Layer average relative humidity from SAPHIR on board Megha-Tropiques: validation with numerical model analyses

Abstract

Subsequent to the launch of the Sondeur Atmosphérique du Profil d’Humidité Intertropicale par Radiométrie (SAPHIR) sensor on board the Megha-Tropiques satellite on 12 October 2011 from Satish Dhawan Space Centre, Indian Space Research Organization (ISRO), Shriharikota, India, the validation of layer averaged relative humidity (LARH) retrieved from SAPHIR has been initiated in different phases along with other retrieved parameters. The Megha-Tropiques is a joint satellite mission executed by the Indian Space Research Organization (ISRO) and the Centre National d’Etudes Spatiales (CNES), and is primarily devoted to study the tropical atmospheric processes influencing both weather and climate. The present study focuses on a validation campaign, where the validation of LARH derived from SAPHIR is carried out with three different numerical model analyses: the European Centre for Medium Range Weather Forecasts (ECMWF) model, the National Centers for Environmental Prediction (NCEP) model, and the National Centre for Medium Range Weather Forecasting (NCMRWF) model, over a period of six months from January 2013 to June 2013. It is observed that the root mean square difference (RMSD) of LARH has improved considerably for layers 1, 2, 3, and 6, and some marginal changes for layers 4 and 5, when a bias correction is applied to the data. The RMSD of SAPHIR LARH after correcting for bias is well within the range of the mission goal of 20% accuracy.

Acknowledgements

The authors would like to thank the reviewers for the comments and corrections that were helpful in substantially improving the presentation and contents of the revised manuscript. The authors would like to thank Shri. A. S. Kiran Kumar, Director, Space Applications Centre, ISRO for his constant encouragement and support throughout this study. The authors would also like to thank Dr J. S. Parihar, Deputy Director, EPSA for timely help during this study; and would also like to acknowledge Dr Jean-Noël Thépaut and Dr. Erik Anderson, ECMWF for providing ECMWF analysis. NCEP and NCMRWF are acknowledged for providing the corresponding model analyses. The authors are thankful to Mrs Puspalata Shah and the entire data products and data reception team of MOSDAC, SAC for their valuable support.