FNMOC 181 x 360 Monthly Mean Interpolated Sea Level Pressure and calculated Air/Ocean Indices

Available on this page are monthly averages of the FNMOC (Fleet Numerical Meteorology and Oceanography Center) 6-hourly analyzed pressure fields interpolated where necessary to a 360 by 181 global spherical grid (1-degree), and Air/Ocean indices computed from the interpolated pressure. These can be subsetted, visualized, and downloaded in a variety of formats.

Please note that these products are calculated differently than the standard historical products on our home page (see links to calculation details below). These new pages are attempt to improve our products, and are currently still under development. We will continue to maintain the old product in order to provide a consistent time series for our long-time users.

Interpolated Sea Level Pressure

As computational and data storage resources have improved over the years, the grid resolution used by FNMOC in running it's models has increased. The following table shows the spatial resolution of the gridded six-hourly pressure fields provided by FNMOC since 1967:

Years	Projection	Coverage	Resolution
1967 - 1980	63 x 63 polar stereographic	Northern Hemisphere	about 3° latitude
1981 - 1996	73 x 144 spherical	global	2.5°
1996 - present	360x181 spherical	global	1°

In order to provide complete time series of upwelling and air/ocean indices, the six-hourly pressure for the years 1967 through 1996 have been interpolated onto a 360 by 180 1-degree grid. Details

For more information on the models used to compute these data please see:

Rosmond, T. E., 1992: A prototype fully coupled Ocean-Atmosphere Prediction System, Oceanography Vol. 5, No. 1, 25-30.

Clancy, R. M., 1992: Operational Modeling: Ocean Modeling at the Fleet Numberical Oceanography Center, Oceanography Vol. 5, No. 1, 31-35.

Air/Ocean Indices Computed from Interpolated Sea Level Pressure

(Global Upwelling Index data group on LAS)

Northern Hemisphere (1967 - 1980) and global (1981 - present) values of the following quantities have been calculated from the interpolated six-hourly 1-degree sea level pressure fields, and can be subsetted, visualized, and downloaded in a variety of formats.

Pressure, mean sea level
N-S and E-W components of geostropic wind
Geostropic wind vector and magnitude
N-S and E-W components of geostropic wind stress
Geostropic wind stress vector and curl
N-S and E-W components of Ekman transport

The standard PFEL procedures have been used in the calculation, with the following exceptions:

Derivatives are computed on a 1-degree mesh length rather than 3-degree. Details
The geostropic winds used to calculate Ekman transport are monthly averages of winds calculated from 6-hourly pressure values.Details
The drag coefficient used in computing wind stress is a function of wind speed rather than a constant. Details
GMT time is used when calculating means rather than local time as was done in the historical products

For details on the standard procedures PFEL uses to compute upwelling index, please see:

Schwing, F. B., O'Farrell, M., Steger, J., and Baltz, K., 1996: Coastal Upwelling Indices, West Coast of North America 1946 - 1995,NOAA Technical Memorandum NMFS-SWFSC-231
The PFEL home page