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Kar J, Vaughan MA, Lee KP, Tackett JL, Avery MA, Garnier A, Getzewich BJ, Hunt WH, Josset D, Liu Z, Lucker PL, Magill B, Omar AH, Pelon J, Rogers RR, Toth TD, Trepte CR, Vernier JP, Winker DM, Young SA. CALIPSO Lidar Calibration at 532 nm: Version 4 Nighttime Algorithm. Atmos Meas Tech 2018; 11:1459-1479. [PMID: 33479568 PMCID: PMC7816828 DOI: 10.5194/amt-11-1459-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Data products from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on board Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) were recently updated following the implementation of new (version 4) calibration algorithms for all of the level 1 attenuated backscatter measurements. In this work we present the motivation for and the implementation of the version 4 nighttime 532 nm parallel channel calibration. The nighttime 532 nm calibration is the most fundamental calibration of CALIOP data, since all of CALIOP's other radiometric calibration procedures - i.e., the 532 nm daytime calibration and the 1064 nm calibrations during both nighttime and daytime - depend either directly or indirectly on the 532 nm nighttime calibration. The accuracy of the 532 nm nighttime calibration has been significantly improved by raising the molecular normalization altitude from 30-34 km to 36-39 km to substantially reduce stratospheric aerosol contamination. Due to the greatly reduced molecular number density and consequently reduced signal-to-noise ratio (SNR) at these higher altitudes, the signal is now averaged over a larger number of samples using data from multiple adjacent granules. As well, an enhanced strategy for filtering the radiation-induced noise from high energy particles was adopted. Further, the meteorological model used in the earlier versions has been replaced by the improved MERRA-2 model. An aerosol scattering ratio of 1.01 ± 0.01 is now explicitly used for the calibration altitude. These modifications lead to globally revised calibration coefficients which are, on average, 2-3% lower than in previous data releases. Further, the new calibration procedure is shown to eliminate biases at high altitudes that were present in earlier versions and consequently leads to an improved representation of stratospheric aerosols. Validation results using airborne lidar measurements are also presented. Biases relative to collocated measurements acquired by the Langley Research Center (LaRC) airborne high spectral resolution lidar (HSRL) are reduced from 3.6% ± 2.2% in the version 3 data set to 1.6% ± 2.4 % in the version 4 release.
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Affiliation(s)
- Jayanta Kar
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | | | - Kam-Pui Lee
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Jason L Tackett
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | | | - Anne Garnier
- Science Systems and Applications Inc., Hampton, VA, USA
| | - Brian J Getzewich
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - William H Hunt
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Damien Josset
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Zhaoyan Liu
- NASA Langley Research Center, Hampton, VA, USA
| | - Patricia L Lucker
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Brian Magill
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Ali H Omar
- NASA Langley Research Center, Hampton, VA, USA
| | - Jacques Pelon
- LATMOS, Université de Versailles Saint Quentin, CNRS, Verrières le Buisson, France
| | | | - Travis D Toth
- NASA Langley Research Center, Hampton, VA, USA
- Department of Atmospheric Sciences, University of North Dakota, Grand Forks, ND, USA
| | | | - Jean-Paul Vernier
- Science Systems and Applications Inc., Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
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Kim MH, Omar AH, Tackett JL, Vaughan MA, Winker DM, Trepte CR, Hu Y, Liu Z, Poole LR, Pitts MC, Kar J, Magill BE. The CALIPSO Version 4 Automated Aerosol Classification and Lidar Ratio Selection Algorithm. Atmos Meas Tech 2018; 11:6107-6135. [PMID: 31921372 PMCID: PMC6951257 DOI: 10.5194/amt-11-6107-2018] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) version 4.10 (V4) level 2 aerosol data products, released in November 2016, include substantial improvements to the aerosol subtyping and lidar ratio selection algorithms. These improvements are described along with resulting changes in aerosol optical depth (AOD). The most fundamental change in V4 level 2 aerosol products is a new algorithm to identify aerosol subtypes in the stratosphere. Four aerosol subtypes are introduced for the stratospheric aerosols: polar stratospheric aerosol (PSA), volcanic ash, sulfate/other, and smoke. The tropospheric aerosol subtyping algorithm was also improved by adding the following enhancements: (1) all aerosol subtypes are now allowed over polar regions, whereas the version 3 (V3) algorithm allowed only clean continental and polluted continental aerosols; (2) a new "dusty marine" aerosol subtype is introduced, representing mixtures of dust and marine aerosols near the ocean surface; and (3) the "polluted continental" and "smoke" subtypes have been renamed "polluted continental/smoke" and "elevated smoke", respectively. V4 also revises the lidar ratios for clean marine, dust, clean continental, and elevated smoke subtypes. As a consequence of the V4 updates, the mean 532 nm AOD retrieved by CALIOP has increased by 0.044 (0.036) or 52 % (40 %) for nighttime (daytime). Lidar ratio revisions are the most influential factor for AOD changes from V3 to V4, especially for cloud-free skies. Preliminary validation studies show that the AOD discrepancies between CALIOP and AERONET/MODIS (ocean) are reduced in V4 compared to V3.
