Presentation is loading. Please wait.

Presentation is loading. Please wait.

UNCLASSIFIED GRIDDING & BETA CORRECTION 11 May 1999 Meteorological Satellite Analyst SSgt Dave Mayer.

Similar presentations


Presentation on theme: "UNCLASSIFIED GRIDDING & BETA CORRECTION 11 May 1999 Meteorological Satellite Analyst SSgt Dave Mayer."— Presentation transcript:

1 UNCLASSIFIED GRIDDING & BETA CORRECTION 11 May 1999 Meteorological Satellite Analyst SSgt Dave Mayer

2 UNCLASSIFIED Gridding Cont. -A grid is an array of points. -Grids are used to record regularly spaced samples over an area. -When sampling over the surface of the earth a grid is determined by a map projection, a sampling interval, an origin, and the number of rows and columns. -A map projection is a one to one mapping of points on the curved surface to points on the plane. -Curved surface is the surface of the Earth and the plane is what we call a "map.

3 UNCLASSIFIED Gridding Cont. -Coordinates for points on the surface of the Earth are given in latitude and longitude. -Coordinates in the map plane (x,y) are defined in the usual manner with x horizontal and increasing to the right and y vertical and increasing upward. -Map transformations are referred to as projections. -Most Maps are either conformal or equal-area.

4 UNCLASSIFIED Gridding Cont. A grid coordinate system is map plane with axes parallel to the rows and columns of the grid and units equal to the sampling interval. A grid cell is the area between grid coordinates. It might be useful to think of the grid as a map drawn on graph paper.

5 UNCLASSIFIED Gridding Cont. -Gridding is calculated by the receiver during or after the processing of an image. -Receiver uses the known (or expected) location of the satellite -Map projection options using TeraScan. Albers conic Mercatororthographic equal area cylindrical Mollweide rectangular equidistant azimuthal perspective stereographic Lambert azimuthal polarstereo UTM Lambert conic polyconic

6 UNCLASSIFIED GRIDDING ERRORS First rule of gridding: Do not trust the computer-generated overlay … it is entirely dependent on faulty ephemeris! Look for geography and compare with map overlay. Add or subtract as needed

7 UNCLASSIFIED Beta Correction -Final adjustment for center displacement -Due to distance of the storm from the subsatellite point or because of storm relative motion. -when upper features are a considerable distance from the subsatellite point, cyclone center appears farther away from the satellite. -Error is related to viewing angle of the satellite and the height of the cloud features.

8 UNCLASSIFIED Beta Correction Cont. -For average tropical cyclones center position should be adjusted -0.05deg latitude for storms 15-25deg from the SST. -0.1deg latitude For storms 30deg latitude or more from the SST. -Corrections are automatically determined by computer at some facilities.


Download ppt "UNCLASSIFIED GRIDDING & BETA CORRECTION 11 May 1999 Meteorological Satellite Analyst SSgt Dave Mayer."

Similar presentations


Ads by Google