Oxford MIPAS meeting#106
14 November 06

Present

Oxford: Anu Dudhia, Jane Hurley, Luis Millan-Valle, Chiara Piccolo, Joanne Walker, Claire Waymark, Corwin Wright
RAL: Alison Waterfall

Instrument Status [Prev] [Next]

According to the Envisat Web-Site, today they should be resuming normal data transmission via the Ka band antenna and the Artemis relay satellite for all instruments.

MIPAS itself continues in a long sequence of nominal mode observations 2 orbits on followed by 3 orbits off (intended to be tested as an input for ECMWF data assimilation).

Current version of Mission Planning Document (2006 up to 11Dec) [XLS] [HTML].
Currently defined measurement modes
Envisat Web-Site

October Monthly Report [Prev] [Next]

MIPAS monthly report for October is now available [Summary]

Full report downloadable from http://earth.esa.int/pcs/envisat/mipas/reports/monthly/

RR27 Retrieval (AD) [Prev] [Next]

Simone Ceccherini (IFAC) has compared retrievals from orbit 10719 using the original operational microwindows and a spectrally degraded version of the L1B file using the proposed RR27 microwindows (not a true test of the new RR27 microwindows since this still uses the original 17 sweeps @ 3km spacing)

[Plot] of differences

Simone comments:

I notice that some significant differences larger than the retrieval errors are obtained between the profiles retrieved from the RR and FR spectra. Large differences are obtained for pressure, temperature and ozone in the altitude range 30km-50km, for methane below 20 km and for N2O at 6 km. No significant differences are observed for H2O,HNO3 and NO2.
Methane and N2O are not a surprise because large errors are often present at the boundaries of the retrieval range.
Differences in temperature and ozone retrieved values are instead a concern. Indeed the results of validation that Ugo and Marco presented at the QWG meeting indicate that the differences between FR MWs and RR MWs are larger than the validation accuracy obtained for temperature and ozone. We expect, therefore, that when the new RR results will be validated a bias will be found for these two targets. These MWs are, however, the best selection that we presently have and, if you agree, we plan to use this set for the temporary ADF2. A warning should be made to the user.

Occupation Matrices have also been delivered for both the Nominal (27 sweep) and UTLS1 (19 sweeps) modes - these are sufficiently similar that the same microwindows will be used for both (see Currently Defined Modes).

Precision Validation (CP) [Prev] [Next]

Using comparisons of pairs of MIPAS retrievals at locations where orbits intersect to see how the observed standard deviation compares with the predicted variability from the retrieval covariance.

[Plot] showing variation of band-averaged NESR with time
[Plot] showing variation of gain with time

Conclude that NESR variations are well explained by gain variations.

TES Radiance Comparisons (CW) [Prev] [Next]

Continuing with comparison of MIPAS and TES limb radiance spectra from Jan 28 2005 using regions where the MIPAS bands and TES filters overlap

At first glance there seem to be a number of spikes in the TES spectra which aren't flagged as such.

CO Retrievals (JW) [Prev] [Next]

Continuing with a joint retrieval of CO and vibrational temperature using RFM being used in non-LTE mode as a forward model within IDL retrieval program

Now implemented Levenberg Marquardt scheme to try to stabilise retrieval of vibrational temperature profile at high altitude (above highest tangent point) - still using just simulated data.

Cloud Parameters (JH) [Prev] [Next]

Attempting to retrieve both Cloud Top Height and Cloud Extinction using a pair of adjacent sweeps (the cloud top being in the FOV of the upper sweep) and a single microwindow 960-961cm-1 (most transparent region of MIPAS spectrum)

Scheme works for thick cloud if atmospheric gases are ignored
Scheme works for thin cloud if a simple model of gas contributions is included
Doesn't work well for intermediate cases - need to try something more sophisticated to separate out line and continuum contributions.

Mesospheric Spectra (LMV) [Prev] [Next]

Analysing contents of MIPAS mesospheric spectra (52, 60 and 68km nominal altitudes), now adapted IDL code to read L1B spectra directly.

Using spectral points identified as containing primarily CO2 lines, applying simple least squares fit to calculate ratio of observed to (RFM) modelled spectrum to 'retrieve' tangent point temperature.
Will then extend this to other gases to perform simple linear retrievals for comparison with upper levels of L2 products (although also need to avoid regions with significant non-LTE effects)

RAL Work (AW) [Prev] [Next]

Recently been analysing O3 validation results using original MIPAS averaging kernels compared to AKs derived for specific polar and equatorial conditions - conclude that there is a negligible difference to validation comparisons.

