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Observational studies of the structure of the Nagqu Prefecture , Qinghai - Tibet Plateau Wind Profiler

Author: LiJianDong
Tutor: BianLinGen；LuLongZuo
School: Chinese Academy of Meteorological Sciences
Course: Atmospheric Physics and Atmospheric Environment
Keywords: Wind profilers Qinghai-Tibet Plateau The wind profilers line structure Atmospheric boundary layer Probe
CLC: P425
Type: Master's thesis
Year: 2005
Downloads: 198
Quote: 4
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Abstract

The weather and climate of the Qinghai-Tibet Plateau region of eastern China, the Asian monsoon, as well as global atmospheric circulation and weather and climate have a major impact, high altitude atmospheric boundary layer as the connection the plateau unique underlying surface and the free atmosphere of bridges in the impact process plays an important role. Lack of Plateau Atmospheric Boundary Layer observations seriously restricting the Qinghai-Tibet Plateau weather and climate research. Chinese Academy of Meteorological Sciences in 2003 and installed in the central plateau, Nagqu of Japan Mitsubishi WPR1300 wind profilers and continuous atmospheric boundary layer structure probing was carried out in April-September 2004. The wind profilers sounding data are compared with the same period in the radiosonde data showed that wind profiler data with high reliability. In this paper, the detection data combined analysis through statistical analysis and typical examples, Nagqu before and after the rainy season the wind profilers structure of the atmospheric boundary layer characteristics. The main results are as follows: a wind profilers, ground and high altitude, and NCEP data integrated analysis showed: after May 20, 2004, Nagqu strong high-altitude westerly winds weaken, significant change in low-altitude wind, the water vapor content of the atmosphere and the ground precipitation surge. The May 20 to determine the start time for the central plateau during the rainy season. After the rainy season, the horizontal wind speed and its vertical shear significantly decreases: the lower atmosphere, in particular, is 600m below the level of the diurnal variation of wind speed low before the rainy season (midnight) - high (afternoon) - Low (Sunset) type variable (midnight) - (Sunrise) - higher (afternoon) - Low (Sunset) type; same time, the lower atmosphere, wind speed increases rapidly after sunrise, the time has also been pushed back, the high-altitude freedom the momentum under pass time in the atmosphere downstream weakened and pushed back. Southerly wind component increased significantly increasing Japanese interannual variability of the lower atmosphere wind, but the high-level wind direction is relatively stable, the diurnal; With the further development of the rainy season, the high, low altitude wind stability test parameters Wc (Wind consistency) was significantly less small wind diurnal boundary layer wind profilers structure becomes more complex, and the atmospheric boundary layer momentum sink effect is also weakened. Ekman spiral effect of the lower atmosphere wind direction with height clockwise rotation significantly. The Wc analysis showed that the daily average of the rainy season before and after the 40 days between 2000-2100m wind direction and stability, diurnal. Ekman theory, and pointed out that the 2004 Nagqu atmospheric boundary layer height of 2000-2100m, this height lower than in the past, the majority of findings wind frequency statistics also show that the southerly winds in the rainy season, a significant increase in daily wind tends to be complex; With the rainy season, the complexity of the process, wind direction extended to the free atmosphere above the atmospheric boundary layer near the ground. Nagqu radiosonde 500hPa and 400hPa wind frequency statistics results confirm the results of the wind profilers. 3. Before the rainy season, sunny sunrise after mixing layer more rapid development of severe convective mixing zone more than 3000m and after the rainy season, in addition to strong convective weather, the sunrise after strong mixed layer development time has been pushed back, but extend the duration of convective activity. Wind profiler signal-to-noise ratio SNR (Signal-to-noise ratio) results similar conclusions. Before the occurrence of the the Nagqu strong thunderstorms, low-altitude often appear strong southwest or southeast wind Rapids, and there is a strong level of vertical wind shear between the two is one of the important reasons the Nagqu thunderstorms frequent. 4 on the basis of the data analysis, this paper also discusses the seasonal variation of the atmospheric boundary layer wind profilers structural features in Nagqu, and analyze the plateau during the rainy season the structure of the boundary layer wind profilers. 5 wind profiler data applicable to synoptic meteorology and climate analysis, and analysis of the resulting low level jet, levels of vertical wind shear and SNR a good forecast Implications of heavy rainfall in the SNR information can also be used to study the sunny border The laminar convective activity.

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CLC: > Astronomy,Earth Sciences > Atmospheric science (meteorology ) > Meteorological elements,atmospheric phenomenon > Wind
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