Error (RRMSE) is 7.4% and 5.7%, and the maximum RRMSE is 35.2% and 13.3% respectively. The error of ground wind speed of ERA5-Land high-resolution data is relatively low, which is conducive to improving the accuracy of wind energy resource assessment.
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XIAO Ziniu, LI Zhangqun, ZHAO Liang, CHEN Hong, FENG Rong
Available online:January 05, 2024 DOI: 10.3878/j.issn.1006-9585.2023.23002
Abstract:In this paper, we summarize the research progress on the influence of the thermal conditions of the Tibetan Plateau and the Indian Ocean on the South Asian monsoon, water vapor transport, and regional climate. This review focuses on the linkage between the thermal conditions of the Tibetan Plateau and the Indian Ocean and Tibetan Plateau-Indian Ocean thermal differences with the important climate indicators including monsoon activity, water vapor transport, and so on. Moreover, the climate prediction indicators and methods for the Indian Ocean and the Plateau at sub-seasonal and seasonal time scales are proposed based on the above aspects. It is expected that this review will be beneficial for understanding the impact of thermal conditions on climate in the Tibetan Plateau and Indian Ocean region and improving the capability of regional climate prediction.
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Xiaoquan Lu, Ying Liu, Bo Li, Yuqin Chen, Huilin Su
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.23053
Abstract:Urban expansion has an impact on the carbon sequestration capacity of terrestrial ecosystems through alterations in gross primary productivity (GPP), which can have implications for ecosystem functioning and regional carbon budgets. Urban expansion leads to the transformation of vegetation into impervious water, resulting in the reduction of vegetation cover, which in turn leads to the reduction of GPP. However, the change of regional climate caused by urbanization will affect vegetation growth, and vegetation productivity also changes with time under the background of climate change. Based on multi-source remote sensing data and downscaled vegetation productivity data, this study examines the spatiotemporal dynamics of urban expansion, its direct and indirect impacts on gross primary productivity (GPP) in Nanjing from 2000 to 2020, and the compensation proportion of the indirect effects of urbanization and climate change for direct effects. The findings indicate a significant expansion of the urban area in Nanjing between 2000 and 2020, resulting in the double of impervious surface from 620.31 km2 in 2000 to 1245.66 km2 in 2020. Due to the increase of urbanization intensity, the direct effect of land cover change resulted in a decrease of -345.98 gC/m2/a in the GPP of Nanjing urban area, while the indirect effect of regional climate change and urbanization resulted in an increase of 298.67 gC/m2/a in the GPP of Nanjing urban area, which offset 86.33% of the direct effect. The increasing trend and contribution rate of indirect influences in urban areas surpass those in suburban areas, demonstrating that the urban environment fosters residual vegetation growth. In the context of the continuous expansion of major cities worldwide, characterizing and understanding the impact of urban expansion on vegetation productivity holds significant practical significance and reference value in addressing global change challenges and promoting ecologically civilized city construction.
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ZHOU Binbin, WANG Youxiang, Chen Hong, LIN Zhaohui, ZHANG He, Wu Chenglai, Jiang Yan, CHEN Kai, ZHANG Congtong
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.23047
Abstract:Based on snow depth dataset over China and CN05 gridded precipitation data over China, the relationship between Tibet Plateau (TP) snow depth and the summer precipitation in Yunnan are investigated by using Singular Vector Decomposition (SVD) and correlation analysis. The results show that the positive snow depth anomalies in the central and western TP during winter and spring can enhance summer precipitation in Yunnan, especially in the Jinsha River basin and the southwest of Yunnan, and the correlations between TP snow depth and Yunnan summer precipitation may be independent of the influence of ENSO on summer precipitation in Yunnan. The possible impact mechanism has been investigated through the diagnostic analyses using ERA5 reanalysis datasets, it is suggested that heavier snow depth in the key region of TP lead to the lower surface air temperature in the central and western parts of the TP and nearby areas in spring, which is conducive to the late onset of the South Asian summer monsoon, hence weaker South Asian summer monsoon and the associated monsoon depression, along with the abnormal westerly wind to the south of the TP. Furthermore, colder surface temperature associated with heavier snow depth in the TP can also initiate the wave train at 200 hPa, which will propagate from the western part of the plateau through Mongolia to Northeast Asia along the westerly jet stream, and an anomalous cyclonic circulation could be found in Northeast Asia, which was conducive to the southward movement of the cold air in the middle and high latitudes, leading to more rainfall in Yunnan province. Meanwhile, wave train at the 850 hPa can also be found, which spread from the southwest side of the plateau to the South China Sea, leading to an anomalous anticyclone circulation in South China Sea. The anomalous low level shear over Yunnan will then be developed from the westerly wind on the south side of the plateau and the southwesterly wind on the northwest side of the South China Sea anticyclone, which is favorable for more precipitation in Yunnan. Meanwhile, cold air flows southward to Yunnan and converges with warm and humid air, which also contributes to enhanced summer precipitation in Yunnan.
