The Evaluation of Return Radiosonde Temperature using GNSS Radio Occultation Retrievaled Temperature

Abstract

It is necessary to evaluate the quality of a new type of observation data before using it for data assimilation.Based on GNSS radio occultation （RO） and ERA-Interim reanalysis data， the quality of temperature in the ascent， drift and descent stage of return radiosonde has been analyzed and evaluated.In the drift stage using the method of Cressman to interpolate the temperature of return radiosonde and compare with the dry temperation （Tdry） of RO， the results show that there is an obvious positive deviation in return radiosonde temperature data caused by the heating of solar radiation in the daytime and a weak negative deviation at night.A further verify of the above results by comparing between ERA-Interim reanalysis， RO Tdry and return radiosonde.The average temperature bias between the drift stage and RO Tdry evoluting with local time ranges is 7~10 ℃ in daytime and -4~0 ℃ at night.The results show that the precision of night temperature observations of return radiosonde reaches the breakthrough target defined by the WMO（world meteorological organization）.The temperature between the ascent and descent stages in return radiosonde and the wet temperation （Twet） of RO shows a good consistency， which the mean bias ranges is -1~1 ℃ in ascent stage as well as below 13 km in descent stage， this bias slightly increases and ranges is 1~3 ℃ above 13km in descent stage.On the whole， the quality of the temperature data in the ascending （descending） stage of return radiosonde is better than the drift stage observations.Meanwhile， the descend stage has the function of space-time encryption for the radiosonde observation， and the data quality meets the application of numerical weather forecast and other analysis study fields.

Keywords

• return radiosonde
• intensive radiosonde observations
• cross comparison
• temperature deviation