Data Assimilation & Prediction
Concurrent
advances in computing power, remote sensing of the atmosphere
from satellites, and forecast models have led to considerable
progress in numerical weather prediction (NWP), as a result extending
the usefulness of weather forecasts to five or six days.
The research in numerical weather prediction at AER spans all scales, from single point, local data assimilation and forecasting to global modeling. It also spans "nowcasting" (up to six hours ahead) to the medium range (five day forecasts). The Numerical Weather Prediction Group's various projects can be grouped around three main avenues of research: variational methods, cloud forecasting and observing systems studies.
Variational methods are used to infer some characteristics of a system by measuring some other quantities in the system. They have become an important focus of research in NWP in the last few years and AER is one of a dozen NWP groups around the world actively involved in these methods. AER has made contributions in:
- retrieval of atmospheric profiles from satellite data: inferring temperature and moisture profiles from radiance measurements;
- meteorological data assimilation: inferring the complete state of the atmosphere from incomplete or indirect measurements;
- optimization of forecast model parameters for local forecasting: inferring the best parameters to use from the forecast errors.
The cloud forecasting problem has been approached at AER with different techniques:
- extrapolation of satellite pictures for the very short range;
- use of cloud data to infer atmospheric moisture;
- complex statistical techniques for long range and climate applications.
Observing system studies have been done mainly in the context of using satellite data in weather forecasting:
- developing methods to optimize the use of existing measurements;
- evaluating the usefulness of proposed new systems such as lidars to measure winds;
- developing methods to use new measurements such as scatterometer data.
The DAP group works very closely with other groups at AER, especially the Remote Sensing group, since much of its work deals with the use of satellite data in NWP.
AER's DAP group also has close contacts with other national and international institutions such as the U.S. National Meteorological Center, the Goddard Space Flight Center and the European Centre for Medium-Range Forecasts. Current or recent sponsors of AER's NWP research are NASA, NSF, NOAA, DOE and the U.S. Air Force