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WANG Hongguo, YAN Lili, ZHANG Jianping, LI Lixia
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.23013
Abstract:In order to explore the characteristics of PM2.5 pollution in autumn and winter in cities along the Taihang Mountains, Jiyuan City, a typical industrial city was selected as the research object. According to the influence characteristics of meteorological factors on the hourly concentration change of PM2.5 in different time periods, the pollution level of PM2.5, and the difference of pollutant growth rate before and after the start of heating in winter (November 15, 2021), October 2021 to March 2022 are divided into four stages, and the hourly data of PM2.5 and meteorological factors in different stages are analyzed by using multiple linear regression model. The results show that in the first stage (2021.10.1-11.14), 26.1% of PM2.5 hourly concentration change is determined by meteorological factors, and the correlation between single factor and PM2.5 is less than 36%; In the second stage (2021.11.15-12.31), 72.4% of the hourly concentration change of PM2.5 was determined by meteorological factors. The wind direction, relative humidity and visibility had significant effects on PM2.5, and the correlation between PM2.5 and relative humidity and visibility reached the highest (61.5% and 73.1%); In the third stage (2022.1.1-1.31), 53.2% of the hourly concentration change of PM2.5 is determined by meteorological factors, and the relative humidity and wind speed have no significant impact on the hourly change of PM2.5, which is related to the large impact of the long-range migration and detention of pollution clusters in this stage; In the fourth stage (2022.2.1-3.31), 32.2% of PM2.5 hourly concentration change is determined by meteorological factors. Affected by sand and dust, wind speed has no significant impact on PM2.5 hourly change. In the process of pollution in autumn and winter in Jiyuan City, the main components of particulate matter are NO3-, NH4+, OC and SO42-, of which the proportion of SNA (SO42-, NO3-, NH4+) is more than 65.7%, and the secondary pollution is serious. On the whole, the growth rate of particle component concentration shows that the growth rate of NO3-, S, EC and Cl- slows down with the increase of pollution, while the growth rate of SO42, OC, K+ and NH4+ shows a "slow-fast" trend with the increase of pollution.
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Evaluation and projection of the Eurasian winter snow water equivalent based on CMIP6 Coupled Models
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.23005
Abstract:Historical simulation outputs of climate models from the Coupled Model Inter-comparison Program Phase 6 (CMIP6) together with the GlobSnow monthly snow water equivalent (SWE) products were used to evaluate the model performance in simulating the Eurasian SWE of winter. Most models can relatively well reproduce the basic features of the climatological Eurasian winter SWE. There are great differences in different models for the trend of SWE, but the multi-model ensemble (MME) can improve the simulation ability. The spatial and temporal characteristics of winter SWE from CMIP6 model simulations and observations were analyzed using the Empirical Orthogonal Function (EOF) analysis, and the results suggested that only a small number of CMIP6 models could reproduce main features of the first eigenvector, but MME can improve the performance. Furthermore, MME can also reproduce the response of Eurasian SWE to precipitation and surface air temperature during winter. The projection of Eurasian winter SWE in the 21st century was estimated by using the CMIP6 MME results under different emission scenarios of Shared socioeconomic pathways (SSPs). With respect to the reference period 1995?2014, projections of SWE by the MME under four scenarios (SSP126, ssp245, ssp370 and ssp585) all shown increasing trend in the northeastern Eurasia continent and decreasing trend in continental Europe to the west of 90°E. There was little difference in SWE change under four SSPs in the early 21st Century. But the difference became larger in the late 21st century. The amplitudes of SWE changes would become larger with time. Further analysis shows that the higher temperature and increased precipitation were conductive to the SWE increase in the northeastern Eurasia.
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hanjiaxing, zhuweibin, wufangkun, haofeng, xiefei, wangpeng, xuman, liuzirui, yuecaiying
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.22137
Abstract:To explore the effect of volatile organic compounds (VOCs) on ozone (O3) formation during summertime when ozone (O3) pollution occurs frequently, the chemical composition characteristics of VOCs and its sources were studied, using high-resolution online monitoring data obtained in an urban site of Hohhot in the summer of 2021. In addition, the sensitivity of O3 pollution days and the control strategy of its precursors were further studied by observation-based model (OBM). Results showed that the averaged total mixing ratio of VOCs was 21.10±9.38 ppbv, with oxygenated volatile organic compounds (OVOCs) as the most abundant group (36.3%), followed by alkanes (23.8%), halogenated hydrocarbons (16.8%), alkynes(10.4%), aromatic hydrocarbons (6.6%), and alkenes (6.1%). Eight emission sources of VOCs, including restaurants emissions/biomass combustion, liquefied petroleum gas emissions, industrial emissions, gasoline vehicle exhaust, petrochemical sources, diesel vehicles, plant emissions and solvent use emissions, were resolved using PMF model, with contributions of 21.9%, 20.9%, 18.7%, 9.5%, 9.3%, 8.3%, 7.9% and 3.5%, respectively. According to the relative incremental reactivity (RIR) and EKMA analysis, O3 sensitivity was in the VOCs-limited regime during the O3 pollution days in Hohhot, with higher RIR values from alkenes, OVOCs and aromatic hydrocarbons. By simulating precursors reduction scenarios from the different VOCs sources resolved by PMF, the results showed that the reduction of VOCs from industrial related processes is most beneficial to the control of O3, while the reduction from traffic exhaust and liquefied petroleum gas emissions has little effect on the control of O3 and a risk of increasing O3.
