THE STUDY OF RETRIEVAL THEORY AND METHODS FROM SATELLITE REMOTE SENSING FOR METEOROLOGICAL PARAMETERS OVER EASTERN ASIA-PARTI:ISPRM AND SRRM

A review of ten-year's practice in developing the improved simultaneous physical retrieval method(ISPRM)is given in the hope that some creative ideas can be drawn from it.The improvement upon the SPRM is associated with the under-determinedness of this ill-posed inverse problem.In our experiment,the precondition is observed that prior information must be independent of the satellite measurements.The well-posed retrieval theory has told us that the forward process is fundamental for the retrieval,and it is the bridge between the input of satellite radiance and the output of retrievals.In order to obtain a better result from the forward process. the full advantage of every prior information available must be taken.It is necessary to turn the ill- posed inverse problem into the well-posed one.Then by using the Ridge regression or Bayes algorithm to find the optimal combination among the first guess,the theoretical analogue information and the satellite observations,the impact of the under-determinedness of this inverse problem on the numerical solution is minimized.

THE IMPACT OF MID-LATITUDE CIRCULATION OVER THE TIBETAN PLATEAU ON THE TRACK OF TYPHOON OVER THE NORTHWEST PACIFIC

There is a close relationship between variation of middle latitude synoptic system over the Tibetan Plateau and movement of typhoon over the Northwest Pacific.This paper tries to discuss the mechanism of it through the numerical simulation and dynamic diagnosis. 25-year statistical results during the period from 1970 to 1995 indicate that the relationship between middle latitude circulation over the Plateau and the track of typhoon over the Northwest Pacific are as follows.When longwave trough in 500 hPa isobaric surface over the Plateau.it is favourable to typhoon's westward movement:on the contrary,large scale anticyclone over the Plateau is favourable to typhoon's recurvature.We simulated the typhoon under these two flow patterns with MM5 model.Numerical simulation results showed that:(a)Longwave trough on 500 hPa surface over the Plateau makes subtropical high extended westward so as to typhoon south to high moves westward in easterly steering flow.(b)Anticyclone over the Plateau will bring about the longwave trough developing along the east coast of Asia,it'will usually cause typhoon recurring in front of the developed trough. In addition,the results of dynamic diagnosis show the physical mechanism on impact of synoptic system over the Plateau on the downstream synoptic system,that is,the transport of disturbance kinetic energy over the upstream Plateau makes the downstream trough developed. And then it affects the steering flow of typhoon.Because of existence of the high ridge over the Plateau.the energy transport channel moves to north.On the contrary,the trough exists over the Plateau,the energy transport channel moves to south.The southerly in front of trough over the Plateau and the southerly in the east part of typhoon transport low potential vorticity of low latitude into subtropical high.That is beneficial to development of subtropical high and affects typhoon's movement.These results fully reflect the impact of interaction between mid-latitude and low latitude on synoptic system.