Evaluation of MODIS water vapour products over China using radiosonde data

Abstract

Radiosonde data collected from 83 stations in China from January to December 2012 were used to evaluate Moderate Resolution Imaging Spectroradiometer (MODIS) near-infrared (NIR) and thermal infrared (IR) total precipitable water vapour (PWV) products. The results indicate that MODIS NIR PWV products shows better agreement with radiosonde data than with IR PWV products, with the correlation coefficients up to 0.95. The root mean square errors (RMSEs) of NIR PWV range from 2 to 8 mm with different stations, which shows significant regional differences over China. The mean RMSE is about 5.03 mm (~35%) with a positive deviation of 2.56 mm (~18%), indicating the occurrence of a slight overestimation. Moreover, MODIS IR PWV during night-time has a better agreement with radiosonde PWV than that during daytime. The mean RMSE of IR PWV during daytime was ~6.02 mm (~42%), with a positive deviation of 1.54 mm (~11%). The mean RMSE of IR PWV during night-time was ~5.81 mm (~40%), with a negative deviation of approximately −0.04 mm (~0.25%). Both the NIR and IR PWV products during daytime tend to be higher than radiosonde PWV.

Acknowledgements

The authors thank the NASA Earth Observing System Data and Information System data centre for sharing MODIS data via the Simple Subset Wizard, as well as the University of Wyoming for providing radiosonde data. The authors also thank the anonymous reviewers for their valuable comments and suggestions to improve the quality of this article.

Additional information

Funding

This work is supported by the National Natural Science Foundation of China (NSFC) [grant number 41305030 and 41375042], and the China Special Fund for Meteorological Research in the Public Interest [grant number GYHY201406001 and GYHY201106014].