Abstract. We present and discuss the Smithsonian Astrophysical Observatory (SAO) formaldehyde (H 2 CO) retrieval algorithm for the Ozone Monitoring Instrument (OMI) which is the operational retrieval for NASA OMI H 2 CO. The version of the algorithm described here includes relevant changes with respect to the operational one, including differences in the reference spectra for H 2 CO, the fit of O 2 -O 2 collisional complex, updates in the high-resolution solar reference spectrum, the use of a model reference sector over the remote Pacific Ocean to normalize the retrievals, an updated air mass factor (AMF) calculation scheme, and the inclusion of scattering weights and vertical H 2 CO profile in the level 2 products. The setup of the retrieval is discussed in detail. We compare the results of the updated retrieval with the results from the previous SAO H 2 CO retrieval. The improvement in the slant column fit increases the temporal stability of the retrieval and slightly reduces the noise. The change in the AMF calculation has increased the AMFs by 20 %, mainly due to the consideration of the radiative cloud fraction. Typical values for retrieved vertical columns are between 4 × 10 15 and 4 × 10 16 molecules cm −2 , with typical fitting uncertainties ranging between 45 and 100 %. In high-concentration regions the errors are usually reduced to 30 %. The detection limit is estimated at 1 × 10 16 molecules cm −2 .
Abstract. There are distinct spectral features of water vapor in the wavelength range covered by the Ozone Monitoring Instrument (OMI) visible channel. Although these features are much weaker than those at longer wavelengths, they can be exploited to retrieve useful information about water vapor. They have an advantage in that their small optical depth leads to fairly simple interpretation as measurements of the total water vapor column density. We have used the Smithsonian Astrophysical Observatory (SAO) OMI operational retrieval algorithm to derive the slant column density (SCD) of water vapor using the 430-480 nm spectral region after extensive optimization. We convert from SCD to vertical column density (VCD) using the air mass factor (AMF), which is calculated using look-up tables of scattering weights and assimilated water vapor profiles. Our Level 2 product includes not only water vapor VCD but also the associated scattering weights and AMF. In the tropics, our standard water vapor product has a median SCD of 1.3 × 10 23 molecules cm −2 and a median relative uncertainty of about 11 %, about a factor of 2 better than that from a similar OMI algorithm that uses a narrower retrieval window. The corresponding median VCD is about 1.2 × 10 23 molecules cm −2 . We have examined the sensitivities of SCD and AMF to various parameters and compared our results with those from the GlobVapour product, the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Aerosol Robotic NETwork (AERONET).
The NASA/Smithsonian Tropospheric Emissions: Monitoring of Pollution (TEMPO; tempo.si.edu) satellite instrument will measure atmospheric pollution and much more over Greater North America at high temporal resolution (hourly or better in daylight, with selected observations at 10 minute or better sampling) and high spatial resolution (10 km 2 at the center of the field of regard). It will measure ozone (O 3 ) profiles (including boundary layer O 3 ), and columns of nitrogen dioxide (NO 2 ), nitrous acid (HNO 2 ), sulfur dioxide (SO 2 ), formaldehyde (H 2 CO), glyoxal (C 2 H 2 O 2 ), water vapor (H 2 O), bromine oxide (BrO), iodine oxide (IO), chlorine dioxide (OClO), as well as clouds and aerosols, foliage properties, and ultraviolet B (UVB) radiation. The instrument has been delivered and is awaiting spacecraft integration and launch in 2022. This talk describes a selection of TEMPO applications based on the TEMPO Green Paper living document (http://tempo.si.edu/publications.html).Applications to air quality and health will be summarized. Other applications presented include: biomass burning and O 3 production; aerosol products including synergy with GOES infrared measurements; lightning NO x ; soil NO x and fertilizer application; crop and forest damage from O 3 ; chlorophyll and primary productivity; foliage studies; halogens in coastal and lake regions; ship tracks and drilling platform plumes; water vapor studies including atmospheric rivers, hurricanes, and corn sweat; volcanic emissions; air pollution and economic evolution; high-resolution pollution versus traffic patterns; tidal effects on estuarine circulation and outflow plumes; air quality response to power blackouts and other exceptional events.
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