ACPD Papers [Prev] [Next]

"MIPAS Level 1B algorithms overview: operational processing and characterization"

A.Kleinert et al. (submitted 26.10.2006, open until 21.12.2006)

Introduced by LMV.

"A study of polar ozone depletion based on sequential assimilation of satellite data from the ENVISAT/MIPAS and Odin/SMR instruments"

J. D. Rösevall et al (submitted 10.10.2006, open until 05.12.2006)

Comments being collected by CW.

"An annual cycle of long lived stratospheric gases from MIPAS"

by M. N. Juckes (submitted 26.09.2006, open until 21.11.2006)

Comments being collected by AD.

There are several more MIPAS-related papers currently open (which may be adopted for group discussion in future meetings)

"Evaluation of ozonesondes, HALOE, SAGE II and III, Odin-OSIRIS and SMR, and ENVISAT-GOMOS, -SCIAMACHY and -MIPAS ozone profiles in the tropics from SAOZ long duration balloon measurements in 2003 and 2004": F.Borchi et al. (submitted 11.10.2006, open until 06.12.2006)
"Detection of organic compound signatures in infra-red, limb emission spectra observed by the MIPAS-B2 instrument": J. J. Remedios et al (submitted 11.10.2006, open until 06.12.2006)
"Validation of MIPAS ClONO2 measurements": M. Höpfner et al (submitted 05.10.2006, open until 30.11.2006)
"Validation of nitric acid retrieved by the IMK-IAA processor from MIPAS/ENVISAT measurements: D. Y. Wang et al (submitted 05.10.2006, open until 30.11.2006)

Summary of the October Report (Fabrizio Niro, ESRIN)

During October 2006 the MIPAS instrument performs extremely well, in fact only 3 unavailabilities were observed due to IDU errors.
The instrument operated the entire month in NOM mode in support to the ECMWF campaign, 2 orbits on and 3 off (see 2.2.1).
The instrument duty cycle for the reporting month was 39.5%, in line with the recommendation of Science Team and industry. The availability of the instrument was really high (99.1% of the planned time) owing to the very good performance of the INT. Also the ground segment performs really well, in fact only 0.6% of the planned measurement time was lost due to PDS failure (see 2.2.4).
An operation anomaly occurred during the reporting month. The problem was that the PAW gain table was not set back to NOM after the LOS calibration of 7th October. As a result the successive scene measurements were all acquired with excessive gain settings, specifically used for the LOS measurements. Since only band D is used for LOS measurements, only this band was affected by the anomaly. The impact on the data is that all the measurements performed in band D were useless since the signal was saturated. The problem was solved on 18 October after a manual intervention by ESOC.
The monthly monitoring of the instrument temperature shows a steady situation, temperatures variation are within 1K over the entire month (see 2.3.1).
The long term monitoring of ADC max counts in channel A1 shows a strong correlation with the instrument self-emission. The decontamination of September 2006 determines an increase of ADC maximum counts, this was expected since the ice removal causes an increase of signal at the detector. During the reporting month ADC counts remain constant (see 2.3.2).
The cooler perform really well during this month, the vibrations being always well below the warning level of 8 mg (see 2.3.3.1).
The long term monitoring of the spectral correction factor shows a stable situation since the variations are of the order of 3 ppm over almost two years of operations (see 2.4.2).
The gain weekly increase during the reporting month is nominal, the maximum of gain increase in the band A remains well below the acceptance criterion of 1% (see 2.4.3.1).
The monitoring of accumulated gain shows that the gain increases linearly after the recent decontamination of September 2006 (see 2.4.3.2).
The mispointing long term monitoring shows that the absolute bias is stable around a value of -20 mdeg. However several problems start to be observed on LOS calibration during this month and no calibration could be performed. The problem seems related to an increasing noise in the channel D2, as a result the algorithm used to fit the star signal is not anymore accurate. An investigation on this issue is on-going with the support of Bomem (see 2.4.4).
The long term monitoring of fringe count errors (FCE) for the RR mission was updated this month; so far no correlation can be appreciated with respect to interferometer degradation.
The level 0 NRT daily reports can be accessed at the following address:

http://earth.esa.int/pcs/envisat/mipas/reports/daily/Level_0_NRT/

The monitoring of the L1 OFL products generated at D-PAC is on going in parallel with the mission. The level 1b daily reports can be accessed at the following address:

http://earth.esa.int/pcs/envisat/mipas/reports/daily/Level_1_OFL/

Oxford MIPAS meeting#106 14 November 06

Oxford MIPAS meeting#106
14 November 06