Advances in higher resolution global ocean observing system: sea surface wind speed perspective

The needs for higher resolution and more accurate global air-sea fluxes (momentum, heat, water, CO2, etc.) have been articulated by several international working groups and modeling studies. Key questions such as, “What spatiotemporal resolutions are really necessary and feasible?” still need to be resolved by the user community and data producers. In this presentation and from observational point of view, we address the question “What are the highest possible resolutions of globally gridded products that can be produced from the existing global observing systems?” in terms of the sea surface wind speed (SSWS) as a case study.

The statistics of spatiotemporal sampling over the global ocean from the US satellite constellation that observes sea surface wind speed are computed to show their evolution in time. Long term SSWS observing satellites ranged from one DMSP satellite (F08) in mid 1987 to the present six satellites. Data sampling rates over the global 0.25º bins evolved from less than one per day to the present more than six times per day. The distributions of the sampling times are relatively uniform over the day, especially for the later years. Hence globally gridded products on a 0.25º grid are possible for increasingly higher temporal resolutions over this time period, from daily to twice daily and 6-hourly. Using a simple spatial-temporally weighted interpolation, 12-hourly SSWS fields were produced on a global 0.25º grid for this time period. Higher resolutions (e.g. 6-hourly) can be produced without significant sampling alias for the later years.