scholarly journals Improved agreement of AIRS tropospheric carbon monoxide products with other EOS sensors using optimal estimation retrievals

2010 ◽  
Vol 10 (5) ◽  
pp. 11851-11883
Author(s):  
J. X. Warner ◽  
Z. Wei ◽  
L. L. Strow ◽  
C. D. Barnet ◽  
L. C. Sparling ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Degrees Of Freedom ◽  
Lower Troposphere ◽  
Optimal Estimation ◽  
Primary Objective ◽  
Retrieval Algorithm ◽  
Atmospheric Infrared Sounder ◽  
Error Covariance ◽  
Transport Experiment ◽  
Northern Pacific

Abstract. We present in this paper an alternative retrieval algorithm for the Atmospheric Infrared Sounder (AIRS) tropospheric Carbon Monoxide (CO) products using the Optimal Estimation (OE) technique, which is different from AIRS operational algorithm. The primary objective for this study was to compare AIRS CO, as well as the other retrieval properties such as the Averaging Kernels (AKs), the Degrees of Freedom for Signal (DOFS), and the error covariance matrix, against the Tropospheric Emission Spectrometer (TES) and the Measurement of Pollution in the Troposphere (MOPITT) CO, which were also derived using OE technique. We also demonstrate that AIRS OE CO results are much more realistic than AIRS V5 operational CO, especially in the lower troposphere and in the Southern Hemisphere (SH). These products are validated with in situ profiles obtained by the Differential Absorption Carbon Monoxide Measurements (DACOM), which took place as part of NASA's Intercontinental Chemical Transport Experiment (INTEX-B) field mission that was conducted over the northern Pacific in Spring 2006. To demonstrate the differences existing in the current operational products we first show a detailed direct comparison between AIRS V5 and TES operational V3 CO for the global datasets from December 2005 to July 2008. We then present global CO comparisons between AIRS OE, TES V3, and MOPITT V4 at selected levels as well as for the total column amounts.

scholarly journals Improved agreement of AIRS tropospheric carbon monoxide products with other EOS sensors using optimal estimation retrievals

2010 ◽  
Vol 10 (19) ◽  
pp. 9521-9533 ◽  
Author(s):  
J. X. Warner ◽  
Z. Wei ◽  
L. L. Strow ◽  
C. D. Barnet ◽  
L. C. Sparling ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Degrees Of Freedom ◽  
Lower Troposphere ◽  
Optimal Estimation ◽  
Primary Objective ◽  
Retrieval Algorithm ◽  
Atmospheric Infrared Sounder ◽  
Error Covariance ◽  
Transport Experiment ◽  
Total Column

Abstract. We present in this paper an alternative retrieval algorithm for the Atmospheric Infrared Sounder (AIRS) tropospheric Carbon Monoxide (CO) products using the Optimal Estimation (OE) technique, which is different from the AIRS operational algorithm. The primary objective for this study was to compare AIRS CO, as well as the other retrieval properties such as the Averaging Kernels (AKs), the Degrees of Freedom for Signal (DOFS), and the error covariance matrix, against the Tropospheric Emission Spectrometer (TES) and the Measurement of Pollution in the Troposphere (MOPITT) CO, which were also derived using the OE technique. We also demonstrate that AIRS OE CO results are much more realistic than AIRS V5 operational CO, especially in the lower troposphere and in the Southern Hemisphere (SH). These products are validated with in situ profiles obtained by the Differential Absorption Carbon Monoxide Measurements (DACOM), which took place as part of NASA's Intercontinental Chemical Transport Experiment (INTEX-B) field mission that was conducted over the northern Pacific in Spring 2006. To demonstrate the differences existing in the current operational products we first show a detailed direct comparison between AIRS V5 and TES operational V3 CO for the global datasets from December 2005 to July 2008. We then present global CO comparisons between AIRS OE, TES V3, and MOPITT V4 at selected pressure levels as well as for the total column amounts. We conclude that the tropospheric CO retrievals from AIRS OE and TES V3 agree to within 5–10 ppbv or 5% on average globally and throughout the free troposphere. The agreements in total column CO amounts between AIRS OE and MOPITT V4 have improved significantly compared to AIRS V5 with global relative RMS differences now being 12.7%.

