Validation fo NOAA-AVHRR Sea Surface Temperatures for Use in NWP-Models

Numerical weather prediction (NWP) models can profit from input of accurate satellite measured sea surface temperatures (SST). In April 1998 the project ‘SST in HIRLAM’ is started at KNMI. The aim of the project is to validate sea surface temperatures measured by the NOAA-AVHRR sensor and to study the impact on the forecast quality of the NWP model HIRLAM (HIgh Resolution Limited Area Model), which runs operationally at KNMI.

In this paper the results of the first part of this project, the validation of the NOAA-AVHRR SST, are presented. The NOAA-AVHRR SST are validated against observed measurements originating from ships and buoys. The validation is performed for a number of periods, spread over the seasons and for the whole HIRLAM area. Due to persistent cloud cover over large areas it is foreseen that SST-maps, to be assimilated in HIRLAM, will be constructed by composing AVHRR SST-images over longer periods. In the study three different types of SST-composites are validated. Furthermore, a statistical algorithm is developed in order to perform quality checks on an SST value at a certain location. This statistical algorithm itself, its effect and the effect of the type of composite on the quality of the NOAA-AVHRR SST for different parts of the European waters will be discussed.