Abstract:Based on the physical-mathematical considerations, the authors discussed the object of the short-term climate prediction. The short-term climate prediction has extremely important potential benefit for the economy and society, but is a very difficult scientific systematic work. Traditionally, the anomaly of a variable to its climatology has been used as the object of the shortterm climate prediction. However, this approach does not necessarily contain physical-mathematical robustness. Considering that the current climate prediction skill, based on the above approach, is quite limited, the authors proposed another approach, using the interannual increment of a variable as the predicting object. The authors also provides discussion on this approach from the physical-mathematical considerations, and validation of this approach based on a climate model prediction experiment.

Abstract:A new Quality Control（QC）technique called spatial difference method is introduced in detail and applied to spatial checking of some basic meteorological elements at seven representative stations in China for the year of 2007 in order to evaluate the applicability of this approach．The checking tests are conducted on ten basic meteorological elements including daily mean pressure，maximum pressure，minimum pressure，mean temperature，maximum temperature，minimum temperature，mean vapor pressure，mean surface temperature, maximum surface temperature, and minimum surface temperature．It is shown that this method works well in identifying errors of single meteorological element．As compared with spatial regression test on discriminating artificial errors，the spatial difference method is more effective．Furthermore，same as the other spatial checking methods，the distribution of neighboring weather stations should be concerned necessarily as influence factors．

Abstract:Based on the method proposed by Sung (2002), the effect of nonlinearity is considered. With this method, the Boussinesq equations which have high precision but are difficult to calculate can be replaced by the shallow water equations. The authors compared the new method with the method proposed by Sung （2002）. It is showed that the new method is suitable for the changing topography.

Abstract:Wetlands are one of the most important sources of atmospheric CH4, but the quantity of this source is still highly uncertain. We developed a biogeophysical model called CH4MODwetland to simulate CH4 emissions from natural wetlands based on CH4MOD that simulates CH4 emissions from irrigated rice paddies. The development of CH4MODwetland focused on the supply of methanogenic substrates, the process of vegetation growth, and the variation of soil redox potential that differ from the rice paddy. CH4MODwetland was validated against independent datasets from Sanjiang Plain and Zoigê Plateau. Model validation showed that the observed seasonal and interannual variations of CH4 emissions from marshland in northeastern China were well captured, but that from peatland in southwest plateau of China were less well; Nevertheless, modeled seasonal amount of CH4 emissions agreed observed well in the two places, yielding an R2 of 0.96 (n=7, p<0.001); The root-mean-squared error, mean deviation, and model efficiency between modeled and observed values are 14.1%， -6.7%, and 0.95, respectively.

Abstract:Sensitivity analysis of the biogeophysical model called CH4MODwetland showed that environmental driving factors such as temperature and standing water depth are the most sensitive contributors to CH4 fluxes from natural wetlands. The response of CH4 fluxes to standing water depth is more sensitive in seasonal flooded wetland than in continuously flooded wetland. The sensitive significance of the model to input parameters increased in the order of the maximum aboveground biomass, the proportion of below-ground biomass to total production biomass, the vegetation index, the required accumulated temperature for reaching maximum biomass, and soil input parameters. The empirical equations of water table are used to support the CH4MODwetland in order to simulate the variations of CH4 fluxes from the 1950s to the 2000s in Sanjiang Plain and from the 1960s to the 2000s in Zoigê Plateau. The interannual change in CH4 fluxes is mainly affected by precipitation, while the climatic warming enhanced the CH4 fluxes from wetlands during similar precipitation years. In the Sanjiang Plain, the simulated CH4 fluxes increased by 9.5% and 8.3% from the 1980s to the 2000s compared with those from the 1950s to the 1970s in the marshland dominated with Carex lasiocarpa and Deyeuxia angustifoli,respectively. In the Zoigê Plateau, the simulated CH4 fluxes increased by 6.0% and 5.5% from the 1990s to the 2000s compared with those from the 1960s to the 1970s in the peatland dominated with Carex meyeriana and Carex muliensis, respectively. The results of this study may be used to project the effects of future climate change on CH4 emissions from Chinese wetlands.

