Research On The Forecast Sensitivity Of The New Round-trip Horizontal Floating Sounding And Conventional Observation Dat

In numerical weather prediction and data assimilation,an accurate understanding of the sensitivity of forecasting to observation is the basis for giving full play to the usefulness of observation data,at the same time,accurately and objectively evaluating the performance of meteorological observation system is also of great scientific significance for the improvement,application and development of its performance.The sensitivity of forecast in the middle and lower reaches of Yangtze River to the new Round-trip Drifting Sounding System(RDSS)observation data and the sensitivity of the forecast of different climate zones from 00:00 on June 10,2018 to 00:00 on July 10 in China to conventional observation data was studied based on forecast sensitivity to observations(FSO)method in this paper.The main conclusions are as follows:(1)The forecast error of 71.4% times in the test period was further reduced after data assimilation combined the new RDSS data,and the meridional wind and humidity observation contributed mostly,which indicated the new radiosonde data has a good potential to further improve the forecast quality in the middle and lower reaches of the Yangtze River.(2)The contribution of wind field observation to the forecast error has obvious spatial difference,and the large value area of the forecast error reduction is mainly distributed in the test station and its vicinity.What’s more,the contribution value of temperature field to forecast error is smaller than that of wind field,but the distribution is uniform,and the test station observation has a more obvious reduction to forecast error.In addition,the wind,temperature and humidity observations of new data in the whole layer have a significant positive contribution to the forecast quality,while the zonal wind observations in the middle and lower troposphere have a weak negative contribution.(3)Assimilation of conventional observations can reduce the forecast error of different climate zones to a certain extent,there are large differences between different observation elements,and the forecast is the most sensitive to wind field observation,among which the positive contribution of wind field to the forecast of different climate zones accounts for 68%-75%,while the contribution of temperature and humidity is slightly smaller,and the proportion of positive contribution time is between 55% and 65%.(4)Sounding observations contributed the most significant to forecast,and most of them contributed positively.Among them,the Alpine climate zone and the subtropical monsoon climate zone have the greatest sensitivity to the sounding wind observation in the target area and its upstream area.The positive contribution of sounding wind field is more obvious than that of temperature and humidity observation,but the local positive and negative difference is large.Sounding temperature observation contributed positively to the prediction of the four climate zones and distributed relatively uniformly,the contribution value of the stations outside the target area was relatively small,and the humidity observation produced a negative contribution to the temperate monsoon zone and the plateau mountain climate zone.The sensitivity of forecasts to ground-based observations is small,and about 44% of the terrestrial stations have a low contribution to the four climatic zones due to the unsatisfactory quality of the observations themselves.