PRODUCT/VERSION: URAP 1998  H2O BASELINE EXTRAS

DATA SOURCE: MLS nonlinear prototype retrieval V0104 and HALOE V18

TIME PERIOD FOR AVERAGING OF DATA: April 1992 to March 1993.

ALTITUDE RANGE: 100 mb to  0.00316228 mb 

LATITUDE RANGE: 80S to 80N 

DESCRIPTION:

MLS Data taken from a prototype retrieval which turns out to be a big
improvement on V4 and has been used in several publications. More
information at http://www.met.ed.ac.uk/~hcp/watvap.shtml . 

A correction factor was applied to both the HALOE and the MLS data to
remove systematic differences. The correction factors were much
smaller than those needed to reconcile MLS V4 and HALOE V18 and do not
change much with altitude.

The daily zonal mean data were smoothed in time with a kalman smoother -
this fills in the yaw cycle gaps. The data were then averaged over
calendar months. 

A short paper describing this process is available on the URAP web site.

The chief features of the data are:

1) Stratosphere drier near equator than in mid-latitudes owing to
   Brewer-Dobson circulation and CH4 oxidation. 

2) Clear seasonal cycle in the mesosphere ( annual at poles, semiannual 
   at equator).

3) "Tape recorder" signal clearly visible in the equatorial lower 
    stratosphere.

4) Dehydration and descent visible in the Southern polar winter.



WARNINGS:

1) Bad data values would be set to -999.9 if there were any

2) Interpolation was necessary poleward of 34N for one or other pole
   in several months and for all of June.  These data are flagged
   negative.

3) The vertical resolution of MLS V0104 is one UARS level (twice as good
    as V4) between 100 mb and 0.1 mb.  Above this it is two UARS levels just
    as in V4. 


REFERENCES:
Lahoz et al., J. Geophys. Res. vol. 101, pp. 10129-10149 (1996)
Harries et al.,   J. Geophys. Res. vol. 101, pp. 10205-10216 (1996)
Pumphrey, J. Geophys. Res. vol 104 No. D8 pp9399-9412 (1999)

CONTACTS
Originator: Hugh Pumphrey 
URAP co-ordinator: John Remedios