Abstract's details

Towards the Retrieval of Atmospheric Information from Altimeter Range Measurements

Noureddine Semane (ECMWF, United Kingdom)

CoAuthors

Sean Healy (ECMWF, United Kingdom); Saleh Abdalla (ECMWF, United Kingdom); Philip Browne (ECMWF, United Kingdom)

Event: 2022 Ocean Surface Topography Science Team Meeting

Session: Instrument Processing: Propagation, Wind Speed and Sea State Bias

Presentation type: Type Oral

One of the basic steps towards providing useful altimeter sea surface height measurements is to apply the proper corrections to the range measurements. Some geophysical corrections are atmospheric dependent. Atmospheric model products have been used to compute these corrections especially in the absence of any other alternative.

ECMWF runs operationally the Integrated Forecast System which is a coupled system composed of several components including atmospheric, ocean and wave models, in addition to an advanced data assimilation system (4D-Var). The IFS will be used for examining whether the altimeter range geophysical corrections that depend on the atmosphere can be used to retrieve useful atmospheric information. Dry and wet tropospheric corrections can be assimilated into atmospheric 4D-Var system.

For the time being, technical changes are being introduced to IFS to be able to retrieve the atmospheric information from altimeter range measurements. This includes reading the necessary data from altimeter products and propagating them within IFS. The data initially will be treated as ground-based GPS data but over the ocean. So, altimeter data are reformatted as such. The various parameters like sea surface height from the ocean model and significant wave height from the ocean wave model are propagated to the 4D-Var assimilation part. For testing, the modified system was used successfully to assimilate the wet tropospheric correction based on the microwave radiances.

This is an early stage of this effort. Several challenges can be seen. The adoption of a common reference (geoid) is just one of them. The theoretical background, the effort, the following steps and the challenges will be presented. The results obtained by the meeting time will be presented. Some of the test results could also be shown.
 

Oral presentation show times:

Room Start Date End Date
Sala Grande Tue, Nov 01 2022,15:30 Tue, Nov 01 2022,15:45
Noureddine Semane
ECMWF
United Kingdom
Noureddine.Semane@ecmwf.int