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LI Xuewu, ZHANG Jingpeng, ZHAO Tianbao, ZHAO Tingning
Available online:September 28, 2023 DOI: 10.3878/j.issn.1006-9585.2023.22097
Abstract:Under the background of climate warming, the climate change in Northwest China has become warmer and wetter in recent decades. Based on various meteorological elements such as precipitation, soil moisture, runoff and drought index, this paper further systematically analyzes and studies the evolution of dry and wet characteristics in Northwest China in the past 60 years, and forecasts the future changes in dry and wet characteristics by using the latest multi-model simulation results of the phase 6 of the Coupled Model Intercomparison Project (CMIP6). The results show that the precipitation, soil moisture and runoff in Northwest China in recent 60 years showed a spatial distribution pattern of decreasing from southeast to northwest. The precipitation and runoff in the cold season are significantly lower than that in the warm season, but the differences of soil moisture and drought index in cold and warm seasons are not significant. The annual precipitation, soil moisture and drought index in Northwest China showed significant increasing trends, with the increasing rates of 5.07 mm/10a, 3.89 mm/10a and 0.26 /10a respectively, and especially after 2000, the increasing trends are more obvious. The largest humidification range mainly occurred in the west of Northwest China. The humidification range in the warm season was higher than that in the cold season. However, the runoff showed an obvious downward trend before 2000 and increased significantly after 2000. Under the future climate change scenario, the northwest region shows a trend of humidification in the middle of the 21st century (2031~2060) and the later period (2071~2100), and the humidification degree in the later period of the 21st century is more significant. The humidification under the high emission scenario (SSP5-8.5) is more obvious than that under the medium emission scenario (SSP2-4.5). This study can provide a reference for the impact assessment of climate change in Northwest China.
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Guzailinuer Yasen, ZhaoTianBao, Zhang Jing Peng
Available online:February 22, 2023 DOI: 10.3878/j.issn.1006-9585.2022.22021
Abstract:Climate warming has led to more frequent and stronger extreme precipitation events in Central Asia (CA) in recent decades, which has seriously affected local socio-economic development and agricultural production. Based on the numerical simulations provided by the latest 14 coupled models of the Sixth Phase of Coupled Model Intercomparison Project (CMIP6), this study predicts and studies the spatial and temporal distribution characteristics of extreme precipitation over CA and its relationship with regional climate warming in the middle and late 21st century under two shared socio-economic paths (SSP2-4.5 and SSP5-8.5). The results show that most CMIP6 models can basically simulate the spatial distribution characteristics of observed precipitation climate states for 1979-2018, but the model simulations underestimate the observations in the southwest and southeast of CA, and overestimate the observations in the north and Central South of CA. Compared with the historical period (1981-2010), the precipitation intensity at the end of the 21st century (2071-2100) increased by 0.54 mm/10a and 2.4 mm/10a under the scenarios of SSP2-4.5 and SSP5-8.5 respectively, while the frequency of extreme precipitation events increased by 5-7% and 6-10% respectively, especially in the high-altitude mountains in central and southern regions. The signal-to-noise ratio (SNR) of the predicted precipitation intensity and frequency in northeast Central Asia to the north of The Tianshan Mountains is more reliable. Climate warming has an obvious regulatory effect on the frequency of extreme precipitation events in CA in the future. For the temperature rises by 1K, the frequency of extreme heavy precipitation events increased by about 7and 9 days, while the maximum continuous dry days increased by 3 and 6 days, respectively.
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Available online:February 22, 2023 DOI: 10.3878/j.issn.1006-9585.2022.21049
Abstract:Fog is a severe weather hazard that greatly influences traffic and daily life with potentially heavy economic loss. Based on the 503 observed fog station data from 1958 to 2007, the temporal and spatial characteristics of fog days in autumn and winter were analyzed. It was found that the fog in autumn and winter occurs frequently over Southwest China. The annual average number of fog days in autumn and winter in Southwest China is more than 18 days, which is twice as many as that in eastern China in the same period. Moreover, there is a significant climate variability of fog days in autumn and winter in Southwest China, which is mainly reflected in the interannual and interdecadal scales, and there are significant differences in the meteorological conditions of fog days in different climate scales. On the interannual scale, the north wind anomaly in the middle and upper levels is more significant, which brings the cold air from the north to the southwest, causing the cold air anomaly in the middle and upper levels over the southwest. Moreover, due to the strong sinking movement over the region, the cold air in the upper levels is brought to the lower levels. At this time, because of the abnormally high temperature and humidity in the lower levels, the cold and warm air converges over Southwest China which is located in the north of the rain belt. In a result, the air is easily oversaturated, resulting the number of fog days increasing. On the interdecadal scale, the anomalous northerly wind in the lower level is more significant compared with the interannual scale, which brings the cold air in the lower level from the north to the southwest. This results in the decreasing of temperature, specific humidity and temperature dew point difference and further leads to the supersaturation of water vapor in the Southwest China because the temperature drops faster than the humidity. At the same time, the atmosphere is relatively stable, increasing the number of fog days.
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Available online:September 30, 2022 DOI: 10.3878/j.issn.1006-9585.2022.22040
Abstract:Air pollution in Yunnan province in spring has been prominent in recent years, which becomes a key resistance for defending the blue sky. Evolution characteristics of air quality and the impacts of meteorological factors and biomass burning in foreign regions on air quality in Yunnan province during spring 2018-2021 were analyzed comprehensively, based on ground monitoring data and satellite remote sensing data. The results revealed that the non-attainment days had reached up to 262 days (including 6 heavy pollution days) in spring in the past four years, accounting for 91.3% for all cities and 96.8% in southern Yunnan of the whole year. For temporal distribution, the pollution was concentrated in mid-March to mid-April, and the heaviest was in 2019, followed by 2021 with decreasing excellent days and increasing fine days significantly. In 2020, the pollutant concentration was the lowest, but heavy pollution occurred for 6 days. For spatial distribution, the pollution in southern Yunnan was far higher than that in central and northern Yunnan, with the highest in Xishuangbannan accounting for 27% of all non-attainment days; but the ozone (O3) concentration is the highest in southwest and central Yunnan, with the highest in Pu’er. PM2.5 was the dominant primary pollutant during 2018-2021, but the proportion of O3 as the primary pollutan in 2018 and 2019 was a little higher than that of PM2.5. Generally, the relationship of PM2.5 and O3 shown a significantly positive synergistic effect, and high O3 levels promoted secondary generation of PM2.5. PM2.5 and O3 pollution was both associated with less precipitation and southwest wind; furthermore, combined with mid-high temperature and mid-low humidity, O3 pollution easily occurred, and PM2.5 pollution was related with mid-high temperature and mid-high humidity, and mid-high temperature and mid humidity caused synergistic pollution of O3 and PM2.5. Highest pollution in 2019 was associated with the highest temperature and the least precipitation. Air pollution in Yunnan was significantly positive correlated with the number of fire points in the day and 1-3 day lags, and the highest correlation for PM2.5 and O3 were 2 day lag and 1 day lag, respectively. Ultimately, in unfavorable meteorological conditions dominated by the southwestern monsoon, biomass burning in foreign regions, especially Myanmar in Indo-china Peninsula is the main source for air pollution in spring in Yunnan, which enhanced the secondary generation of air pollution. Thus, these results indicated that the focus of spring pollution control in Yunnan is to establish a perfect cross-border air pollution prevention and control mechanism and to strengthen the early warning of biomass burning in foreign regions under unfavorable weather conditions.
