Dr Jörg Schulz is Climate Service Product Manager at EUMETSAT. He is leading a group that is responsible for the generation of Climate Data Records using data from EUMETSAT and other space agency missions. He is particularly interested in providing satellite measurements of high quality to reanalyses and activities associated with climate model evaluation.
What is the role of EUMETSAT in ERA-CLIM2?
EUMETSAT provides reprocessed satellite data records to ECMWF that have a higher quality compared to the data distributed in real time. The data significantly enhance the quality of the reanalysis by providing information in regions where traditional measurements do not exist.
The increase in quality is achieved by carefully analysing the raw data for artefacts and artificial trends due to changes in instrument behaviour over time. In particular, instrument calibration is improved by applying our latest knowledge about the instrument and also by inter-calibrating with reference data from other space-based measurements which are more accurate. For instance, currently we are referencing the Meteosat infrared channels against Metop IASI measurements and other similar instruments to provide a homogeneous time series of Meteosat radiances which can be assimilated into the NWP model. The data are also used to consistently derive other parameters such as upper-air wind vectors that are also assimilated.
What is the greatest challenge working with old satellite data?
The basic technology for monitoring weather from space was established about 50 to 60 years ago, and was very successful in measuring what it set out to do. But at the time very few were thinking about using the data for climate monitoring. Luckily most of the data have been archived but information about the data (e.g. about laboratory tests and activities during the life time of the mission that impact the quality of the data) was not systematically documented. In addition, applied algorithms for satellite navigation, calibration, etc. were not documented in the way they are now. Missing information makes the improvement of data quality a challenge. For example, knowledge of the spectral response in an individual instrument channel is key to understanding the measurements and the differences between similar instruments.
Does EUMETSAT also benefit from the ERA-CLIM2 project?
Yes, in three ways.
- Scientifically, the new observation feedback archive will provide us with additional information from the data assimilation process that will help us to further improve our data records. Additionally, reanalysis is increasing the user base for our satellite data.
- Technically, the experience acquired during the first ERA-CLIM project enabled us to learn how we need to enhance our infrastructure to reprocess satellite data more efficiently.
- We provide reprocessed satellite data to maybe a handful of centres doing global reanalyses, but the number of users of the reanalyses is beyond 10,000. So many more users benefit from us improving the quality of our historic satellite measurements.