JPL has developed the airborne rain-mapping radar ARMAR to help study the
problems that will be faced by the space-borne TRMM precipitation radar.
The following table summarizes the characteristics of both systems:
ARMAR TRMM
Frequency 13.8 GHz 13.8 GHz
Nominal Altitude 12.0 km 350.0 km
Scanning swath 9.0 km 220.0 km
Surface horizontal resolution 0.8 km 4.0 km
Range resolution 80.0 m 250.0 m
Signal type Chirp CW
Peak power 200.0 W 600.0 W
Polarization(s) HH,VV,HV,VH VV
The similarities between ARMAR and TRMM include:
- ARMAR operates at 13.8 GHz, the same frequency as the TRMM
precipitation radar.
- ARMAR operates by looking downward and scanning its antenna in the cross-track
direction, matching the TRMM radar's operating geometry.
ARMAR's additional capabilities include:
- multiple polarization
- Doppler velocity measurement
- A 13.8 GHz radiometer channel for brightness temperature measurement
ARMAR was field-tested in a ground-based configuration during several occasions
in 1991-92, and was flight-tested on the NASA DC-8 aircraft in May and December
of 1992. These tests confirmed that the radar did meet design specifications.
In particular, the use of time-domain weighting of the transmitted chirp achieves
a remarkable range sidelobe level of -55 dB or better.
ARMAR has been used:
- in the
TOGA-COARE experiment (click
here to jump directly to the ARMAR page in NASA-GSFC's TOGA-COARE web site).
- to develop simulated TRMM PR data based on
the TOGA-COARE measurements.
To retrieve a copy of the 1994 J.Tech. paper describing ARMAR:
To retrieve a copy of the pre-print describing ARMAR's observations of
the melting layer during TOGA-COARE:
For further info email sdurden@jpl.nasa.gov
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