Biomass Burning Aerosol Heating Rates from the ORACLES 2016 and 2017 Experiments

Abstract. Aerosol heating due to shortwave absorption has implications for local atmospheric stability and regional dynamics. The derivation of heating rate profiles from space-based observations is challenging because it requires the vertical profile of relevant properties such as the aerosol extinction coefficient and single scattering albedo (SSA). In the southeast Atlantic, this challenge is amplified by the presence of stratocumulus clouds below the biomass burning plume advected from Africa, since the cloud properties affect the magnitude of the aerosol heating aloft, which may in turn lead to changes in the cloud properties and life cycle. The combination of spaceborne lidar data with passive imagers shows promise for future derivations of heating rate profiles and curtains, but new algorithms require careful testing with data from aircraft experiments where measurements of radiation, aerosol and cloud parameters are better collocated and readily available. In this study, we derive heating rate profiles and curtains from aircraft measurements during the NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) project in the southeastern Atlantic. Spectrally resolved irradiance measurements and the derived column absorption allow for the separation of total heating rates into aerosol and gas (primarily water vapor) absorption. The nine cases we analyzed capture some of the co-variability of heating rate profiles and their primary drivers, leading to the development of a new concept: The Heating Rate Efficiency (HRE; the heating rate per unit aerosol extinction). The HRE, which accounts for the overall aerosol loading as well as vertical distribution of the aerosol layer, varies little with altitude as opposed to the standard heating rate. The large case-to-case variability for ORACLES is significantly reduced after converting from heating rate to HRE, allowing us to quantify its dependence on SSA, cloud albedo, and solar zenith angle.

[1]  A. Ekman,et al.  Impact of smoke and non-smoke aerosols on radiation and low-level clouds over the southeast Atlantic from co-located satellite observations , 2021, Atmospheric Chemistry and Physics.

[2]  C. Flynn,et al.  An overview of the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project: aerosol–cloud–radiation interactions in the southeast Atlantic basin , 2021 .

[3]  C. Flynn,et al.  Exploring the elevated water vapor signal associated with the free-tropospheric biomass burning plume over the southeast Atlantic Ocean , 2021, Atmospheric Chemistry and Physics.

[4]  C. Flynn,et al.  Empirically derived parameterizations of the direct aerosol radiative effect based on ORACLES aircraft observations , 2020, Atmospheric Measurement Techniques.

[5]  P. Formenti,et al.  Direct and semi-direct radiative forcing of biomass-burning aerosols over the southeast Atlantic (SEA) and its sensitivity to absorbing properties: a regional climate modeling study , 2020, Atmospheric Chemistry and Physics.

[6]  M. Miller,et al.  Radiative heating rate profiles over the southeast Atlantic Ocean during the 2016 and 2017 biomass burning seasons , 2020, Atmospheric Chemistry and Physics.

[7]  C. Flynn,et al.  Above-cloud aerosol optical depth from airborne observations in the southeast Atlantic , 2020 .

[8]  P. Zuidema,et al.  The diurnal cycle of the smoky marine boundary layer observed during August in the remote southeast Atlantic. , 2019, Atmospheric chemistry and physics.

[9]  P. Goloub,et al.  Satellite inference of water vapour and above-cloud aerosol combined effect on radiative budget and cloud-top processes in the southeastern Atlantic Ocean , 2019, Atmospheric Chemistry and Physics.

[10]  C. Flynn,et al.  Above-cloud aerosol radiative effects based on ORACLES 2016 and ORACLES 2017 aircraft experiments , 2019, Atmospheric Measurement Techniques.

[11]  P. Formenti,et al.  Simulation of the transport, vertical distribution, optical properties and radiative impact of smoke aerosols with the ALADIN regional climate model during the ORACLES-2016 and LASIC experiments , 2018, Atmospheric Chemistry and Physics.

[12]  K. Powell,et al.  Estimations of global shortwave direct aerosol radiative effects above opaque water clouds using a combination of A-Train satellite sensors , 2018, Atmospheric Chemistry and Physics.

[13]  S. Howell,et al.  Time-dependent entrainment of smoke presents an observational challenge for assessing aerosol–cloud interactions over the southeast Atlantic Ocean , 2018, Atmospheric Chemistry and Physics.

[14]  P. Saide,et al.  Calibration of a high spectral resolution lidar using a Michelson interferometer, with data examples from ORACLES. , 2018, Applied optics.

[15]  P. Field,et al.  Large simulated radiative effects of smoke in the south-east Atlantic , 2018, Atmospheric Chemistry and Physics.

[16]  D. Tanré,et al.  Consistency of aerosols above clouds characterization from A-Train active and passive measurements , 2017 .

