Atmospheric & Oceanic Science Research Works

Permanent URI for this collectionhttp://hdl.handle.net/1903/1596

Formerly known as the Department of Meteorology.

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    Wildfire Smoke Particle Properties and Evolution, from Space-Based Multi-Angle Imaging
    (MDPI, 2020-02-26) Noyes, Katherine Junghenn; Kahn, Ralph; Sedlacek, Arthur; Kleinman, Lawrence; Limbacher, James; Li, Zhanqing
    Emitted smoke composition is determined by properties of the biomass burning source and ambient ecosystem. However, conditions that mediate the partitioning of black carbon (BC) and brown carbon (BrC) formation, as well as the spatial and temporal factors that drive particle evolution, are not understood adequately for many climate and air-quality related modeling applications. In situ observations provide considerable detail about aerosol microphysical and chemical properties, although sampling is extremely limited. Satellites offer the frequent global coverage that would allow for statistical characterization of emitted and evolved smoke, but generally lack microphysical detail. However, once properly validated, data from the National Aeronautics and Space Administration (NASA) Earth Observing System’s Multi-Angle Imaging Spectroradiometer (MISR) instrument can create at least a partial picture of smoke particle properties and plume evolution. We use in situ data from the Department of Energy’s Biomass Burning Observation Project (BBOP) field campaign to assess the strengths and limitations of smoke particle retrieval results from the MISR Research Aerosol (RA) retrieval algorithm. We then use MISR to characterize wildfire smoke particle properties and to identify the relevant aging factors in several cases, to the extent possible. The RA successfully maps qualitative changes in effective particle size, light absorption, and its spectral dependence, when compared to in situ observations. By observing the entire plume uniformly, the satellite data can be interpreted in terms of smoke plume evolution, including size-selective deposition, new-particle formation, and locations within the plume where BC or BrC dominates.
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    Wildfire Smoke Particle Properties and Evolution, From Space-Based Multi-Angle Imaging II: The Williams Flats Fire during the FIREX-AQ Campaign
    (MDPI, 2020-11-21) Junghenn Noyes, Katherine T.; Kahn, Ralph A.; Limbacher, James A.; Li, Zhanqing; Fenn, Marta A.; Giles, David M.; Hair, Johnathan W.; Katich, Joseph M.; Moore, Richard H.; Robinson, Claire E.; Sanchez, Kevin J.; Shingler, Taylor J.; Thornhill, Kenneth L.; Wiggins, Elizabeth B.; Winstead, Edward L.
    Although the characteristics of biomass burning events and the ambient ecosystem determine emitted smoke composition, the conditions that modulate the partitioning of black carbon (BC) and brown carbon (BrC) formation are not well understood, nor are the spatial or temporal frequency of factors driving smoke particle evolution, such as hydration, coagulation, and oxidation, all of which impact smoke radiative forcing. In situ data from surface observation sites and aircraft field campaigns offer deep insight into the optical, chemical, and microphysical traits of biomass burning (BB) smoke aerosols, such as single scattering albedo (SSA) and size distribution, but cannot by themselves provide robust statistical characterization of both emitted and evolved particles. Data from the NASA Earth Observing System’s Multi-Angle Imaging SpectroRadiometer (MISR) instrument can provide at least a partial picture of BB particle properties and their evolution downwind, once properly validated. Here we use in situ data from the joint NOAA/NASA 2019 Fire Influence on Regional to Global Environments Experiment-Air Quality (FIREX-AQ) field campaign to assess the strengths and limitations of MISR-derived constraints on particle size, shape, light-absorption, and its spectral slope, as well as plume height and associated wind vectors. Based on the satellite observations, we also offer inferences about aging mechanisms effecting downwind particle evolution, such as gravitational settling, oxidation, secondary particle formation, and the combination of particle aggregation and condensational growth. This work builds upon our previous study, adding confidence to our interpretation of the remote-sensing data based on an expanded suite of in situ measurements for validation. The satellite and in situ measurements offer similar characterizations of particle property evolution as a function of smoke age for the 06 August Williams Flats Fire, and most of the key differences in particle size and absorption can be attributed to differences in sampling and changes in the plume geometry between sampling times. Whereas the aircraft data provide validation for the MISR retrievals, the satellite data offer a spatially continuous mapping of particle properties over the plume, which helps identify trends in particle property downwind evolution that are ambiguous in the sparsely sampled aircraft transects. The MISR data record is more than two decades long, offering future opportunities to study regional wildfire plume behavior statistically, where aircraft data are limited or entirely lacking.
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    Validation of SO2 retrievals from the Ozone Monitoring Instrument (OMI) over NE China
    (American Geophysical Union (AGU), 2008) Krotkov, N. A.; McClure, B.; Dickerson, R. R.; Carn, S.; Li, C.; Bhartia, P. K.; Yang, K.; Krueger, A.; Li, Z.; Levelt, P. F.; Chen, Hongbin; Wang, Pucai; Lu, Daren
    The Ozone Monitoring Instrument (OMI) launched on the NASA Aura satellite in July 2004 offers unprecedented spatial resolution, coupled with contiguous daily global coverage, for space-based UV measurements of sulfur dioxide (SO2). We present a first validation of the OMI SO2 data with in-situ aircraft measurements in NE China in April 2005. The study demonstrates that OMI can distinguish between background SO2 conditions and heavy pollution on a daily basis. The noise (expressed as the standard deviation, σ) in the PBL SO2 data is ~1.5DU (Dobson Unit, 2.691016 molecules/cm2) for instantaneous field of view (IFOV) data. By looking at the pristine South Pacific under optimal conditions we have determined that temporal and spatial averaging can improve the resolution of the instrument to σ ~ 0.3 DU; the long term average over this remote location was within 0.1 DU of zero. Under polluted conditions, however, Collection 2 data are higher than aircraft measurements by a factor of two in most cases. Parameterization of the airmass factor (AMF) appears to enhance the accuracy of the SO2 data. Improved calibrations of the radiance and irradiance data (Collection 3) result in better agreement with aircraft measurements on polluted days. The re-processed and AMF-corrected Collection 3 data still show positive bias and sensitivity to UV absorbing aerosols. The difference between the in situ data and the OMI daily PBL SO2 measurements within 30 km of the aircraft profiles was about 1 DU, equivalent to ~5 ppb from 0 to 3000 m altitude. Quantifying the SO2 profile and spectral dependence of aerosol absorption between 310 and 330 nm are critical for accurate estimates of SO2 from satellite UV measurements.