LAADS MYD

This document describes the LAADS MYD data files. This document is sub-divided into three sections: Aqua MODIS Level 1, Aqua MODIS Level 2 and Aqua MODIS Level 3.

Please pay attention on the special usage of scale and offset attributes for some files.

Aqua MODIS Level 1

HDF-EOS2 Swath files

For the swath files using the dimension map, users need to either find the corresponding geolocation HDF-EOS2 files or calculate the latitude/longitude based on dimension map parameters.
The size of dimension varies in geolocation fields and data fields. For example, in file MYD02HKM.A2002193.0000.005.2009192212603.hdf, the dimension size of geolocation is 2030 (10*nscans) x 1354 (Max_EV_frames), while the dimension size of data fields is 4060 (20*nscans) x 2708 (2*Max_EV_frames).

The following table summarizes the information collected for the files:

File type	File size(avg.)	Geolocation Field	Datafield Dim. Range	CF-compliant information	Other special issues
HDF-EOS2 (Swath)	15.4MB - 155.8MB	Lat/Lon = 2D	2D, 3D	1. Geolocation fields have ‘units’ attribute, and Datafields have both ‘units’and 'long_name' attributes; 2.'units' attribute for latitude and longitude is 'degree'.	Some files contain following issues: 1. There are several pairs of 'scales' and 'offsets' attributes for some variables; 2. Use dimension map

pseudo eos_2 files

The pseudo eos_2 files contain between 120-138 datasets. They have no geolocation fields and their data fields are mostly 3-Dimension fields.

Aqua MODIS Level 2

HDF-EOS2 Swath file

For the swath files using the dimension map, users need to either find the corresponding geolocation HDF-EOS2 files or calculate the latitude/longitude based on dimension map parameters.
The size of dimension varies in geolocation fields and data fields. For example, in file MYD05_L2.A2002184.2200.005.2007068182040.hdf, the dimension size of geolocation is 406 (Cell_Along_Swath_5km) x 270 (Cell_Across_Swath_5km), while the dimension size of data fields is 2030 (Cell_Along_Swath_1km) x 1354 (Cell_Across_Swath_1km)

The MYDCSR_G files do not have geolocation fields but the other swath files do.

The following table summarizes the information collected for the files:

File type	File size(avg.)	Geolocation Field	Datafield Dim. Range	CF-compliant information	Other special issues
HDF-EOS2 (Swath)	748KM -39MB	Lat/Lon = 2D( MYDCSR_G files do not have )	2D, 3D	Both geolocation fields and data fields have ‘units’ attribute and 'long_name' attributes.	Some files contain following issues: 1. Use dimension map; 2. Special usage of scale and offset attributes;

pseudo eos_2 file:

The pseudo eos_2 file contain 37 datasets. It has 2 dimension latitude and longitude fields and its data fields are 2-Dimension or 3-Dimension fields.

Aqua MODIS Level 3

HDF-EOS2 Swath files

The following table summarizes the information collected for the files:

File type	File size(avg.)	Geolocation Field	Datafield Dim. Range	CF-compliant information
HDF-EOS2 (Swath)	803MB	No	2D	Datafields have both ‘units’and 'long_name' attributes.

HDF-EOS2 Grid files

The following table summarizes the information collected for the files:

File type	File size(avg.)	Number of grid	Has lat/lon	Projection	Datafield Dim. Range	CF-compliant information	Other special issues
HDF-EOS2 (Grid)	18.4MB	1	No	GEO	2D-4D	Data fields do not have either 'units' or 'long_name' attributes'	Special usage of scale and offset attributes;

To retrieve sample MYD files and read the detailed description of these files, please click here.

Last modified: 06/02/2017