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Available online:May 21, 2022 DOI:
Abstract:Ammonia (NH3) is the most abundant alkaline gas in the atmosphere and the only source of particulate NH4+, playing an important role in the formation of secondary inorganic salts. NH3 can easily react with nitric acid (HNO3) and sulfuric acid (H2SO4) in the atmosphere to form secondary inorganic aerosols such as ammonium nitrate (NH4NO3) and ammonium sulfate ((NH4)2SO4). Therefore, the emission, transportation, and chemical transformation of NH3 have an important impact on the spatial and temporal distribution of global inorganic aerosols. In this paper, the atmospheric NH3 concentration observed by the Michelson interferometer (MIPAS) on ENVISAT satellite and the AIRS detector on Aqua satellite, as well as simulated by the global atmospheric chemistry climate model EMAC, are used to analyze the spatial distribution characteristics of atmospheric NH3 in East Asia from June to September in 2008-2011. The results show that the highest concentration of NH3 near the surface appears in northern India, and deep convection exists in the Bay of Bengal near northern India in summer. The upward transport column of NH3 appears over northern India and the Qinghai-Tibet Plateau. Although NH3 has a short lifetime, it can be transported to the upper troposphere and lower stratosphere (UTLS) in the deep convection region. During the Asian summer monsoon, the location of the anticyclone dominates the spatial distribution of NH3 in the UTLS. The location of the Asian summer monsoon anticyclone dominates the spatial distribution of NH3 in the UTLS area. The high concentration center of NH3 continues to exist in the anticyclone. The position of the high concentration center of NH3 corresponds well to the position of the center of the anticyclone, and there exist one or two NH3 high concentration centers, indicating that the change of the circulation pattern in the anticyclone has an important influence on the distribution of NH3 in the anticyclone.
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WANG Zhe, WANG Zifa, LI Jie, ZHENG Haitao, YAN Pingzhong, LI Jianjun
2014,19(2):153-163, DOI: 10.3878/j.issn.1006-9585.2014.13231
Abstract:An aerosol-optical module based on Mie scattering theory has been implemented in the Nested Air Quality Prediction Modeling System (NAQPMS), and a new coupler has been developed to deal with the interaction between the mesoscale meteorology model WRF (Weather Research and Forecasting Model) and NAQPMS. The one-way off-line and two-way coupled WRF-NAQPMS models are compared to simulate the severe haze in the Beijing-Tianjin-Hebei area from 27 September to 1 October 2013. The results show that the simulated meteorological elements and PM2.5 concentrations from the two-way coupled model with the aerosol direct radiation effect are more consistent with observations. During the haze period, the boundary layer meteorological elements change significantly because of the aerosol direct radiation effect over the Beijing-Tianjin-Hebei area: Incoming solar radiation is reduced by 25%, the 2-m temperature decreases by 1 ℃, the turbulent kinetic energy is reduced by 25%, the 10-m wind speed decreases by up to 0.2 m/s, and the planetary boundary layer (PBL) height is reduced by 25%. These changes make the atmospheric boundary layer more stable and further exacerbate air pollution over the areas where it is already severe, for example, the PM2.5 concentration increases by up to 30% over Shijiazhuang City. The analysis indicates that there is a positive feedback mechanism between haze and boundary layer meteorology, and the two-way coupled model incorporating this feedback is helpful for accurate simulation and forecasting of haze pollution processes.
