An improved HIRS upper tropospheric water vapor dataset and its correlations with major climate indices

Abstract. A new version of the upper tropospheric water vapor dataset is developed using intersatellite calibrated all-sky High-Resolution Infrared Radiation Sounder (HIRS) data. In this dataset, the majority of pixels that do not affect the water vapor processing in the upper troposphere are retained. Compared to the previous version that was based on column-clear-sky data, the new version has a much better daily spatial coverage and provides a better representation of the atmosphere. The HIRS observation patterns are compared to microwave sounder measurements. The differences between the two types of sounders are examined, and the analysis displays that the differences vary with respect to brightness temperature. An examination of the correlations of the HIRS upper tropospheric water vapor with major climate indices shows that the dataset is well correlated with climate indices especially in cold seasons. The selected climate indices track climate variation signals covering regions from the tropics to the poles. The correlation analysis shows the potential of using the upper tropospheric water vapor dataset together with a suite of many atmospheric variables to monitor regional climate changes and locate global teleconnection patterns.