Dr. Pawan K. Bhartia Profile

Dr. Pawan K. Bhartia

Branch Head at NASA Goddard Space Flight Ctr

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 17 October 2014 Paper

Paper

Release 2 data products from the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler

Philippe Xu, Pawan Bhartia, Glen Jaross, Matthew DeLand, Jack Larsen, Albert Fleig, Daniel Kahn, Tong Zhu, Zhong Chen, Nick Gorkavyi, Jeremy Warner, Michael Linda, Hong Chen, Mark Kowitt, Michael Haken, Peter Hall

Proceedings Volume 9242, 92420K (2014) https://doi.org/10.1117/12.2067320

KEYWORDS: Ozone, Aerosols, Ultraviolet radiation, Satellites, Mass attenuation coefficient, Data modeling, Sensors, Clouds, Associative arrays, Atmospheric optics

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SPIE Journal Paper | 1 October 2007

Algorithm for the charge-coupled-device scanning actinic flux spectroradiometer ozone retrieval in support of the Aura satellite validation

Irina Petropavlovskikh, R. Shetter, S. Hall, K. Ullmann, Pawan Bhartia

JARS, Vol. 1, Issue 01, 013540, (October 2007) https://doi.org/10.1117/12.10.1117/1.2802563

KEYWORDS: Ozone, Clouds, Calibration, Satellites, Charge-coupled devices, Reflectivity, Aerosols, Atmospheric sensing, Spectroscopy, Sun

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Proceedings Article | 8 December 2006 Paper

Paper

Recent results from the Ozone Monitoring Instrument (OMI) on EOS Aura

Pawan Bhartia, Pieternel Levelt, Johanna Tamminen, Omar Torres

Proceedings Volume 6408, 64080Y (2006) https://doi.org/10.1117/12.706521

KEYWORDS: Aerosols, Ozone, Clouds, Ultraviolet radiation, Satellites, Absorption, Artificial intelligence, Scattering, Reflectivity, Atmospheric modeling

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SPIE Journal Paper | 1 April 2005

Aerosol ultraviolet absorption experiment (2002 to 2004), part 2: absorption optical thickness, refractive index, and single scattering albedo

Nickolay Krotkov, Pawan Bhartia, Jay Herman, James Slusser, Gwendolyn Scott, Gordon Labow, Alexander Vasilkov, Tom Eck, Oleg Doubovik, Brent Holben

OE, Vol. 44, Issue 04, 041005, (April 2005) https://doi.org/10.1117/12.10.1117/1.1886819

KEYWORDS: Aerosols, Ultraviolet radiation, Absorption, Refractive index, Atmospheric modeling, Ozone, Atmospheric particles, Calibration, Visible radiation, Scattering

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SPIE Journal Paper | 1 April 2005

Aerosol ultraviolet absorption experiment (2002 to 2004), part 1: ultraviolet multifilter rotating shadowband radiometer calibration and intercomparison with CIMEL sunphotometers

Nickolay Krotkov, Pawan Bhartia, Jay Herman, James Slusser, Gordon Labow, Gwendolyn Scott, George Janson, Tom Eck, Brent Holben

OE, Vol. 44, Issue 04, 041004, (April 2005) https://doi.org/10.1117/12.10.1117/1.1886818

KEYWORDS: Calibration, Aerosols, Ultraviolet radiation, Absorption, Ozone, Diffusers, Atmospheric modeling, Atmospheric optics, Sun, Radiometry

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Proceedings Article | 14 October 2004 Paper

Paper

Measuring aerosol UV absorption optical thickness by combining use of shadowband and almucantar techniques

Nickolay Krotkov, Pawan Bhartia, Jay Herman, James Slusser, Gwen Scott, Gordon Labow, Alexander Vasilkov, Thomas Eck, Oleg Dubovik, Brent Holben

Proceedings Volume 5545, (2004) https://doi.org/10.1117/12.559557

KEYWORDS: Aerosols, Ultraviolet radiation, Absorption, Refractive index, Visible radiation, Scattering, Ozone, Radiometry, Calibration, Atmospheric modeling