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2008,13(2):123-134, DOI: 10.3878/j.issn.1006-9585.2008.02.02
Abstract:利用1961～2000年北京13个台站的气候观测资料及北京统计年鉴资料，分析了过去40年北京城区、郊区的气温、相对湿度和降水等气候因子的年际、季节变化趋势，结合北京城市化进程中人口、基本设施投资额、房屋施工面积和道路面积等城市发展数据的年际变化进行分析。结果表明：在这40年中，北京城区、郊区的年平均温度都呈明显上升趋势，城区比郊区上升幅度快，热岛强度也在不断加强，其中以城区最低温度上升最为明显，并且热岛强度与北京人口等城市发展数据的年际变化有较强的相关性。城区年平均相对湿度总体呈下降趋势，郊区则略有上升；本地年均降水量呈下降趋势，城区下降幅度比郊区明显，并且波动性增强。各气候因子的季节变化趋势总体上与年平均变化趋势一致，个别季节变化趋势受城市化及季节自身因素影响，与年平均变化趋势有所差异。过去40年北京城区、郊区的气候演变趋势及与城市发展数据的关系表明，城市的快速发展和城市化进程的加快已经对北京局地气候变化产生了重要的影响。
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Ren Guoyu, Feng Guolin, Yan Zhongwei
2010,15(4):337-353, DOI: 10.3878/j.issn.1006-9585.2010.04.01
Abstract:国家“十一五”科技支撑计划重点项目“我国主要极端气候事件及重大气象灾害监测、检测和预测”对相关科学问题研究工作做了部署，其中课题二“近百年来我国极端天气气候事件变化特征及其影响（2007BAC29B02）”重点探讨全球变暖背景下中国区域极端气候变化规律。经过近两年多时间的研究，课题组取得了若干可喜的成果。
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Zhao Tianbao, Ailikun, Feng Jingming
2004,9(2):278-294, DOI: 10.3878/j.issn.1006-9585.2004.02.05
Abstract:美国国家环境预报中心(NCEP)和国家大气中心(NCAR)的全球再分析资料,在很多气候模拟和预测研究中都被作为区域气候模式的驱动场和初始场资料,并用来检验模拟结果的.作者通过对NCEP的2种再分析资料NCEPI和NCEPⅡ与中国台站观测资料的月平均温度和月降水总量进行相互插值,分析和比较了NCEPⅠ、NCEPⅡ再分析值与中国区域内观测值之间的差异以及2种再分析资料之间的差异.从结果可以看到,NCEP再分析资料的月平均温度较观测值普遍偏低,而月降水总量较观测值则偏高;就季节变化而言,NCEP再分析值在夏季和年平均模拟的较好,冬季较差.同时可以看到,在温度和降水方面NCEPⅡ较NCEPⅠ都有所改进,尤其在中国东部地区,改进较为明显.
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1999,4(1):98-103, DOI: 10.3878/j.issn.1006-9585.1999.01.21
Abstract:将1951～1980年郑州地区的气象要素（气温、风速、降雨量）的距平值与“五运六气”学说所推论气象作对比分析，两者结果比较一致。继之，收集了1953～1983年同一地区传染性肝炎、痢疾、伤寒、流行性感冒、猩红热、流行性乙型脑炎（这6种病在1983年以前均无疫苗或无有效预防）的流行资料进行分析，说明“五运六气”学说中的发病率与气候变化有较好的关系。
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Xia Junrong, Wang Pucai, Min Min
2011,16(6):733-741, DOI: 10.3878/j.issn.1006-9585.2011.06.07
Abstract:A field performance of Doppler wind lidar Windcube (released by Leosphere Company) was conducted by Institute of Atmospheric Physics, Chinese Academy of Sciences (IAP/CAS) and Leosphere Company (from France) at the 325 m meteorological tower site (a part of IAP, located between 3rd North Ring Road and 4th North Ring Road) from 11 December to 14 December 2007. The intercomparison of wind speed and wind direction obtained by Windcube and wind cup anemometers (fixed in the meteorological tower) shows that：1) 10 min averaged wind speed is highly consistent between two types of wind data at six matched levels (63 m, 80 m, 100 m, 120 m, 160 m, and 200 m), the correlation coefficients all equal or exceed 0.98. 2) 10 min averaged wind direction is calculated with the vector method, the correlation coefficients of averaged wind direction at the six levels are 0.99. 3) In comparison with domestic Doppler wind lidar, Windcube performs slightly better in wind speed measuring, and equally well in wind direction measuring. The intercomparison indicates that Windcube is a reliable and swift mobile system mea suring wind profile at low levels.
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JI Dongsheng, WANG Yuesi, SUN Yang, MA Zhiqiang
2009,14(1):69-76, DOI: 10.3878/j.issn.1006-9585.2009.01.08
Abstract:作为酸雨和细粒子的前体物，SO2对空气质量和人体健康乃至气候与环境的影响十分重要，特别是在不利于扩散的气象条件下，SO2可造成城市短时间严重污染事件。作者以2006年北京325 m气象塔15 m观测平台SO2观测数据为基础，结合同步气象资料分析研究发现：1) SO2浓度冬季高、夏季低；全年日均值为(22.5±22.1)×10-9，最大日均值能达到113×10-9。日变化呈现双峰型，峰值出现在北京时间08:00和22:00；并且季节差异明显，冬季浓度为夏季的4.5倍，采暖期为非采暖期的3.2倍。2) 风向、风速与SO2扩散和输送密切相关，高浓度SO2在东北、东、西方向上出现频率分别为25.8%、13.8%和11.8%；而西北、北方向上的风速越大对SO2清除效果越好。3)利用平均晴空指数划分采暖期阴霾天和晴天，发现阴霾天混合层高度与平均风速仅为(376±204) m和1.1 m·s-1，容易造成SO2累积。4) SO2污染过程呈现周期性的局地累积—清除特征，地形、静风和暖低压是造成北京2006年1月一次重污染事件的成因。
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Ren guoyu, Chen Yu, Zou Xuki, Zhou Yaqing, Wang Xiaoling, Jiang Ying, Ren Fumin, Zhang Qiang
2010,15(4):354-364, DOI: 10.3878/j.issn.1006-9585.2010.04.02
