Using techniques very similar to those used in comparing SBUV total ozone with Dobson [Fleig et a... more Using techniques very similar to those used in comparing SBUV total ozone with Dobson [Fleig et al. 1986A], seven years of total ozone data derived from the TOMS instrument on Nimbus‐7 are compared with results from 41 Dobson stations. In this study however, a ...
Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus ... more Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as ...
The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-vi... more The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-visible satellite spectrometer Global Ozone Monitoring Experiment (GOME) has been modeled by means of a feed forward neural network. This Neural Network Ozone Retrieval System (NNORSY) was trained exclusively on a data set of GOME radiances collocated with ozone measurements from ozonesondes, Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Polar Ozone and Aerosol Measurement III. Network input consists of a combination of spectral, geolocation, and climatological information (time and latitude). In the stratosphere the method globally reduces standard deviation with respect to an ozone climatology by around 40%. Tropospheric ozone can also be retrieved in many cases with corresponding reduction of 10-30%. All GOME data from January 1996 to July 2001 were processed. In a number of case studies involving comparisons with ozonesondes from Hohenpeissenberg, Syowa, and results from the classical Full Retrieval Method, we found good agreement with our results. The neural network was found capable of implicitly correcting for instrument degradation, pixel cloudiness, and scan angle effects. Integrated profiles generally agree to within ±5% with the monthly Total Ozone Mapping Spectrometer version 7 total ozone field. However, some problems remain at high solar zenith angles and very low ozone values, where local deviations of 10-20% have been observed in some cases. In order to better characterize individual ozone profiles, two local error estimation methods are presented. Vertical resolution of the profiles was assessed empirically and seems to be of the order of 4-6 km. Since neural network retrieval is a mathematically simple, one-step procedure, NNORSY is about 10 3-10 5 times faster than classical retrieval techniques based upon optimal estimation.
IEEE Transactions on Geoscience and Remote Sensing, 2013
The presence of absorbing aerosols above cloud decks reduces the amount of upwelling ultraviolet ... more The presence of absorbing aerosols above cloud decks reduces the amount of upwelling ultraviolet (UV), visible (VIS), and shortwave infrared radiation reaching the top of atmosphere. This effect is often referred to as "cloud darkening," which can be seen by eye in images and quantitatively in the spectral reflectance measurements made by passive sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) in the regions where light-absorbing carbonaceous and dust aerosols overlay low-level clouds. Radiative transfer simulations support the observational evidence and further reveal that the reduction in the spectral reflectance and color ratio between a pair of wavelengths is a function of both aerosol and cloud optical thickness (AOT and COT). For a prescribed set of aerosol and cloud properties and their vertical profiles, thus, the measured reflectance can be associated with a pair of AOT and COT. Based on these results, a retrieval technique has been developed, which is named as the "color ratio method," which utilizes the measurements at a shorter (470 nm) and a longer (860 nm) wavelength for the simultaneous derivation of AOT and COT. The retrieval technique has been applied to the MODIS 1-km reflectance measurements for the two distinct above-cloud smoke and dust aerosols events. This study is an extension of the previously developed near-UV method to the VIS spectral region. However, it constitutes the first attempt to use non-UV wavelengths to retrieve above-cloud AOT by a passive nonpolarized sensor. An uncertainty analysis has been presented, which estimates the expected error associated with these retrievals.
The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-vi... more The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-visible satellite spectrometer Global Ozone Monitoring Experiment (GOME) has been modeled by means of a feed forward neural network. This Neural Network Ozone Retrieval System (NNORSY) was trained exclusively on a data set of GOME radiances collocated with ozone measurements from ozonesondes, Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Polar Ozone and Aerosol Measurement III. Network input consists of a combination of spectral, geolocation, and climatological information (time and latitude). In the stratosphere the method globally reduces standard deviation with respect to an ozone climatology by around 40%. Tropospheric ozone can also be retrieved in many cases with corresponding reduction of 10-30%. All GOME data from January 1996 to July 2001 were processed. In a number of case studies involving comparisons with ozonesondes from Hohenpeissenberg, Syowa, and results from the classical Full Retrieval Method, we found good agreement with our results. The neural network was found capable of implicitly correcting for instrument degradation, pixel cloudiness, and scan angle effects. Integrated profiles generally agree to within ±5% with the monthly Total Ozone Mapping Spectrometer version 7 total ozone field. However, some problems remain at high solar zenith angles and very low ozone values, where local deviations of 10-20% have been observed in some cases. In order to better characterize individual ozone profiles, two local error estimation methods are presented. Vertical resolution of the profiles was assessed empirically and seems to be of the order of 4-6 km. Since neural network retrieval is a mathematically simple, one-step procedure, NNORSY is about 10 3-10 5 times faster than classical retrieval techniques based upon optimal estimation.
