PSAS

Abstract

The Physical-space Statistical Analysis System (PSAS) is a software package that supports atmospheric data assimilation. Data assimilation is the synthesis of observational data with a weather forecast to obtain an analysis of the state of the atmosphere. This process requires the solution of a large linear system on the unstructured observation grid and use of this solution to calculate analysis increments on the structured forecast grid. Application of the analysis increments to the forecast yields the analysis. PSAS solves for the analysis increments. The source code is written in C and Fortran 77 and implements parallelism using a message passing paradigm. The software comprises: 1) an inertial recursive bisection partitioner, 2) a static load-balancing algorithm, 3) a preconditioned conjugate gradient solver, and 4) a scheme for transforming the solution on the unstructured grid back to the forecast grid. This code is the parallel implementation of an early version of the NASA Data Assimilation Office (DAO) PSAS. PSAS is in continual development and use at the NASA DAO.

DateOfInformation

Thr Jul 9 15:08:53 1998

Domain

Scientific and Engineering Applications

Keyword

Atmospheric Sciences, data assimilation, unstructured grid methods

Language

C with some Fortran 77

Name

PSAS

TargetEnvironment

CRAY T3E and SGI systems using MPI

Webpage

http://dao.gsfc.nasa.gov/DAO_people/jlarson/JPL_PSAS/index.html

ContactIs

J.W. Larson

Files

PSAS