The mapping of irregular observations to three dimensional data is accomplished using Objective Analysis techniques. Objective Analysis utilizes the Gauss-Markov or minimum error variance criterion to map the available data onto horizontal grids. The process repeats for different vertical levels and analysis times. HOPS includes two flavors of Objective Analysis: the full-matrix (global) Objective Analysis (OAG) and a local approximation (OA). Both OA's are actually 2-level OA's producing first a slowly varying "mean" field from synoptic data and/or climatology. A 2^nd level OA maps the synoptic data onto this mean field.

Objective Analysis in Action

OA

The local objective analysis program uses a local approximation to the full correlation matrix. In particular, it allows the user to limit the contributions to a pre-specified number of the most strongly correlate points. (Historically, this package was developed after a student "burned up" an entire year's allocation on a supercomputer for one analysis.) This approximation gives the local OA an advantage in speed, but tends to produce noisier output.

OAG

The global objective analysis program inverts the entire correlation matrix. This produces naturally smooth fields at a cost of time and the memory requirements of the program. In the cases where these costs are acceptable, the global OA is highly recommended over the local OA.

Local vs Global OA

Objective Analysis Software

(pub/HOPS)

Directory	Files	Date (MM/DD/YYYY)	Size Compressed (bytes)	Size Uncompressed (bytes)
OA/	Readme.oa	01/23/2001		21733
	oa_6.6.tar.Z	01/23/2001	139905	552960
	Ex_oa_6.6.tar.gz	01/23/2001	4866091	7809024
OAG/	Readme.oag	01/23/2001		21315
	oag_5.6.tar.Z	01/23/2001	135854	534528
	Ex_oag_5.6.tar.gz	01/23/2001	4874217	7821312