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HIRDLS SPARC Applications and Development Status

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Title: No Slide Title Author: Linda Henderson Last modified by: Linda Henderson Created Date: 7/13/2000 5:32:49 PM Document presentation format: On-screen Show – PowerPoint PPT presentation

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Title: HIRDLS SPARC Applications and Development Status


1
HIRDLS SPARC Applications and Development Status
John Gille University of Colorado and NCAR John
Barnett Oxford University
Alyn Lambert, David Edwards, Christopher
Palmer Michael Dials, Chris Halvorson, Eric
Johnson, Wayne Rudolf Ken Stone, Bob Wells, John
Whitney, Douglas Woodard
2
HIRDLS Scientific Goals The primary goals of the
High Resolution Dynamics Limb Sounder (HIRDLS)
experiment are to acquire data with which to
investigate 1) the recovery of the ozone layer
following the phase-out of some
halogen-containing chemicals 2) the role of
the upper troposphere and lower stratosphere
(UT/LS) in climate and 3) the chemistry of
the upper troposphere.
3
Recovery of the Ozone Layer
  • Stratospheric chlorine is predicted to decrease
    as a result of the Montreal Protocol and
    subsequent agreements
  • Chlorine abundances are decreasing in the
    troposphere, and now, in the stratosphere
  • The recovery of the ozone layer with decreasing
    Cl will be complicated by the lower temperatures
    in the lower stratosphere, due to greenhouse
    effects as well as the reduction in ozone itself
  • HIRDLS, and the Aura spacecraft, will fly during
    the unique period near the maximum loading of
    stratospheric chlorine. It will be important to
    acquire a record of atmospheric composition and
    behavior during this singular period.
  • One of the goals of HIRDLS is to document this
    period in the atmosphere, and use these data to
    understand ozone chemistry and radiative effects
    in this unique period.

4
Stratospheric Chlorine
Growth of stratospheric chlorine according to
various scenarios Figure 1
5
The Role of the UT/LS in Climate
  • The structure and behavior of the atmosphere
    around the tropopause are now known to be more
    complex than previously thought.
  • Exchange of material between the troposphere and
    the stratosphere takes place not only through
    ascent through the tropical tropopause, but also
    through transports along isentropic surfaces that
    cross the tropopause. These transports include
    those of radiatively active (e.g. CO2, H2O, CH4,
    etc.) and chemically active (N2O, CFC11, CFC12,
    H2O, etc.) gases that directly or indirectly
    influence the earths radiative balance.
  • Many of these transports are on finer scales than
    have been observed before. In addition, there
    are other features which lead to the formation of
    fine scale filaments.
  • One of HIRDLS goals is to observe these
    small-scale transports and subsequent mixing, and
    to clarify their effects in the climate system.

6
Transport Features Observed by HIRDLS
Figure 2 (from J. Holton/UGAMP)
7
Stratosphere-troposphere exchange on small scales
Passive tracers on the 320 K isentrope. Coloured
air is stratospheric, blank is tropospheric
Figure 3 From Appenzeller et al. 1995
8
  • UT/LS Chemistry
  • HIRDLS measurements will extend down into the
    lower stratosphere and upper troposphere when
    clouds are not too optically thick.
  • Trace species in this region are rapidly
    transported over long distances.
  • HIRDLS will obtain measurements of
  • O3, H2O, and HNO3, CFC11, CFC12, CH4, N20 and
    aerosols.
  • These data will greatly augment knowledge of
    composition and transports at these levels.

9
Summary of Measurement Requirements
  • Temperature lt50 km 0.4 K precision
  • 1 K absolute
  • gt50 km 1 K precision
  • 2 K absolute
  • Constituents O3, H2O, CH4, H2O, HNO3, NO2, N2O5,
    1-5 precision
  • ClONO2, CF2Cl2, CFCl3, Aerosol 5-10
    absolute
  • Geopotential height gradient 20
    metres/500 km (vertical/horizontal)
  • (Equivalent 60oN geostrophic wind)
    (3 m s-1)
  • Coverage
  • Horizontal - global 90oS to 90oN (must include
    polar night)
  • Vertical - upper troposphere to mesopause
    (8-80 km)
  • Temporal - long-term, continuous (5 years
    unbroken)
  • Resolution
  • Horizontal - profile spacing of 5o latitude x
    5o longitude (approx 500 km)
  • Vertical - 1-1.25 km
  • Temporal - complete field in 12 hours