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Affiliation(s)
- Man-Hae Kim
- NASA Postdoctoral Program (USRA), Hampton, VA, USA
| | - Ali H. Omar
- NASA Langley Research Center, Hampton, VA, USA
| | | | | | | | | | | | - Zhaoyan Liu
- Science Systems and Applications, Inc., Hampton, VA, USA
| | | | | | - Jayanta Kar
- Science Systems and Applications, Inc., Hampton, VA, USA
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Kim MH, Omar AH, Tackett JL, Vaughan MA, Winker DM, Trepte CR, Hu Y, Liu Z, Poole LR, Pitts MC, Kar J, Magill BE. The CALIPSO Version 4 Automated Aerosol Classification and Lidar Ratio Selection Algorithm. Atmos Meas Tech 2018; 11:6107-6135. [PMID: 31921372 DOI: 10.1175/2009jtecha1231.1] [Citation(s) in RCA: 101] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) version 4.10 (V4) level 2 aerosol data products, released in November 2016, include substantial improvements to the aerosol subtyping and lidar ratio selection algorithms. These improvements are described along with resulting changes in aerosol optical depth (AOD). The most fundamental change in V4 level 2 aerosol products is a new algorithm to identify aerosol subtypes in the stratosphere. Four aerosol subtypes are introduced for the stratospheric aerosols: polar stratospheric aerosol (PSA), volcanic ash, sulfate/other, and smoke. The tropospheric aerosol subtyping algorithm was also improved by adding the following enhancements: (1) all aerosol subtypes are now allowed over polar regions, whereas the version 3 (V3) algorithm allowed only clean continental and polluted continental aerosols; (2) a new "dusty marine" aerosol subtype is introduced, representing mixtures of dust and marine aerosols near the ocean surface; and (3) the "polluted continental" and "smoke" subtypes have been renamed "polluted continental/smoke" and "elevated smoke", respectively. V4 also revises the lidar ratios for clean marine, dust, clean continental, and elevated smoke subtypes. As a consequence of the V4 updates, the mean 532 nm AOD retrieved by CALIOP has increased by 0.044 (0.036) or 52 % (40 %) for nighttime (daytime). Lidar ratio revisions are the most influential factor for AOD changes from V3 to V4, especially for cloud-free skies. Preliminary validation studies show that the AOD discrepancies between CALIOP and AERONET/MODIS (ocean) are reduced in V4 compared to V3.