Abstract:综合极端气候指数对于极端气候变化监测、整体认识区域极端气候变化趋势及其原因和影响，具有实际意义。根据中国常年极端气候特点和不同种类极端气候事件的经济社会影响，选取全国平均高温日数、低温日数、强降水日数、沙尘天气日数、大风日数、干旱面积百分率和登陆热带气旋频数等7种极端气候指标，定义两个综合极端气候指数，分别为7种极端气候指标简单（等值权重）合成的综合指数I和加权（差异权重）合成的综合指数II。综合指数II主要依据各种极端气候事件引发的灾害严重程度及其社会影响大小，分别确定其对应指标的相对重要性和权重系数。分析结果表明：1956~2008年，综合指数I序列表现出明显的下降趋势，说明中国地区常见的极端气候事件总体有不断减少、减弱的趋势；同期综合指数II序列没有表现出明显的升降趋势变化，说明对中国地区具有重大经济和社会影响的极端气候事件频率总体上没有发生明显变化。就各个单项极端气候指数变化来看，全国平均年高温日数、强降水日数和干旱面积百分率呈上升趋势，但除高温日数外，其他指数趋势变化均不显著；全国平均年低温日数、沙尘天气日数和大风日数呈下降趋势，且趋势性均很显著；登陆中国大陆的热带气旋频数有所减少，但趋势不很明显。因此，在全球气候显著变暖的半个多世纪内，中国地区多数常见的极端气候事件发生频率，或者显著减少，或者变化不明显；而对全国经济和社会具有重大影响的主要极端气候事件，其频率总体上未见明显趋势变化。
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REN Guo-Yu, CHU Zi-Ying, ZHOU Ya-Qing, XU Ming-Zhi, WANG Ying, TANG Guo-Li, ZHAI Pan-Mao, SHAO Xue-Mei, ZHANG Ai-Ying, CHEN Zheng-Hong, GUO Jun, LIU Hong-Bin, ZHOU Jiang-Xing, ZHAO Zong-Ci, ZHANG Li, BAI Hu-Zhi, LIU Xue-Feng, TANG Hong-Yu
2005,10(4):701-716, DOI: 10.3878/j.issn.1006-9585.2005.04.01
Abstract:总结了"十五"攻关课题有关中国温度变化研究的若干进展.在资料质量控制和序列非均一性检验及订正的基础上,更新了中国地面近50年、100年和1 000年气温序列.研究表明,不论是近54年还是近100年全国年平均地面气温升高趋势一般比原来分析结果表明的要强,分别达到0.25℃/10 a和0.08℃/10 a.中国现代增暖最明显的地区包括东北、华北、西北和青藏高原北部,最显著的季节在冬季和春季.近50多年中国近地面气候变暖主要是平均最低气温明显上升的结果,全国范围内极端最低气温也显著升高,而极端最高气温升高不多.中国与温度相关的极端气候事件强度和频率一般呈降低趋势或稳定态势.研究发现,城市化因素对中国地面平均气温记录具有显著影响,但在现有的全国和区域平均温度变化分析中一般没有考虑,因此需要在将来的研究中给予密切关注.在增温明显的华北地区,1961～2000年间城市化引起的年平均气温增加值达到0.44℃,占全部增温的38%,城市化引起的增温速率为0.11℃/10 a.中国其他地区的增温趋势中也或多或少反映出增强的城市热岛效应影响.20世纪60年代初以来中国对流层中下层温度变化趋势不明显,仅为0.05℃/10 a,比地面气温变化小一个量级;对流层上层和平流层底层年平均温度呈明显下降趋势,变化速率分别为-0.17℃/10 a和-0.22℃/10 a;整个对流层平均温度呈微弱下降趋势.中国对流层温度与地面气温变化趋势存在明显的差异,但这种差异在20世纪80年代初以后趋于减小.近千年来中国地面气温变化史上可能确存在"中世纪温暖期"和"小冰期"等特征性气候阶段,但"中世纪温暖期"的温暖程度似乎没有过去认为的那样明显.从全国范围看,11世纪末和13世纪中的温暖程度可能均超过了20世纪30～40年代暖期,表明20世纪的增暖可能并非史无前例.中国20世纪气候增暖的原因目前还不能给出明确回答.一些迹象表明,人类活动可能已经对中国的地面气温变化产生了影响,但太阳活动及气候系统内部的低频振动对现代气候变暖可能也具有重要影响.
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2006,11(1):14-32, DOI: 10.3878/j.issn.1006-9585.2006.01.02
Abstract:再分析资料在气候变化研究中有着广泛的应用,但是再分析资料在不同时空尺度上的可信度能够影响到研究结果.作者就中国区域的月平均地表(2 m)气温和降水两种基本气候变量在空间分布及其变化趋势上对ERA-40和NCEP-2与观测资料之间的差异做了一些比较和分析,对两套再分析资料的可信度进行了初步的检验.结果表明:两套再分析资料基本上都能反映出中国区域的温度场和降水场的时空分布,尽管在中国西部,尤其是青藏高原地区的差异比较较大;再分析资料在东部地区的可信度高于西部,温度场的可信度要高于降水场,ERA-40可信度要高于NCEP-2.
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YU Haiyan, LIU Shuhua, ZHAO Na, YU Yongtao, YU Liping, CAO Haiwei
2011,16(3):389-398, DOI: 10.3878/j.issn.1006-9585.2011.03.14
Abstract:Using the data of sunshine duration, temperature, wind speed， and precipitation from 194 basic/reference stations over China from 1951 to 2009, according to the climatic division, the whole domain of China is classified into 11 climatic regions. The authors studied the changes in annual and seasonal trends of the sunshine duration by using linear trend analysis and Morlet wavelet analysis, and analyzed the characteristics between the sunshine duration and the temperature, the wind speed, and the precipitation. It was found that the annual sunshine duration showed a significant decreasing tendency during the recent 59 years with a decreasing rate of 36.9 h·(10 a)-1. The trend variations of the annual sunshine duration in 11 climatic regions were similar with that in the whole nation, only had the difference in degree. The sunshine duration of China changed from intensive to weak in 1981. There is an obvious 7－10-year periodic oscillation for the annual sunshine duration of China before the mid 1990s. The sunshine duration of the four seasons had a bigger decreasing amplitude in the coastal areas than in the inland areas, and in the South than in the North. There was a negative correlation between the annual sunshine duration and the temperature (correlation coefficient is -0.52), but a positive correlation between the annual sunshine duration and the wind speed (correlation coefficient is 0.76), and a negative correlation between the annual sunshine duration and the precipitation (correlation coefficient is -0.27). The first two correlation coefficients and the last correlation coefficient passed 99.9% and 95% confidence levels，respectively.