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resol... more The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resolution, coupled with global coverage, for space-based UV measurements of sulfur dioxide (SO 2). This paper describes an OMI SO 2 algorithm (the band residual difference) that uses calibrated residuals at SO 2 absorption band centers produced by the NASA operational ozone algorithm (OMTO3). By using optimum wavelengths for retrieval of SO 2 , the retrieval sensitivity is improved over NASA predecessor Total Ozone Mapping Spectrometer (TOMS) by factors of 10 to 20, depending on location. The ground footprint of OMI is eight times smaller than TOMS. These factors produce two orders of magnitude improvement in the minimum detectable mass of SO 2. Thus, the diffuse boundaries of volcanic clouds can be imaged better and the clouds can be tracked longer. More significantly, the improved sensitivity now permits daily global measurement of passive volcanic degassing of SO 2 and of heavy anthropogenic SO 2 pollution to provide new information on the relative importance of these sources for climate studies.
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resol... more The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resolution, coupled with global coverage, for space-based UV measurements of sulfur dioxide (SO 2). This paper describes an OMI SO 2 algorithm (the band residual difference) that uses calibrated residuals at SO 2 absorption band centers produced by the NASA operational ozone algorithm (OMTO3). By using optimum wavelengths for retrieval of SO 2 , the retrieval sensitivity is improved over NASA predecessor Total Ozone Mapping Spectrometer (TOMS) by factors of 10 to 20, depending on location. The ground footprint of OMI is eight times smaller than TOMS. These factors produce two orders of magnitude improvement in the minimum detectable mass of SO 2. Thus, the diffuse boundaries of volcanic clouds can be imaged better and the clouds can be tracked longer. More significantly, the improved sensitivity now permits daily global measurement of passive volcanic degassing of SO 2 and of heavy anthropogenic SO 2 pollution to provide new information on the relative importance of these sources for climate studies.
IEEE Transactions on Geoscience and Remote Sensing, 2006
Aura, the last of the large Earth Observing System observatories, was launched on July 15, 2004. ... more Aura, the last of the large Earth Observing System observatories, was launched on July 15, 2004. Aura is designed to make comprehensive stratospheric and tropospheric composition measurements from its four instruments, the High Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), and the Tropospheric Emission Spectrometer (TES). With the exception of HIRDLS, all of the instruments are performing as expected, and HIRDLS will likely be able to deliver most of their planned data products. We summarize the mission, instruments, and synergies in this paper.
... REFERENCES 1. GHB Dobson and DN Harrison, Proc. Roy. Soc., Ser. A 110, 660 (1926) 2. FE Fowle... more ... REFERENCES 1. GHB Dobson and DN Harrison, Proc. Roy. Soc., Ser. A 110, 660 (1926) 2. FE Fowle, Smithsonian Miscellaneous Collections 81, 1 (1929) 3. GM Keating, L. Frank, JD Craven, D. Young, J. Nicholson, P. Bhartia, D. Gordon, EOS, Trans. ...
