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Local Weather
Oberpfaffenhofen

The HIRDLS instrument is an international joint development project between the USA and UK and is flying on the Earth Observing System (EOS) AURA Mission Spacecraft.

The infrared limb-scanning radiometer is designed to sound the upper troposphere, stratosphere, and mesosphere to determine temperature; the concentrations of O3, H2O, CH4, N2O, NO2, HNO3, N2O5, ClONO2, CFCl2, CFCl3, and aerosols; and the locations of polar stratospheric clouds and cloud tops. The goals are to provide sounding observations with horizontal and vertical resolution superior to that previously obtained; to observe the lower stratosphere with improved sensitivity and accuracy; and to improve understanding of atmospheric processes through data analysis, diagnostics, and use of two- and three-dimensional models..

Objectives

Overall science goals of HIRDLS are to observe the global distributions of temperature and several trace species in the stratosphere and upper troposphere at high vertical and horizontal resolution. Specific issues to be investigated include:

  • Fluxes of mass and chemical constituents between the troposphere and stratosphere
  • Chemical processes, transport, and mixing by day and night(particularly in the lower stratosphere)
  • Momentum, energy, heat, and potential vorticity balances of the upper troposphere and middle atmosphere
  • Geographically and seasonally unbiased long-term climatologies and interannual variability of middle atmosphere temperature, constituents, dynamical fields, and gravity waves
  • Tropospheric cloud-top heights
  • Tropospheric temperature and water vapor retrievals (by providing high-resolution limb data for joint retrieval with EOS nadir sounders)
  • Diagnostic studies of atmospheric dynamics, chemistry, and transport processes to test and improve models of these processes.

Instrument

The instrument has a long heritage extending back to Nimbus-4, and will obtain profiles over the entire globe, including the poles, both day and night. Complete Earth coverage (including polar night) can be obtained in 12 hours. High horizontal resolution is obtained with a commandable azimuth scan which, in conjunction with a rapid elevation scan, provides a 2,000- to 3,000-km-wide swath of profiles along the satellite track. Vertical profiles are spaced every 5 degrees in latitude and longitude, with 1- to 1.5-km resolution. Observations of the lower stratosphere are improved through the use of special narrow and more transparent spectral channels. The instrument is programmable; thus, a variety of observation modes can be used, and may be adapted in flight to observe unexpected geophysical events.

HIRDL Parameters:

Swath

Typically six profiles across 2,000- to 3,000-km-wide swath

Standard profile spacing 5o longitude x 5o latitude, and 1-km vertical resolution; programmable to other modes and resolutions
Spectral Range 6 to 18 mm
Spatial Resolution Profile spacing 500 x 400 km horizontally (equivalent to 5 degrees long x 4 degrees lat) x 1 km vertically; averaging volume for each data sample 1 km vertical x 10 km across x 400 km along line-of-sight
Wavelength 6 to 18 µm (Band 1-21)
Detector CCD: 780 x 576 (spectral x spatial) pixels
Data Rate 65 kbps
Thermal Control By 65K Stirling cycle coolers, passive radiator, heaters, sun baffle
Field of View (FOV) Elevation, +-2.5 degrees about -25.3 degrees be low horizontal; azimuth, -20 degrees (sun side) to +50 degrees (anti-sun side)
Instrument Instantaneous FOV 1 km vertical x 10 km (2.5 degrees ) horizontal

Data Access

General Data Product Level Definition

Data received by the ground station, is processed at the University of Boulder Science Processing Suite (SIPS) before being archived at the Distributed Active Archive Center (DAAC). As HIRDLS is a joint US-UK programme, the BADC will mirror the data stored in the DAAC for ease of access. BADC data will be subject to the same access constraints as the data in the DAAC. HIRDLS data is currently being collected and several teams are undertaking calibration and validation studies.

The Aura Platform

The Aura spacecraft was launched on July 15, 2004 aboard a Delta II 7920-10L, a two stage expendable rocket, from the Vandenberg Western Test Range. The mission hosts a suite of scientific instruments designed to make the most comprehensive measurements ever undertaken of trace gases in the environment that surrounds earth. The satellite's orbit will allow measurements to be taken at all latitudes; instruments will make continuous scans at altitudes ranging from the stratosphere down through the troposphere. EOS Aura is the third in a series of major Earth observing satellites to study the environment and climate change and is part of NASA's Earth Science Enterprise. The first and second missions, Terra and Aqua, are designed to study the land, oceans, and the Earth's radiation budget.

The satellite carries four state-of-the-art instruments:

  • High Resolution Dynamics Limb Sounder (HIRDLS)
  • Microwave Limb Sounder (MLS)
  • Ozone Monitoring Instrument (OMI)
  • Tropospheric Emission Spectrometer (TES)

Links

Contact

If you would like to have more information about the HIRDLS data, please contact wdc@dlr.de.