Historical AMVs from THIR
The Temperature Humidity Infrared Radiometer (THIR) was flown on four NASA Nimbus satellites (Nimbus-4 to -7) in the 1970s to the mid-1980s. THIR is a two channels infrared radiometer. The instruments were mostly identical, however, the data from Nimbus-7 are available at a slightly higher horizontal resolution. Within the Copernicus Climate Change Service (C3S), a Fundamental Data Record (FDR) of Nimbus-4 to -6 THIR was produced the Nimbus-7 FDR is currently being finalised. This FDR is a first candidate for deriving AMV CDR. In this satellite data sparse era the availability of additional observation is a great opportunity for future production of centennial reanalysis.
As part of the second phase of C3S, EUMETSAT has assessed these FDR and their usability for AMV retrieval. The swath of THIR is very large (about 5000 km). Depending of the quality of the results closer to the edges of the swath, it opens the opportunity to retrieve AMV at a global scale and not only over polar areas. However, as expected for such early satellite observations, the FDR time series include gaps in the time series as well as for almost each orbit. The FDR quality provides challenges for the AMV retrievals.
This presentation will give an overview of THIR characteristics and data availability. It will present the results of the feasibility assessment of AMV production. It will illustrate the challenges associated with AMV retrievals from early satellite data and how EUMETSAT is addressing these.
