Taking A Look At Raw AMSR-E Data

In this post we're going to take a look at the data in the Level 2A AMSR-E file. But first, a short review on how the AMSR-E scans data.

The AMSRE-E scans at 6 frequencies: 6.9, 10.7, 18.7, 23.8, 36.5, and 89.0 GHz. There are 5 scanning resolutions. The first four scanning resolutions are considered "low res" and stored in an array of data that is 1994 by 243 positions. The fifth scanning resolution is "high res" and stored in an array that is 1994 by 486 positions.

There are also smoothed and unsmoothed versions of the data. The chart below shows which versions of data for each frequency are stored in the Level 2A file.

Link to original table

AMSR-E Spatial Characteristics of Observations

Reso-lution	Foot print	Mean spatial resolution	Channels
			89.0 GHz	36.5 GHz	23.8 GHz	18.7 GHz	10.7 GHz	6.9 GHz
1	75 km x 43 km	56 km	•	•	•	•	•	• o
2	51 km x 29 km	38 km	•	•	•	•	• o
3	27 km x 16 km	21 km	•	•	• o	o
4	14 km x 8 km	12 km	•	o
5	6 km x 4 km	5.4 km	o

•  Includes Level-2A (smoothed) data
o  Includes Level 1B (un smoothed) data at original spatial resolution

In addition to all this each scan has two components, a vertical (V) component and a horizontal (H) component. These different components are used to measure electric and magnetic values which in turn are used to make determinations about exactly what is being scanned (land, sea, ice, water vapor, etc.)

All of these variations are stored in the Level 2A AMSR-E file. The table below provides the variable names for all this data.

Level 2A Variable names

Variable Name	Data
6.9V_Res.1_TB_(not-resampled)	6.9 V Res 1
6.9H_Res.1_TB_(not-resampled)	6.9 H Res 1
10.7V_Res.2_TB_(not-resampled)	10.7 V Res 2
10.7H_Res.2_TB_(not-resampled)	10.7 H Res 2
18.7V_Res.3_TB_(not-resampled)	18.7 V Res 3
18.7H_Res.3_TB_(not-resampled)	18.7 H Res 3
23.8V_Approx._Res.3_TB_(not-resampled)	23.8 V Res 3
23.8H_Approx._Res.3_TB_(not-resampled)	23.8 H Res 3
36.5V_Res.4_TB_(not-resampled)	36.5 V Res 3
36.5H_Res.4_TB_(not-resampled)	36.5 H Res 3
6.9V_Res.1_TB	6.9 V Res 1 Smoothed
6.9H_Res.1_TB	6.9 H Res 1 Smoothed
10.7V_Res.1_TB	10.7 V Res 1 Smoothed
10.7H_Res.1_TB	10.7 H Res 1 Smoothed
10.7V_Res.2_TB	10.7 V Res 2 Smoothed
10.7H_Res.2_TB	10.7 H Res 2 Smoothed
18.7V_Res.1_TB	18.7 V Res 1 Smoothed
18.7H_Res.1_TB	18.7 H Res 1 Smoothed
18.7V_Res.2_TB	18.7 V Res 2 Smoothed
18.7H_Res.2_TB	18.7 H Res 2 Smoothed
23.8V_Res.1_TB	23.8 V Res 1 Smoothed
23.8V_Res.1_TB	23.8 H Res 1 Smoothed
23.8V_Res.2_TB	23.8 V Res 2 Smoothed
23.8H_Res.2_TB	23.8 H Res 2 Smoothed
23.8V_Res.3_TB	23.8 V Res 3 Smoothed
23.8H_Res.3_TB	23.8 H Res 3 Smoothed
36.5V_Res.1_TB	36.5 V Res 1 Smoothed
36.5H_Res.1_TB	36.5 H Res 1 Smoothed
36.5V_Res.2_TB	36.5 V Res 2 Smoothed
36.5H_Res.2_TB	36.5 H Res 2 Smoothed
36.5V_Res.3_TB	36.5 V Res 3 Smoothed
36.5H_Res.3_TB	36.5 H Res 3 Smoothed
89.0V_Res.1_TB	89.0 V Res 1 Smoothed
89.0H_Res.1_TB	89.0 H Res 1 Smoothed
89.0V_Res.2_TB	89.0 V Res 2 Smoothed
89.0H_Res.2_TB	89.0 H Res 2 Smoothed
89.0V_Res.3_TB	89.0 V Res 3 Smoothed
89.0H_Res.3_TB	89.0 H Res 3 Smoothed
89.0V_Res.4_TB	89.0 V Res 4 Smoothed
89.0H_Res.4_TB	89.0 H Res 4 Smoothed
89.0V_Res.5A_TB_(not-resampled)	89.0 V Res 5
89.0H_Res.5A_TB_(not-resampled)	89.0 H Res 5

The different frequencies are used to measure different attributes of the Earth, as shown in the table below.

Frequency Measurements

Frequency	Measurement
6.9	Sea Surface Temperature, Soil Moisture, Vegetation
10.7	Sea Surface Temperature, Wind Speed
18.7	Wind Speed, Water Vapor
23.8	Unknown
36.5	Cloud Liquid Water
89.0	Rain Rate

With the above information, you can pull the desired data from the Level 2A file. The data for an actual file for 36.5V_Res.4_TB_(not-resampled), which the cloud liquid water frequency,  is shown below. It shows a single scan line.

References And Previous Posts In this Series:
AMSRE_4_NWS.ppt
Taking A Look At Raw UAH Data
HDF Reader C++ Code Is Written!
Some Useful Climate Code
Summary Of Aqua Satellite Data, Computer Code, And Broken Equipment
Aqua Satellite Raw AMSR-E Data
Aqua Satellite Raw UAH Data, Part 2
Aqua Satellite Raw UAH Data, Part 1
Satellite Summary
Aqua Satellite Data Processing
A Note On The UAH And RSS Raw Data
How UAH And RSS Temperatures Are Measured
Overview Of The Aqua Satellite
Looking At The Aqua Satellite Data
UAH Satellite Data
Dangit! More Climate Stuff. UAH and RSS Raw Data