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Data from in situ probes and a vertically-pointing mm-wave Doppler radar aboard a research aircraft are used to study the cloud microphysical effect of glaciogenic seeding of cold-season orographic clouds. A previous study (Geerts et al., 2010) has shown that radar reflectivity tends to be higher during seeding periods in a shallow layer above the ground downwind of ground-based silver iodide (AgI) nuclei generators. This finding is based on seven flights, conducted over a mountain in Wyoming (the Unites States), each with a no-seeding period followed by a seeding period. In order to assess this impact, geographically fixed flight tracks were flown over a target mountain, both upwind and downwind of the AgI generators. This paper examines data from the same flights for further evidence of the cloud seeding impact. Composite radar data show that the low-level reflectivity increase is best defined upwind of the mountain crest and downwind of the point where the cloud base intersects the terrain. The main argument that this increase can be attributed to AgI seeding is that it is confined to a shallow layer near the ground where the flow is turbulent. Yet during two flights when clouds were cumuliform and coherent updrafts to flight level were recorded by the radar, the seeding impact was evident in the flight-level updrafts (about 610 m above the mountain peak) as a significant increase in the ice crystal concentration in all size bins. The seeding effect appears short-lived as it is not apparent just downwind of the crest. 相似文献
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NUMERICAL EXPERIMENTS FOR THE IMPACT OF ANTARCTIC ICE COVER AND SEA SURFACE TEMPERATURE ON CLIMATE VARIABILITY 总被引：2，自引：0，他引：2 
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下载免费PDF全文 By using a three-level atmospheric general circulation model (AGCM),we have completed severalnumerical experiments to study the impacts of sea surface temperature anomaly (SSTA) and antarctic icecover anomaly (AICA) during 1981—1983 on climate variability.The results show that during the ElNino period of 1982—1983 the impact of SSTA overrides that of AICA.SSTA mainly affects equatorialzonal circulation and produces PNA wave train,and SE-NW wave train in East Asia to influence theweather of China.AICA produces west-east anomalous vortex streets in the middle latitudes of bothhemispheres and affects the intensity of the polar vortex of Southern Hemisphere. 相似文献
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NUMERICAL EXPERIMENTS FOR CLIMATE VARIABILITY OF MONSOON UNDER THE UNITED EFFECTS OF ANTARCTIC ICE COVER AND SEA SURFACE TEMPERATURE 总被引：1，自引：0，他引：1
In order to study the mechanisms of climate natural variability under the united effects of antarc-tic ice cover(AIC)and sea surface temperature(SST),we have done a series of numerical experi-ments for the climate variability of the period from January 1981 to December 1983 by using a three-level atmospheric general circulation model(AGCM).Firstly we conduct climate integration for sixyears,then 3 years'control integration from January 16 of the seventh year.Moreover,we do threesensitivity experiments,which are the sensitivity experiments forced by observed SST and AIC.ob-served SST and climatic AIC,observed AIC and climatic SST respectively,to study the climate vari-ability and its mechanisms affected by SST and AIC.We put emphasis on the variability of East Asiamonsoon and the Southern Hemisphere(SH)circulation.In this paper,introduction is made to theresults of control test and the sensitivity experiment forced by observed SST and AIC,and the pre-dictability of the monsoon climate variability is discussed. 相似文献
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