Summary of September Report
Forwarded by Thorsten Fehr/esrin/ESA on 17/10/2007 15:57
Summary
During
the reporting month MIPAS performs really well; in fact only 1 instrument
anomaly occurred due to IDU errors. However the instrument was not operational
from the 24th to the 29th September due to a platform switch-off (PLSOL)
(see 2.2.2).
The
instrument planning for the reporting month is hereafter summarized (see
2.2.1):
o The
Equinox scenario was planned in the week 19 – 26 Sep, the Baseline
scenario was planned the other days
o Aircraft
Emissions (AE) Mode (ascending and descending passes) were planned
over North Atlantic corridor during 9-11 September
All
the planned measurements were acquired. The availability of the instrument
was high (99 % of the planned time) due to the good performances of the
interferometer. The measurement segments not processed to level 0 due to
failures at the ground segment were about 2% of the planned measurement
time (see 2.2.4).
The
long term analysis of MIPAS L0 product availability shows the increased
duty cycle since April 2006 and highlights the improved instrument performances
(see 2.2.4.2).
The
instrument temperatures are stable over the reporting month with variation
in the range of 1K (see 2.3.1).
The
cooler performs well during the reporting month; the vibrations were always
well below the warning level of 8 mg, however one out-of-limit value was
observed on 24 Oct due to a single event upset (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 detector ice contamination.
During the reporting month the ADC counts decrease in line with the seasonal
variation of the instrument temperature (see 2.3.4).
The
monitoring of the spectral correction factor shows a slight decreasing
trend; however the variations over more than two years of operations are
really small ( 2 ppm). The observed spreading of the points is due to the
noise in the determination of this parameter (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%/week. However due to the PLSOL and the subsequent cooler
switch-off we obtain a non-intended decontamination with a decrease of
the gain by more than 8% at its maximum (see § 2.4.3.1).
The
analysis of the accumulated gain allows to infer the level of detector
ice contamination. During the last year we observed a decreasing slope
of the gain curve, showing that the detector is more and more ice-free.
This is due to the better performances of the cooler obtained with more
frequent decontamination (see §2.4.3.2).
The
absolute mispointing error is stable around a value of -25mdeg. The seasonal
variations of the pointing error are small and below the fixed threshold
of 8mdeg (see §2.4.4).
The
long term monitoring of fringe count errors (FCE) 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 strongly correlated with the number of IDU errors (see §
2.4.5.1).
The
long term monitoring of the detected spikes shows that the number of detected
spikes in channels A1, A2, B1 and B2 is varying with time with some peaks
probably related to variation of the solar activity. The channels C and
D (the detector most affected by spikes) didn’t show any trend so far.
From this analysis we can conclude that the number of detected spikes is
too small to impact the L1b products quality (see § 2.4.5.2).
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
level 1b OFL daily reports can be accessed at the following address:
http://earth.esa.int/pcs/envisat/mipas/reports/daily/Level_1_OFL/
