| Popis: |
Observations from the WPR located in Zhanjing are used to analysis the characteristics of wind field and virtual temperature in boundary layer under three kinds of synoptic processes during 5th–12th April, 2010. The results show that: (1) The horizontal wind velocity first increased and then decreased with altitude in low level of spring fair weather over Zhanjing, with maxima range of 7–16 m/s, and the velocity also first increased and then decreased, with maxima less than 20 m/s in the middle level, the wind velocity was increased with altitude in high level. The horizontal wind direction was easterly in low level and southwesterly in high level, and the direction veered with altitude accompanied by warm advection. It appeared varied velocity of downdraft except for the weak updraft at the altitude of 2500–4000m. (2) During the spring fog process, the wind velocity fluctuated around 5 m/s with easterly direction in the low level and increased with altitude above 1100m which up to 19 m/s with southeasterly direction, but the velocity turned decreasing apparently around 5500m, with wind direction veering with altitude accompanied by warm advection. (3) There were two downdraft areas during precipitation, the first one was under the height of 1000m, and the second one was at the mid-level of 3000m. Updraft appeared before the onset of precipitation, and the low level was dominated by downdraft airflow after the beginning of rainfall. At the beginning of rainfall, the horizontal wind velocity shook at mid- and low-level with wider fluctuation margin of 3–9 m/s. The wind velocity increased with altitude accompanied by single warm advection and the direction was easterly below the height of 1000m, and the wind direction became more volatile with height above 1000m with alternated appeared warm and cold advection. |
