Speaker
Description
Since 2006, the Metop satellites have orbited the Earth equipped with different instruments to collect atmospheric data. Among them, the GRAS receiver providing GNSS Radio Occultation (GNSS-RO) data, the Infrared Atmospheric Sounding Interferometer (IASI), the Advanced Microwave Sounding Unit (AMSU) and the Microwave Humidity Sounder (MHS).
These sensors operate in different frequency bands and different geometries. GNSS-RO is a limb-view technique, whereas the others aforementioned are nadir systems sensing within a span of zenith angles. Common among them is the capability of providing vertical profiles of water vapour, which is one of the essential variables to model the weather and track climate change.
Given the independence in the data acquisition, we present an assessment of tropospheric differences between the RO-GRAS water vapour (WV) product processed by Radio Occultation Meteorology Satellite Application Facility (ROM SAF) and the Rutherford Appleton Laboratory (RAL) Infrared Microwave Sounding (IMS) data set, which is composed by WV profiles jointly retrieved from IASI, AMSU and MHS measurements.
Profiles used in this study are collocated assuming the maximum time interval of 3 hours and distance of 300 km. The matchups are grouped in three different latitude bands (low, mid, and high latitude) during 2006 and 2016, and the comparison assumes ERA5 forecasted WV profiles as the reference.
The results are presented as two data sets. One uses GRAS-RO and ERA-5 profiles simply interpolated to IMS pressure levels in the analysis, and the other assumes filtered profiles by IMS averaging kernels (AKs). Besides the primary goal of this study, i.e., comparison between the data sets, the results motivate a discussion about the relevance of AKs filtering to equalize the difference in footprints and vertical representativeness among the data.
These are preliminary results of the RO contribution to the ESA Water Vapour Climate Change Initiative (ESA WV_cci) project. They should lead to a better understanding of the differences between RO and IMS WV products and their uncertainties.
| You plan to attend | On site (at FZ Jülich) |
|---|
