Atmospheric data such as temperature, moisture, winds, etc., collected by satellites flying balloons etc are assimilated to numerical model forecast through a statistical process called Kalman filter to provide a coherent, consistent, regular gridded dataset. These observation-based datasets, collected and processed every 6 hours by NASA, are useful for climate models validations, better understanding of weather patterns, etc.

The Physical-space Statistical Analysis System is an advanced data analysis system developed at the Data Assimilation Office of NASA's Goddard Space Flight Center. The T3E implementation of this code reduces the solution time is reduced to 24.6 seconds on NERSC's 512-PE T3E from 5 hours on a single head of Cray C90 for a real problem of 80,000 observations, a 740-fold reduction of turn-around time.

Related papers :

• "A Parallel Climate Data Assimilation Package",
  C.H.Q. Ding and R.D.Ferraro. Front page article on Nov 1996 issue of SIAM News.

• "An 18 GFLOPS Parallel Climate Data Assimilation PSAS Package", C.H.Q.Ding and R.D.Ferraro. Intel Supercomputer User Group Conference '96, Knoxville,TN, June 1996 ( Best Paper Award of the conference). Extended version appeared in Int'l J. Mathematics & Computation. Vol. 35, No. 7, 1998, pp. 55-63.

• "Climate Data Assimilation on a Massively Parallel Supercomputer" .
  C.H.Q.Ding and R.D. Ferraro
  Proceedings of Supercomputing'96.

• "Atmospheric Data Assimilation on Distributed-Memory Parallel Supercomputers .
  C.H.Q.Ding, P.M. Lyster, J. W. Larson, J. Guo, A. da Silva.
  Lecture Notes in Computer Science, vol.1401. Eds. P. Sloot, M. Bubak, R. Hertzbeger. 1998. pp.115-124.