Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC4RS aircraft observations over the Southeast US.

نویسندگان

  • Lei Zhu
  • Daniel J Jacob
  • Patrick S Kim
  • Jenny A Fisher
  • Karen Yu
  • Katherine R Travis
  • Loretta J Mickley
  • Robert M Yantosca
  • Melissa P Sulprizio
  • Isabelle De Smedt
  • Gonzalo Gonzalez Abad
  • Kelly Chance
  • Can Li
  • Richard Ferrare
  • Alan Fried
  • Johnathan W Hair
  • Thomas F Hanisco
  • Dirk Richter
  • Amy Jo Scarino
  • James Walega
  • Petter Weibring
  • Glenn M Wolfe
چکیده

Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs) but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC4RS campaign over the Southeast US in August-September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the Southeast US (r=0.4-0.8 on a 0.5°×0.5° grid) and in their day-to-day variability (r=0.5-0.8). However, all retrievals are biased low in the mean by 20-51%, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation and correcting this would eliminate its bias relative to the SEAC4RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved.

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Interactive comment on “Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEACRS aircraft observations over the Southeast US” by L. Zhu et al

This manuscript presents an intercomparison exercise of tropospheric HCHO retrieved from satellites measurements using several products obtained from independent retrieval approaches. In order to validate the products, the authors use aircraft observations during the short term field deployment of SEAC4RS in the Southeast of the US. This is an important validation effort. In general, the paper ...

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Interactive comment on “Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEACRS aircraft observations over the Southeast US” by L. Zhu et al

This manuscript presents an intercomparison exercise of tropospheric HCHO retrieved from satellites measurements using several products obtained from independent retrieval approaches. In order to validate the products, the authors use aircraft observations during the short term field deployment of SEAC4RS in the Southeast of the US. This is an important validation effort. In general, the paper ...

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عنوان ژورنال:
  • Atmospheric chemistry and physics

دوره 16 21  شماره 

صفحات  -

تاریخ انتشار 2016