Oxford MIPAS meeting#117
08 May 07

Present

Oxford: Anu Dudhia, Luis Millan-Valle, Joanne Walker, Claire Waymark

MIPAS currently half way through a standard 10day operating sequence (1 day MA, 3 days NOM, 2 days off, 2 days NOM, 2 days off)

Mission Planning Document for 2007 [XLS] [HTML].
Currently defined measurement modes
Envisat Web-Site

L1B Data (AD) [Prev] [Next]

ftp-ops.de.envisat.esa.int site missing a lot of L1B data before 2007 (although, from the directory dates, it seems that these are still being restored)

[L1B Data Coverage]

MORSE Update (AD) [Prev] [Next]

New version of the Oxford MIPAS retrieval code v01may07 (Web Page)

Now able to retrieve vibrational temperatures

N2O5 (JW) [Prev] [Next]

Revisiting N2O5 retrieval.

Previous retrievals never seem to reach the low values that models predict.
This might be because we retrieve ln(VMR) rather than VMR so any 'noise' on the measurement, even negative radiances, are 'rectified' and can never produce a negative VMR
If so, would a linear retrieval would improve this?

Polar Mesospheric Clouds (LMV) [Prev] [Next]

Following Manuel Lopez-Puertas presentation at the Envisat Symposium showing a radiance enhancement at high latitude between around 800-900cm-1 which may be due to the presence of PMCs

Attempt to reproduce this result
Filter out atmospheric lines and see if a similar enhancement occurs in other regions of the MIPAS spectrum

Mesospheric Retrievals (LMV) [Prev] [Next]

Trying a linear least-squares fit retrieval for pT, O3 and H2O using entire MIPAS bands (screening out lines affected by non-LTE effects and gases other than CO2).

Seems to work reasonably well for full resolution data nominal mode, but problems attempting to apply analysis to reduced resolution data at high altitude (MA mode)
Look at 28Jan05 to see if problem occurs with nominal mode reduced-resolution data.

MIPAS/TES Retrievals (CW) [Prev] [Next]

Aim is to combine MIPAS limb measurements of stratospheric O3 with TES nadir-viewing measurements to obtain more information on tropospheric O3 profile (basically how TES was supposed to work before their problems with limb-views)

Initial conclusion was that the TES nadir retrieval on its own provides information on stratospheric rather than tropospheric ozone, so combination with MIPAS does not improve things.
Taking another look at the TES nadir microwindow selection

Oxford L2 Processing (AD) [Next]

Starting to run MORSE retrieval to process L1B data for selected days throughout the full and reduced resolution dataset.

pT, H2O, O3, HNO3, CH4, N2O, NO2, CFC-11, CFC-12, ClONO2, N2O5 and CO (LTE assumption).

List of days processed so far
Next: working through MA mode at start of Jan 2005

Envisat Symposium

Montreux, 23-27 Apr 2007 (www.envisat07.org)

Posters/Talks and associated papers from the Oxford MIPAS group

MIPAS Observations of Stratospheric Trends, A. Dudhia et al [Paper]
Cloud Parameter Retrieval from MIPAS Spectra, J. Hurley et al [Poster] [Paper]
Mesospheric Retrievals from MIPAS, L. Millan-Valle et al [link to Poster not yet avaialable] [Paper]
Global Observation of ozone isotopic ratios from MIPAS limb emission spectra, C. Piccolo et al [Poster] [Paper]
A joint retrieval of CO and vibrational temperature from MIPAS-ENVISAT, J. Walker et al [Poster] [Paper]
Combined ozone retrieval using MIPAS and TES, C. Waymark et al [Poster] [Paper]

Also, from the previous week's EGU in Vienna

Observations of Stratospheric NOx using MIPAS-ENVISAT, J. Walker et al. [Poster]

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"Vertical profiles of lightning-produced NO2 enhancements in the upper troposphere observed by OSIRIS": C. Sioris et al. (published 11.04.2007, open until 06.06.2007); (Re-)Introduced by JW.
"Global statistics of liquid water content and effective number density of water clouds over ocean derived from combined CALIPSO and MODIS measurements": Y. Hu et al. (published 28.03.2007, open until 23.05.2007); Comments being collected by JH.
"Retrieval of temperature profiles from CHAMP for climate monitoring: intercomparison with Envisat MIPAS and GOMOS and different atmospheric analyses": A. Gobiet et al. (published 27.02.2007, open until 24.04.2007); Comments were being collected by CP, but discussion closed before anything submitted.
"Validation of MIPAS-ENVISAT NO2 operational data": G. Wetzel et al. (published 02.03.2007, open until 27.04.2007); Comments were being collected by CW, but discussion closed before anything submitted.