Abstract:There are uncertainties in calculating atmospheric diffusion parameters on assessments of the environment. Footprint analysis method is used to confirm the horizontal diffusion scale and time,and finally calculate the horizontal diffusion parameters by using the data measured by the threedimensional sonic anemometers on the coast of Balong，Guangxi Province. The results show that：1) diffusion scale and time have obvious influences on determination of diffusion parameters. 2) The diffusion parameters of the land breeze are larger than that of the sea breeze, which implies that land breeze is in favor of pollution diffusion. 3) The diffusion parameters are conservative and depend on local topography and regional characteristics. Footprint analysis method may be helpful in obtaining diffusion parameters.

Abstract:Dust aerosols have distinct impacts on the energy balance of the land surface by adjusting short wave/long wave radiative processes, and thereby affect the meteorological elements over the near surface. In turn, the impacts are reflected by modifying the heat transfer processes between the land surface and the atmosphere. The semi-arid area is known as the most typical region characterized by the remarkable aridity trend. It is also the region in which sandstorm events occur frequently and is regarded as one of the main sources of sandstorms. The enhanced observational meteorological data, radiative fluxes, and concentration of dust aerosols collected from the Tongyu station, one of the international Coordinated Enhanced Observing Period (CEOP) reference sites in the semi-arid region of China from April to June 2006 are used to investigate the differences of meteorological elements and energy budget in this area under different weather conditions, namely, clear days, light storm days, and sand storm days. The results indicate that in the semi-arid area, dust aerosols have significant influences on the meteorological elements and energy balance of the land surface, which is different from the impacts in the arid areas in some aspects. In the semi-arid area, a higher wind speed is identified in the duststorm period than that in clear days, while atmosphere relative humidity is lower in dust days. The land surface receives less net radiation during the duststorm period, as well as the latent/sensible heat fluxes. The correlationships between aerosol concentration and daily mean sensible heat flux, relative humidity, and latent heat flux are significant. During the daytime, the daily mean air temperature responds to sandstorm more significantly, while 2-cm ground temperature responds more significantly at night. It is meaningful that the sensible heat flux is less during duststorm events in the semi-arid area, which is different from the case in the arid region.

Abstract:The Himalayas is an important area of the Tibetan Plateau, and is also a typical large-scale mountain region. The strong solar irradiance under the steep topography and complex terrains of the Himalayas introduces a distinguished local circulation system. The distinct mountain system could cause a different surface-to-air exchange process from that over the plateau flat areas and other mountain regions. Besides, the Himalayas is adjacent to the South Asian monsoon regions, the air mass exchange between the surface and free atmosphere could also be affected by the monsoon evolution. In this study, the surface-to-air mass exchange in the Rongbuk Valley on the north side of the Himalayas is analyzed, based on the observational and large scale grid data in June 2006. Results show that：1) The surface-to-air exchange is dominated by the strong downward transfer from afternoon to early morning. The averaged downward transfer of the air volume flux is 7.9×106 m3·s-1, equivalent to around 38 times of the enclosed valley volume; 2) the surface-to-air mass exchange is closely related to the South Asian summer monsoon (SASM) activities, with strong air mass transfer (air volume flux of 97×106 m3·s-1) in the SASM break period and weak transfer (air volume flux of 6.6×106 m3·s-1) in the SASM active period; 3) the SASM can possibly affect the Himalayan surface-to-air exchange mainly by changing the local radiation conditions.

Abstract:The atmosphere ozone content forecast model was established based on the combination of wavelet decomposition and advanced Least Square Support Vector Machine (LSSVM) regression. This can be approached in three steps: (1)The observations were decomposed into several different frequency signal subsets,(2)the independent prediction models of decomposed signals with Takens delay embedding theorem and Least-Squares Support Vector Machine (LSSVM) were set up, (3)independent predicted results were integrated as the final prediction with wavelet reconstruction. Application experiments with data from Xianghe and the other three observation stations show that the method can make better prediction effectively for the atmospheric ozone content, as compared with conventional Support Vector Machine(SVM) and Artificial Neural Network(ANN).

