Abstract:Using monthly MODIS remote sensing data of leaf area index during 2000-2006 and the observed monthly air temperature and precipitation data, the spatiotemporal variation of vegetation in Guizhou was analyzed. The results show that the spatial pattern of vegetation over Guizhou in the past seven years is controlled by air temperature and precipitation, and presents different response to the climate factors. The response of vegetation distribution to precipitation is more obvious than that to temperature, especially in winter and spring. In summer and autumn, the vegetation growth is mainly dominated by temperature and its relationship with precipitation is not obvious. In view of temporal variations at seasonal and interannual scales, the response of vegetation to temperature is more marked in contrast with that to precipitation, and the correlations coefficients between vegetation and temperature are 0.89 and 0.73, respectively (passing Student t-test at 99.9% and 95% confidence levels).

Abstract:What controls ENSO amplitude remains controversial. The authors explore the effect of a kind of idealized equatorial highfrequency zonal wind forcing on ENSO amplitude. This problem is first transformed into a nonlinear optimization problem related to model parameters. Based on a theoretical ENSO model, the role of highfrequency zonal wind forcing in modulating ENSO amplitude is explored. The results show that there are two kinds of highfrequency zonal wind forcings for ENSO events, where the differences lie in the amplitude of the forcing, the period, and the phase. These differences make one kind of forcing enhance the El Nino event, but suppress the La Nina event,while the other kind suppresses the El Nino event and enhances the La Nina event. The further analysis shows that the phase of the highfrequency zonal wind forcing determines the forcing whether enhances ENSO events or suppresses them, while the amplitude and period of the forcing control the degree of its effect on ENSO intensity. Both of these two types of forcings affect ENSO amplitude mainly by the adjustment of oceanic wave on the thermocline.

Abstract:Aerosol samples of PM2.5 were collected from 1 January to 31 January and 6 February to 24 February 2008 in Guangzhou. The concentrations of organic carbon, element carbon, watersolubility ions of all particle samples were obtained by chemical analyses. Ambient light extinction coefficients were calculated by IMPROVE visibility formula. The results indicated that the average mass concentration of PM2.5, OC, EC, watersolubility ions was 890±53.4, 16.9±11.9, 5.9±3.4, and 43.9±23.5 μg·m-3, respectively. The averaged value of extinction coefficient was 342±185 Mm-1 in winter. The major contributors to ambient light extinction coefficients included (NH4)2SO4(36.3%), NH4NO3(14.5%), POM(26.6%), EC(17.4%), and NO2(5.2%), respectively.

Abstract:Using weekly snow cover data (Version 3) during 1966-2005 from the National Snow and Ice Data Center, new indexes for the seasonal fresh snow extent are defined: Percent of fresh snow extent (PFSE), area of fresh snow extent (AFSE) and total AFSE over northern Eurasia (TFSE). Then, the analyses are performed based on the new indexes and seasonal mean snow extent index (PSE, ASE, and TSE) to investigate the snow cover characteristics over Eurasia. The results show that the distinguished differences for the spatial distributions and temporal variations fromAFSE and ASE are observed from seasonal to decadal time scales, particularly in winter and spring. The variabilities of PFSE are stronger than those of PSE although their temporal and spatial distributions in summer and autumn are more consistent than in winter and spring. The winter AFSE in Europe is found to have close relations with TFSEand TSEin winter and the subsequent spring, and the spring AFSE in Europe and midlatitude Asia is controlled by the snow cover status both in winter and spring. Further analysis indicates that the fresh snow extent in winter and spring is independent of ENSO in general, except for some small regions in northern Siberia, mideastern Europe and Tibet.

Abstract:A coupled atmosphereoceanland model,GOALSAVIM, is developed in the Institute of Atmospheric Physics (IAP), and its performance is described. The coupled model is based on an IAP/LASG climate model (GOALS) and a landsurface model with dynamic vegetation processes(Atmosphere-Vegetation Interaction Model,AVIM). It has been run 100 model years and the last 40year output is analyzed. The coupled model (GOALSAVIM) simulates some significant interannual variability of atmospheric circulation and terrestrial ecosystem. Using singular value decomposition (SVD) analysis, the relationship between ecosystem and atmospheric circulation in the East Asia is explored. It shows that the strengthening and weakening of East Asian monsoon characterized by the geopotential height at 500 hPa and the wind field at 850 hPa correspond to the spatiotemporal pattern of net primary production (NPP). The correlation coefficients between NPP and air temperature, precipitation and solar radiation are different in interannual variability because of the variation in vegetation types.

