Current Issue

• Application of AMSR-E Brightness Temperature Data in Observation andSimulation of Soil Moisture Variation over Northeast Plateau
• 2010 Vol. 29 (3): 545-553. 
• Abstract ( ) PDF (1043KB) ( )
• An estimation model of soil moisture from the AMSR\|E brightness temperature data was coupled into the WRF\|Noah mesoscale numerical model for improving the observation and model simulation ability of soil moisture over Northeast Plateau. The main condusions are as follows: Firstly the land surface soil moisture(SM) in the northeastern part of the Qinghai-Tibet Plateauwas estimated by the AMSR-E brightness temperature data. Its value was somethinglower than the observedand the NCEP reanalysed data, but regional distribution was reasonable and the temporalvariation showed a quick response to the daily precipitation. Sencondly,the estimated SM was assimilated into the WRF-Noahmodel byusingthe Newtonianrelaxation assimilation method. By fine tuning of the quality factor inthe Newtonianrelaxationmethod, the simulated SM valueswere obviouslyimproved in desert areas, somewhat improvements also occurred grassland, shruband grass mixed zones. Ontemporal scale, the difference between the simulated and observed SM were alsodecreased.

• Comparative Study on Mass and Ozone Fluxes Cross Tropopauseover Qinghai\|Xizang Plateau and its Surrounding Areas
• 2010 Vol. 29 (3): 554-562. 
• Abstract ( ) PDF (1077KB) ( )
• Using the Wei\|formula in isentropic coordinates, mass and ozone fluxes cross the dynamical and thermal tropopauses over the Qinghai\|Xizang Plateau(QXP)and its surrounding areas were calculated and comparative analyzed. The results show that when the two kinds of tropopause are used, the mass and ozone fluxes cross tropopause in tropical latitudes are TST flux areas, and convers to the STT flux in the sub\|tropics. Because of the height of thermal tropopause is higher than that of dynamical one, the change of mass and ozone fluxes cross the thermal tropopause is greater than that of cross the dynamical tropopause. In addition, it is also found that exchange of mass and ozone fluxes cross tropopause in this area show the significent interdecadal variation, the trend in 1958-2001 shows that the situation of mass and ozone flux exchanges over the QXP is first to weakening after enhancement. The upward mass and ozone of transmission over the southern QXP and on its south side have downword the process of gradually weakened, which indicates that these areas in the role of the mass and ozone exchange channel gradually weaken; downward mass and ozone fluxes over the northern QXP showed gradually weakened process, here the role of the transmission channel is also weakened. It indicates that these regions play an increasingly important role in the process of mass and ozone exchanges.

• Features of Summer Precipitation Change of the Sichuan and ChongqingBasin and Its Relationship with Large-Scale Circulation
• 2010 Vol. 29 (3): 587-594. 
• Abstract ( ) PDF (1037KB) ( )
• Monthly mean precipitationdata at 18 stations of Sichuan and Chongqing basin from 1955 to 2006 is used to analyze the variation of summer precipitation. Then the NCEP/NCAR reanalysis data and OLR data from NOAA are used to analyze the precipitation change with the large\|scale circulation. The results show that: (1) The summer precipitation change phase of the west and east parts of Sichuan and Chongqing basin is opposite, and the most frequent rain pattern is less precipitation in the west of Sichuan and Chongqing basin and more precipitation in the east. (2) In more summer precipitationyears of the west, it is associated withthe circulation that two ridges and one trough in mid\|high latitudes. And the low pressure in the Bay of Bengal reduces so that the south-west vapor transport enhances. South Asian High(SAH) enhanced in the west. These result in the more precipitationin the west of Sichuan and Chongqing basin. At the same time, in more summer precipitationin the east of Sichuan and Chongqing basin, the meridional circulation in East Asia and the west spread of the subtropical high as well as the reduce of the SAH result in the more precipitation in the east of Sichuan and Chongqing basin. (3) The previous spring OLR has indicative signal of the change of summer precipitationin the west and east of Sichuan and Chongqing basin. In more rain years of the west of Sichuan and Chongqing basin, the previous spring OLR decreases from Indian Ocean to the Bay of Bengal. While in more rain years of the east of Sichuan and Chongqing basin, the vapor transportation from the South China Ocean enhances.