On the quality of the Nimbus 7 LIMS Version 6 water vapor profiles and distributions 1NASA Langley Research Center, 21 Langley Blvd., Mail Stop 401B, Hampton, VA 23681, USA
2SSAI, 1 Enterprise Parkway, Hampton, VA 23661, USA
3GATS, Inc. 11864 Canon Blvd., Suite 101, Newport News, VA 23606, USA
Received: 22 Jun 2009 – Published in Atmos. Chem. Phys. Discuss.: 01 Sep 2009 Abstract. This report describes the quality of the Nimbus 7 Limb Infrared Monitor of
the Stratosphere (LIMS) water vapor (H2O) profiles of 1978/79 that were
processed with a Version 6 (V6) algorithm and archived in 2002. The V6
profiles incorporate a better knowledge of the instrument attitude for the
LIMS measurements along its orbits, leading to improvements for its
temperature profiles and for the registration of its water vapor radiances
with pressure. As a result, the LIMS V6 zonal-mean distributions of H2O
exhibit better hemispheric symmetry than was the case from the original
Version 5 (V5) dataset that was archived in 1982. Estimates of the precision
and accuracy of the V6 H2O profiles are developed and provided.
Individual profiles have a precision of order 5% and an estimated
accuracy of about 19% at 3 hPa, 14% at 10 hPa, and 26% at 50 hPa.
Profile segments within about 2 km of the tropopause are often affected by
emissions from clouds that appear in the finite field-of-view of the
detector for the LIMS H2O channel. Zonally-averaged distributions of
the LIMS V6 H2O are compared with those from the more recent Microwave
Limb Sounder (MLS) satellite experiment for November, February, and May of
2004/05. The patterns and values of their respective distributions are
similar in many respects. Effects of a strengthened Brewer-Dobson
circulation are indicated in the MLS distributions of the recent decade
versus those of LIMS from 1978/79. A tropical tape recorder signal is
present in the 7-month time series of LIMS V6 H2O with lowest values in
February 1979, and the estimated, annually-averaged "entry-level" H2O
is 3.5 to 3.8 ppmv. It is judged that this historic LIMS water vapor dataset
is of good quality for studies of the near global-scale chemistry and
transport for pressure levels from 3 hPa to about 70 to 100 hPa.
Revised: 25 Nov 2009 – Accepted: 26 Nov 2009 – Published: 07 Dec 2009
Citation: Remsberg, E. E., Natarajan, M., Lingenfelser, G. S., Thompson, R. E., Marshall, B. T., and Gordley, L. L.: On the quality of the Nimbus 7 LIMS Version 6 water vapor profiles and distributions, Atmos. Chem. Phys., 9, 9155-9167, doi:10.5194/acp-9-9155-2009, 2009.