Description and PurposeThe Tower Mounted Radiometer System (TMRS1 and TMRS2) was a ground-based SSM/I simulator and surface energy balance monitoring system. The primary application of TMRS1 and TMRS2 were to collect long-term (months) time-series data sets at sites representative of various biomes in support of land surface process modeling and remote sensing research. The system was also used in support of studies in the passive remote sensing of soil moisture, frozen/thawed soil state determination, permafrost, and snow.
As such, it was environmentally hardened and designed to operate autonomously with remote monitoring and control capabilities via a low-bandwidth communications link such as a long-distance voice telephone channel.
History
TMRS1 was tested during REBEX-0 (Matthaei, 1992) and deployed during REBEX-1 (S. Dakota, 10/92-4/93) by John Galantowicz. Ed Kim spearheaded a redesign of TMRS1, later named TMRS2, in 1992. Components were tested during the summers of 1993 and 1994 at the University of Michigan (REBEX-2). TMRS2 system was first deployed for a full experiment by Ed Kim during REBEX-3 in arctic Alaska (9/94-9/95). It was later re-deployed by Jasmeet Judge for summer prairie experiments in S. Dakota (REBEX-4, 1996) and by the entire group in Oklahoma (REBEX-5, 1997) after improvements made by Mark Fischman and David Boprie.
Summary of Improvements Over TMRS1
The entire system was hardened for operation at temperatures down to -40C, and instruments for the measurement of soil moisture, Bowen ratio, snow temperature, and upwelling shortwave radiation were added. All the MMS instruments were co-mounted on self-supporting structures, necessary for REBEX-3 since unfrozen tundra is mushy. The microwave radiometers at the SSM/I frequencies of 19.35 and 37.0 GHz were redesigned and dual-polarization capability (horizontal and vertical) was added. A larger, more robust movable reflector was added for measurements of sky radiobrightnesses. Heaters were liberally added throughout the system. Optical fiber links were designed and installed to allow instruments to be located 30 meters away from the controlling computer - necessary for REBEX-3 since vehicles are not permitted to drive over the fragile tundra (so the support trailer could not be located next to the instruments as with TMRS1) - and to provide electrical isolation. Signal multiplexers were added to avoid having to run dozens of cables over that distance.
List of TMRS2 Instruments
TMRS2 was composed of a Radiometer Subsystem, a Micro-Meteorological Subsystem (MMS), and a Control and Data Management Subsystem (CDMS). The components of each subsystem are listed below.
| Description | Mfr/Model |
| Micro-Meteorological Instruments |
|
| 10-meter anemometer | Met-One 014A |
| 2-meter anemometer and wind vane | Davis Instruments 7911 |
| 2m Air temperature and Relative humidity | Vaisala HMP-35AC |
| Bowen Ratio (intakes at 1 and 2 m) | Campbell 023 |
| Downwelling shortwave hemispherical flux | Eppley 8-48 (black and white) |
| Upwelling shortwave hemispherical flux | Eppley 8-48 (black and white) |
| Net radiometer w/aspirator | REBS Q-6 |
| Rain gage | Texas Electronics 525 |
| Rain gage wind screen | Novalynx Alter-type |
| TDR Soil moisture (10 probes) | Campbell & Tektronix |
| Subsurface temperature (12 probes) | Campbell thermistor 107, 107B |
| Snowpack temperature (12 probes) | Campbell-equivalent thermistors |
| Snowpack depth | graduated rod and video camera |
| Subsurface heat flux (3 disks) | Thornthwaite 610 |
| CDMS Componets |
|
| Data logger and controller (hardware) | Apple Macintosh, National Instruments |
| Data logger and controller (software) | custom Hypercard program |
| Microwave/IR Radiometers |
|
| 19.35 GHz V & H polarizations | custom UMich design |
| 37.0 GHz V & H polarizations | custom UMich design |
| 85.5 GHz V or H polarization | custom UMich design |
| thermal IR radiometer | Everest Interscience 4000ALCS |
| Other Instruments |
|
| Video camera | Panasonic 1410 |
| TMRS2 Images | |
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(Note: Ed is not technically part of TMRS2) |
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