The Meteorological Operational satellite programme Second Generation (MetOp-SG) satellites will replace the current MetOp system in the 2020+ timeframe. One instrument to be carried on-board the MetOP-SG is a C-band scatterometer (SCA), similar to ASCAT of MetOp, but with a higher spatial resolution and stability.
The prime objective of SCA, (herein referred to as ASCAT-SG), will be to measure wind speed and direction over the oceans which are an important input to global and regional Numerical Weather Prediction (NWP). Operational nowcasting services of National Meteorological Services may also be users of the ASCAT-SG data. As well, there are also non real-time users, such as oceanographic researchers and climate system modelers.
The products to be derived from the ASCAT-SG mission include, in decreasing order of priority:
• Ocean surface wind vector
• Land surface soil moisture
• Leaf area index
• Snow water equivalent
• Snow cover
• Sea-ice type
• Sea-ice extent
As a baseline, the minimum expected performance of the ASCAT-SG mission is that of ASCAT. Determination of wind speeds in the range 4 – 24 m/s with an accuracy of 2 m/s (or 10%) and wind directions with accuracy of ± 20 deg is required.
The forecasting of hurricane intensities and tracks is extremely important for the protection of coastal residents and infrastructure. Accurate near-real time wind speed measurements, with reduced performance above 25 m/s are therefore desirable.
This report describes the possibility of meeting the desired retrieval performance by including VH channels on the scatterometer mid beams. These VH channels will not only improve the retrieval of extreme (hurricane) winds, but also provide improved soil moisture index and sea ice (drift) characterization.
G van Zadelhoff, A Stoffelen, P Vachon, J Wolfe. Cross polarization measurements on the ASCAT second generation
2012, OSI-SAF, 2012