Abstract:Measurements of aerosol particle number concentrations and precipitation intensity during the winter of 2007-2008 were made by WideRange Particle Spectrometer(WPS),disdrometer (OTT Parsivel) and fog monitor (FM_100), in the north suburb of Nanjing. The size distribution characteristics of particles and the relationships between particle size and scavenging coefficients were studied. With a bimodal distribution of diurnal variation, the aerosol particle number concentration, which is much affected by vehicle emission, change of boundary layer height, and the advection of particles, mostly falls between 0.02 and 0.2 μm. Rainfall, snowfall, and fog have different scavenging efficiency on particles. Aitken mode and coarse mode particles are more efficiently scavenged by rainfall and dense fog. Snowfall is efficient in the scavenging of particles smaller than 0.03 m.

Abstract:By using the detailed data of 1464 daily heat stroke cases and daily meteorological factors from 1994 to 2006 in Wuhan , the linear and nonlinear correlation coefficients between the daily number of heat stroke cases and meteorological factors are calculated, the key factors are selected, the nonlinear models are established, and the meteorological grades for heat stroke are divided. The results show: 1) The air temperature is the key factor which leads to the heat stroke events, and the accumulation of meteorological factors in or over three days will be more effective for numerous heat stroke cases; 2) nonlinear correlation will be more suitable for the number of heat stroke cases and meteorological factors. The nonlinear models are established between the daily average number of heat stroke cases and the mean temperature, the minimum relative humidity in the preceding three days (including the present day). The standards of five grades are worked out according to the daily average number of heat stroke cases, the test indicates a good result through historical and independent samples.

Abstract:The aerosol scattering coefficient (σsp) data observed at Shangdianzi atmospheric background station from 2004 to 2006 have been used to analyze the characteristics of aerosol in the background region. The results show that the mean annual σsp was relatively low with a slight increase in 2006, which is specially caused by frequent dust pollutions happening during the spring. Diurnal change has a dropping trend in the daytime and a rising trend at night, which accords with the daily change of atmospheric stratification. Seasonally, the values of σsp in winter and spring were lower than that in summer and autumn. Moreover, weather impacts aerosol obviously. The mean σsp in sunny days was much lower than that in cloudy condition, due to the strong convection that can increase the aerosol diffusion in sunny days. The air from eastnortheast east was clean, which could decrease σsp, while southwest wind could bring more polluted air and cause the increase in σsp, which shows that the city activities had an effect on the atmosphere at the observing site. Finally, the background value was calculated through the most frequent statistics value, which was in the range of 10-20 Mm-1.

Abstract:Annual mean temperature, frequency of annual durative warm days and cold nights, and frequency of seasonal durative warm days and cold nights were calculated based on the daily mean, maximum and minimum temperature at Mohe during 1961-2004. Linear trends, increments, significance tests and stationarity test were analyzed. Annual mean temperature increased by 1.61 ℃ and the frequency of annual durative warm days rose by four times. There were significant increasing trends in both frequency of winter durative warm days and summer durative cold nights. Significance tests were made on linear regression relationship between annual mean temperature and frequency of annual durative series, and frequency of seasonal durative series. As the linear regression relationship was statistically significant, significance tests were made on every frequency series to the annual mean temperature individually, to indicate the correlation among them. The results were as follows: From annual aspect, the increase in the annual mean temperature was significantly influenced by the increase of annual durative warm day frequency and the decrease of annual durative cold night frequency; from seasonal aspect, the increase in annual mean temperature was significantly influenced by the increase of spring and summer durative warm day frequency, together with the decrease of spring and autumn durative cold night frequency.

Abstract:Characteristics of precipitation extremes and the differences between the large cities with a population over one million and the surrounding stations with a population below 500 thousand were investigated based on daily precipitation data of 753 stations of China from 1951 to 2005. Results reveal that changes of precipitation extremes at large city stations display similar regional features. Moreover, the large city stations also have their own characteristic of change. More than a half of the large city stations experienced a more obvious change of the extreme precipitation than the surrounding stations. On the whole, if extreme precipitation intensity and frequency at the large city stations were increased, the increasing trends were more obvious than the surrounding stations. Most of such large city stations are in northern China, especially in the south of North China. Different from the decrease trends in North China, mean extreme precipitation intensity at the large city stations in southern North China has increased obviously.

Abstract:Using daily meteorological factors of the meteorological observatory from 1971 to 2007 during the period of “Shu Jiu” (the nine periods following the winter solstice) in Beijing ,on the basis of the statistical method, the climate features and the change during the period are analyzed. The results reveal that the cold stage in Beijing happens from the third period to the fifth period. From the end of the third period to the start of the fourth period, the average temperature is 3.8 degrees below zero which is the minimum value and lasts for 4 days. The extreme lowest temperature is 18.3 degrees below zero which appears in the first day of the fifth period. The lowest average temperature is 3.5 degrees below zero and appears in the third period. The coldest period is the third period. Moreover, the average temperature for the 81 days in the period of “Shu Jiu” turns warmer quickly from the 1970s to the 1990s, with an amplitude of 1.25 degrees.The average temperature of each period shows a trend of warming, the fifth period has the biggest variation range which is 1.38 degrees each decade.