Evaluation of single-footprint AIRS CH<sub>4</sub> profile retrieval uncertainties using aircraft profile measurements
-
Published:2021-01-15
Issue:1
Volume:14
Page:335-354
-
ISSN:1867-8548
-
Container-title:Atmospheric Measurement Techniques
-
language:en
-
Short-container-title:Atmos. Meas. Tech.
Author:
Kulawik Susan S., Worden John R., Payne Vivienne H., Fu DejianORCID, Wofsy Steven C., McKain KathrynORCID, Sweeney ColmORCID, Daube Jr. Bruce C., Lipton Alan, Polonsky Igor, He Yuguang, Cady-Pereira Karen E., Dlugokencky Edward J., Jacob Daniel J., Yin YiORCID
Abstract
Abstract. We evaluate the uncertainties of methane optimal estimation retrievals from single-footprint thermal infrared observations from the Atmospheric Infrared Sounder (AIRS). These retrievals are primarily sensitive to atmospheric methane in the mid-troposphere through the lower stratosphere
(∼2 to ∼17 km). We compare them to in situ observations made from aircraft during the
HIAPER Pole to Pole Observations (HIPPO) and Atmospheric Tomography Mission (ATom) campaigns, and
from the NOAA GML aircraft network, between the surface and 5–13 km, across a range of
years, latitudes between 60∘ S to 80∘ N, and over land and ocean. After a
global, pressure-dependent bias correction, we find that the land and ocean have similar biases
and that the reported observation error (combined measurement and interference errors) of
∼27 ppb is consistent with the SD between aircraft and individual AIRS
observations. A single observation has measurement (noise related) uncertainty of
∼17 ppb, a ∼20 ppb uncertainty from radiative interferences (e.g., from
water or temperature), and ∼30 ppb due to “smoothing error”, which is partially
removed when making comparisons to in situ measurements or models in a way that accounts for this
regularization. We estimate a 10 ppb validation uncertainty because the aircraft typically
did not measure methane at altitudes where the AIRS measurements have some sensitivity, e.g., the
stratosphere, and there is uncertainty in the truth that we validate against. Daily averaging only
partly reduces the difference between aircraft and satellite observation, likely because of
correlated errors introduced into the retrieval from temperature and water vapor. For example,
averaging nine observations only reduces the aircraft–model difference to ∼17 ppb
vs. the expected ∼10 ppb. Seasonal averages can reduce this ∼17 ppb
uncertainty further to ∼10 ppb, as determined through comparison with NOAA aircraft,
likely because uncertainties related to radiative effects of temperature and water vapor are
reduced when averaged over a season.
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference70 articles.
1. Alvarado, M. J., Payne, V. H., Cady-Pereira, K. E., Hegarty, J. D., Kulawik, S. S.,
Wecht, K. J., Worden, J. R., Pittman, J. V., and Wofsy, S. C.: Impacts of updated spectroscopy on
thermal infrared retrievals of methane evaluated with HIPPO data, Atmos. Meas. Tech., 8, 965–985,
https://doi.org/10.5194/amt-8-965-2015, 2015. 2. Aumann, H. H., Chahine, M. T., Gautier, C., Goldberg, M. D., Kalnay, E., McMillin, L. M., Revercomb, H., Rosenkranz, P. W., Smith, W. L., Staelin, D. H., Strow, L. L., and Susskind, J.: AIRS/AMSU/HSB on the aqua mission: Design, science objectives, data products, and processing systems, IEEE T. Geosci. Remote, 41, 253–264, 2003. 3. Bowman, K. W., Rodgers, C. D., Kulawik, S. S., Worden, J., Sarkissian, E., Osterman, G.,
Steck, T., Lou, M., Eldering, A., and Shephard, M.: Tropospheric emission spectrometer: Retrieval
method and error analysis, IEEE T. Geosci. Remote Sens., 44, 1297–1307, 2006. 4. Brasseur, G. P., Hauglustaine, D. A., Walters, S., Rasch, P. J., Muller, J. F.,
Granier, C., and Tie, X. X.: MOZART, a global chemical transport model for ozone and related
chemical trac- ers 1. Model description, J. Geophys. Res.-Atmos., 103, 28265–28289, 1998. 5. Connor, B. J., Bösch, H., Toon, G., Sen, B., Miller, C., and Crisp, D.: Orbiting Carbon
Observatory: Inverse method andprospective error analysis, J. Geophys. Res., 113, A05305,
https://doi.org/10.1029/2006JD008336, 2008.
Cited by
13 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|