TEMPO at Night

The NASA Tropospheric Emissions: Monitoring of Pollution (TEMPO) instrument is
hosted on a commercial geostationary satellite at 91°W longitude. TEMPO is an
imaging spectrometer covering Greater North America (CONUS and parts of Canada,
Mexico, and the Caribbean including Puerto Rico). The primary mission of TEMPO is
retrieval of trace-gas concentrations from the spectra of reflected sunlight. TEMPO has
an ultraviolet (290 nm – 490 nm) and a visible (540 nm – 740 nm) band with spectra
that have 0.6 nm spectral resolution and 0.2 nm spectral sampling. Direct sunlight into
or close to the aperture of TEMPO represents a potential hazard to its spectrometer. At
night, when sun safety constraints allow the aperture to be open, TEMPO can see city
lights, gas flares, maritime lights, moonlit clouds, aurorae, and nightglow without taking
time away from its primary mission. These nighttime uses had not been envisioned
when TEMPO was first proposed. This paper shows some early results from TEMPO at
night, including clearest-sky composites similar to VIIRS Day-Night Band (DNB) “Black
Marble” mosaics, classifications of city lights by their spectral signatures with radiance
by lighting type, moonlit cloud images, gas flare and wildfire pyrometry, lightning,
maritime lights, aurorae, and nightglow. Level-1 nighttime data from TEMPO are
available from the NASA Atmospheric Science Data Center (ASDC) as the “twilight”
radiance product (RADT). These data are now released in Version 4. They require no
post-processing and are easier to use than Version 3. The Version 4 RADT products
contain background-subtracted radiances that are registered to VIIRS-DNB and include
collocated DNB radiances.