Validation and error estimation of AIRS MUSES CO profiles with HIPPO, ATom, and NOAA GML aircraft observations
<p>Single-footprint retrievals of carbon monoxide from the Atmospheric Infrared Sounder (AIRS) are evaluated using aircraft in situ observations. The aircraft data are from the HIAPER Pole-to-Pole Observations (HIPPO, 2009–2011), the first three Atmospheric Tomography Mission (ATom, 2016–2017)...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-01-01
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| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://amt.copernicus.org/articles/15/205/2022/amt-15-205-2022.pdf |
| Summary: | <p>Single-footprint retrievals of carbon monoxide from the
Atmospheric Infrared Sounder (AIRS) are evaluated using aircraft in situ
observations. The aircraft data are from the HIAPER Pole-to-Pole Observations (HIPPO,
2009–2011), the first three Atmospheric Tomography Mission (ATom,
2016–2017) campaigns, and the National Oceanic and Atmospheric
Administration (NOAA) Global Monitoring Laboratory (GML) Global Greenhouse
Gas Reference Network aircraft program in years 2006–2017. The retrievals
are obtained using an optimal estimation approach within the MUlti-SpEctra,
MUlti-SpEcies, MUlti-SEnsors (MUSES) algorithm. Retrieval biases and
estimated errors are evaluated across a range of latitudes from the
subpolar to tropical regions over both ocean and land points.</p>
<p>AIRS MUSES CO profiles were compared with HIPPO, ATom, and NOAA GML aircraft
observations with a coincidence of 9 h and 50 km to estimate retrieval
biases and standard deviations. Comparisons were done for different pressure
levels and column averages, latitudes, day, night, land, and ocean
observations. We found mean biases of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>+</mo><mn mathvariant="normal">6.6</mn><mo>±</mo><mn mathvariant="normal">4.6</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="8f16aa2a640bce11c55bc53da4bf8eae"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-205-2022-ie00001.svg" width="52pt" height="10pt" src="amt-15-205-2022-ie00001.png"/></svg:svg></span></span> %, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>+</mo><mn mathvariant="normal">0.6</mn><mo>±</mo><mn mathvariant="normal">3.2</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="01012cbedfda3fe47687d2f0f4862d9a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-205-2022-ie00002.svg" width="52pt" height="10pt" src="amt-15-205-2022-ie00002.png"/></svg:svg></span></span> %, and <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">6.1</mn><mo>±</mo><mn mathvariant="normal">3.0</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="52pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="b897abc2f456bea4cac7c25431516d40"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-15-205-2022-ie00003.svg" width="52pt" height="10pt" src="amt-15-205-2022-ie00003.png"/></svg:svg></span></span> % for three representative pressure
levels of 750, 510, and 287 hPa, as well as column average mean biases of
<span class="inline-formula">1.4±3.6</span> %. The mean standard deviations for the three
representative pressure levels were 15 %, 11 %, and 12 %, and the column
average standard deviation was 9 %. Observation errors (theoretical
errors) from the retrievals were found to be broadly consistent in magnitude
with those estimated empirically from ensembles of satellite aircraft
comparisons, but the low values for these observation errors require
further investigation. The GML aircraft program comparisons generally had
higher standard deviations and biases than the HIPPO and ATom comparisons.
Since the GML aircraft flights do not go as high as the HIPPO and ATom
flights, results from these GML comparisons are more sensitive to the choice
of method for extrapolation of the aircraft profile above the uppermost
measurement altitude. The AIRS retrieval performance shows little
sensitivity to surface type (land or ocean) or day or night<span id="page206"/> but some
sensitivity to latitude. Comparisons to the NOAA GML set spanning the years
2006–2017 show that the AIRS retrievals are able to capture the distinct
seasonal cycles but show a high bias of <span class="inline-formula">∼20 <i>%</i></span> in the lower
troposphere during the summer when observed CO mixing ratios are at annual
minimum values. The retrieval bias drift was examined over the same years
2006–2017 and found to be small at <span class="inline-formula"><0.5 <i>%</i></span>.</p> |
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| ISSN: | 1867-1381 1867-8548 |