scholarly journals Global carbon monoxide products from combined AIRS, TES and MLS measurements on A-train satellites

2013 ◽  
Vol 13 (6) ◽  
pp. 15409-15441
Author(s):  
J. X. Warner ◽  
R. Yang ◽  
Z. Wei ◽  
F. Carminati ◽  
A. Tangborn ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Data Fusion ◽  
Lower Troposphere ◽  
Atmospheric Infrared Sounder ◽  
Upper Troposphere ◽  
In Situ Data ◽  
Diode Laser Spectrometer ◽  
Spatial Coverage ◽  
Transport Experiment

Abstract. This study tests a novel methodology to add value to satellite datasets. This methodology, data fusion, is similar to data assimilation, except that the background model-based field is replaced by a satellite dataset, in this case AIRS (Atmospheric Infrared Sounder) carbon monoxide (CO) measurements. The observational information comes from CO measurements with lower spatial coverage than AIRS, namely, from TES (Tropospheric Emission Spectrometer) and MLS (Microwave Limb Sounder). We show that combining these datasets with data fusion uses the higher spectral resolution of TES to extend AIRS CO observational sensitivity to the lower troposphere, a region especially important for air quality studies. We also show that combined CO measurements from AIRS and MLS provide enhanced information in the UTLS (upper troposphere/lower stratosphere) region compared to each product individually. The combined AIRS/TES and AIRS/MLS CO products are validated against DACOM (differential absorption mid-IR diode laser spectrometer) in situ CO measurements from the INTEX-B (Intercontinental Chemical Transport Experiment: MILAGRO and Pacific phases) field campaign and in situ data from HIPPO (HIAPER Pole-to-Pole Observations) flights. The data fusion results show improved sensitivities in the lower and upper troposphere (20–30% and above 20%, respectively) as compared with AIRS-only retrievals, and improved coverage compared with TES and MLS CO data.

scholarly journals An online aerosol retrieval algorithm using OMI near-UV observations based on the optimal estimation method

2015 ◽  
Vol 15 (12) ◽  
pp. 16615-16654 ◽  
Author(s):  
U. Jeong ◽  
J. Kim ◽  
C. Ahn ◽  
O. Torres ◽  
X. Liu ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Degrees Of Freedom ◽  
Northeast Asia ◽  
Estimation Method ◽  
Optimal Estimation ◽  
Single Scattering ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Near Ultraviolet ◽  
Aerosol Retrieval

Abstract. An online version of the OMI (Ozone Monitoring Instrument) near-ultraviolet (UV) aerosol retrieval algorithm was developed to retrieve aerosol optical thickness (AOT) and single scattering albedo (SSA) based on the optimal estimation (OE) method. Instead of using the traditional look-up tables for radiative transfer calculations, it performs online radiative transfer calculations with the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model to eliminate interpolation errors and improve stability. The OE-based algorithm has the merit of providing useful estimates of uncertainties simultaneously with the inversion products. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in Northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved AOT and SSA. The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The estimated retrieval noise and smoothing error perform well in representing the envelope curve of actual biases of AOT at 388 nm between the retrieved AOT and AERONET measurements. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface albedo at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for future studies.

scholarly journals Characterization and evaluation of AIRS-based estimates of the deuterium content of water vapor

2019 ◽  
Vol 12 (4) ◽  
pp. 2331-2339 ◽  
Author(s):  
John R. Worden ◽  
Susan S. Kulawik ◽  
Dejian Fu ◽  
Vivienne H. Payne ◽  
Alan E. Lipton ◽  
...  
Keyword(s):  
Degrees Of Freedom ◽  
Optimal Estimation ◽  
Estimation Algorithm ◽  
Latitudinal Variation ◽  
Deuterium Content ◽  
Atmospheric Infrared Sounder ◽  
Single Target ◽  
Similar Accuracy ◽  
The Tropics

