What is the TMPA (3B42, 3B43) grid structure?
Posted: Tue Sep 01, 2026 1:55 pm America/New_York
Answer:
Each 3B42 file contains a 3-hourly estimate and each 3B43 file contains a one-month estimate. The grid on which each field of values is presented is a 0.25 deg x 0.25 deg latitude--longitude (Cylindrical Equal Distance) array of points over the latitude range 50N-S. It is size 400x1440, with X (latitude) incrementing most rapidly South to North, and then Y (longitude) incrementing West to East from the Date Line. Grid edges are located at whole-degree values:
First point center = (49.875S,179.875W)
Second point center = (49.625S,179.625W)
Last point center = (49.875N,179.875E)
The same grid-box definition applies to the RT (use 59.875S) and to the monthly.
Each 3B42 file contains a 3-hourly estimate and each 3B43 file contains a one-month estimate. The grid on which each field of values is presented is a 0.25 deg x 0.25 deg latitude--longitude (Cylindrical Equal Distance) array of points over the latitude range 50N-S. It is size 400x1440, with X (latitude) incrementing most rapidly South to North, and then Y (longitude) incrementing West to East from the Date Line. Grid edges are located at whole-degree values:
First point center = (49.875S,179.875W)
Second point center = (49.625S,179.625W)
Last point center = (49.875N,179.875E)
The same grid-box definition applies to the RT (use 59.875S) and to the monthly.