TYPICAL WEATHER CHARACTERISTICS ASSOCIATED WITH AIR POLLUTION IN HONG KONG AREA

With the hourly data of Air Pollution Index （AP1） by Hong Kong Environmental Protection Department （HKEPD） during the 6 years of 2000 - 2005 and NCEP / NCAR reanalysis data of 2.5°× 2.5° wind and pressure fields, the characteristics of API in Hong Kong area and the impacts of typical weather characteristics on the air pollution in Hong Kong have been studied. The results are shown as follows. （1） The API exhibits obvious seasonal variability as the number of air pollution days increases by the year. For most of the local monitoring stations, it is the most from January to March, a little less from July to September and the least from April to June. （2） There are four typical types of weather situations that are responsible for the air pollution in Hong Kong： tropical cyclones, continental cold highs, transformed highs that have moved out to sea and low pressure troughs.

Summer weather characteristics on the Grove Mountain of East Antarctica

The summer weather characteristics of the Grove Mountain, East Antarctica, are presented based on the data obtained by Chinese National Antarctic Expedition (CHINARE) in January 1999. The result shows that the pattern of daily variation of temperature and the prevailing wind direction in Grove is similar to that of Zhongshan Station. However, the daily range of temperature and strong wind frequency are much higher than those of Zhongshan Station.The change of wind direction is close to the weather system that impacted the Grove Mountain. The warm and wet air from northern parts often causes the precipitation. The clear weather appears when controlled by eastern winds in January.

Comparison study of environmental influences on the intensification of different deep Changjiang-Huaihe cyclones over the East China and Yellow Seas

Abstract： Statistical classification of the intensification of different deepChangiang-Huaihe Cyclones （CHCs） over the East China and Yellow Seas （ECYSs）during 2008 to 2012 is studied using the FNL reanalysis data. Based on the penetrationdepth and the season of occurrence, the CHCs are divided into four categoriesincluding warm-season-deep （WSD）, warm-season-shallow （WSS）, winter-shallow（WTS） and early-spring-bottom （ESB）. Statistics show the CHCs take either aneastward or a northeastward path after entering ECYSs. After moving to the seas, theintensification of CHCs is more significant in cold season than that in warm season.They all have the reduction of the friction of the underlying surface and the increase ofthe near surface winds. The area of strong winds extends and migrates from the east tothe southeast of the CHCs. A significant increase of precipitation during the warmseasons is consistent with the penetration depth of the cyclones. While a slight increaseof precipitation in cold season cyclones and scattered precipitation is observed behindthe ESB cyclones in the early stage of spring. Synthetic diagnosis analysis of the CHCsover ECYSs shows that the latent heat release plays an important role in theamplification of cyclones during the warm season. The ESB cyclones are sensitive tothe dynamic and thermal effects from the underlying surface. The vertical stretching of the positive vorticity volume is much more significant in ESB cyclones than that in othercyclones. The height of maximum upper level divergence is proportional to thepenetration depth of the cyclone for all the categories. Diabatic heating from the underlying surface is more prominent in cold season cyclones. Downward transport ofthe kinetic energy from upper level jet and the reduced friction both have positivecontributions to intensification of the CHCs. Moist Potential Vorticity （MPV） has morecontribution to the intensification of warm season cyclones, especially WSD cyclones.The combined effects from inertial stability and shear stability are beneficial to theamplification of the cyclones in cold season. The position and strength of thetemperature and moisture front from MPV2 term at 1000 hPa coincides with the areaand intensity of precipitation, which shows that the MPV2 is an effective reference forCHCs rainfall forecast.