Comparative Analysis Between ASCAT Satellite Ocean Wind Field Data Inversion And 10m Wind Field In Numerical Model

Chinese coast is vast,spanning the tropics,subtropics and temperate zones.It has abundant marine resources,which are the basis for the development of the marine economy.The increasing of marine meteorological disasters caused by global warming is harmful to marine production,transportation and other activities.It seriously influences and restricts economic development.At present,further improvements are need in the technology of meteorological monitoring equipment in our marine,and there are still many gaps between meteorological observations.These directly cause insufficient capability in the marine meteorological disaster monitoring and early warning.It has become the focus of the research that how to use new technology and information to provide accurate and timely forecast,as well as efficient and quality meteorological service.Through comparative analysis in advantages and disadvantages of forecasts in different situations between three numerical models,this work provides a reference for further improvements in acuracy rate of our marine wind filed.In recent years,the application of satellite remote sensing data has been mature.Its advantages,including large coverage,high temporal and spatial resolution and strong ability in continuously observing,make huge contributions to practical work and research.This work introduced comparisons between previous ASCAT marine wind fields and ocean buoy stations,and fully demonstrated the feasibility in the replacement of live data with the ASCAT data(nearshore wind field product of 12.5km resolution),as well as in comparative analysis in forecasts of marine wind fields between T639,EC and NECP-GFS.The test is over region(3°~42°N,105°~130°E)from September 1,2012 to August 31,2013.Referring to "coastal area wind forecast quality inspection procedures" published by China Meteorological Bureau,this work used error checking and TS scoring test to investigate the accuracy of model forecast.Meanwhile,this work applied the inverse distance weighted interpolation method to interpolate ASCAT wind data to the forecasting wind field grids of the three numerical models.Taking T639 as an example,this work analyzed the average error,the mean absolute error,the mean square root error,the monthly variation and spatial distribution of the wind speed accuracy,the monthly variation and spatial distribution of the TS score of T639 data,the monthly forecasts in 10 m wind fields of EC and NCEP,and the wind speed and wind direction of the three data.The main conclusions are as follows:(1)T639 model forecasts a smaller 10 m wind speed than the inversion,but their monthly variations in the mean absolute error and root mean square error are broadly consistent.The forecast deviation of wind speed increases with the extension of the forecast.The average of accuracy rate in forecasted wind direction is 0.82.The spatial distribution of error statistics shows that the mean error of wind speed is small in the northern sea,and larger in East China Sea and South China Sea.The spatial distribution of the mean absolute error and root mean square error is similar,with larger values over Bohai,the Bohai Strait,Taiwan Strait,BaShi gorge and Beibu Gulf and smaller values over other regions.The TS score tests illustrate that the higher the wind speed is,the lower the accuracy rate of wind forecast is,and the higher the omission and the empty forecast rate are.The spatial distribution of TS score of 5~7 wind shows that accuracy rate is higher and the omission and the empty forecast rate are smaller over broad regions,including central and southern the Yellow Sea,the most East China Sea,the Taiwan Strait andthe most South China Sea,while areas largely affected by the gulf and islands are characterized by worse forefast.(2)the model EC forecasts a negative average monthly mean wind speed,and the annual average is-0.8m/s.Its predicted wind speed is smaller than that of the inversion,with smaller average error in months 5~7,and larger average error in other months.The average accuracy of wind direction prediction is 0.88.In terms of monthly variation,the accuracy of the wind direction is higher in months from October to April next year,and lower in months 5~9.(3)the NCEP forecasts postive average monthly wind speed in most months except months Novermber–February,in which the average errors are negative.The annual average absolute error is 1.5m/s,and the annual mean square error is 2m/s.Their monthly variations are generally consistent,with lower values in the winter and higher values in the summer.In terms of monthly variations,the accuracy of the wind direction was higher in months from October to March next year and lower in months 4~9.(4)Comprehensively comparisons in error statistics between EC,NCEP and T639,illustrate that NCEP shows the minimum wind speed mean error,and EC is with the minimum mean absolute error and root mean square error as well as the highest wind direction accuracy.The T639 model is characterized by the largest prediction error in all the error statistics.(5)The TS score of this three models report that NCEP shows the highest prediction accuracy rate and the lowest omission forecast rate in wind field,and the lowest empty forecast rate in wind field is the EC model.Comprehensive analysis show that the forecasted wind speed of NCEP is close to the wind speed of ASCAT inversion.