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Affiliation(s)
- Man-Hae Kim
- NASA Postdoctoral Program (USRA), Hampton, VA, USA
| | - Ali H Omar
- NASA Langley Research Center, Hampton, VA, USA
| | | | | | | | | | | | - Zhaoyan Liu
- Science Systems and Applications, Inc., Hampton, VA, USA
| | - Lamont R Poole
- Science Systems and Applications, Inc., Hampton, VA, USA
| | | | - Jayanta Kar
- Science Systems and Applications, Inc., Hampton, VA, USA
| | - Brian E Magill
- Science Systems and Applications, Inc., Hampton, VA, USA
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Kim MH, Omar AH, Vaughan MA, Winker DM, Trepte CR, Hu Y, Liu Z, Kim SW. Quantifying the low bias of CALIPSO's column aerosol optical depth due to undetected aerosol layers. J Geophys Res Atmos 2017; 122:1098-1113. [PMID: 31534879 PMCID: PMC6749610 DOI: 10.1002/2016jd025797] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The CALIOP data processing scheme only retrieves extinction profiles in those portions of the return signal where cloud or aerosol layers have been identified by the CALIOP layer detection scheme. In this study we use two years of CALIOP and MODIS data to quantify the aerosol optical depth of undetected weakly backscattering layers. Aerosol extinction and column-averaged lidar ratio is retrieved from CALIOP Level 1B (Version 4) profile using MODIS AOD as a constraint over oceans from March 2013 to February 2015. To quantify the undetected layer AOD (ULA), an unconstrained retrieval is applied globally using a lidar ratio of 28.75 sr estimated from constrained retrievals during the daytime over the ocean. We find a global mean ULA of 0.031 ± 0.052. There is no significant difference in ULA between land and ocean. However, the fraction of undetected aerosol layers rises considerably during daytime, when the large amount of solar background noise lowers the signal to noise ratio (SNR). For this reason, there is a difference in ULA between day (0.036 ± 0.066) and night (0.025 ± 0.021). ULA is larger in the northern hemisphere and relatively larger at high latitudes. Large ULA for the Polar Regions is strongly related to the cases where the CALIOP Level 2 Product reports zero AOD. This study provides an estimate of the complement of AOD that is not detected by lidar, and bounds the CALIOP AOD uncertainty to provide corrections for science studies that employ the CALIOP Level 2 AOD.
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Affiliation(s)
- Man-Hae Kim
- NASA Langley Research Center, Hampton, VA, USA
- Universities Space Research Association, Columbia, Maryland, USA
| | - Ali H. Omar
- NASA Langley Research Center, Hampton, VA, USA
| | | | | | | | | | - Zhaoyan Liu
- NASA Langley Research Center, Hampton, VA, USA
- Science Systems and Applications, Inc., Hampton, VA, USA
| | - Sang-Woo Kim
- School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
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Zhai PW, Hu Y, Trepte CR, Winker DM, Josset DB, Lucker PL, Kattawar GW. Inherent optical properties of the coccolithophore: Emiliania huxleyi. Opt Express 2013; 21:17625-17638. [PMID: 23938635 DOI: 10.1364/oe.21.017625] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A realistic nonspherical model for Emiliania huxleyi (EHUX) is built, based on electron micrographs of coccolithophore cells. The Inherent Optical Properties (IOP) of the EHUX are then calculated numerically by using the discrete dipole approximation. The coccolithophore model includes a near-spherical core with the refractive index of 1.04 + m(i)j, and a carbonate shell formed by smaller coccoliths with refractive index of 1.2 + m(i)j, where m(i) = 0 or 0.01 and j(2) = -1. The reported IOP are the Mueller scattering matrix, backscattering probability, and depolarization ratio. Our calculation shows that the Mueller matrices of coccolithophores show different angular dependence from those of coccoliths.
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Affiliation(s)
- Peng-Wang Zhai
- SSAI, MS 475 NASA Langley Research Center, Hampton, VA 23681-2199, USA.
