Abstract
Formaldehyde (HCHO) has been measured from space for more than 2 decades. Owing to its short atmospheric lifetime, satellite HCHO data are used widely as a proxy of volatile organic compounds (VOCs; please refer to Appendix A for abbreviations and acronyms), providing constraints on underlying emissions and chemistry. However, satellite HCHO products from different satellite sensors using different algorithms have received little validation so far. The accuracy and consistency of HCHO retrievals remain largely unclear. Here we develop a validation platform for satellite HCHO retrievals using in situ observations from 12 aircraft campaigns with a chemical transport model (GEOS-Chem) as the intercomparison method. Application to the NASA operational OMI HCHO product indicates negative biases (-44.5% to -21.7%) under high-HCHO conditions, while it indicates high biases (+66.1% to +112.1%) under low-HCHO conditions. Under both conditions, HCHO a priori vertical profiles are likely not the main driver of the biases. By providing quick assessment of systematic biases in satellite products over large domains, the platform facilitates, in an iterative process, optimization of retrieval settings and the minimization of retrieval biases. It is also complementary to localized validation efforts based on ground observations and aircraft spirals.
| Original language | English |
|---|---|
| Pages (from-to) | 12329-12345 |
| Number of pages | 17 |
| Journal | Atmospheric Chemistry and Physics |
| Volume | 20 |
| Issue number | 20 |
| DOIs | |
| State | Published - Oct 29 2020 |
Funding
Financial support. This research has been supported by the Acknowledgements. We acknowledge contributions from science teams of the 12 aircraft campaigns. This work is funded by NOAA Atmospheric Chemistry Carbon Cycle and Climate NA18OAR4310108, NASA Aura Science Team NNX17AH47G, NASA Science of TERRA, AQUA, and SUOMI NPP 80NSSC18K0691, and NASA Making Earth System Data Records for Use in Research Environments 80NSSC18M0091 grants. This work is supported by the Center for Computational Science and Engineering at the Southern University of Science and Technology. Lei Zhu acknowledges support from the Smithsonian Astrophysical Observatory (SAO) Visiting Scientist Fellowship. The 2018 WE-CAN campaign was supported by the National Science Foundation (grants NSF AGS-1650275, AGS-1650786, AGS-1650288, AGS-1650493, and AGS-1652688). Lu Hu and Wade Permar would like to acknowledge operational, technical, and scientific support provided by NCAR’s Earth Observing Laboratory, sponsored by the National Science Foundation. This material is based upon work supported by the National Center for Atmospheric Research, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement No. 1852977. The NASA Goddard Space Flight Center (GSFC) team acknowledges support for the ATom campaign from the NASA Earth Venture Suborbital-2 Program and support for DC3 and SEAC4RS campaigns from NASA.
| Funders | Funder number |
|---|---|
| NPP 80NSSC18K0691 | |
| AGS-1650493, AGS-1650786, AGS-1652688, AGS-1650275, AGS-1650288 | |
| 1852977 | |
| National Aeronautics and Space Administration | 80NSSC18K0691, 80NSSC18M0091, NNX17AH47G |
| National Oceanic and Atmospheric Administration | NA18OAR4310108 |
| National Center for Atmospheric Research | |
| Southern Taiwan University of Science and Technology |