10
The LIMB Scanning Technique
Infrared radiance emitted by the earths
atmosphere, seen at the limb, is measured as a
function of relative altitude
11
Spectral Locations of the HIRDLS Channels
Figure 5
12
Examples of Calculated Radiance Profiles
13
Driving Requirements on Accuracy and
Precision Retrieval based on N (h).
This leads to the most stringent requirements
Radiance Accuracy 1 (temperature channels
0.5), Random noise1-12 x 10-4 Wm-2 sr-1
(channel dependent) Sample spacing Accuracy 0.25
, random error of 1 arcsec (1 ?).
Requirements are divided between -
encoder on the scan mirror (motion relative to
optical bench), and - gyroscope on the
optical bench (motion of bench in inertial
space).
14
HIRDLS Alternative Global Mode Sub-Tangent Point
HIRDLS Boresight Tangent Point Latitudes and
Longitudes in the Alternative Global Mode
Figure 6
15
HIRDLS Instrument Consists of 9 Subsystems
  • SUN-SHIELD SUBSYSTEM (SSH)

IN-FLIGHT CALIBRATION SUBSYSTEM (IFC) OPTICAL
ITEMS AND ELECTRONICS TO ENABLE RADIOMETRIC
CALIBRATION DURING FLIGHT OPERATIONS.
TELESCOPE SUBSYSTEM (TSS) INSTRUMENT TELESCOPE
AND RELATED ELECTRONICS UNITS
POWER SUBSYSTEM (PSS) PROVIDES BASIC POWER
CONVERSION AND SWITCHING
  • UK
  • US

DETECTOR SUBSYSTEM (DSS) MULTI-CHANNEL INFRARED
RADIOMETRIC DETECTOR ARRAY AND DEWAR ASSEMBLY
INSTRUMENT PROCESSING SUBSYSTEM (IPS) SIGNAL AND
DATA PROCESSING TO SUPPORT MISSION SCIENCE
OPERATIONS AND HOUSEKEEPING FUNCTIONS
GYRO SUBSYSTEM (GSS) PROVIDES PRECISION BASE
MOTION DISTURBANCE DATA
STRUCTURAL THERMAL SUBSYSTEM (STH) PRIMARY
STRUCTURAL SUPPORT AND ENVIRONMENTAL ENCLOSURE
FOR ELECTRONIC UNITS AND TELESCOPE
COOLER SUBSYSTEM (CSS) PROVIDES ACTIVE
CRYO-COOLING FOR THE INSTRUMENT DETECTOR ARRAY
Figure 7
16
INSTRUMENT SUBSYSTEMS - EXPLODED VIEW
  • LEGEND
  • STH
  • SSH
  • TSS
  • DSS
  • GSS
  • CSS
  • IFC
  • PSS
  • IPS

Fixed Sunshield (STH)
Sunshield-Door (SSH)
Black Body Assembly (IFC)
Optical Bench Assy. with Shroud (TSS)
External Connector Bulkhead
Encoder Electronics Assy. (TSS)
Power Converter Unit (PSS)
Telescope Electronics Unit (TSS)
Cooler Control Unit (CSS)
Space-View Aperture Assembly (SSH)
Signal Processing Unit (IPS)
Gyro Electronics Unit (GSS)
Detector Dewar (DSS)
Gyro Mechanical Unit (GSS)
Baseplate (STH)
Black Body Electronics Unit (IFC)
S-Link (CSS)
Cooler Radiator Panel with Compressors
Displacer (CSS)
Inst. Processor Unit (IPS)
Flexible Vacuum Enclosure (CSS)
Vibration Isolators (TSS)
17
Optical Schematic
Figure 8
18
Figure 9
19
Figure 10
20
Structure Thermal Subsystem Status
Dummy MLI on Flight Structure in MMS Clean Room
Figure 11
21
HIRDLS Calibration Facility
Chamber optical bench
Clean room and vacuum chamber
Seismic isolator
Monochromator turret
22
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23
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24
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25
Verification of 1 KM Resolution
True Temperature Wave
Retrieved Temperature Wave
26
Figure 12
27
Summary
  • HIRDLS is a powerful and flexible instrument for
    the global measurement from the upper troposphere
    into the mesosphere of
  • Temperature, 10 trace species and aerosols
  • New features are
  • Fine spacing of measured profiles in the
    longitudinal direction (lt500km)
  • High vertical resolution (lt2 km vertical
    wavelength)
  • Ability to sound the upper troposphere and low
    stratosphere (UT/LS) regions
  • Measurement of many species with a range of
    chemical lifetimes
  • 5-6 year instrument life
  • Standard data will provide long-term detailed
    data and important insights into
  • Evolution of the ozone layer
  • Climate processes, especially in the tropopause
    region
  • Upper troposphere chemistry

28
Additional information on HIRDLS can be found at
the HIRDLS website, http//www.eos.ucar.edu/hird
ls/home.html.
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