Introduction
The Microwave Limb Sounder (MLS) is a satellite-borne instrument
making limb sounding measurements of atmospheric composition at
microwave frequencies. It was built by an instrument team based
at the Jet Propulsion Laboratory and launched on the Upper
Atmosphere Research Satellite (UARS) on the 12th September 1991.
The water vapour data was collected by the 183 GHz radiometer
which was developed in the UK by Heriot-Watt University and the
Rutherford Appleton Laboratory.
This data set is a prototype version of the MLS water vapour
data developed by Dr Hugh
Pumphrey in the Meteorology Department at the University of
Edinburgh. This work was funded by the NERC. Much more detail about the data is contained
in Hugh's 00README
file in the data set directories. The BADC also holds the official MLS data set obtained from the
NASA Goddard distributed active archive center (DAAC).
The data coverage extends from 80°S to 80°N,
but at any one time this is restricted to 34°S to 80°N or 34°N to 80°S. In the vertical, measurements are
usually available between 68hPa and 0.031hPa and may extend down
100hPa and up to 0.0031hPa. The data set covers the time period
from UARS day 8 (19th September 1991) to UARS day 580 (13th April
1993).
Access Restrictions
Access to the MLS prototype Water vapour data archive is now public but you will need a BADC login account to download the data. If you are not a BADC registered user, please follow the instructions onlione to register as a new user. If you are already registered with the BADC but have forgotten your BADC user ID and/or password, please contact the BADC helpdesk at badc@rl.ac.uk
Data Availability
The data consist of along-track vertical profiles at regular
time interval of approximately 1 minute (level 3AT). The data
are provided in IEEE binary files which have been tagged with a version number of 0006 (v0006) to distinguish them from the MLS version 5 (v0005) data (to be soon uploaded at BADC).
IMPORTANT NOTE:
MLS-H2O Version 0104 (data and documentation) is still available at BADC to go along the other MLS v4 data (currently available at BADC). The V0104 data is documented in reference (1) below and is further described in reference (2).
The current (and almost certainly last) version of the UARS MLS data,
for most species, is version 5 (see reference (3) - soon to be uploaded at BADC. On examination, altough version 5 was an improvement for most species, the version 5 H2O product was found to be less satisfactory than the V0104 data. It was therefore decided that the V0104 data would become the officially-sanctioned MLS H2O product. But it could not do so under a strange-looking version number like V0104. It had to become V0006 and for this to be achieved, the data files needed to be tidied up somewhat.
- The file names were changed so that the version number was V0006
- The first record of the file was changed so that it was padded out correctly and did not contain a hidden silly remark.
- Some of the items in the second record were corrected.
- The time of the last record was fixed to be correct. It was a bit
random in the V0104 files.
- The version was set to 6.
Otherwise, the data were not altered in the slightest: V0006 is EXACTLY
THE SAME DATA as V0104, exactly as documented in references (1) and (2).
Documentation, Links to further information and references
The main source of information for these prototype retrievals
is the 00README
file produced by Edinburgh University. The status
summary gives more detailed information about each data file
- for example the quality flags and the numbers of profiles available.
Other documents are available in the MLS L3 doc directory.
Detailed documentation about the MLS instrument and the other
parameters available can be found in the main MLS
help files.
The main sources of information about this and the "official"
MLS data are the MLS
home page at JPL and the Goddard Earth Sciences Data and Information Services Center (GES DISC) which is the prime
archive of the UARS data.
References:
- Hugh C. Pumphrey. Validation of a new prototype water vapor retrieval for UARS MLS. J. Geophys. Res, 104(D8):9399-9412, 1999.
- Hugh C. Pumphrey, Hannah L. Clark, and Robert S. Harwood. Lower stratospheric water vapor as measured by UARS MLS. Geophysical Research Letters, 27(D12):1691-1694, 2000.
- Nathaniel J. Livesey, W.G. Read, L. Froidevaux, J.W. Waters, M.L. Santee, H.C. Pumphrey, D.L. Wu, Z. Shippony, and R.F. Jarnot. Microwave limb sounder version 5 dataset: Theory, characterization and validation. Journal of Geophysical Research, 108(D13):4378, 2003.
Citation
Jet Propulsion Laboratory, [Pumphrey, H.; Waters, J.]. Microwave Limb Sounder (MLS) prototype H2O data, [Internet]. NCAS British Atmospheric Data Centre, 2006-, Date of citation. Available from http://badc.nerc.ac.uk/view/badc.nerc.ac.uk__ATOM__dataent_MLS-PRO-H2
Who to contact
For information relating to this or other data held by the
BADC, the first point of contact should be the BADC
support line.
If you are using these data, please keep in contact with Hugh Pumphrey. Hugh is keen
to get some feedback abut the data and will be able to let you
know about forthcoming changes. For more information about the
MLS instrument contact Joe Waters
or members of his team at JPL.
Please wait...
