|
| EDG Data Set Name |
Granule Shortname |
| MODIS/Aqua Geolocation Angles Daily L2G Global 1km SIN Grid Day |
MYDMGGAD |
| Version |
Acquisition Range |
Science Quality Status |
| V003 |
March 6 2003 (2003065) |
Validated |
|
Data Set Characteristics
Area = 10° x 10° lat/long
Image Dimensions = 2 (1200x1200 row/column)
Average File Size = ~27 MB
Resolution = 1 kilometer
Projection = Sinusoidal
Processing Level = 2G
Data Format = HDF-EOS
Science Data Sets (SDSs) = 7
Product Description
The MODIS Global Geolocation Angle Day-mode (MYDMGGAD) files contain information
on solar illumination and instrument viewing geometry. These data can be used to
model the geometric relationship and distance between the area of the Earth's
surface that was imaged, the sun, and the sensor. This is often required to
perform atmospheric corrections, composite data from multiple days, and/or to
convert or calibrate spectral data to known (absolute) radiance or reflectance
units.
|
| Color |
Azimuth Angle |
| Black |
Fill |
| Yellow |
-180° to -160° |
| Green |
-160° to -140° |
| Blue |
-140° to -120° |
| Purple |
-120° to -100° |
| Color |
Zenith Angle |
| Black |
Fill |
| Purple |
10° to 15° |
| Green |
15° to 20° |
| Orange |
20° to 25° |
| Pink |
25° to 30° |
|
|
The above images
represent daytime geolocation information acquired over the western coast of
North America on July 26, 2003. The example shown of solar azimuth (top image)
quantifies the direction from which the sun was illuminating the area at the
time of observation. The example of solar zenith (bottom image) quantifies the
angle between the ground surface normal (local vertical) and the sun at the same
time. MYDMGGAD also contains information on sensor angle quantified in a similar
manner as the examples shown above, as well as the range from the sensor to the
ground point. The combination of sensor and solar angle information allows the
solar illumination and instrument viewing geometry of the surface target to be
determined.
MYDMGGAD files are
used as input to higher level products such as MODIS Surface Reflectance
(MYD09). Geometric information for each sensor observation is stored on a
geolocated grid, with Level 2 geophysical parameters stored as Level 2 Gridded
(L2G) products. Each file contains all of the MODIS day-mode data acquired for a
single data-day (24 hours GMT) that intersects the tile. The observations stored in the L2G grids are examined by the Level 3 products to extract the most relevant observations for each grid cell.
NOTE: These
products are validated, meaning that product uncertainties are well defined over
a range of representative conditions. Although there may be later improved
versions, these data are ready for use in scientific publications.
| SDS |
Units |
Data Type -bit |
Fill Value |
Valid Range |
Multiply by
Scaling Factor |
| Solar Azimuth |
Degree |
16-bit signed integer |
-32767 |
-18000 - 18000 |
0.01 |
| Solar Zenith |
Degree |
16-bit signed integer |
-32767 |
0 - 18000 |
0.01 |
| Sensor Azimuth |
Degree |
16-bit signed integer |
-32767 |
-18000 - 18000 |
0.01 |
| Sensor Zenith |
Degree |
16-bit signed integer |
-32767 |
0 - 18000 |
0.01 |
| Range (pixel-sensor) |
Meters |
16-bit unsigned integer |
0 |
27000 - 65535
|
25 |
| Geolocation Flags |
Bit Field |
8-bit unsigned integer |
255 |
0 - 248 |
na |
| Number of Observations |
na |
8-bit signed integer |
255 |
0 - 127 |
na |
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EOS Data Gateway Search Tips
| Data Center: |
LPDAAC |
| Sensor: |
MODIS |
| Dataset: |
MODIS/Aqua Geolocation Angles Daily L2G Global 1km SIN Grid Day |
| Spatial: |
HORIZONTALTILENUMBER Max/Min VERTICALTILENUMBER Max/Min |
| Geographic Extent: |
Type Lat/Long Range or Draw on Map |
| Temporal Extent: |
2003-03-06 to present |
Product Information
Contact Information
|