[17]  S. Piketh,et al.  Smoke and Clouds above the Southeast Atlantic: Upcoming Field Campaigns Probe Absorbing Aerosol’s Impact on Climate , 2016 .

[18]  G. Feingold,et al.  Stratocumulus to cumulus transition in the presence of elevated smoke layers , 2015 .

[19]  Arve Kylling,et al.  The libRadtran software package for radiative transfer calculations (version 2.0.1) , 2015 .

[20]  P. Zuidema,et al.  The Convolution of Dynamics and Moisture with the Presence of Shortwave Absorbing Aerosols over the Southeast Atlantic , 2015 .

[21]  J. Kar,et al.  Evaluation of CALIOP 532 nm aerosol optical depth over opaque water clouds , 2015 .

[22]  S. Somot,et al.  Direct and semi-direct aerosol radiative effect on the Mediterranean climate variability using a coupled regional climate system model , 2015, Climate Dynamics.

[23]  C. Flynn,et al.  Tracking elevated pollution layers with a newly developed hyperspectral Sun/Sky spectrometer (4STAR): Results from the TCAP 2012 and 2013 campaigns , 2014 .

[24]  C. Flynn,et al.  Hyperspectral aerosol optical depths from TCAP flights , 2013 .

[25]  Eric M. Wilcox,et al.  Direct and semi-direct radiative forcing of smoke aerosols over clouds , 2011 .

[26]  Michael D. King,et al.  Solar spectral absorption by marine stratus clouds: Measurements and modeling , 2011 .

[27]  E. Wilcox.  Stratocumulus cloud thickening beneath layers of absorbing smoke aerosol , 2010 .

[28]  C. Liousse,et al.  Simulation of the direct and semidirect aerosol effects on the southern Africa regional climate during the biomass burning season , 2010 .

[29]  Mark A. Vaughan,et al.  The Retrieval of Profiles of Particulate Extinction from Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observations (CALIPSO) Data: Algorithm Description , 2009 .

[30]  Robert Wood,et al.  Satellite-derived direct radiative effect of aerosols dependent on cloud cover , 2009 .

[31]  Wayne C. Welch,et al.  Airborne high spectral resolution lidar for profiling aerosol optical properties. , 2008, Applied optics.

[32]  A. Hill,et al.  The impact of aerosols on non‐precipitating marine stratocumulus. I: Model description and prediction of the indirect effect , 2008 .

[33]  Zhaoyan Liu,et al.  The depolarization - attenuated backscatter relation: CALIPSO lidar measurements vs. theory. , 2007, Optics express.

[34]  P. Pilewskie,et al.  Airborne measurements of spectral direct aerosol radiative forcing in INTEX/ICARTT (2004) and comparisons to previous campaigns , 2005 .

[35]  Piers M. Forster,et al.  The semi‐direct aerosol effect: Impact of absorbing aerosols on marine stratocumulus , 2004 .

[36]  Peter V. Hobbs,et al.  Effects of humidity on aerosols in southern Africa during the biomass burning season , 2003 .

[37]  P. Formenti,et al.  The mean physical and optical properties of regional haze dominated by biomass burning aerosol measured from the C-130 aircraft during SAFARI 2000 , 2003 .

[38]  J. Haywood,et al.  Solar radiative forcing by biomass burning aerosol particles during SAFARI 2000: A case study based on measured aerosol and cloud properties , 2003 .

[39]  O. Boucher,et al.  A satellite view of aerosols in the climate system , 2002, Nature.

[40]  Michael D. King,et al.  A flexible inversion algorithm for retrieval of aerosol optical properties from Sun and sky radiance measurements , 2000 .

[41]  Catherine Gautier,et al.  SBDART: A Research and Teaching Software Tool for Plane-Parallel Radiative Transfer in the Earth's Atmosphere. , 1998 .

[42]  Makiko Sato,et al.  The missing climate forcing , 1997 .

[43]  C. Wehrli,et al.  Comparison of Sun photometer calibration by use of the Langley technique and the standard lamp. , 1995, Applied optics.

[44]  F. X. Kneizys,et al.  AFGL atmospheric constituent profiles (0-120km) , 1986 .

[45]  C. Flynn,et al.  Intercomparison of biomass burning aerosol optical properties from in-situ and remote-sensing instruments in ORACLES-2016 , 2019 .

[46]  M. Herman,et al.  Radiative transfer in the Earth’s atmosphere , 2013 .

[47]  C. Flynn,et al.  4STAR Spectrometer for Sky-Scanning Sun-Tracking Atmospheric Research: Instrument Technology Development , 2011 .

[48]  LI-COR's LI190SB.  Solar Radiation Sensors , 2000 .