The fundamental aim of the Cloud Archive User Service (CLAUS) project is to provide dimate modellers with easy access to an archive of satellite based doud data. This aim can be sub-divided into three separate, measurabie objectives: Objective 1Data set provision
It is proposed to prepare an archive of integrated satellite images based upon data from the Intemationai Satellite Cloud Climatology Project (ISCCP) and covering the period 1983 - present. In response to customer requirements these data will be produced on a reguiar 0.5ø grid at 3-hourly intervals. The data processing method wili be based on a technically proven method developed using single year of data.
Objective 2Data Access
The data, and descriptions of the integration methods employed, would be made freely available over the network using the CEO European Wide Service Exchange (EWSE).
Objective 3 Operational Testing
The archived data will be tested by the participating dimate research groups in an operational environment over an extended period. Folbwing an inffial testing phase, modffications may be made in consultation with the users. The customers for CLAUS are global climate modeilers and climate researchers who need to compare observed data (as provided by CLAUS) with their own model outputs. Such comparisons would allow the models to be improved and be of enormous benefit to the dimate modelling community. The developrnent of General Circulation Models (GCMs) able to reproduce climate variables on various spatial and temporal scales, coupled with increases in computing power, has ied to greatly increased understanding of the world's climate. However, there are very real difficulties in validating the models; the Intergovemmental Panel on Climate Change (IPCC) has identified the provision ot observational data tor GCMs as oelng a critkal tactor in thelr validation and Improvement (IPCC, 1992).
Further, the IPCC identified inadeeguate understanding ot clouds as belng among the key uncertalnties in climate understanding (IPCC, 1992). These concerns were re-emphasised in the recent 1996 report tlPCC, 1996).
This project is customer driven. The project will be co-ordinated by the UK NERC Environmental Systems Science Centre (ESSC), who are an interdisciplinary group with a stong background in linking models with observations. Five of the six major climate modelling centres in Europe are active partners: Centre National de Recherches Meteorologie (CNRM), France; laboratoire de Meteorologie Dynamique (LMD), France; Max-Pianck- Institut fur Meteorologie (MPI), Germany; UK Universities Global Atmospheric Modelling Programme (UGAMP). UK; European Centre for Medium-Range Weather Forecasts (ECMWF), European; and the other major climate modelling centre, the UK Hadley Centre, will be collaborating closely.
The National Remote Sensing Centre, UK will be acting as a subcontractor to the other partners in order to develop the necessary data pocessing software and the archiving system.
The UK Department of the Environment (DoE) have expressed an interest in continuing with operational funding beyond the completion of an initial pre-operational CEO project.
KEYWORDS: Cloud Archive, Satellite data, GCM, EWSE, operational testing, data access
Funding SchemeCSC - Cost-sharing contracts
RG6 6BB Reading