Oxford MIPAS meeting#47
27 Jan 04

Present

Oxford: Alastair Burgess, Anu Dudhia, Vivienne Payne, Chiara Piccolo, Analia Quijano
RAL: Jolyon Reburn

Instrument Status [Prev] [Next] (Some details on the Envisat Web-Site and times taken from Instrument Availability web-site)

Unavailable 2004-01-12 03:21:08 2004-01-15 10:12:00 restabilising after warming up interferometer
Unavailable 2004-01-17 18:17:23 2004-01-18 15:12:00 ?
Unavailable 2004-01-18 23:51:16 2004-01-19 09:50:00 ?
Unavailable 2004-01-19 17:19:12 2004-01-20 10:59:00 ?

L2 NRT Data [Prev] [Next]

In /home/crun/mipas/L2/NL/ [Plots of profile locations]

NRT Data received up until 26th January, plotted up until 26th January.
Software version 4.59 in use since 23 Jul 2003.
Although L2 data is being received there have been no valid profiles since 12 Jan. (See 30km daily mean traces).
NRT L2 files just contain message
```
Failed to select an occupation matrix for scan [i] Retrieval [j]
```
Presumably associated with L1 spectra being flagged as unusable
See email from Rob Koopman

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

In /home/crun/mipas/L2/2PODPA/

L2 OFL (off-line) data now received covering 21 Oct - 24 Dec
Profile location plots] now show availability of both NRT and OFL data
No OFL data received since 20 Jan 04.

NH3 Retrievals (AB) [Prev] [Next]

Using local retrieval code OPTIMO to retrieve NH3 from MIPAS spectra.

Atmospheric NH3 seems to be an order of magnitude lower than IG climatology, resulting in worse precision than predicted from microwindow selection (which is based on climatological concentrations)
Attempting to improve S/N by using sequential estimation - a priori for each profile is (mostly) retrieval from previous scan.
Plot of orbital average (solid line) and scatter

H2O & CH4 Isotopic Retrievals (VP) [Prev] [Next]

Microwindows and error analyses now derived for isotopes treated as independent gases using 2 different selection criteria: 003 (equal weight to random and systematic errors) and 103 (3x weight for systematic errors)

003 Jacobians & Microwindows and predicted retrieval accuacy
103 Jacobians & Microwindows and predicted retrieval accuacy
In the error plots, triangles are total error, squares are random error and diamonds are systematic errors
Notation: eg 3h2o = 3rd most abundant isotope of H2O

Joint Retrieval Microwindows (AD) [Prev]

Selecting microwindows for joint retrieval of pT, H2O and O3. 3 sets of 10 MWs selected corresponding to maximum widths of 1cm-1, 2cm-1 and 3cm-1

Set of 10 3cm-1 now finally completed (and LUTs, irreg.grids generated)
Plot of Information Content v No.Measurements for 3 sets of joint MWs and operational pT, H2O and O3 microwindows for comparison

Occupation Matrices (AD) [Prev] [Next]

A problem has been reported with the operational processor when retrievals are attempted with fewer than 3 altitudes. This occurs more frequently when cloud detection is implemented since all current OMs are either

single corrupted sweep at altitude j, or
all sweeps up to some altitude i assumed cloud contaminated

So, if a high altitude sweep is corrupted and at least one low altitude sweep is detected as having cloud contamination, the only valid OMs are those which delete all sweeps up to and including the high altitude. The intended solution is

Remove all OMs with only one or two retrieval levels
Add OMs which allow combinations of cloud-contaminated sweeps and (single) corrupted sweeps at high altitude

Email from Rob Koopman (ESA) 27 Jan 04

To: mipas-qwg
Subject: MIPAS anomalies update
Dear QWG colleagues,
Good news on MIPAS hardware and software issues: After a long stabilisation period, and after initial worsening, the switchon of the interferometer heaters has brought the first positive results: ASTRIUM has detected a strong reduction in relative velocity errors, and also no further absolute velocity errors have occurred during the last days. On the processor side investigations by BOMEM, IFAC, Oxford and ESA have detected several common sources to the variety of errors observed:
1) A number of coding errors exist in the operational processor. One particular error in the handling of the offset has led to corruption in spectra.
2) An increase in NESR is observed after the switchon of the heater
Final tests are being performed to confirm the causal relation with the observed product anomalies, and subsequently configuration changes will be implemented to resolve item (2) and work around item (1) on the short term. Independently, the ground-segment provider has begun to develop a patch for the processor to eliminate the known software problems.

Oxford MIPAS meeting#47 27 Jan 04

Oxford MIPAS meeting#47
27 Jan 04