Abstract. Single-pixel tropospheric retrievals of HDO and H2O concentrations are retrieved from Atmospheric Infrared Sounder (AIRS) radiances using the optimal estimation algorithm developed for the Aura Tropospheric Emission Spectrometer (TES) project. We evaluate the error characteristics and vertical sensitivity of AIRS measurements corresponding to 5 d of TES data (or five global surveys) during the Northern Hemisphere summers between 2006 and 2010 (∼600 co-located comparisons per day). We find that the retrieval characteristics of the AIRS deuterium content measurements have similar vertical resolution in the middle troposphere as TES but with slightly less sensitivity in the lowermost troposphere, with a typical degrees of freedom (DOFS) in the tropics of 1.5. The calculated measurement uncertainty is ∼30 ‰ (parts per thousand relative to the deuterium composition of ocean water) for a tropospheric average between 750 and 350 hPa, the altitude region where AIRS is most sensitive, compared to ∼15 ‰ for the TES data. Comparison with the TES data also indicates that the uncertainty of a single target AIRS HDO ∕ H2O measurement is ∼30 ‰. Comparison of AIRS and TES data between 30∘ S and 50∘ N indicates that the AIRS data are biased low by ∼-2.6 ‰ with a latitudinal variation of ∼7.8 ‰. This latitudinal variation is consistent with the accuracy of TES data compared to in situ measurements, suggesting that both AIRS and TES have similar accuracy.

scholarly journals Validation and Error Estimation of AIRS MUSES CO Profiles with HIPPO, ATom and NOAA GML Aircraft Observations

2021 ◽  
Author(s):  
Jennifer D. Hegarty ◽  
Karen E. Cady-Pereira ◽  
Vivienne H. Payne ◽  
Susan S. Kulawik ◽  
John R. Worden ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Optimal Estimation ◽  
Reference Network ◽  
Atmospheric Infrared Sounder ◽  
Tropical Regions ◽  
Mixing Ratios ◽  
Bias Drift ◽  
Time Period ◽  
Aircraft Observations ◽  
Standard Deviations

Abstract. 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 (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 from 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 sub-polar to tropical regions over both ocean and land points. AIRS MUSES CO profiles were compared with HIPPO, ATom, and NOAA GML aircraft observations with a coincidence of 9 hours 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 find mean biases of +6.6 % +/− 4.6 %, +0.6 % +/− 3.2 %, −6.1 % +/− 3.0 %, and 1.4 % +/− 3.6 %, for 750 hPa, 510 hPa, 287 hPa, and the column averages, respectively. The mean standard deviation is 15 %, 11 %, 12 %, and 9 % at these same pressure levels, respectively. 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. 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 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 ~20 % 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 period and found to be small at < 0.5 % over the 2006–2017 time period.

scholarly journals The global tropospheric ammonia distribution as seen in the 13 year AIRS measurement record

2015 ◽  
Vol 15 (24) ◽  
pp. 35823-35856 ◽  
Author(s):  
J. X. Warner ◽  
Z. Wei ◽  
L. L. Strow ◽  
R. R. Dickerson ◽  
J. B. Nowak
Keyword(s):  
South America ◽  
A Priori ◽  
Optimal Estimation ◽  
Retrieval Algorithm ◽  
Aerosol Formation ◽  
Atmospheric Infrared Sounder ◽  
Animal Feeding Operations ◽  
Source Regions ◽  
Summer Maximum ◽  
Spring Maximum