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We report final results of an aerosol UV absorption closure experiment where a UV-shadow-band radiometer (UV-MFRSR, USDA UVB Monitoring and Research Network) and 4 rotating sun-sky radiometers (CIMEL, NASA AERONET network) were run side-by-side continuously for 17 months at NASA/GSFC site in Greenbelt, MD. The aerosol extinction optical thickness τ_ext, was measured by the CIMEL direct-sun technique in the visible and at two UV wavelengths 340 and 380 nm. These results were used for UV-MFRSR daily on-site calibration and 3-min measurements of τ_ext at 325nm, 332nm and 368nm. The τ_ext measurements were used as input to the radiative transfer model along with AERONET retrievals of the column-integrated particle size distribution (PSD)to infer an effective imaginary part of the UV aerosol refractive index, k, by fitting MFRSR measured voltage ratios. Using all cases for cloud-free days, we derive diurnal and seasonal dependence of the aerosol absorption optical thickness, τ_abs with an uncertainty 0.01-0.02. At our site τ_abs follows pronounced seasonal dependence with maximum values ~0.07 at 368nm (~0.15 at 325nm) occurring in summer hazy conditions and <0.02 in winter-fall seasons, when aerosol loadings are small. Inferred values of k allow calculation of the single scattering albedo, ω, in UVA and comparisons with AERONET almucantar ω₄₄₀ retrievals at 440nm. Overall, ω was slightly lower in UV than in the visible: case average <ω₃₆₈>=0.93 compared to <ω₄₄₀>=0.95. However, the differences (<ω₄₄₀ - ω₃₆₈> ~0.02, rms difference ~0.016) are smaller than uncertainties of both retrievals (δω~0.03). Low <ω₃₆₈> values are consistent with higher values for imaginary refractive index, k: <k₃₆₈> ~0.01 compare to <k₄₄₀> ~0.006. However, mean differences in k (<k₃₆₈-k₄₄₀>~0.004) were only slightly larger than AERONET retrieval uncertainty δk ~0.003²⁷. We also found that ω decreases with decrease in τ_ext, suggesting different aerosol composition in summer and winter months. So far, our results do not allow explaining the causes of apparent larger aerosol absorption in UV. Continuing co-located measurements at GFSC is important to improve the comparison statistics, but conducting aerosol absorption measurements at different sites with varying conditions is also desirable.

Proceedings Article | 10 November 2003 Paper

Paper

Atmospheric products from the ozone monitoring instrument (OMI)

Suraiya Ahmad, Pieternel Levelt, Pawan Bhartia, Ernest Hilsenrath, Gilbert Leppelmeier, James Johnson

Proceedings Volume 5151, (2003) https://doi.org/10.1117/12.506042

KEYWORDS: Ozone, Clouds, Aerosols, Ultraviolet radiation, Data archive systems, Gases, Calibration, Satellites, Sensors, Atmospheric chemistry

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Proceedings Article | 4 November 2003 Paper

Paper

Goddard UV aerosol absorption closure experiment (2002-03)

Nickolay Krotkov, Pawan Bhartia, Jay Herman, James Slusser, Gwendolyn Scott, Gordon Labow, Alexander Vasilkov, Tom Eck, Oleg Dubovik, Brent Holben

Proceedings Volume 5156, (2003) https://doi.org/10.1117/12.508967

KEYWORDS: Aerosols, Ultraviolet radiation, Refractive index, Clouds, Absorption, Atmospheric modeling, Scattering, Calibration, Atmospheric particles, Radiometry

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SPIE Journal Paper | 1 December 2002

Comparisons between ground measurements of broadband ultraviolet irradiance (300 to 380 nm) and total ozone mapping spectrometer ultraviolet estimates at Moscow for 1979 to 2000

Nataly Chubarova, Alla Yurova, Nickolay Krotkov, Jay Herman, Pawan Bhartia

OE, Vol. 41, Issue 12, (December 2002) https://doi.org/10.1117/12.10.1117/1.1516819

KEYWORDS: Ultraviolet radiation, Aerosols, Clouds, Molybdenum, Satellites, Line edge roughness, UV optics, Ozone, Radiometry, Reflectivity

SPIE Journal Paper | 1 December 2002

Version 2 total ozone mapping spectrometer ultraviolet algorithm: problems and enhancements

Nickolay Krotkov, Jay Herman, Pawan Bhartia, Colin Seftor, Antti Arola, Jussi Kaurola, S. Kalliskota, Petteri Taalas, Igor Geogdzhayev

OE, Vol. 41, Issue 12, (December 2002) https://doi.org/10.1117/12.10.1117/1.1519541

KEYWORDS: Clouds, Ultraviolet radiation, Aerosols, Satellites, Atmospheric modeling, Reflectivity, Data modeling, Ozone, Spectroscopy, 3D modeling

Proceedings Article | 17 January 2002 Paper

Paper

Version 2 TOMS UV algorithm: problems and enhancements

Nickolay Krotkov, Jay Herman, Pawan Bhartia, Colin Seftor, Antti Arola, Jussi Kaurola, Lasse Koskinen, S. Kalliskota, Petteri Taalas, Igor Geogdzhaev

Proceedings Volume 4482, (2002) https://doi.org/10.1117/12.452956

KEYWORDS: Clouds, Ultraviolet radiation, Aerosols, Satellites, Reflectivity, Data modeling, Atmospheric modeling, Evolutionary algorithms, Signal attenuation, Ozone

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Proceedings Article | 17 January 2002 Paper

Paper

Comparisons between ground measurements of UV irradiance 290 to 380nm and TOMS UV estimates over Moscow for 1979-2000

