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The HIRDLS instrument can obtain profiles over most of the globe, both day and night. Complete Earth coverage can be obtained in twelve hours. Observations of the lower stratosphere and upper troposphere are possible through the use of special narrow and more-transparent spectral channels.
After launch, activation of the HIRDLS instrument revealed that the optical path was blocked so that 20% of the aperture could view the earth's atmosphere. Engineering studies suggest that a piece of thermal blanketing material ruptured from the back of the instrument during the explosive decompression of launch. Attempts to remove this material mirror failed. However, even with the 80% blockage, measurements at high vertical resolution can be made at one scan angle.
HIRDLS Parameters
| Spectral
Range: |
6 to
18 mm |
| Standard
profile spacing: |
5o
longitude x 5o latitude, and 1-km
vertical resolution; programmable to other modes and resolutions |
| Spatial
resolution: |
Profile
spacing 500 km horizontally
(5o lat) x 1 km
vertically; averaging volume for each data sample 1 km
vertical x 10 km across x 300 km
along line-of-sight |
| Mass: |
220
kg |
| Duty
cycle: |
100% |
| Power: |
220
W (average), 239 W
(peak) |
| Data
rate: |
65
kbps |
| Thermal
control: |
Stirling
cycle cooler, heaters, sun baffle, radiator panel |
| Thermal
operating range: |
20o-30o C |
| Scan
range: |
Elevation,
22.1o to 27.3o below horizontal, Azimuth, -21o (sun side) to +43o
(anti-sun side) |
| Detector
IFOV: |
1
km vertical x 10 km
horizontal |
|
Pointing
requirements (platform+instrument, 3s):
|
| Control
& Knowledge: |
Such
that scan range will allow all channels to observe from 0.25o
below the hard horizon to 3.25o above it |
| Stability: |
30
arcsec/sec
per axis |
| Jitter: |
84-Hz
sample spacing uniform to ±7 arcsec |
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Key Facts
|
+ Heritage: LRIR
(Nimbus-6), LIMS
and SAMS
(Nimbus-7), ISAMS
and CLAES
(UARS)
+ Observes global distribution of temperature and concentrations
of O3,
H2O,
CH4,
N2O,
NO2,
HNO3,
N2O5,
CFC11, CFC12,
ClONO2,
and aerosols in the upper troposphere, stratosphere, and mesosphere
+ Scanning infrared limb sounder
+ 21 photoconductive HgCdTe detectors cooled to 65 K;
each detector has a separate band-pass interference filter
+ Joint program between University of Colorado and Oxford University
Prime Contractors: Lockheed Martin (U.S.)
and Astrium (U.K.)
Multimedia
Scan mirror rotating inside the optical assembly.
+ View Animation
Internal components of the optical assembly
+ View Animation
Related Links
+ HIRDLS Homepage at UCAR
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