Abstract. Ammonia (NH3) plays an increasingly important role in the global biogeochemical cycle of reactive nitrogen as well as in aerosol formation and climate. We present extensive and nearly continuous global ammonia measurements made by the Atmospheric Infrared Sounder (AIRS) from the Aqua satellite to identify and quantify major persistent and episodic sources as well as to characterize seasonality. We examine the 13 year period from September 2002 through August 2015 with a retrieval algorithm using an optimal estimation technique with a set of three, spatially and temporally uniform a priori profiles. Vertical profiles show good agreement (~5–15 %) between AIRS NH3 and the in situ profiles from the winter 2013 DISCOVER-AQ field campaign in central California, despite the likely biases due to spatial resolution differences between the two instruments. AIRS captures the strongest consistent NH3 emissions from the anthropogenic (agricultural) source regions, such as, South Asia (India/Pakistan), China, the US, parts of Europe, SE Asia (Thailand/Myanmar/Laos), the central portion of South America, as well as Western and Northern Africa. These correspond primarily to croplands with extensive animal feeding operations and fertilizer applications where a summer maximum and secondary spring maximum are reliably observable. In the Southern Hemisphere (SH) regular agricultural fires contribute to a spring maximum. Regions of strong episodic emissions include Russia and Alaska as well as parts of South America, Africa, and Indonesia. Biomass burning, especially wildfires, dominate these episodic NH3 emissions.

scholarly journals An optimal-estimation-based aerosol retrieval algorithm using OMI near-UV observations

2016 ◽  
Vol 16 (1) ◽  
pp. 177-193 ◽  
Author(s):  
U. Jeong ◽  
J. Kim ◽  
C. Ahn ◽  
O. Torres ◽  
X. Liu ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Degrees Of Freedom ◽  
Optimal Estimation ◽  
Retrieval Algorithm ◽  
Ozone Monitoring Instrument ◽  
Near Ultraviolet ◽  
Aerosol Retrieval ◽  
Operational Error ◽  
Estimated Error ◽  
Better Than

Abstract. An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional look-up tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OE-based estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper.

scholarly journals Technical Note: Temporal change in averaging kernels as a source of uncertainty in trend estimates of carbon monoxide retrieved from MOPITT

2013 ◽  
Vol 13 (22) ◽  
pp. 11307-11316 ◽  
Author(s):  
J. Yoon ◽  
A. Pozzer ◽  
P. Hoor ◽  
D. Y. Chang ◽  
S. Beirle ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atmospheric Chemistry ◽  
Temporal Change ◽  
A Priori ◽  
Optimal Estimation ◽  
Technical Note ◽  
Retrieval Algorithm ◽  
Near Surface ◽  
Surface Level ◽  
Surface Carbon

Abstract. It has become possible to retrieve the global, long-term trends of trace gases that are important to atmospheric chemistry, climate, and air quality from satellite data records that span more than a decade. However, many of the satellite remote sensing techniques produce measurements that have variable sensitivity to the vertical profiles of atmospheric gases. In the case of constrained retrievals like optimal estimation, this leads to a varying amount of a priori information in the retrieval and is represented by an averaging kernel (AK). In this study, we investigate to what extent the estimation of trends from retrieved data can be biased by temporal changes of averaging kernels used in the retrieval algorithm. In particular, the surface carbon monoxide data retrieved from the Measurements Of Pollution In The Troposphere (MOPITT) instrument from 2001 to 2010 were analyzed. As a practical example based on the MOPITT data, we show that if the true atmospheric mixing ratio is continuously 50% higher or lower than the a priori state, the temporal change of the averaging kernel at the surface level gives rise to an artificial trend in retrieved surface carbon monoxide, ranging from −10.71 to +13.21 ppbv yr−1 (−5.68 to +8.84 % yr−1) depending on location. Therefore, in the case of surface (or near-surface level) CO derived from MOPITT, the AKs trends multiplied by the difference between true and a priori states must be quantified in order to estimate trend biases.

scholarly journals Global carbon monoxide as retrieved from SCIAMACHY by WFM-DOAS