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CAI Rongshuo, CHEN Jilong, TAN Hongjian
2011,16(1):94-104, DOI: 10.3878/j.issn.1006-9585.2011.01.09
Abstract:Based on the long time series of mean Sea Surface Temperature (SST) and high-resolution wind field reanalysis data such as HadISST and ERA-40 reanalysis data, the variations of the SST in the offshore area of China and their relationship with the East Asian Monsoon (EAM) in winter (December to the next February) and summer (June to August) are analyzed using the Empirical Orthogonal Function (EOF) and linear regression analysis methods. The results show that: 1) The SST in the offshore area of China in winter or summer exhibited significant interannual and interdecadal variations, and experienced a climate shift in the mid-1980s. The areas with the strongest increase in SST are located in the East China Sea (ECS) in winter and in the Yellow Sea in summer. The SST increased by 1.96°C in winter for the period of 1955-2005 and 1.10 °C in summer for the period of 1971-2006. 2）The EAM has displayed distinct interannual and interdecadal variations with a weakening trend since the end of the 1980s in winter, and since the end of the 1970s in summer. In addition, the linear regression analysis indicates the relationship of the SST to EAM in winter on interdecadal timescale is closer than that on interannual timescale. The interdecadal weakening trend of EAM in winter contributes to the rise in SST in the offshore areas of China, particularly significant in the ECS. Moreover, the related areas of winter or summer mean SST on the interannual timescale in the offshore area of China to the EAM are located in the South China Sea (SCS), and the relationship in winter is much more obvious than that in summer. It is found that the interannual variation of SST in the SCS has obvious relation to the anomalies of the meridional southward and northward winds over the SCS and zonal migration of the subtropical anticyclone over the western Pacific.
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Abstract:The LPJ DGVM (Lund Potsdam Jena Dynamic Global Vegetation Model), which is a process based model, is used to simulate the vegetation distribution and estimate the interannual variation of net primary production (NPP), heterotrophic respiration (Rh) and net ecosystem production (NEP)in China from 1981 to 1998. It is shown that there are six main plant functional types (PFTs) besides the desert,that is tropical broadleaved evergreen tree, temperate broadleaved evergreen tree, temperate broadleaved summergreen tree, boreal needleleaved evergreen tree, boreal needleleaved summergreen tree and C3 perennial grass. In China, the total NPP varies between 2.91 Gt·a-1(C) (1982) and 3.37 Gt·a-1(C) (1990), increases by 0.025 Gt (C) average per year and has an increasing trend of 0.96%. The total Rh varies between 2.59 Gt·a-1(C) (1986) and 319 Gt·a-1(C)(1998), grows by 1.05% per year and by 0.025 Gt(C) per year. The linear trend of NPP and Rh for C3 perennial grass is more remarkable than those for other PFTs. The simulation of NEP is reasonable when the fire is brought in the model. Annual total NEP varies between -0.06 Gt·a-1(C)(1998)and 0.34 Gt·a-1(C)(1992). It is demonstrated that the terrestrial ecosystem is carbon sink in China. The above results are similar to those simulated by other models.
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TANG Xiao, WANG Zifa, ZHU Jiang, WU Qizhong, GBAGUIDI Alex
2010,15(5):541-550, DOI: 10.3878/j.issn.1006-9585.2010.05.02
Abstract:The Nested Air Quality Prediction Modeling System (NAQPMS) has been applied to the routine air quality forecast in Beijing during the Olympic Games. Monte Carlo method is used to analyze the uncertainty of ozone simulation of NAQPMS during the Olympic Games, from 8 to 24 Aug 2008. Latin hypercube sampling has been used for multi-variables sampling, and 50 ensemble runs have been made with 154 parameter uncertainties being considered together. By the temporal average, the most important parameter to the surface ozone output uncertainty in Beijing is the local precursor emissions during the day time. Other important factors include NO2 photolysis coefficient, wind direction, precursor emissions from the surrounding areas of Beijing, and vertical diffusion coefficient. The wind direction and precursor emissions from the surrounding areas of Beijing have the greatest impact on the uncertainty of daytime ozone simulation at higher levels (above about 150 m). The main uncertainty factors in ozone simulation at night are local NOx emissions and vertical diffusion coefficient. Given the predefined input uncertainties, the average uncertainty of ozone simulation is 19 ppb, ranging from 2 ppb to 49 ppb.
