(Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears...
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![Page 1: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/1.jpg)
(Very) Preliminary Quality Assessment of Stratospheric AMSU Channels
(Channels 9 – 14)
Carl Mears
Remote Sensing Systems
![Page 2: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/2.jpg)
AMSU and SSU Weighting Functions
AMSU 9
AMSU 10
AMSU 11
AMSU 12
AMSU 13
SSU 15x
SSU 25
SSU 26SSU 27
![Page 3: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/3.jpg)
Some Results from the Troposphere and Lower Stratosphere
![Page 4: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/4.jpg)
Problems with AMSUMid-Troposphere
Funny behavior for near-limb views
![Page 5: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/5.jpg)
Problems with AMSU(Near Tropopause)
Other channels at least as bad!
Some indication that target factor could be FOV dependent!
![Page 6: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/6.jpg)
Problems with AMSU
How do we figure out which AMSU instrument is bad (or at least, less bad)
• Radiosondes probably not accurate enough
• Time period too short for water vapor to help
• NOAA-16 farther way from NOAA-14 MSU (but this is an old instrument)
Solution: Figure out which AMSU has a more consistent dataset by looking at all channels (and nadir vs limb views)
![Page 7: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/7.jpg)
Probable vertical structure of trends
Trend
Height
Tropopause
![Page 8: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/8.jpg)
Trends – NOAA-15 and NOAA-16Tropical Oceans, 30S to 30N
NOAA-15: Fairly consistent
except for Channel 6.
NOAA-16: All channels inconsistent except for (maybe) channel 4.
![Page 9: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/9.jpg)
Trends – NOAA-15 and NOAA-16 Tropical Oceans, 30S to 30N, 2002-2006
NOAA-15: Fairly consistent
except for Channel 6.
NOAA-16: All channels inconsistent except for (maybe) channel 4.
Conclusion: NOAA-16 more likely to be the problem – NOAA-16 is removed.
![Page 10: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/10.jpg)
Now, the Stratosphere
• Basis strategy – apply the same analysis to the stratospheric channels to see if NOAA-16 has problems for these channels too.
• Very preliminary, since we have not performed any diurnal adjustment.
• Difficult to evaluate channels 11 and 14 due to short (or zero) overlap
![Page 11: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/11.jpg)
Trends, 2002-2006, K/decade60S to 60N
Trends broadly consistent for all stratospheric channels
Nadir-limb difference seems too large
- related to diurnal drift?
![Page 12: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/12.jpg)
Channel 10 Time Series
Tem
pera
ture
Tem
pera
ture
Ano
mal
yN
OA
A-1
6 –
NO
AA
15
For Channel 10, everything is fairly well behaved.
![Page 13: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/13.jpg)
Channel 12 Time Series
Tem
pera
ture
Tem
pera
ture
Ano
mal
yN
OA
A-1
6 –
NO
AA
15
For Channel 12, descending node shows significant drift.
![Page 14: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/14.jpg)
Adjusting for drifts in measurement time
NOAA satellites drift in local measurement time
If uncorrected, these would lead to spurious long-term
signals in the dataset.
NOAA-15
NOAA-16
![Page 15: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/15.jpg)
NOAA-16 minus NOAA-15 differencesby field of view.
Drift in descending node strongly dependent on field of view.
At least part of this is due to drift in measurement time.
![Page 16: (Very) Preliminary Quality Assessment of Stratospheric AMSU Channels (Channels 9 – 14) Carl Mears Remote Sensing Systems.](https://reader035.fdocuments.net/reader035/viewer/2022062619/5515fa3d550346d46f8b582e/html5/thumbnails/16.jpg)
Conclusions
• Where we can evaluate them, the stratospheric channels on AMSU appear to be in better shape than the tropospheric channels.
• Need to come up with a reasonable diurnal adjustment– 4 AMSUs with different measurement times
– Stratospheric model data with output every 3 hours
– Microwave Limb Sounder probably not useful.