MEaSUREs project for H2CO, C2H2O2 and H2O long-term consistent records from GOME to OMI and beyond

Formaldehyde is ubiquitous in the Earth’s atmosphere being the principal intermediate product in the oxidation of methane and non-methane volatile organic compounds (NMVOCs). Formaldehyde, in particular when observed from space, is an effective proxy to estimate short-lived NMVOC emissions on a global scale. Quantifying NMVOC emissions is of paramount importance to atmospheric chemistry modeling efforts given the important role NMVOCs play in tropospheric chemistry and therefore in air quality and climate. Glyoxal, another short-lived product of NMVOC oxidation can also be observed from space. Since glyoxal and formaldehyde have different source speciation, simultaneous observations of these two species can be combined to produce glyoxal to formaldehyde ratios and constrain processes responsible for NMVOC emissions. Water vapor is an Essential Climate Variable (ECV) that critically contributes to the characterization of the Earth climate and weather, as well as participates in atmospheric photochemistry. Having access to long-term, consistent and calibrated data products of formaldehyde, glyoxal and water vapor will provide information to enhance our understanding of the Earth atmospheric system, the pathways to tropospheric ozone formation and secondary organic aerosol formation.

With support from NASA’s MEaSUREs program we are developing long-term data sets of formaldehyde, glyoxal and water vapor combining measurements from six UV-VIS space-borne sensors: GOME, SCIAMACHY, OMI, GOME 2A/B and OMPS-NM on Suomi NPP. We describe the strategies that we are using to develop consistent retrieval algorithms. We describe the Smithsonian Astrophysical Observatory (SAO) trace gas retrieval and examples of its implementation for a variety of sensors. We discuss the state-of–the-art air mass factor calculations we are developing, and comment on validation efforts involving in-situ ground and aircraft measurements, as well as ground-based remote sensing observations. As an example we show validation of formaldehyde using aircraft measurements from several flight campaigns spanning near a decade. We also present the approach we are following for the generation of regularly gridded level 3 products showing as example the newly implemented OMHCHOd data product that provides quality controlled, daily OMI formaldehyde retrievals on a 0.1°x0.1° latitude-longitude regular grid. Finally, we will discuss our plans for data dissemination during the development phase, which is key to obtaining user feedback in the early stage of the project.