Oxford MIPAS meeting#66
23 Nov 04

Present

Oxford: Alastair Burgess, Anu Dudhia, Vivienne Payne, Chiara Piccolo, Joanne Walker, Claire Waymark
U.Bologna: Enzo Papandrea

Instrument Status [Prev] [Next]

Some details on the Envisat Web-Site including Instrument Availability web-site

No recent news

L1 Data (CP) [Prev] [Next]

Reprocessed ("consolidated") ESA L1B data continue to arrive at BADC, now available via ftp.

However, no easy way of seeing what is currently available. Maybe we should set up a web-page to display the data available ...?

L2 OFL Data (CP) [Prev] [Next]

[Plots of profile locations]

v4.62 data continues to arrive for Dec02/Jan03, also Dec03.

MORSE [Prev] [Next]

New Oxford retrieval code. Started on documentation:

Basic Web pages now set up: http://www.atm.ox.ac.uk/MORSE
Also a mailling list

H2O (VP) [Prev] [Next]

Investigating cause of high retrieved H2O at high altitudes.

Non C-band microwindows show same high H2O values, so using C-band itself seems not to be an issue
Investigated contribution of the H2O column above the retrieval
- changing the fixed climatology, and
- adapting the retrieval to retrieve the entire column as part of the top layer,
but no significant change in results, so high altitude H2O assumptions can be ruled out as cause
Currently two possible remaining explanations to be investigated are
- High altitude temperature (most likely)
- Instrument AILS characterisation (less likely)

CH4 (VP) [Prev]

Investigating cause of persistent low value in CH4 at 18km above the equatorial tropopause (also in N2O), coupled with high value at 12km, eg Mar 2004

Investigated shape of `kink' as a function of
- lowest retrieval altitude (ie cloud top height), and
- cloud index
but no significant difference, so assume that cloud contamination is not a contributing factor
Kink can be reproduced in retrievals from a simulated spectrum based on a equatorial profile modelled at 1km vertical spacing (also less pronounced for the equivalent mid-latitude atmosphere) so most likely to be caused by representation of the temperature profile at the equatorial tropopause.

SF6 (AB) [Prev] [Next]

Having identified large oscillations at 9km as being due to cloud-index values for 9km indicating a clear atmosphere where higher altitudes are flagged as cloud contaminated, now investigating residual oscillations using 1km simulated atmosphere.

As with CH4, these also appear to be due to the representation of the atmosphere on a coarse 3km grid
SF6 oscillations can be reduced if SF6 retrieved jointly with temperature.

O3 Isotopes (CP) [Prev] [Next]

Using new microwindows to retrieve O3 isotopic ratios.

Although retrieved fields look reasonable, observed depletions of the order of 100% seem much larger than model predictions.

EQUAL Project Report (CW) [Next]

Recently circulated first issue of the monthly report of the EQUAL project comparing Envisat O3 and Temp with NDSC LIDAR measurements

Report covers Jan-Oct 2004, indicating LIDAR measurements that are available
Report discusses improvements in the GOMOS O3 retrieval but, other than references, no comparisons with MIPAS or SCIAMACHY

HO2 (EP)

HO2 is a new species as far as MIPAS is concerned, not even previously considered as a contaminant. Important component of HOx chemistry in the stratosphere, but no reliable profiles available.

Some signature is present in the infrared in the B-band (around 1400-1420cm-1)
No reliable profile, but initial microwindow selection has been performed
Trial run for orbit 2081 suggests something is being retrieved but with precision close to a priori uncertainty (100%), so need to relax a priori constraint further before we believe anything.

Oxford MIPAS meeting#66 23 Nov 04

Oxford MIPAS meeting#66
23 Nov 04