Other papers with 'MIPAS' in the title in the Open Discussion phase, which may be adopted at a future meeting

"Geophysical validation of MIPAS-ENVISAT operational ozone data": U. Cortesi et al. (published 07.05.2007, open until 02.07.2007)
"Geophysical validation of temperature retrieved by the ESA processor from MIPAS/ENVISAT atmospheric limb-emission measurements": M. Ridolfi et al. (published 25.04.2007, open until 20.06.2007)
" Validation of MIPAS HNO3 operational data": D. Y. Wang et al. (published 17.04.2007, open until 12.06.2007)
"Bias determination and precision validation of ozone profiles from MIPAS-Envisat retrieved with the IMK-IAA processor": T. Steck et al. (published 30.03.2007, open until 25.05.2007)

Summary of the March Monthly Report (F. Niro, ESRIN,

During March 2007 the MIPAS instrument performs extremely well, in fact we report only two instrument failures due to IDU errors. However the instrument was switched off during 16 – 18 March due to a Macro-Command (MCMD) transfer error. Furthermore a short unavailability (4min) was planned on 19th March in order to perform on-board time maintenance (see 2.2.2).

The instrument planning for the reporting month is hereafter summarized (see 2.2.1):

The instrument operates during 4 – 18 March in NOM mode in support to ECOWAR campaign; 3 orbits/day both ascending and descending tracks over Plateau Rosa (45.9°N, 7.7°E)
LOS sideways observations were planned for the first time over one full orbit on 8th and 27th March in order to investigate the roll mispointing
On 19th March special NOM mode observations with fixed azimuth angle were planned for testing purposes
Upper Atmosphere and Middle Atmosphere mode were planned during 22 – 23 March 2007 close to the Equinox. NOM operations were resumed on 24th March.

The instrument duty cycle during the reporting month was 49.29%, in line with the recommendation of Science Team and industry. The availability of the instrument was high (95.6% of the planned time) owing to the very good performance of the INT. The measurement segments not processed to L0 due to failures at the PDS were about 2.2% of the planned measurement time (see 2.2.4).

The monitoring of the instrument temperatures shows an increase of about 2K over the reporting month due to the seasonal variation of the instrument temperature. However a big jump of about 4K in the FCA temperature was detected after the MCMD transfer error of 16 March. This problem was already observed after a platform switch-off (see 2.3.1).

The cooler performs really well during this month, the vibrations were always well below the warning level of 8 mg. However we start to observe orbital dependent spikes in the compressor vibrations, these features are usually appearing in correspondence to the hottest period of the year (see 2.3.3).

The long term trend of ADC max counts in channel A1 shows a strong correlation with the instrument self-emission and with the decontamination events. During the reporting month a slight increase of ADC max counts is observed linked to the seasonal variation (increase) of the instrument temperature (see 2.3.4).

The 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, in particular the variations are due to noise (see 2.4.2).

The gain weekly increase during the reporting month is nominal, the maximum of gain increase in all the MIPAS bands remains well below the acceptance criterion of 1% (see 2.4.3.1).

The analysis of the accumulated gain shows a steady increase of the gain with a constant rate and highlights the decontamination events throughout the mission. During the last months we observed a decreasing slope of the gain curve, showing that the detector is more and more ice-free (see 2.4.3.2).

The absolute mispointing error is stable around a value of -30mdeg. The seasonal variations of the pointing error are small and below the fixed threshold of 8mdeg (see 2.4.4).

The attempt to retrieve a roll mispointing from the sideways LOS measurements (planned on 8th and 27th of March) has failed since the number of measured stars was too few to retrieve any information. Sideways LOS will be routinely performed every two weeks from now on, therefore it is expected to have some information about roll mispointing in the future.

The long term monitoring of fringe count errors (FCE) for the RR mission was investigated this month. A statistical analysis was suggested during QWG#11 and it is reported in this MR, this analysis shows that the width of the statistical distribution of the FCE can be used as a measure of the INT performances. In fact the long term variation of the FCE statistical dispersion is highly correlated with the number of IDU velocity errors (see 2.4.5.1).

The long term monitoring of the detected spikes is reported in this MR. The presence of spikes on the scene IGM is detected by the L1 processor, these spikes are corrected in order to avoid artefacts in the spectrum. The number of spikes in channels A1, A2, B1 and B2 is increasing up to Dec 2006, while since Jan 2007 we observe a decrease. The channels C and D (the detector most affected by spikes) didn’t show any trend so far (see 2.4.5.2).