Applicability Evaluation of NCEP/NCAR Reanalysis Temperature,Geopotential Height and Wind Field Data in the Upper Troposphere and Lower Stratosphere

By using the data in 169 sounding stations over the world,NCEP/NCAR reanalysis data were tested,and the distribution characteristics of standard errors of geopotential height,temperature and wind speed field from the upper troposphere to the lower stratosphere over the world(most were the land zone) were analyzed.The results showed that the standard error distribution of reanalysis wind speed field data was mainly affected by the jet stream zone.There existed the obvious difference between the jet stream zone and the actual wind field.The distribution of standard error in the wind speed field had the obvious seasonal difference in winter,summer,and the average deviation was larger near the coastline.The high value zones of standard errors of reanalysis geopotential height and temperature field mainly concentrated in the low-latitude region in the Eastern Hemisphere(Indian Ocean coast).The distribution of standard error was basically consistent with average error.Therefore,the standard error could be explained well by the average error.The standard errors of reanalysis temperature and geopotential height data in the inland zone were lower.The high value zone mainly distributed along the coastline,and the average error of wind speed field was bigger near the coastline.It closely related to the quality of data in the sounding stations,the regional difference and the fact that the land observation stations were dense,and the ocean observation stations were fewer.

Reanalysis on Hail Suppression Weather Prewarning of the "8.21" Rare Hail in Shenyang

[Objective]The research aimed to analyze hail weather during 18：30-19：30 on August 21,2011.[Method]Based on NCEP 6 h reanalysis data,Micaps data and FY-2 satellite cloud image,weather situation field,meteorological element field and satellite cloud image of the hail during 18：30-19：30 on August 21,2011 were reanalyzed.Weather causes of the hail and characteristics of the satellite cloud image were discussed.We summed up how to conduct prewarning analysis of the hail suppression weather from live weather data and numerical forecast products.[Result]In occurrence and development process of the hail weather,cold vortex at 500 hPa was background weather system.850 hPa warm tongue and ground wind shear were essential conditions for forming strong convective hail cloud.Early weather chart was analyzed.It could analyze occurrence reason of the weather from mechanism aspect of the weather system,and issue weather prewarning as early as possible.Numerical forecast products were used to analyze meteorological element field.It could further analyze and accurately predict probability,time and range of the hail occurrence.Infrared satellite cloud image was more accurate for monitoring strong convective hail cloud,which could intuitively predict occurrence of the hail weather.[Conclusion]The research offered some hail suppression prewarning experiences for the future similar hail weather.

Thermal Anomalies and Earthquakes:Evidence from Wenchuan,China

Earthquake prediction is a difficult problem in Earth sciences.Unsuccessful predictions one after another urged people to explore more synthetic and comprehensive methods for earthquake prediction.The Lithosphere-Atmosphere-Ionosphere(LAI)coupling theory pays great attention to the processes taking place within the near ground layer of atmosphere.It has achieved great results recently,and can enlighten us about the nature of an earthquake's precursor.Based on the NCEP reanalysis dataset,this paper attempts to track the anomalies of the surface's upward long wave radiation flux(ULWRF),the temperature at the depth of 10cm～20cm below ground surface layer(BGL)and the air temperature at 2 meters above ground surface(AIR)around the time of the strong Wenchuan earthquake.Thermal anomalies were observed before and after May 12,2008,the time of the Wenchuan earthquake.Perhaps the thermal anomaly that occurred prior to the earthquake can be taken as indicators of the earthquake,but in view of the complexity of the earthquake phenomena,using thermal anomaly as a precursor should be done with caution.

Statistical Guidance on Seasonal Forecast of Korean Dust Days over South Korea in the Springtime

This study aimed to develop the seasonal forecast models of Korean dust days over South Korea in the springtime. Forecast mode was a ternary forecast （below normal, normal, above normal） which was classified based on the mean and the standard deviation of Korean dust days for a period of 30 years （1981-2010）. In this study, we used three kinds of monthly data： the Korean dust days observed in South Korea, the National Center for Environmental Prediction in National Center for Atmospheric Research （NCEP/NCAR） reanalysis data for meteorological factors over source regions of Asian dust, and the large-scale climate indices offered from the Climate Diagnostic Center and Climate Prediction Center in NOAA. Forecast guidance consisted of two components; ordinal logistic regression model to generate trinomial distributions, and conversion algorithm to generate ternary forecast by two thresholds. Forecast guidance was proposed for each month separately and its predictability was evaluated based on skill scores.