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) flies on NASA's Earth Observing System AURA satellite, laun... more The Ozone Monitoring Instrument (OMI) flies on NASA's Earth Observing System AURA satellite, launched in July 2004. OMI is an ultraviolet/visible (UV/VIS) nadir solar backscatter spectrometer, which provides nearly global coverage in one day, with a spatial resolution of 13 km 24 km. Trace gases measured include O 3 , NO 2 , SO 2 , HCHO, BrO, and OClO. In addition OMI measures aerosol characteristics, cloud top heights and cloud coverage, and UV irradiance at the surface. OMI's unique capabilities for measuring important trace gases with daily global coverage and a small footprint will make a major contribution to our understanding of stratospheric and tropospheric chemistry and climate change along with Aura's other three instruments. OMI's high spatial resolution enables detection of air pollution at urban scales. Total Ozone Mapping Spectrometer and differential optical absorption spectroscopy heritage algorithms, as well as new ones developed by the international (Dutch, Finnish, and U.S.) OMI science team, are used to derive OMI's advanced backscatter data products. In addition to providing data for Aura's prime objectives, OMI will provide near-real-time data for operational agencies in Europe and the U.S. Examples of OMI's unique capabilities are presented in this paper. Index Terms-Air quality, atmospheric composition, ozone monitoring, satellite measurements. I. INTRODUCTION T HE Ozone Monitoring Instrument (OMI), a contribution of the Netherlands Agency for Aerospace Programs (NIVR) in collaboration with Finnish Meteorological Institute (FMI) to the Nationa Aeronautics and Space Administration's (NASA) Aura mission, is orbiting the Earth on the Aura spacecraft. Aura is part of NASA's long-term Earth Observing System (EOS) mission and was launched in July 2004 from Vandenberg Air Force base in California into a polar sun-synchronous orbit.
<p>The NASA TOMS V9 (TOMS-V9) total ozone retrieval algorithm is tested<br>for sensit... more <p>The NASA TOMS V9 (TOMS-V9) total ozone retrieval algorithm is tested<br>for sensitvity to boundary-layer ozone and suitability to make daily<br>maps of tropospheric ozone residual (TOR). &#160;Daily maps of TOR are<br>derived by differencing co-located MERRA-2 assimilated MLS<br>stratospheric column ozone (SCO) from total column ozone from the Aura<br>Ozone Monitoring Instrument (OMI). &#160;The TOMS-V9 algorithm uses a few<br>discrete channels with an order of magnitude range in ozone<br>senstivity. We compare the TOR results from TOMS-V9 with results from<br>several hyper-spectral total ozone retrievals: GODFIT v4 (BIRA-IASB),<br>OMI-DOAS (KNMI), and total ozone from the SAO PROFOZ algorithm. We<br>compare all satellite-retrieved TOR with TOR derived from ozonesondes,<br>lidar, and the Goddard Modeling Initiative (GMI) model simulation.</p><p>&#160;</p><p>&#160;</p>
An assessment of OMI retrievals of aerosol properties is presented. We compare OMI retrieved valu... more An assessment of OMI retrievals of aerosol properties is presented. We compare OMI retrieved values of extinction and absorption optical depth, and aerosol single scattering albedo to AERONET ground-based measurements. An evaluation of the accuracy of the retrievals for a limited number of observations under cloud-free conditions shows a positive offset of about 0.03 in retrieved optical depth. This small offset is an indication of accurate sensor calibration to the 1% level. The retrieved SSA values agree well with RMS differences of 0.02-0.03 compared with the AERONET observations. This result shows that the UV technique is a very valuable tool for measuring aerosol absorption from space.
We discuss collection 2 SO2 data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) on boar... more We discuss collection 2 SO2 data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA EOS/Aura spacecraft and show examples of detected volcanic and anthropogenic SO2 emissions. Quantification of anthropogenic SO2 emissions requires collection 3 reprocessing available in the fall 2007.
Using techniques very similar to those used in comparing SBUV total ozone with Dobson [Fleig et a... more Using techniques very similar to those used in comparing SBUV total ozone with Dobson [Fleig et al. 1986A], seven years of total ozone data derived from the TOMS instrument on Nimbus‐7 are compared with results from 41 Dobson stations. In this study however, a ...
Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus ... more Three ozone tape products from the Solar Backscatter Ultraviolet (SBUV) experiment aboard Nimbus 7 were archived at the National Space Science Data Center. The experiment measures the fraction of incoming radiation backscattered by the Earth's atmosphere at 12 wavelengths. In-flight measurements were used to monitor changes in the instrument sensitivity. Total column ozone is derived by comparing the measurements with calculations of what would be measured for different total ozone amounts. The altitude distribution is retrieved using an optimum statistical technique for the inversion. The estimated initial error in the absolute scale for total ozone is 2 percent, with a 3 percent drift over 8 years. The profile error depends on latitude and height, smallest at 3 to 10 mbar; the drift increases with increasing altitude. Three tape products are described. The High Density SBUV (HDSBUV) tape contains the final derived products - the total ozone and the vertical ozone profile - as ...
The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-vi... more The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-visible satellite spectrometer Global Ozone Monitoring Experiment (GOME) has been modeled by means of a feed forward neural network. This Neural Network Ozone Retrieval System (NNORSY) was trained exclusively on a data set of GOME radiances collocated with ozone measurements from ozonesondes, Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Polar Ozone and Aerosol Measurement III. Network input consists of a combination of spectral, geolocation, and climatological information (time and latitude). In the stratosphere the method globally reduces standard deviation with respect to an ozone climatology by around 40%. Tropospheric ozone can also be retrieved in many cases with corresponding reduction of 10-30%. All GOME data from January 1996 to July 2001 were processed. In a number of case studies involving comparisons with ozonesondes from Hohenpeissenberg, Syowa, and results from the classical Full Retrieval Method, we found good agreement with our results. The neural network was found capable of implicitly correcting for instrument degradation, pixel cloudiness, and scan angle effects. Integrated profiles generally agree to within ±5% with the monthly Total Ozone Mapping Spectrometer version 7 total ozone field. However, some problems remain at high solar zenith angles and very low ozone values, where local deviations of 10-20% have been observed in some cases. In order to better characterize individual ozone profiles, two local error estimation methods are presented. Vertical resolution of the profiles was assessed empirically and seems to be of the order of 4-6 km. Since neural network retrieval is a mathematically simple, one-step procedure, NNORSY is about 10 3-10 5 times faster than classical retrieval techniques based upon optimal estimation.
IEEE Transactions on Geoscience and Remote Sensing, 2013
The presence of absorbing aerosols above cloud decks reduces the amount of upwelling ultraviolet ... more The presence of absorbing aerosols above cloud decks reduces the amount of upwelling ultraviolet (UV), visible (VIS), and shortwave infrared radiation reaching the top of atmosphere. This effect is often referred to as "cloud darkening," which can be seen by eye in images and quantitatively in the spectral reflectance measurements made by passive sensors such as the Moderate Resolution Imaging Spectroradiometer (MODIS) in the regions where light-absorbing carbonaceous and dust aerosols overlay low-level clouds. Radiative transfer simulations support the observational evidence and further reveal that the reduction in the spectral reflectance and color ratio between a pair of wavelengths is a function of both aerosol and cloud optical thickness (AOT and COT). For a prescribed set of aerosol and cloud properties and their vertical profiles, thus, the measured reflectance can be associated with a pair of AOT and COT. Based on these results, a retrieval technique has been developed, which is named as the "color ratio method," which utilizes the measurements at a shorter (470 nm) and a longer (860 nm) wavelength for the simultaneous derivation of AOT and COT. The retrieval technique has been applied to the MODIS 1-km reflectance measurements for the two distinct above-cloud smoke and dust aerosols events. This study is an extension of the previously developed near-UV method to the VIS spectral region. However, it constitutes the first attempt to use non-UV wavelengths to retrieve above-cloud AOT by a passive nonpolarized sensor. An uncertainty analysis has been presented, which estimates the expected error associated with these retrievals.