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ZHANG He, LIN Zhaohui, ZENG Qingcun
2011,16(1):15-30, DOI: 10.3878/j.issn.1006-9585.2011.01.02
Abstract:A study of the interaction and mutual response between dynamical core and physical parameterizations by atmospheric general circulation models CAM3.1 and IAP AGCM4.0 is presented. Both the two models were integrated 60 d with ideal physics (Held-Suarez forcing) and with full physical package, respectively. The results show that the mutual responses between dynamical core and physical parameterizations are very different in the troposphere at low latitudes and high latitudes. In the tropical troposphere, the variability of temperature tendency due to dynamical core and that due to physical parameterizations are both large and have significant contributions to the variability of total temperature tendency, and they are in inverse correlation to compensate each other. In the polar middle and upper troposphere, the variability of total temperature tendency mainly relies on the tendency due to dynamical core, while the variation of temperature tendency due to physics is very slow, which can be seen as a stationary forcing. Unlike the tropical regions, there is a positive correlation between the temperature tendency due to dynamics and that due to physics in Polar regions. Moreover, the interactions and mutual responses between the individual physical parameterizations are also analyzed. The results show that the variation of temperature tendency due to moist process is the largest of all the physical parameterizations, and it contributes most to the total temperature tendency due to physics. The variation of temperature tendency due to long wave radiation is also large at high latitudes, while the variation of temperature tendency due to short wave radiation and that due to vertical diffusion are relatively small. There is a negative feedback between the cooling rate of long wave radiation and the heating rate of short wave radiation.
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Li Chongyin, Zhu Jinhong, Sun Zhaobo
2002,7(2):209-219, DOI: 10.3878/j.issn.1006-9585.2002.02.08
Abstract:概括的介绍了中国科学家近几年在年代际气候变化方面的研究进展,包括中国气候的年代际变化特征,北大西洋涛动(NAO)和北太平洋涛动(NPO)与中国年代际气候变化的关系,北太平洋海面温度(SST)年代际模及其影响,大气环流系统的年代际变化以及气候突变问题.
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YANG Jin Hu, JIANG Zhi Hong, WANG Peng Xiang, CHEN Yan Shan
2008,13(1):75-83, DOI: 10.3878/j.issn.1006-9585.2008.01.10
Abstract:基于中国1955～2004年314个台站逐日降水资料，根据百分位值方法定义了不同台站的极端降水阈值，进而对中国年极端降水事件的时空特征进行了探讨分析。结果表明：江淮北部、湖南、四川西南部及西藏和新疆西部地区与中国其他区域呈反向变化特征，是中国年极端降水事件的主要空间异常模态；中国年极端降水事件的时间变化存在明显的区域性差异，东北、西北东部、华北表现为减少趋势，其中东北和华北发生了突变，而西北西部、长江中下游、华南及青藏高原表现为增加趋势，其中西北西部、长江中下游发生了突变；中国各分区年极端降水事件的周期振荡不完全一致；中国年极端降水事件与年降水量之间存在较好的相关性，从季节来看，夏季极端降水事件与年降水量的相关性最好。
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2009,14(1):9-20, DOI: 10.3878/j.issn.1006-9585.2009.01.02
Abstract:利用1951～2000年我国西北干旱、半干旱区地温、气温和表面风场逐日4个时次（北京时间2、8、14和20时）的台站观测资料，以及NCEP/NCAR和ERA-40再分析资料，计算并比较了在我国西北地区春夏季感热输送的差异。分析结果表明：NCEP/NCAR和ERA-40的感热输送再分析资料都能显示出我国西北地区是欧亚大陆上的感热中心之一。从年代际时间尺度上，ERA-40再分析资料的感热资料更接近于实际台站观测资料计算得到的感热资料。
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Zou Xukai, Ren Guoyu, Zhang Qiang
2010,15(4):371-378, DOI: 10.3878/j.issn.1006-9585.2010.04.04
Abstract:基于中国606个地面台站1951~2008年的逐日降水量和气温资料，采用综合气象干旱指数CI统计分析了中国全国及十大江河流域近60年的干旱变化趋势。结果表明，近60年来，从整体来看，中国干旱面积呈现出弱的增加趋势。干旱持续时间长的几个中心分别位于北方的辽河流域西部、黄河流域东部、海河流域、西南诸河流域东南部等地，最长持续时间可达4个月以上；北方江河流域干旱面积一般表现出增加趋势，其中松花江流域、辽河流域、海河流域干旱面积出现显著的增加趋势，辽河流域、海河流域、黄河流域在20世纪90年代中后期至21世纪前期连续数年出现大范围干旱，南方大多数江河流域干旱面积的变化趋势不明显，只有西南诸河流域有显著的减少趋势。
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Sun Jianqi, Wang Huijun, Yuan Wei
2011,16(2):199-208, DOI: 10.3878/j.issn.1006-9585.2011.02.09
Abstract:Using observational daily maximum temperature of Chinese 181 stations for the period of 1957~2004, the spatio temporal features of the climatology and decadal variability of the extreme hot event (EHE) frequency, intensity, onset date (EHE OD), and termination date (EHE_TD) are investigated. The climatological analysis indicates that southeastern China and Xinjiang are the two major domains for the EHE, and eastern China is a region with a strong interannual variability. The EHE experienced strong decadal variability in the last 48 years. The variabilities of the frequency and intensity are consistent, and the variabilities of the EHE_OD and EHE_TD are similar. Based on the EHE spatio temporal feature, the whole China can be divided into four sub regions: Southern China, central China, eastern northern China, and Northwest China. The EHE frequency is high in the 1960s and the 1980s for southern China,in the 1960s and the 1990s for central China, and in the 1990s for northern China. Further, the atmospheric circulations which are responsible for the interannual and decadal variability of the EHE in the above four sub-regions are explored. It suggests that the circulations impacting on the interannual and decadal variability are consistent. For northern China, the major circulation is the overlying geopotential height anomaly at middle to upper levels. For southern and central China, the major circulations are the overlying geopotential height anomaly at middle to upper levels and temperature advection by the meridional wind at lower levels.