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Zhai PW, Hu Y, Trepte CR, Lucker PL. A vector radiative transfer model for coupled atmosphere and ocean systems based on successive order of scattering method. Opt Express 2009; 17:2057-2079. [PMID: 19219111 DOI: 10.1364/oe.17.002057] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
A vector radiative transfer model has been developed for coupled atmosphere and ocean systems based on the Successive Order of Scattering (SOS) Method. The emphasis of this study is to make the model easy-to-use and computationally efficient. This model provides the full Stokes vector at arbitrary locations which can be conveniently specified by users. The model is capable of tracking and labeling different sources of the photons that are measured, e.g. water leaving radiances and reflected sky lights. This model also has the capability to separate florescence from multi-scattered sunlight. The delta - fit technique has been adopted to reduce computational time associated with the strongly forward-peaked scattering phase matrices. The exponential - linear approximation has been used to reduce the number of discretized vertical layers while maintaining the accuracy. This model is developed to serve the remote sensing community in harvesting physical parameters from multi-platform, multi-sensor measurements that target different components of the atmosphere-oceanic system.
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Affiliation(s)
- Peng-Wang Zhai
- NASA Langley Research Center, Hampton, VA 23681-2199, USA.
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Manney GL, Daffer WH, Zawodny JM, Bernath PF, Hoppel KW, Walker KA, Knosp BW, Boone C, Remsberg EE, Santee ML, Harvey VL, Pawson S, Jackson DR, Deaver L, McElroy CT, McLinden CA, Drummond JR, Pumphrey HC, Lambert A, Schwartz MJ, Froidevaux L, McLeod S, Takacs LL, Suarez MJ, Trepte CR, Cuddy DC, Livesey NJ, Harwood RS, Waters JW. Solar occultation satellite data and derived meteorological products: Sampling issues and comparisons with Aura Microwave Limb Sounder. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007jd008709] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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McGill MJ, Vaughan MA, Trepte CR, Hart WD, Hlavka DL, Winker DM, Kuehn R. Airborne validation of spatial properties measured by the CALIPSO lidar. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2007jd008768] [Citation(s) in RCA: 132] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Kar J, McElroy CT, Drummond JR, Zou J, Nichitiu F, Walker KA, Randall CE, Nowlan CR, Dufour DG, Boone CD, Bernath PF, Trepte CR, Thomason LW, McLinden C. Initial comparison of ozone and NO2profiles from ACE-MAESTRO with balloon and satellite data. ACTA ACUST UNITED AC 2007. [DOI: 10.1029/2006jd008242] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
The latest in a series of solar occultation satellite instruments, Stratospheric Aerosol and Gas Experiment (SAGE) III, was placed into orbit in December 2001, and data were obtained until March 2006. Measurements were made of the extinction attributable to aerosols and cloud at a number of wavelengths between 290 and 1550 nm. The analysis of data obtained by its predecessor, SAGE II, has shown that an intercomparison of such data at two or more wavelengths may be used to separate the effects of cloud and aerosol. This analysis has been done on a routine basis for many years using SAGE II data at 525 and 1020 nm and applied extensively to global studies of tropospheric cloud and aerosol. Here we describe the aerosol-cloud separation algorithm developed for use with the SAGE III data, which uses the extinction at 525, 1020, and 1550 nm. This algorithm is now being used to produce vertical profiles of cloud presence as a standard SAGE III data product. These profiles have a vertical resolution of 0.5 km and cover the altitude range from 6.0 to 30.0 km, and data are presently available from March 2002 onward. An outline is given of the development of this algorithm, the nature of the SAGE III data, and the algorithm performance. To maintain continuity with SAGE II cloud data, the relative performances of the SAGE II and SAGE III algorithms are also examined. An example of the application of the algorithm to SAGE III tropospheric data is shown and discussed.
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Affiliation(s)
- G S Kent
- Science and Technology Corporation, Hampton, Virginia, USA.
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Wang PH, Cunnold DM, Trepte CR, Wang HJ, Jing P, Fishman J, Brackett VG, Zawodney JM, Bodeker GE. Ozone variability in the midlatitude upper troposphere and lower stratosphere diagnosed from a monthly SAGE II climatology relative to the tropopause. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2005jd006108] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Wang PH, Rind D, Trepte CR, Kent GS, Yue GK, Skeens KM. An empirical model study of the tropospheric meridional circulation based on SAGE II observations. ACTA ACUST UNITED AC 1998. [DOI: 10.1029/98jd00204] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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