Studies On On-orbit Stability Evaluation And Tropical Cyclone Temperature Structure Retrieval Of Advanced Technology Microwave Sounder (ATMS)

The Advanced Technology Microwave Technology(ATMS)onboard the Suomi National Polar-orbiting Partnership(SNPP)was successfully lauched on October 28,2011.The ATMS is a cross-track scanning instrument of 22 channels with frequencies ranging from 23 to 183 GHz.It can be used to detect atmospheric temperature and humidity in clear and cloudy conditions,which is important for severe weather monitoring and predition such as tropical cyclones.In this study,the geolocation and calibration accuracy of the ATMS observations was carefully assessed,and the astmospheric temperature was retrieved using the corrected ATMS data.The main results and conclusion are summarized as follows:(1)The Coastline Detection Method(CDM)was used to characterize and quantify the ATMS geolocation accuracy,and the results were validated by the Land-sea Fraction Method(LFM).ATMS geolocation errors estimated from both methods are generally consistent from40 cases in June 2014.The ATMS along-track(cross-track)errors at nadir are within ±4.2 km(±1.2 km)for K/Ka,±2.6 km(±2.7 km)for V bands,and ±1.2 km(±0.6 km)at W and G bands,respectively.At the W band,the geolocation errors derived from both algorithms are probably less reliable due to a reduced contrast of brightness temperatures in coastal areas.These estimated ATMS along-track and cross-track geolocation errors are well within the uncertainty requirements for all bands.(2)After assessment and correction of ATMS geolocation error,the detail processes of calibration were introduced.And the ATMS absolute calibration accuracy was evaluated using background data,and the collocated background profiles were input into the CRTM to simulate the brightness temperatures for the ATMS.The evaluation shows that the difference between observed and simulated brightness temperature was negative greater than-0.6K,in channel 5-13.The scan bias is slightly asymmetrical about the sub-satellite point.(3)After the correction of the ATMS geolocation error and the calibration accuracy,the ATMS observed brightness temperatures were used to derive the atmospheric temperature using 1DVAR technique,and then the warming structure of the tropical cyclone can be achieved via the environmental temperature.In order to derive a more realistic and reasonable tropical cyclone warm core structure.It's explored that the effects of different ATMS channel combinations on the microwave retrievals of tropical cyclone thermodynamic structures.The results show that the warm core anomaly from the regression of the ATMS temperature detection channel 4-15 is relatively reasonable.Especially,where the cold anomaly lies,it is more affected by the scattering effects of heavy precipitation,the traditional retrievals in cold anomalies was as low as-10 K.When only using the oxygen souding channels,the magnitude of the retrieved cold temperature anomaly can be reduced to about-2 K.