23 Mar 2022
23 Mar 2022
Status: this preprint is currently under review for the journal AMT.

Intercomparison of airborne and surface-based measurements during the CLARIFY, ORACLES and LASIC field experiments

Paul Alan Barrett1, Steven J. Abel1, Hugh Coe2, Ian Crawford2, Amie Dobracki3, James M. Haywood4,1, Steve Howell5, Anthony Jones1,4, Justin Langridge1, Greg McFarquhar6,7, Graeme Nott8, Hannah Price8, Jens Redemann6, Yohei Shinozuka9, Kate Szpek1, Jonathan Taylor2, Robert Wood10, Huihui Wu2, Paquita Zuidema3, Stephane Bauguitte8, Ryan Bennett11, Keith Bower2, Hong Chen12, Sabrina P. Cochrane12, Michael Cotterell4,13, Nicholas Davies4,14, David Delene15, Connor Flynn16, Andrew Freedman17, Steffen Freitag5, Siddhant Gupta6,7, David Noone18,19, Timothy B. Onasch17, James Podolske20, Michael R. Poellot15, Sebastian K. Schmidt12,21, Stephen Springston22, Arthur J. Sedlacek III22, Jamie Trembath8, Alan Vance1, Maria Zawadowicz22, and Jianhao Zhang3,23,24 Paul Alan Barrett et al.
  • 1Met Office, Exeter, EX1 3PB, UK
  • 2Department of Earth and Environmental Sciences, University of Manchester, M13 9PL, UK
  • 3Rosential School of Marine and Atmospheric Science, University of Miami, Miami, FL 33149, USA
  • 4University of Exeter, Exeter, EX4 4PY, UK
  • 5Department of Oceanography, University of Hawai’i at Mānoa,, Honolulu, HI, USA
  • 6School of Meteorology, University of Oklahoma, Norman, OK, USA
  • 7Cooperative Institute for Severe and High-Impact Weather Research and Operations, University of Oklahoma, Norman, OK, USA
  • 8FAAM Airborne Laboratory, Cranfield, MK43 0AL, UK
  • 9Universities Space Research Association, Columbia, MD, USA
  • 10Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
  • 11Bay Area Environmental Research Institute, NASA Ames Research Centre, Moffett Field, Mountain View, CA, USA
  • 12Department of Atmospheric and Oceanic Sciences, University of Colorado, Boulder, CO, USA
  • 13School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
  • 14Haseltine Lake Kempner, Bristol, BS1 6HU, UK
  • 15Department of Atmospheric Sciences, University of North Dakota, Grand Forks, ND, USA
  • 16School of Meteorology, University of Oklahoma, Norman, OK, USA
  • 17Aerodyne Research Inc., Billerica, MA, USA
  • 18College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis OR, USA
  • 19Department of Physics, University of Auckland, Auckland, New Zealand
  • 20NASA Ames Research Centre, Moffett Field, Mountain View, CA, USA
  • 21Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
  • 22Brookhaven National Laboratory, Upton, NY, USA
  • 23NOAA Chemical Sciences Laboratory (CSL), Boulder, CO, USA
  • 24Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, Boulder, CO, USA

Abstract. Data are presented from intercomparisons between two research aircraft, the FAAM BAe-146 and the NASA Lockheed P3, and between the BAe-146 and the surface-based DOE (Department of Energy) ARM (Atmospheric Radiation Monitoring) Mobile Facility at Ascension Island (8 S, 14.5W, a remote island in the mid-Atlantic). These took place from 17 August to 5 September 2017, during the African biomass burning season. The primary motivation was to give confidence in the use of data from multiple platforms with which to evaluate numerical climate models. The three platforms were involved in the CLouds-Aerosol-Radiation Interaction and Forcing for Year 2017 (CLARIFY-2017), ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES), and Layered Atlantic Smoke and Interactions with Clouds (LASIC) field experiments. Comparisons from flight segments on six days where the BAe-146 flew alongside the ARM facility on Ascension Island are presented, along with comparisons from wing-tip to wing-tip flight of the P3 and BAe-146 on 18th August 2017. The intercomparison flight sampled a relatively clean atmosphere overlying a moderately polluted boundary layer, while the 6 fly-bys of the ARM site sampled both clean and polluted conditions 2–4 km upwind. We compare and validate characterisations of aerosol physical, chemical, and optical properties, atmospheric radiation, and cloud microphysics between platforms. We assess the performance of measurement instrumentation in the field, under conditions where sampling conditions are not tightly controlled as in laboratory measurements where calibrations are performed. Solar radiation measurements compared well between airborne platforms. Optical absorption coefficient measurements compared well across all three platforms, even though absolute magnitudes were often low (< 10 Mm−1) and close to the sensitivity limits of measurement instrumentation thereby confounding assessments of the comparability of absorption Ångström exponent characterisations. Aerosol absorption measurements from airborne platforms were more comparable than aircraft-to-ground observations. Scattering coefficient observations compared well between airborne platforms, but agreement with ground-based measurements was worse, potentially caused by small differences in sampling conditions or actual aerosol population differences. Chemical composition measurements followed a similar pattern, with better comparisons between the airborne platforms. Thermodynamics, aerosol, and cloud microphysical properties generally compared well.

Paul Alan Barrett et al.

Status: open (until 28 Jun 2022)

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Paul Alan Barrett et al.

Paul Alan Barrett et al.


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Short summary
In order to better understand weather and climate it is vital to go into the field and collect observations. Often measurements take place in isolation but here we compared data from two aircraft and one ground-based site. This was done in order to understand how well measurements made on one platform compared to those made on another. Whilst this is easy to do in a controlled laboratory setting it is more challenging in the real-world and so these comparisons are as valuable as they are rare.