Nataly Chubarova, Alla Yurova, Nickolay Krotkov, Jay Herman, Pawan Bhartia

Proceedings Volume 4482, (2002) https://doi.org/10.1117/12.452945

KEYWORDS: Ultraviolet radiation, Clouds, Aerosols, Satellites, Line edge roughness, Atmospheric modeling, Reflectivity, Molybdenum, Atmospheric particles, Error analysis

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Proceedings Article | 15 November 2000 Paper

Paper

Spectral band calibration of the Total Ozone Mapping Spectrometer (TOMS) using a tunable laser technique

Robert Haring, Frederick Williams, Ulli Hartmann, Doug Becker, Gary Vanstone, Hongwoo Park, Pawan Bhartia, Richard McPeters, Glen Jaross, Matthew Kowalewski

Proceedings Volume 4135, (2000) https://doi.org/10.1117/12.494208

KEYWORDS: Calibration, Dye lasers, Ultraviolet radiation, Monochromators, Sensors, Mirrors, Integrating spheres, Power meters, Visible radiation, Lamps

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The Total Ozone Mapping Spectrometer (TOMS) provides daily global mapping of the total column ozone in the earth’s atmosphere. It does this by measuring the solar irradiance and the backscattered solar radiance in 6 spectral bands falling within the range from 308.6 nm to 360 nm. The accuracy of the ozone retrieval is highly dependent on the knowledge of the transfer characteristics and center wavelength for each spectral band. A 0.1 nm wavelength error translates to a 1.6% error in ozone. Several techniques have historically been used to perform the wavelength calibration of the TOMS instruments. These methods include the use of film and reference spectra from low-pressure spectral line lamps and the use of continuum sources with a narrow-band scanning monochromator. The spectral transfer characteristic of the Flight Model 5 instrument for the QuikTOMS mission was calibrated using a new technique employing a frequency doubled tunable dye laser. The tunable laser has several advantages that include a very narrow spectral bandwidth; accurate wavelength determination using a wavemeter; and the ability to calibrate the instrument system level of assembly (prior methods required that the calibration be performed at the monochromator sub assembly level). The technique uses the output from a diode-pumped solid state Nd:V04 laser that is frequency doubled to provide a continuous wave 532 nm pump laser beam to a Coherent Model 899-01 frequency doubled ring dye laser. The output is directed into the entrance port of a 6-inch diameter Spectralon integrating sphere. A GaP photodiode is used to monitor the sphere wall radiance while a Burleigh Wavemeter (WA-1500) is used to monitor the wavelength of the visible output of the dye laser. The TOMS field of view is oriented to view the exit port of the integrating sphere. During the measurement process the response of the instrument is monitored as the laser source is stepped in 0.02-nm increments over each of the six TOMS spectral bands. Results of the new technique allow establishing the wavelength center to a precision of better than 0.1 nm. In addition to the spectral band measurements, the laser provided a means to calibrate the radiometric linearity of the QuikTOMS instrument and yield new insights into the stray light performance of the complete optical system.

Proceedings Article | 28 December 1999 Paper

Paper

Prelaunch tests for the calibration of Total Ozone Mapping Spectrometer (TOMS) flight model 5 (FM-5)

Hongwoo Park, F. Cunningham, Jay Herman, Richard McPeters, Pawan Bhartia, Ulli Hartmann, Robert Haring

Proceedings Volume 3870, (1999) https://doi.org/10.1117/12.373203

KEYWORDS: Calibration, Diffusers, Ozone, Free electron lasers, Monochromators, Optical spheres, Satellites, Polarization, Sensors, Lamps

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Proceedings Article | 21 December 1998 Paper

Paper

Joint Russian-USA Meteor-3M(2)/TOMS-5 mission

Hongwoo Park, Shahid Habib, F. Cunningham, Jay Herman, Pawan Bhartia, Rashid Salikhov, Albert Chernikov

Proceedings Volume 3498, (1998) https://doi.org/10.1117/12.333659

KEYWORDS: Ozone, Space operations, Diffusers, Interfaces, Control systems, Spectroscopy, Data processing, Calibration, Satellites, Aerosols

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Proceedings Article | 8 November 1996 Paper

Paper

Remote sensing applications of continuous spectral backscatter ultraviolet measurements

Joanna Joiner, Pawan Bhartia, Ernest Hilsenrath

Proceedings Volume 2831, (1996) https://doi.org/10.1117/12.257188

KEYWORDS: Clouds, Ozone, Ultraviolet radiation, Calibration, Backscatter, Satellites, Scattering, Remote sensing, Ions, Radiative transfer

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Proceedings Article | 15 December 1995 Paper

Paper

Monitoring atmospheric ozone from space limb scatter measurements

Benjamin Herman, David Flittner, Richard McPeters, Pawan Bhartia

Proceedings Volume 2582, (1995) https://doi.org/10.1117/12.228527

KEYWORDS: Ozone, Scattering, Light scattering, Spherical lenses, Atmospheric modeling, Multiple scattering, Solar radiation models, Scatter measurement, Absorption, Knowledge management

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Showing 5 of 17 publications

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