The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-vi... more The inverse radiative transfer equation to retrieve atmospheric ozone distribution from the UV-visible satellite spectrometer Global Ozone Monitoring Experiment (GOME) has been modeled by means of a feed forward neural network. This Neural Network Ozone Retrieval System (NNORSY) was trained exclusively on a data set of GOME radiances collocated with ozone measurements from ozonesondes, Halogen Occultation Experiment, Stratospheric Aerosol and Gas Experiment II, and Polar Ozone and Aerosol Measurement III. Network input consists of a combination of spectral, geolocation, and climatological information (time and latitude). In the stratosphere the method globally reduces standard deviation with respect to an ozone climatology by around 40%. Tropospheric ozone can also be retrieved in many cases with corresponding reduction of 10-30%. All GOME data from January 1996 to July 2001 were processed. In a number of case studies involving comparisons with ozonesondes from Hohenpeissenberg, Syowa, and results from the classical Full Retrieval Method, we found good agreement with our results. The neural network was found capable of implicitly correcting for instrument degradation, pixel cloudiness, and scan angle effects. Integrated profiles generally agree to within ±5% with the monthly Total Ozone Mapping Spectrometer version 7 total ozone field. However, some problems remain at high solar zenith angles and very low ozone values, where local deviations of 10-20% have been observed in some cases. In order to better characterize individual ozone profiles, two local error estimation methods are presented. Vertical resolution of the profiles was assessed empirically and seems to be of the order of 4-6 km. Since neural network retrieval is a mathematically simple, one-step procedure, NNORSY is about 10 3-10 5 times faster than classical retrieval techniques based upon optimal estimation.
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resol... more The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resolution, coupled with global coverage, for space-based UV measurements of sulfur dioxide (SO 2). This paper describes an OMI SO 2 algorithm (the band residual difference) that uses calibrated residuals at SO 2 absorption band centers produced by the NASA operational ozone algorithm (OMTO3). By using optimum wavelengths for retrieval of SO 2 , the retrieval sensitivity is improved over NASA predecessor Total Ozone Mapping Spectrometer (TOMS) by factors of 10 to 20, depending on location. The ground footprint of OMI is eight times smaller than TOMS. These factors produce two orders of magnitude improvement in the minimum detectable mass of SO 2. Thus, the diffuse boundaries of volcanic clouds can be imaged better and the clouds can be tracked longer. More significantly, the improved sensitivity now permits daily global measurement of passive volcanic degassing of SO 2 and of heavy anthropogenic SO 2 pollution to provide new information on the relative importance of these sources for climate studies.
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resol... more The Ozone Monitoring Instrument (OMI) on EOS/Aura offers unprecedented spatial and spectral resolution, coupled with global coverage, for space-based UV measurements of sulfur dioxide (SO 2). This paper describes an OMI SO 2 algorithm (the band residual difference) that uses calibrated residuals at SO 2 absorption band centers produced by the NASA operational ozone algorithm (OMTO3). By using optimum wavelengths for retrieval of SO 2 , the retrieval sensitivity is improved over NASA predecessor Total Ozone Mapping Spectrometer (TOMS) by factors of 10 to 20, depending on location. The ground footprint of OMI is eight times smaller than TOMS. These factors produce two orders of magnitude improvement in the minimum detectable mass of SO 2. Thus, the diffuse boundaries of volcanic clouds can be imaged better and the clouds can be tracked longer. More significantly, the improved sensitivity now permits daily global measurement of passive volcanic degassing of SO 2 and of heavy anthropogenic SO 2 pollution to provide new information on the relative importance of these sources for climate studies.
IEEE Transactions on Geoscience and Remote Sensing, 2006
Aura, the last of the large Earth Observing System observatories, was launched on July 15, 2004. ... more Aura, the last of the large Earth Observing System observatories, was launched on July 15, 2004. Aura is designed to make comprehensive stratospheric and tropospheric composition measurements from its four instruments, the High Resolution Dynamics Limb Sounder (HIRDLS), the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), and the Tropospheric Emission Spectrometer (TES). With the exception of HIRDLS, all of the instruments are performing as expected, and HIRDLS will likely be able to deliver most of their planned data products. We summarize the mission, instruments, and synergies in this paper.
... REFERENCES 1. GHB Dobson and DN Harrison, Proc. Roy. Soc., Ser. A 110, 660 (1926) 2. FE Fowle... more ... REFERENCES 1. GHB Dobson and DN Harrison, Proc. Roy. Soc., Ser. A 110, 660 (1926) 2. FE Fowle, Smithsonian Miscellaneous Collections 81, 1 (1929) 3. GM Keating, L. Frank, JD Craven, D. Young, J. Nicholson, P. Bhartia, D. Gordon, EOS, Trans. ...
