2000 Innovation Collection Case Study - Smithsonian's Permanent Research Collection
Abstract
Computer models have formed the basis for weather forecasting for more than 35 years. Global atmospheric models are run daily on the largest available supercomputers, dedicated to this single task, by national governments and super-national consortia. First the previous forecast and all available observations are blended in a data assimilation phase to form "nowcast" of the current state of the atmosphere, and then this state is advanced in time to form a 3-10 day forecast. This must all be performed under real time constraints, typically within a 4-6 hour window. The results are then used directly for general weather forecasting and as input to higher resolution local models (e.g. for storm forecasting). Ocean forecasting is in principle similar to atmospheric forecasting, but with two major complications: (a) ocean eddies, at about 60 miles across, are typically 20 to 30 times smaller than comparable atmospheric highs and lows which means that roughly four orders of magnitude more computer time and three orders of magnitude more computer memory are required; and (b) there are relatively few observations below the ocean surface so data assimilation is effectively confined to using satellite observations of the surface. The duration of forecast skill for the ocean is not restricted to the 10 to 14 day limit for atmospheric highs and lows. We have demonstrated at least 30-day predictive skill for ocean eddies and the meandering of ocean currents and fronts, given sufficient ocean model resolution and satellite altimeter data from ERS-2 and TOPEX/POSEIDON. Forecasts of several months, or even years, are possible for some ocean phenomena.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 2000
- Accession Number
- ADA378436
Entities
People
- Harley Hurlburt
Organizations
- United States Naval Research Laboratory