Oxford MIPAS meeting#104
17 October 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]

Envisat problem with Ka band antenna continues (details on the Envisat Web-Site) - see Summary of the September report.

MIPAS itself should now be 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 12Nov) [XLS] [HTML].
Currently defined measurement modes
Envisat Web-Site

September Monthly Report [Prev] [Next]

MIPAS monthly report for September is now available [Summary]

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

L1B Data (JH) [Prev] [Next]

L1B coverage maps showing locations and operating mode of RR L1B data since Jan 2005

Coverage maps now updated to show MIPAS observations up to the end of September 2006

L2 Data Anomalies [Prev] [Next]

CP Previously noted that 2002 data often missing near S.Pole, eg 25 Jul 02

The [Summary] of the September monthly report explains this as due to the presence of the scan pattern being shifted upwards higher than normal (>72km instead of the nominal 68km) so that no microwindow occupation matrices are defined for the retrieval.
This should be fixed in the next software update.

RR27 pT Retrieval (AD) [Prev] [Next]

Trying to find a set of microwindows for pT retrieval that work satisfactorily with the ORM.

Original selection led to a discontinuity at 21km where microwindows switched from 940cm-1 region (low altitudes) to longer wavelengths
Assume retrieved uncertainties in H2O and O3 rather than climatological uncertainties to see if microwindows spanning intermediate altitude range can be gound
A bug was found in the last selection, meaning that O3 variability was not being considered (hence problems with high chi^2).
Currently reselecting microwindows 351-360.

Middle Atmosphere Mode (AD) [Prev] [Next]

Microwindow selection for MA mode observations (29 sweeps from 18-102km @ 3km steps). Intention is to use these to retrieve mesospheric data taken Jan 10-15 2005.

Microwindows#401-410 selected for pT, H2O, HNO3, O3, CH4, N2O, NO2 and CO
LUTs & irregular grids now complete

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] shows time series Jul02-Mar04 of the ratio (observed/predicted) standard deviation for pT and 5 molecules (this technique cannot be applied to NO2 since there is a significant diurnal variation between the ascending/descending orbits)
Different colours represent different latitude bands
In general ratio is about 2-4, although noticeably larger in the polar winter vortex (possibly due to horizontal gradient effects)
pT propagation error should also be taken into account (not shown in these plots) which increases the predicted variability, therefore decreases the ratio towards the "expected" value of 1.
Another reason for the larger-than-predicted variability may be oscillations in the retrieved profiles

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

Started on a comparison of MIPAS and TES radiance spectra where the MIPAS bands and TES filters overlap

[Plot] of spectral coverage of MIPAS, HIRDLS and TES - TES filters are 1A1, 2A1 etc.

CO Retrievals (JW) [Prev] [Next]

Starting to attempt a joint retrieval of CO and vibrational temperature

RFM being used in non-LTE mode as a forward model within IDL retrieval program
Still at the stage of testing with simulated data assuming a 10cm-1 region of spectrum near the strongest CO lines

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).

As a separate issue, has also been comparing the preferred MIPAS "window" channel 960-961cm-1 with the ISAMS (filter) 12 micron channel reconstructed from MIPAS spectra, although the main conclusion seems to be that, while they are both reasonable "window" channels, their combination does not seem to add any information on cloud composition - probably need to look at different spectral regions for this.

Noctilucent Clouds (LMV) [Prev] [Next]

As a first step towards detection of NLCs (or calibration artefacts) from the complete MIPAS spectrum, the first step is to construct a filter to remove spectral points influenced by atmospheric lines, leaving just the background continuum terms. Currently just using the RFM to simulate CO2 in the A-band.

ACVE-3 Workshop 4-7th Dec, Frascati [Prev] [Next]

Website: www.congrex.nl/06m25/

Although the official deadline for abstracts was a couple of days ago, the website says that late submissions will be accepted up until 24th November

Nothing submitted from Oxford so far.

RAL Work (AW) [Prev] [Next]

Finishing up work for MIPAS validation papers on pT and O3, also sent off something for H2O but haven't heard back

About to start, once again, looking at the 2D UTLS joint O3+H2O retrieval.

ACPD Papers [Prev] [Next]

Papers selected from the ACPD website for discussion

"An annual cycle of long lived stratospheric gases from MIPAS": by M. N. Juckes (submitted 26.09.2006, open until 21.11.2006); Introduced by AD
" Reflection and transmission of solar light by clouds: asymptotic theory": by A. A. Kokhanovsky & T. Nauss (submitted 31.08.2006, open until 26.10.2006); Comments being collected by JH.

