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.
Technical Specifications
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 |