Abstract:Based on the NCAR/NCEP reanalysis and ERA-40 datasets, the relationship between the North Pacific subtropical mode water (STMW) and the interannual change of autumn－winter air temperature over China was revealed by using composite and correlation (regression) analysis. It was found that the relationship between the autumn－winter air temperature over China and the summer STMW intensity was linked by the anomalous patterns of the Asian－Pacific atmospheric circulation and the sea surface temperature （SST） anomalies over the collocated reemergence area of STMW (20°N－27°N, 125°E－150°E), that is the Kuroshio area. The main conclusions are: 1）The strong summer STMW is usually accompanied by the low air temperature over the northwestern and northeastern parts of China and the Changjiang－Huaihe valley during autumn; and the high air temperature over the northwestern and northeastern parts of China during winter,and vice versa. 2）A possible process that links the summer STMW with the autumn－winter air temperature is also revealed. First of all, the authors pointed out that the summer STMW anomaly can impose an effect on the thermocline depth and the SST anomaly over the Kuroshio area during autumn. The strong summer STMW is usually companied by the shallow thermocline depth and negative SST anomalies over the Kuroshio area during autumn and positive SST anomalies during winter, and vice versa. 3）In the strong summer STMW cases, the anomalous northerly to the western flank of the anomalous cyclone, which is corresponding to the autumn cold SST over the collocated reemergence area, guides the cold air to China, meanwhile, the anomalous cold high pressure over eastern Europe extents southeastward, leading to the low air temperature over the northwestern and northeastern parts of China and the ChangjiangHuaihe valley during autumn. Affected by the continuous accumulation of the endothermic process over the cold SST area in autumn, the positive SST anomaly emergences over the Kuroshio area during winter. Then the anomalous southerly to the western flank of the anomalous anticyclone, which is accompanied by the warm SST anomaly， weakens the winter monsoon intensity over the northeastern part of China, and leads to the high air temperature there. Meanwhile, the weak cold air over eastern Europe is blocked by the downstream cyclonic circulation, causing the warm air temperature over the northwestern part of China during winter. The situation in the weak STMW cases contains the opposite features to the aforementioned strong STMW cases.

Abstract:The decadal variation of precipitation in March over South China and its relationship with PDO(Pacific Decadal Oscillation) are analyzed by using the observational rainfall data, PDO index, and NCEP reanalysis data. The Mann-Kendall test performed on precipitation in March over South China shows that the turning year for decadal change in about 1978, precipitation experienced a notable low to high transition. In the decadal period of low rainfall, PDO is in negative phase (high sea surface temperature in the North Pacific, low sea surface temperature in the middleEast Pacific), sea level pressure and height at 500 hPa in North Pacific are high, sea level pressure and height at 500 hPa on the Asian continent are low, the troposphere atmosphere in East Asia is warm, the western Pacific subtropical high is easterly, East Asian uppertropospheric jet stream is northerly, Hadley circulation in East Asian is weak. In the decadal period of high rainfall, PDO is in positive phase, the situation is completely the opposite. The variability of the precipitation in March has a very significant correlation with PDO index in February and March, the correlation coefficients between them were positive at 99% confidence level. It can be summed up the changes of precipitation in March over South China is closely related to the changes of sea surface temperature in the North Pacific Ocean on decadal time scales, and a possible mechanism is proposed about how the PDO influences the precipitation anomaly over South China in March.

Abstract:Dozens of people died from the severe winter weather with cold temperatures and heavy snow in the western and central Europe at the beginning of 2009. Hundreds of people died from the wildfires caused by the heat wave and drought in summer in Australia. Tropical cyclone Ketsana struck Philippines and Vietnam in September, and 5 million people were affected by the storm. Hurricanes Ida brought widespread floods across the Americas and affected 200 thousand people in Novemeber. Most parts of mid-high latitude region in the Northern Hemisphere experienced the extreme cold temperature and set the earlier snowfall records during the period of autumn to winter. In China, the destroyed typhoon Morakot struck Taiwan; severe and exceptional drought conditions were present in Heilongjiang and Inner Mongolia in spring and in southern China in autumn. Strong storm brought severe wind, thunders and lightning across seven provinces of China in November. The year 2009 is nominally ranked as the fifth warmest year within instrumental climate records since 1985. Extreme events of weather and climate happened frequently in the world this year.