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)
"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)
"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)
"Comparisons between ground-based FTIR and MIPAS N2O and HNO3 profiles before and after assimilation in BASCOE": by C. Vignouroux et al (submitted 01.09.2006, open until 27.10.2006)

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

During the reporting month the MIPAS mission was strongly impacted by two ENVISAT anomalies; one occurred the 7th September and causes the switch-off of all the payload instruments, the second occurred on 26th September and consists on a problem with Ka Band antenna that transmits data via the Artemis satellite. The effect of these two anomalies on the MIPAS mission is detailed below.

The ENVISAT payload switch-off, occurred on 7th September, gives the opportunity to perform the instrument decontamination, originally planned for week 39. This decision allowed minimizing measurement data loss. As a result no MIPAS measurements were taken from 7 Sept 16:46 UTC to 19 Sept 02:00 UTC. The MIPAS mission restarts with the MA/UA scenario in correspondence to the Equinox. The performances of the instrument after the switch-off were nominal.
The anomaly on the Ka-Band antenna occurred on 26th September prevents Envisat to transmit data via the Artemis Relay Satellite. ESA put in place a temporary data acquisition scenario based on the use of European polar acquisition stations (9 orbits send to Kiruna and 5 orbits to Svalbard, with X-Band downlink). This scenario is similar to what was arranged at the beginning of the mission before the start of Artemis operation. This configuration started during night of 1st October. This means that from 26 September to 1st October the orbits to be acquired via Artemis satellite were lost. The impact of this anomaly on MIPAS data acquisition was actually less important with respect to other ENVISAT instruments due to the planned mission interruption of 28 September – 1 October; in total only 10 orbits segments were not acquired due to this anomaly.

The instrument operated during the reporting month with the following planning (see § 2.2.1):

Decontamination was planned during week #37 (from 11 to 19 Sept)
NOM measurements during 30 Aug – 2 Sept and 25 – 28 Sept.
UTLS-1 measurements during 5 – 8 Sept.
MA/UA mode during 19 – 22 Sept in correspondence to the Equinox.

The MIPAS instrument performs really well during the reporting month; in fact only 5 instrument anomalies were observed due to IDU velocity error (see § 2.2.4).

The L0 statistics are reported on § 2.2.4; the statistics of the reporting month are highly influenced by the payload anomalies reported above and by the planned decontamination period.

The effect of the instrument decontamination was an overall reduction of all the instrument temperatures by few degrees, this is due to the better performance of the cooler after the switch-off (see § 2.3.1).

The long term trend of the ADC max counts in channel A1 shows to be highly correlated with the seasonal variation of the instrument thermal condition. The recent decontamination results in an increase of ADC maximum counts, this was expected since the ice removal causes an increase of signal at the detector (see § 2.3.2).

The cooler perform really well during this month, the spikes that were observed in the hottest part of the year (starting from May 2006) are now significantly reduced; the effect of the decontamination was a decrease of the cooler vibration by about 1mg (see § 2.3.3.1).

The spectral correction factor long term monitoring 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 decontamination induced a gain reduction of about 10%. The gain increase restarted nominally after the 19th September with weekly increase below the acceptance criterion of 1% (see § 2.4.3.1).

The long term gain analysis was updated during this month, in particular the reference gain was set to the first disseminated gain after the recent decontamination (see § 2.4.3.2).

The mispointing long term monitoring shows a steady situation; in fact during the last year the relative bias seems to be stable around a value of few mdeg. To be noted that the last disseminated LOS ADF was on March 2005. During the reporting month only one LOS calibration was performed since two planned weekly calibrations were lost due to the decontamination and the PLSOL (see § 2.4.4).

The investigation on the anomaly of L2 OFL data detected by C. Piccolo (OU) is now concluded. The problem was that during July - November 2002 several L2 profiles are missing in the Antarctic region, due to retrieval failure. The investigation shows that the problem appears at the South Pole when the tangent altitude of the highest sweep exceeds 72km; this value corresponds to the upper limit defined in the OM. A solution for this problem would be to relax the OM altitude range definition, however with the new algorithm baseline (V5.0) this problem will be overcome owing to the capability of handling floating altitude scenario (see § 2.5.3).

Another L2 anomaly was investigated during this month, it was the continuum problem detected by C. Bellotti and reported at the QWG #10. The problem was that the processor retrieves sometimes the continua above the limit defined in the PS2 setting file (20 km). The anomaly happens whenever the lowest fitted altitude is higher than the continuum altitude limit (20 km). The problem was recognized as a weakness in the L2 processor baseline and it will be corrected within the new prototype delivery (see § 2.5.3).

The long term monitoring of fringe count errors (FCE) for the RR mission was updated this month; this analysis shows that so far no correlation can be appreciated with respect to interferometer degradation.

The level 1 quality monitoring of the OFL products created 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/
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/

Oxford MIPAS meeting#104 17 October 06

Oxford MIPAS meeting#104
17 October 06