Reanalysis Impact on Quality Controls of Long-term Satellite Sounding Observation

Satellite Sounding observations by TIROS Operational Vertical Sounders (TOVS) are one of the most important observations for a reanalysis. For production of long-term climatic and hydrological data, TOVS observations are also beneficial. Therefore quality controls of TOVS observations are crucial to a project. Discontinuity and inhomogeneity of long-term TOVS observations can cause serious problem.

It has been found that a reanalysis project can have a considerable impact on quality controls of long-term observations as well as historical observation data mining, because of serious needs for reliable observations and their precise quality controls in such a project.

Generally TOVS observations can differ among spacecraft, instruments, and each period of time, and they need appropriate reference data to maintain their consistency and uniformity. Reanalysis data can be useful as such reference datasets. And now new reanalysis dataset is going to be available for those purposes; Japan Meteorological Agency (JMA) and Central Research Institute of Electric Power Industry (CRIEPI) are about to complete the 26-year (1979 - 2004) reanalysis project: JRA-25.

In this study, Satellite Sounding data by TOVS on board from TIROS-N to NOAA-14 are compared with reanalysis datasets. Each reanalysis adapted the different way to use TOVS observations, and therefore each one is affected by TOVS observations themselves to some extent. Moreover Each has the unique characteristics caused by various factors. However Reanalyses, as a whole, can provide valuable materials for case studies and pertinent information with regard to discontinuity and difference among spacecraft and instruments. JRA-25 project also provides opportunity to compare the long-term sounding observation to radio-sonde observation.