IEEE Transactions on Geoscience and Remote Sensing, 2006
The Ozone Monitoring Instrument (OMI) flies on NASA's Earth Observing System AURA satellite, laun... more The Ozone Monitoring Instrument (OMI) flies on NASA's Earth Observing System AURA satellite, launched in July 2004. OMI is an ultraviolet/visible (UV/VIS) nadir solar backscatter spectrometer, which provides nearly global coverage in one day, with a spatial resolution of 13 km 24 km. Trace gases measured include O 3 , NO 2 , SO 2 , HCHO, BrO, and OClO. In addition OMI measures aerosol characteristics, cloud top heights and cloud coverage, and UV irradiance at the surface. OMI's unique capabilities for measuring important trace gases with daily global coverage and a small footprint will make a major contribution to our understanding of stratospheric and tropospheric chemistry and climate change along with Aura's other three instruments. OMI's high spatial resolution enables detection of air pollution at urban scales. Total Ozone Mapping Spectrometer and differential optical absorption spectroscopy heritage algorithms, as well as new ones developed by the international (Dutch, Finnish, and U.S.) OMI science team, are used to derive OMI's advanced backscatter data products. In addition to providing data for Aura's prime objectives, OMI will provide near-real-time data for operational agencies in Europe and the U.S. Examples of OMI's unique capabilities are presented in this paper. Index Terms-Air quality, atmospheric composition, ozone monitoring, satellite measurements. I. INTRODUCTION T HE Ozone Monitoring Instrument (OMI), a contribution of the Netherlands Agency for Aerospace Programs (NIVR) in collaboration with Finnish Meteorological Institute (FMI) to the Nationa Aeronautics and Space Administration's (NASA) Aura mission, is orbiting the Earth on the Aura spacecraft. Aura is part of NASA's long-term Earth Observing System (EOS) mission and was launched in July 2004 from Vandenberg Air Force base in California into a polar sun-synchronous orbit.
<p>The NASA TOMS V9 (TOMS-V9) total ozone retrieval algorithm is tested<br>for sensit... more <p>The NASA TOMS V9 (TOMS-V9) total ozone retrieval algorithm is tested<br>for sensitvity to boundary-layer ozone and suitability to make daily<br>maps of tropospheric ozone residual (TOR). &#160;Daily maps of TOR are<br>derived by differencing co-located MERRA-2 assimilated MLS<br>stratospheric column ozone (SCO) from total column ozone from the Aura<br>Ozone Monitoring Instrument (OMI). &#160;The TOMS-V9 algorithm uses a few<br>discrete channels with an order of magnitude range in ozone<br>senstivity. We compare the TOR results from TOMS-V9 with results from<br>several hyper-spectral total ozone retrievals: GODFIT v4 (BIRA-IASB),<br>OMI-DOAS (KNMI), and total ozone from the SAO PROFOZ algorithm. We<br>compare all satellite-retrieved TOR with TOR derived from ozonesondes,<br>lidar, and the Goddard Modeling Initiative (GMI) model simulation.</p><p>&#160;</p><p>&#160;</p>
An assessment of OMI retrievals of aerosol properties is presented. We compare OMI retrieved valu... more An assessment of OMI retrievals of aerosol properties is presented. We compare OMI retrieved values of extinction and absorption optical depth, and aerosol single scattering albedo to AERONET ground-based measurements. An evaluation of the accuracy of the retrievals for a limited number of observations under cloud-free conditions shows a positive offset of about 0.03 in retrieved optical depth. This small offset is an indication of accurate sensor calibration to the 1% level. The retrieved SSA values agree well with RMS differences of 0.02-0.03 compared with the AERONET observations. This result shows that the UV technique is a very valuable tool for measuring aerosol absorption from space.
We discuss collection 2 SO2 data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) on boar... more We discuss collection 2 SO2 data from the Dutch-Finnish Ozone Monitoring Instrument (OMI) on board NASA EOS/Aura spacecraft and show examples of detected volcanic and anthropogenic SO2 emissions. Quantification of anthropogenic SO2 emissions requires collection 3 reprocessing available in the fall 2007.
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Papers by Pawan Bhartia