Problem to be solved
Understanding and detecting seasonal climatic variability and climate change.
Objectives and approach
ERA-40 will use a variational data assimilation system to make a new synthesis of the in-site and remotely-sensed measurements made over the period since mid-1957, when a major improvement was made to the atmospheric observing system in preparation for the International Geophysical Year, 1958. The products will be of high temporal and spatial resolution, provided three-hourly throughout the period with a grid spacing close to 125km in the horizontal and with sixty levels in the vertical located between the surface and a height of about 65km. The basic analysed variables will include not only the conventional meteorological wind, temperature and humidity fields, but also stratospheric ozone and ocean-wave and soil conditions. Additional information will be produced concerning the quality of both the observations used and the analyses generated. A sophisticated archival/retrieval system will be used to store the results and make them widely available. Particular attention will be given to generating data sub-sets on compact media that can be made available to users at affordable cost. Extensive documentation will enable customers and users of the results to gain maximum benefit. Validation and demonstration studies form an important component of ERA-40. A major aim of these is to provide checks on the quality of the analyses by comparison with independent measurements. This will be done either by direct verification of analysed or simply-derived values, or by verifying the output of different types of model that have been forced by the analysed values, for example an ocean circulation model and a snow model. This verification will be complemented by a selection of diagnostic, process and climatological studies based on the analyses which will not only provide examples to the general user of the ways in which the data can be applied, but also provide specific contributions towards meeting some of the broader targets of the EC's Work Programme in Energy, Environment and Sustainable Development. The studies will focus on trends in the observing system, the hydrological cycle, clear-sky radiation, Alpine snow simulation, upper-tropospheric and stratospheric ozone and water vapour, ocean waves, global mass, heat, energy and moisture budgets, and diagnosis of atmospheric circulation systems.
The results of the project will make a major contribution to climate research and monitoring particularly in the areas of seasonal prediction, impacts, change detection and atmospheric chemistry. The availability of ERA-40 analyses will revitalise the use of data from past field experiments, as well as documenting the benefit of enhancements to global climate observing systems and the deployment of satellite systems over the past three decades.
Funding SchemeCSC - Cost-sharing contracts
3730 AE De Bilt
EX1 3PB Exeter
RG6 6BB Reading / Silchester