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MODIS Airborne Simulator (MAS/eMAS)

The Moderate Resolution Imaging Spectroradiometer (MODIS) Airborne Simulator (MAS) sensor was developed for NASA's high-altitude ER-2 research aircraft by Daedalus Enterprises, Inc., in support of the MODIS remote sensing algorithm development. The overall goal was to modify the spectral coverage and gains of the MAS to emulate as many of the MODIS spectral channels as possible. With its much higher spatial resolution (50 m vs. 250-1000 m for MODIS), MAS is able to provide unique information on the small-scale distribution of various geophysical parameters. The MAS instrument has been deployed on multiple platforms for many field campaigns since its first mission in 1991, as the prototype Wildfire Spectrometer.

The locations of the MAS spectral channels were chosen to enable a wide variety of Earth science applications. Of the 50 MAS channels, 19 have corresponding channels on MODIS. The remaining MAS channels fill in the spectral region around MODIS locations and some provide unique coverage. One application of the MAS solar channels is the study of cloud properties at high spatial resolution. In addition to the remote sensing of cloud radiative and microphysical properties, MAS is valuable for the remote sensing of land and water properties under clear-sky conditions. MAS visible and near-infrared channels have been used to estimate suspended sediment concentration in near-shore waters and to identify water types (Moeller et al. 1993, Huh et al. 1995). Land vegetation properties can also be studied.

Prior to 1995, the MAS was deployed on the NASA's ER-2 and C-130 aircraft platforms using a 12-channel, 8-bit data system that somewhat constrained the full benefit of having a 50-channel scanning spectrometer. Beginning in January 1995, a 50-channel, 16-bit digitizer was used on the ER-2 platform, which greatly enhanced the capability of MAS to simulate MODIS data over a wide range of environmental conditions. Recently, it has undergone extensive upgrades to the optics and other components. New detectors have been installed and the spectral bands have been streamlined. The Enhanced MAS sensor (eMAS) instrument is now a 38-channel instrument, sensing in the range from 0.445 to 13.844 um.

The eMAS instrument is maintained and operated by the Airborne Sensor Facility at NASA Ames Research Center in Mountain View, California, under the oversight of the EOS Project Science Office at NASA Goddard.

Platform:NASA ER-2 aircraft
Altitude:20 kilometers (nominal)
Spatial Resolution:50 meters (at 20 km altitude)
Pixels per Scan Line:716 (roll corrected)
Swath width:37.25km or 22.9mi (at 20km altitude)
Total Field of View:85.92 deg
Roll Correction:Plus or minus 15 degrees (approx)
Data Channels:50 (pre-1995 data had 12 selected from 50 spectral bands)
Spectral Bands:50 (digitized to 16-bit resolution)
Port 1: 9 bands from 0.445 - 0.967 micron
Port 2: 16 bands from 1.593 - 2.402 microns
Port 3: 15 bands from 3.053 - 5.389 microns
Port 4: 9 bands from 8.339 -14.428 microns
Bits per Channel:12 bits (pre-1995: 8 bits, configured with 4 chs @ 10 bits, 7 chs @ 8bits)
Data Rate:246 Mb/hour
Visible Calibration:Integrating sphere on the ground
Infrared Calibration:Two black bodies on board

MAS 12 Channel Sensor

Band Number Peak Response Wavelength Bandwidth @ 50% Response
1 0.547 0.043
2 0.664 0.055
3 0.745 0.040
4 0.786 0.040
5 0.834 0.042
6 0.875 0.041
7 0.945 0.043
8 1.623 0.057
9 2.142 0.047
10 3.900 0.150
10 3.900 0.150
11 11.002 0.448
12 12.032 0.447

MAS 50 Channel Sensor

Band Number Peak Response Wavelength Bandwidth @ 50% Response
1 0.465 0.020
2 0.549 0.021
3 0.655 0.026
4 0.703 0.021
5 0.743 0.021
6 0.825 0.022
7 0.867 0.021
8 0.908 0.021
9 0.947 0.020
10 1.619 0.026
11 1.675 0.026
12 1.727 0.025
13 1.779 0.025
14 1.832 0.025
15 1.882 0.025
16 1.932 0.024
17 1.982 0.024
18 2.032 0.024
19 2.081 0.025
20 2.130 0.024
21 2.179 0.024
22 2.229 0.024
23 2.279 0.024
24 2.328 0.024
25 2.378 0.025
26 3.134 0.081
27 3.296 0.074
28 3.448 0.081
29 3.609 0.077
30 3.760 0.073
31 3.922 0.080
32 4.071 0.077
33 4.086 0.078
34 4.185 0.034
35 4.418 0.063
36 4.556 0.075
37 4.713 0.079
38 4.869 0.075
39 5.019 0.073
40 5.174 0.070
41 5.323 0.067
42 8.537 0.198
43 9.723 0.269
44 10.507 0.229
45 11.012 0.236
46 11.986 0.210
47 12.901 0.188
48 13.270 0.229
49 13.808 0.268
50 14.240 0.189

eMAS Sensor

Band Number Peak Response Wavelength Bandwidth @ 50% Response
1 0.465 0.020
2 0.549 0.021
3 0.655 0.026
4 0.703 0.021
5 0.743 0.021
6 0.825 0.022
7 0.867 0.021
8 0.908 0.021
9 0.947 0.020
10 1.619 0.026
11 1.675 0.026
12 1.727 0.025
13 1.779 0.025
14 1.832 0.025
15 1.882 0.025
16 1.932 0.024
17 1.982 0.024
18 2.032 0.024
19 2.081 0.025
20 2.130 0.024
21 2.179 0.024
22 2.229 0.024
23 2.279 0.024
24 2.328 0.024
25 2.378 0.025
26 3.732 0.095
27 6.730 0.114
28 7.310 0.117
29 8.251 0.128
30 8.542 0.126
31 9.728 0.126
32 10.197 0.122
33 11.034 0.132
34 12.025 0.120
35 12.603 0.122
36 13.354 0.123
37 13.639 0.124
38 13.957 0.114

Last updated: June 11, 2018