Meteorological Characteristics of a Typical Dust Weather Process in the Eastern Qinghai-Tibet Plateau

Based on the comprehensive ground observation and the remote sensing data of Fengyun-4 satellite of a typical sand-dust weather process in the eastern part of the Qinghai-Tibet Plateau from November 26 to 27,2018,the weather situation,air mass trajectory,meteorological conditions,and pollution characteristics of this process were analyzed.The results show that the floating dust process was caused by the transmission of the northwest cold air flow in the Tarim Desert area,which caused dust and sand mixed with the Qaidam Desert particles to be transported to Xining.The wind field change caused by the difference of ground heat in the eastern plateau was a potential factor for dust transmission,and tropospheric subsidence,temperature inversion conditions,and the decrease in wind speed over Xining Station were the direct factors leading to the daily change of pollutant concentration in this process.

Local Meteorological and Synoptic Characteristics of Fogs Formed over Incheon International Airport in the West Coast of Korea

Fogs observed over Incheon international airport （IIA） in the west coast of Korea from January 2002 to August 2006 are classified into categories of coastal fog, cold sea fog, and warm sea fog based on the areal extent of the fogs and the difference between the air temperature （T ） and the SST, i.e., cold sea fog if TSST = T -SST 〉 0~0C and warm sea fog if TSST 〈 0~0C. The numbers of coastal, cold, and warm sea fog cases are 64, 26, and 9. Coastal fogs form most frequently in winter, while cold sea fogs occur mostly in summer and warm sea fogs are observed from January to May but not in November and December. On average the air gets colder by 1.6~0C during the three hours leading up to the coastal fog formation, and an additional cooling of 1.1~0C occurs during the fog. The change in the dew point temperature （T_d） is minimal except during the fog （0.6~0C）. Decreases in T for the cold and warm sea fogs are relatively smaller. The average Td is higher than SST during the cold sea fog periods but this T_d is more than 4~0C higher than that for the corresponding non-fog days, suggesting that cold sea fogs be formed by the cooling of already humid air （i.e., T_d〉SST）. Increases of T_d are significant during the warm sea fog periods （1.4~0C）, implying that effcient moisture supply is essential to warm sea fog formation. Four major synoptic patterns are identified in association with the observed fogs. The most frequent is a north Pacific high that accounts for 38% of cases. Surface or upper inversions are present in 77%, 69%, and 81% of the fog periods for coastal, cold, and warm sea fogs, respectively.

Seasonal Characteristics of Surface Radiation Fluxes on the East Rongbuk Glacier in the Mt.Everest Region

Ground-based measurements are essential for understanding alpine glacier dynamics,especially in remote regions where in-situ measurements are extremely limited.Prom 1 May to 22 July 2005（the spring-summer period）,and from 2 October 2007 to 20 January 2008（the autumn-winter period）,surface radiation as well as meteorological variables were measured over the accumulation zone on the East Rongbuk Glacier of Mt. Qomolangma/Everest at an elevation of 6560 m a.s.l.by using an automatic weather station（AWS）.The results show that surface meteorological and radiative characteristics were controlled by two major synoptic circulation regimes：the southwesterly Indian monsoon regime in summer and the westerlies in winter.At the AWS site on the East Rongbuk Glacier,north or northwest winds prevailed with high wind speed（up to 35 m s^（-1） in January） in winter while south or southeast winds predominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer.Intensity of incoming shortwave radiation was extremely high due to the high elevation,multiple reflections between the snow/ice surface and clouds,and the high reflective surrounding surface.These factors also caused the observed 10-min mean solar radiation fluxes around local noon to be frequently higher than the solar constant from May to July 2005.The mean surface albedo ranged from 0.72 during the spring-summer period to 0.69 during the autumn-winter period. The atmospheric incoming longwave radiation was greatly affected by the cloud condition and atmospheric moisture content.The overall impact of clouds on the net all-wave radiation balance was negative in the Mt. Qomolangma region.The daily mean net all-wave radiation was positive during the entire spring-summer period and mostly positive during the autumn-winter period except for a few overcast days.On monthly basis,the net all-wave radiation was always positive.