Oxford MIPAS meeting#98
04 July 06

Present

Oxford: Anu Dudhia, Jane Hurley, Joanne Walker, Claire Waymark, Chiara Piccolo

The instrument is scheduled to perform 3 days of continuous nominal mode measurements from 4-7 July, and again from 12-15 July, followed by a long period (21Jul-21Aug) of UTLS1 measurements over W. Africa in support of the AMMA campaign.

Current version of Mission Planning Document (2006 up to Jun26) [.xls] [.html].
Envisat Web-Site contains additional information
Marta de Laurentis (ESRIN) has produced some statistics on the MIPAS measurement modes since Jan 2005 [.ppt] [.pdf], which have generated some discussion amongst Science Team members as to whether MIPAS has been spending too much time recently being used to support localised campaigns and not enough time making global measurements.

May Monthly Report [Prev] [Next]

May monthly report now available [Summary below]. Full report downloadable from http://earth.esa.int/pcs/envisat/mipas/reports/monthly/

L1B Data (JH) [Prev] [Next]

L1B coverage maps showing measurements taken since Jan 2005 in reduced resolution mode and processed as far as L1B (ie spectra).

Web-pages now being maintained by Jane Hurley with slight modifications (eg changing location files from *orbitdata.txt to *loc.txt) - Jan'05 done and will gradually proceed through entire dataset.

HiRDLS Comparisons (CW) [Prev] [Next]

Continuing to investigate MIPAS/HIRDLS relative altitude offsets for each HIRDLS channel overlapped by MIPAS spectra: applying height offset to radiance profiles in stratosphere.

MIPAS Precision (CP) [Prev] [Next]

Investigating MIPAS L2 precision values by comparing scatter between retrieved profiles where orbital tangent tracks intersect with scatter predicted by retrieval SD.

pT error propagation is also considered, but usually only a small fraction of the estimated random error
For most species quite good agreement is obtained
Unexplained large differences in temperature comparisons
Also may have a problem with algorithm that calculates distance between two profiles for colocation purposes

ACE Comparisons (CP) [Prev] [Next]

Using ACE data (Jan04-onwards) for MIPAS L2 validation papers.

Problem trying to find any estimates of ACE systematic error budget.

Cloud Top Height (JH) [Prev] [Next]

Generating cirrus climatology using MIPAS spectra, trying to fit cloud-top-height within 3km vertical box represented by MIPAS FOV

Uses A-band microwindow 960-961cm^-1 (most optically thin region of MIPAS spectrum) to determine best fit of cloud top height within field of view.

Comparing results with equivalent B-band microwindow 1231-1232 produces results which seem to have a systematically higher bias by a few hundred metres - investigating reason for this.

N2O Anomaly Mar03 (AD) [Next]

Jens-Uwe Grooss (FZ Juelich) has noticed anomalously high N2O concentrations around 7-8 March and 13-15 March 2003 [email 22Jun06]

The following comments have been made in response

Daily zonal mean plots show the variation in the MIPAS L2 data at the 30km nominal altitude from Feb-Apr 2003.
The features that Jens-Uwe Grooss has noted in the low altitude N2O retrievals on 8th and 15th March are also evident at 30km: positive spikes in the N2O, CH4 and O3; negative spikes in the temperatures, HNO3, H2O and NO2.
Since these features are evident at all latitudes, altitudes and species, it looks to me like a calibration problem. I note that MIPAS was also switched off for much of 8th March and the whole Envisat platform was shut down from 15-18 March - in the past we've had problems with radiometric calibration where there has been a gap in coverage.

MIPAS QWG-10 & ST-4 [Prev] [Next]

Quality Working Group Meeting#10 was held in Frascati 13-15 Jun 06, followed by the MIPAS Science Team Meeting#4 15-16 Jun 06. [Next]

Oxford Presentation [.ppt] [.pdf] covering

PT Error Propagation Matrix (CP) [Prev]
Additional Microwindows for high mesospheric NO2 (AD)
Status of Error Spectra (AD)
Aug'04 L2 Data Quality (AD)

Minutes of both meetings will be put here when they become available.

QWG10 Minutes (F.Niro, 13th July) [DOC] [PDF]
ST4 Minutes (C.Zehner, 24th July) [DOC] [PDF]

ACVE3 [Prev] [Next]

Email from Paul Snoeij, ESTEC, 23 Jun 06

A new date has been announced for the Atmospheric Chemistry Validation for Envisat workshop: 4-7 December 2006 at ESRIN