2004 ◽  
Vol 4 (3) ◽  
pp. 2805-2837 ◽  
Author(s):  
M. Buchwitz ◽  
R. de Beek ◽  
K. Bramstedt ◽  
S. Noël ◽  
H. Bovensmann ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Near Infrared ◽  
Weighting Function ◽  
Lower Troposphere ◽  
Quantitative Information ◽  
Scaling Factor ◽  
Retrieval Algorithm ◽  
Absorption Bands ◽  
Spectral Fitting ◽  
Data Product

Abstract. Vertical columns of CO have been retrieved from SCIAMACHY/ENVISAT short wave/near infrared (~2.3µm) nadir spectra using the Weighting Function Modified (WFM) DOAS retrieval algorithm. WFM-DOAS has been applied to a small spectral fitting window located in SCIAMACHY's channel 8 (~2365 nm) covering four CO absorption lines. The focus of this paper is to demonstrate that quantitative information on carbon monoxide (CO) on a global scale can be retrieved from SCIAMACHY. It is shown that plumes of CO resulting from, e.g. biomass burning in Africa, are clearly detectable with SCIAMACHY. The SCIAMACHY CO columns are in good agreement with the CO column data product of MOPITT (V3). For example, the correlation between SCIAMACHY and MOPITT CO columns for cloud free pixels over land is typically in the range r=0.4–0.7, where r is the correlation coefficient. In order to retrieve good CO columns it was necessary to improve the calibration of the SCIAMACHY nadir spectra. Nevertheless, there is still room for significant improvement. The fit residuals, for example, are dominated by stable and systematic spectral artifacts on the order of the weak CO lines. These artifacts are most pronounced in spectral regions of strong overlapping methane and water vapour absorption bands. They might result from spectrometer slit function uncertainties. The CO columns of the WFM-DOAS Version 0.4 CO column data product presented in this paper have been multiplied by a constant and ground scene independent scaling factor of 0.5 to quantitatively adjust the WFM-DOAS retrieved CO columns to the MOPITT CO data. If and how this scaling factor is influenced by SCIAMACHYs much higher sensitivity to the lower troposphere and boundary layer CO and/or by the currently not perfect spectral fitting needs further investigation.

scholarly journals Technical Note: Temporal change in averaging kernels as a source of uncertainty in trend estimates of carbon monoxide retrieved from MOPITT

2013 ◽  
Vol 13 (8) ◽  
pp. 20319-20340
Author(s):  
J. Yoon ◽  
A. Pozzer ◽  
P. Hoor ◽  
D. Y. Chang ◽  
S. Beirle ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Atmospheric Chemistry ◽  
Temporal Change ◽  
A Priori ◽  
Optimal Estimation ◽  
Technical Note ◽  
Retrieval Algorithm ◽  
Near Surface ◽  
Surface Level ◽  
Surface Carbon

Abstract. It is now possible to monitor the global and long-term trends of trace gases that are important to atmospheric chemistry, climate, and air quality with satellite data records that span more than a decade. However, many of the remote sensing techniques used by satellite instruments produce measurements that have variable sensitivity to the vertical profiles of atmospheric gases. In the case of constrained retrievals like optimal estimation, this leads to a varying amount of a priori information in the retrieval and is represented by an averaging kernel. In this study, we investigate to what extent such trends can be biased by temporal changes of averaging kernels used in the retrieval algorithm. In particular, the surface carbon monoxide data retrieved from the Measurements Of Pollution In The Troposphere (MOPITT) instrument from 2001 to 2010 were analysed. As a practical example based on the MOPITT data, we show that if the true atmospheric mixing ratio is continuously 50% higher or lower than the a priori state, the temporal change of the averaging kernel at the surface level gives rise to an artificial trend in retrieved surface carbon monoxide, ranging from −10.71 to +13.21 ppbv yr−1 (−5.68 to +8.84% yr−1) depending on location. Therefore, in the case of surface (or near-surface level) CO derived from MOPITT, the AKs trends multiplied by the difference between true and a priori states must be quantified in order to estimate trend biases.

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