The objective of the Limb Infrared Monitor of the Stratosphere (LIMS) experiment was to map the vertical profiles of temperature and the concentration of ozone, water vapour, nitrogen dioxide, and nitric acid in the lower to middle stratosphere range, with extension to the stratopause for water vapour and into the lower mesosphere for temperature and ozone. This experiment was a follow-on to the Limb Radiance Inversion Radiometer (LRIR) flown on Nimbus-6. The LIMS mapped vertical profiles of thermal IR emission coming from the horizon in six bands of CO₂N, CO₂, O₃, HNO₃, H₂O, and NO₂.

Infrared radiances from the Limb Infrared Monitor of the Stratosphere (LIMS) instrument, mounted on the Nimbus-7 satellite, were stored on a Radiance Archive Tape (RAT). RAT data was used to derive a series of products, two of which are held here:

1. LIMS Inverted Profile Archival Tape (LAIPAT):

   This data set contains corrected IR radiance profiles from the Nimbus-7 Limb Infrared Monitor of the Stratosphere (LIMS). The data were derived from the Radiance Archival Tapes (RAT) files. The data set contains inverted daily profiles of temperature, and mixing ratios for ozone, water vapour, nitric acid, and nitrogen dioxide, all as a function of pressure. In addition, earth location, time, cloud-top, and housekeeping information are included.

   Radiances are corrected and profiled at 4° latitude zones from 64° S to 84° N. Vertical coverage extends from approximately 10 to 50 km, with the ozone channel measuring through the lower mesosphere to 65 km. Each LAIPAT tape contains 2 to 6 days of data, covering the period from October 26, 1978, through May 28, 1979. This data is used to generate another LIMS data product, called Master Archival Tape (LAMAT), which contains daily global maps of 6 atmospheric parameters, given in the form of Fourier Coefficients.

2. LIMS Map Archival Tape (LAMAT):

   This data set contains daily global maps of 6 atmospheric parameters (temperature, ozone, nitrogen dioxide, water vapour, nitric acid, and geopotential height) derived from radiance measurements by the Nimbus-7 Limb Infrared Monitor of the Stratosphere (LIMS). The daily maps are given in the form of Fourier coefficients for each parameter at 18 pressure levels (from 0.05 to 100 mbar). Data are organised and averaged into 38 four-degree latitude bands. Data for the daily maps are interpolated to the two synoptic times (0000 GMT for night and 1200 GMT for day). Also included is the day/night combined (averaged) data.

   The Nimbus-7 LIMS provides nearly global coverage from 64° S to 84° N for all six spectral channels centred at wavelengths ranging from 6.2 to 15 microns. In general, only temperature and ozone are mapped at all 18 pressure levels. Maps for the other four parameters usually stop at altitudes where signal-to-noise values become inadequate for data reduction. In addition, the analyses at 70 and 100 mbar are often missing at tropical latitudes due to clouds rendering the results unreliable. Each tape contains maps for 23 to 30 days of data. Related LIMS data sets include Radiance Archive Tape (RAT), Inverted Profile Archival Tape (LAIPAT), and Radiance Profile Tape (PROFILE-R). The entire 7 months of LAMAT data are stored on a single 8mm Exabyte tape obtainable from the Goddard Distributed Active Archive Centre (DAAC).

Infrared radiances from the LIMS instrument have also been used to derive the LIMS Stacked Map Archival Tape (LASMAT), which are monthly and seasonal means of LAMAT data. Unfortunately, this data set is not currently held at the BADC. To obtain a copy of this data please contact the LIMS User Support Office.

Note: A major reprocessing of the Nimbus 7 LIMS data supersedes the previous version 5, known as the LAIPAT. The purpose of this activity was to take advantage of the changes in the spectral line parameters that occurred since the original archived version was created and to generate a data version that is compatible with the UARS data sets. Improvements in the algorithm have also been made. More information is available from the LIMS homepage and LIMS version 6 data is available for download at GES DAAC.