For MIPAS comparisons the following datasets will be used

MIPAS Full resolution (FR) mode (launch - March 2004): Level 1 and level 2 reprocessing with IPF version 4.61 has been finalised. Due to an IPF anomaly Level 2 data processed with IPF 4.62 should used carefully. If available, IPF version 4.61 Level 2 should be used. Level 1 and Level 2 data are already on-line at DPAC.
MIPAS Reduced resolution (RR17) mode with 17 sweeps (09-22 Aug 2004, 16-17 Sept 2004): Level 1 and level 2 reprocessing with IPF version 4.65 has been finalized. Level 1 and Level 2 data are already on-line at DPAC.
MIPAS Reduced resolution (RR27) mode with 27 sweeps (10 Jan 2005 - present): Level 1 processing with IPF version 4.65. Level 1 data is already available on-line at D-PAC
MIPAS Reduced resolution (RR27) mode with 27 sweeps - Validation Dataset: The data for this mode will be processed on a best effort basis with the prototype processors. Level 1 processing with the prototype processor MIGSP corresponding to upcoming IPF 5.xx. Level 2 processing with the prototype processor ML2PP corresponding to upcoming IPF 5.xx. Level 1 and Level 2 validation data distribution by D-PAC FTP server as soon as the data is available. Only a limited data set will be processed covering the major campaigns executed for the above mentioned mission scenario. There will also be a small number of validation data for the Full Resolution mission processed with the prototype processors. It is the intention to have the limited data set available by November 2006. There is a potential risk that there will be minor differences between the prototype used for the reprocessing and the IPF 5.xx.

Summary of May Monthly Report (F. Niro, ESRIN).

The MIPAS instrument performs really well during May 2006; in fact only 7 slide errors occurred. As already noted in the previous MR the effect of the last Envisat anomaly (6th April 2006) was an overall improvement of the instrument performances, in particular the cooler, this yields also to improved interferometer performances.
The instrument operated the first two weeks of the month in UTLS-1 mode in support of the INTEX-B campaign (4 orbits per day). Nominal modes were performed during 2 - 4 May and 29 May - 1 June and UTLS-1 modes were acquired during 22 - 25 May. During these measurement segments the instrument was operating 3 days-on followed by 4 days-off.
The monitoring of the instrument temperatures continued nominally this month; we observe an overall warming of the instrument devices since start of the month by 1 - 2 K, in particular the FCA radiator temperature increase by about 5K and the CBB temperatures by almost 3K (see § 2.3.1). This situation is nominal during this period, which is the hottest part of the year.
The cooler performance was closely monitored on a daily and monthly basis. The cooler seems to perform really well, even though the compressor vibrations start to increase in the second half of the month, in particular we observed some orbit-dependent spikes that reach the limit of 8 mg at their maxima (see § 2.3.3.1), these are due to the warmer environment conditions typical of this part of the year.
The gain, spectral and line of sight calibrations were carried out nominally during the reporting period, including the dissemination of the related ADF. The gain weekly increase remains stable around the nominal value of 1%, the spectral correction factor and the mispointing are also stable (see § 2.4.2, § 2.4.3, § 2.4.4).
A monitoring of the absolute gain increase since the last decontamination (June 2005) is presented in this MR besides the long term weekly increase. This monitoring will help the planning of the future decontamination activity. We can observe that the gain increase looks linear with time after the decontamination induced by the PLSOL of April (see § 2.4.3).
The level 1 quality monitoring of the OFL products created at D-PAC is on going in parallel with the mission. The check of the considered L1 products has demonstrated an overall good quality of the D-PAC results. Nevertheless a major problem was observed on L1 data from 3 - 23 June 2005 and 29 July - 11 Aug 2005. These data have very poor quality due to a wrong offset calibration. This problem is now resolved with the generation of a new set of ADFs, the reprocessing of this part of mission will be carried out the next days at D-PAC (see § 2.4.6.1).
A quality control of the entire set of L2 products processed at D-PAC with IPF 4.65 was completed, revealing an overall good quality of the products, nevertheless an anomaly was found for some orbits of 21 - 22 Aug 2004. After the investigation we found that the problem was due to a corruption in the band D spectrum. Indeed the processor flags all the sweep as corrupted even though only one single band is corrupted. This processor specification which seems really restrictive, in particular for the band D which is not used in the retrieval, should be probably revised in the next QWG (see § 2.5.3.1).

Email from Jens Uwe-Grooss 22Jun06 forwarded to MIPAS QWG

I write this email to you, as I have found some strange features in the MIPAS N2O data from the ESA retrieval. I got the data from Reinhold Spang and they are the ESA reprocessed MIPAS data.

On specific dates the N2O values seem to be much too high as they exceed the tropospheric value. To visualize that I have [plotted] for each MIPAS profile in March between 20S and 20N latitude the pressure at which N2O=300ppb. On March 7/8 and March 13-15 this pressure level is much too high consistently for all data (that is also for the higher latitudes).

Did you (or anyone else from the QWG) see such behaviour and do you have any idea what may be the cause for this potential artefact?

AD Jul 06

Oxford MIPAS meeting#98 04 July 06

Oxford MIPAS meeting#98
04 July 06