The High Resolution Dynamics Limb Sounder (HIRDLS)

Level 2 version 4.00 (also called v02-04-19) now publicly available - see Archive Summary table for details

Introduction

HIRDLS is an mid-infrared limb-scanning radiometer (21 channels from 6.12 to 17.76 µm) designed to monitor the global distributions of temperature, clouds, aerosols, and 10 trace species O₃, H₂O, CH₄, N₂O, NO₂, HNO₃, N₂O₅, CFC₁₁, CFC₁₂, and ClONO₂ in the stratosphere and upper troposphere at high vertical and horizontal resolution in the Earth's atmosphere between about 8 and 100 km. HIRDLS aims 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.

The instrument is performing well, providing high vertical resolution information despite the fact that the optical beam is partially obstructed between the scan mirror and the aperture, probably by a piece of inner lining material that became detached during launch. HIRDLS science team members have produced correction algorithms that make use of the partial view of the atmosphere (vertical scans around azimuth angle of 47° line of sight to the orbital plane, on the side away from the sun). In spite of this anomaly, HIRDLS has retained most of its scientific capabilities to support the Aura Mission.

HIRDLS is carried on the Aura mission, part of NASA's Earth Observing System (EOS). Aura was successfully launched on 15th July 2004 at 11:01:59 a.m. BST from Vandenberg Air Force Base, California. HIRDLS is a joint US-UK development effort, with sponsorship by the British National Space Centre and the Natural Environment Research Council in the UK, and by NASA in the US. The Principal Investigators for the HIRDLS mission are John Gille, from the University of Colorado and the National Center for Atmospheric Research, and John Barnett from the University of Oxford.

Data

Data received by the ground station, is processed at the HIRDLS Science Investigator-led University of Boulder Science Processing Suite (SIPS) before being archived at the Goddard Earth Sciences Data and informations Services Center (GES DISC). As HIRDLS is a joint US-UK programme, the BADC will mirror the data stored in the GES DISC for ease of access. This BADC data will be subject to the same access constraints as the data in the GES DISC. HIRDLS data is currently being collected and several teams are undertaking calibration and validation studies. Further information on this work can be seen on the validation status page.

The BADC archive currently holds Level 0 and Level 2 data - see the Archive Summary table for links to the data. The latest version 4.00 level 2 data, (also known as v02-04-19), has now been released for public access and is available at BADC. This release adds three new data products (F11, F12 and aerosol extinction), and significantly enhances those previously available (T, O3, HNO3, Cloud tops). Each HIRDLS Level 2 data file contains one day's worth of data. The HIRDLS team is in the process of refining the algorithms for other species, which will be available in later versions.

Levels 0, 1 and earlier, preliminary versions of Level 2 data remain restricted to the HIRDLS science and validations teams and to those working on HIRDLS related projects. Previous publicly released level 2 data versions remain available but have been superceded by the latest release and should no longer be used without advice from the HIRDLS team. Further data and re-processed versions will follow when released. The HIRDLS data at BADC is mirrored from the GES DISC (with the same access conditions).

The data for the high level products will be in HDF5 format with the EOS extension. The lower level products will be in an instrument specific binary format. Level 0 data is currently available to the validation team.

Data Access

General access to released Level 2 data

Following an extended validation period, the latest version of the level 2 data has been released and is available to the public. Although no registration is required to view this data, you are invited to register as a BADC user and log in so that usage statistics can be noted. This online registration only takes a few seconds.
Directions for HIRDLS science/validation teams only
Access to Level 0, level 1 and early versions of Level 2 data are restricted to the HIRDLS science/validation teams, and to holders of HIRDLS related grants. To apply for access to the restricted hirdls data:
1. You will need your BADC username and password.
  New users register here. For a reminder of your login details contact the BADC Helpdesk.
2. Apply for access to the restricted HIRDLS archive. You will need to agree to the HIRDLS conditions of use and your application be approved by the HIRDLS UK co-PI. This may take a few days to complete.

Documentation

Documentation to describe the data format and software to assist in the viewing of the data files are available. The BADC archive also stores documentation about the HIRDLS instrument and mission.

Users of the Level 2 data are directed to read and note the documentation about data quality.

Several papers based on HIRDLS data have been published in the AGU-JGR Aura 2007, 2008 Special Collection Editions: See the UCAR HiRDLS website for further details.

A web-based uploader is available for HIRDLS team members to upload documents or software related to the HIRDLS project. Access to the restricted part of the HIRDLS data archive is required in order to use the uploader.

The presentations given at the HIRDLS Science meeting, Oxford September 2006 are now available in the documents archive.

Services

An email list has been set up at BADC to distribute information/updates about the HIRDLS data and other HIRDLS related issues to UK users. For information about this list and to subscribe, see the NERC-BADC HIRDLS mailing list page. An archive of previous messages can also be viewed. Another HIRDLS email list at UCAR is also available to receive information from the HIRDLS US Science team. Please note only HIRDLS science team can post to this list.