EMIRS water-ice cloud optical depth retrievals across the full diurnal cycle at Mars

Approximately two million thermal infrared spectra from the Emirates Mars Infrared Spectrometer (EMIRS) were utilized for this dataset [Ls ≈ 49° in Mars Year (MY) 36 through Ls ≈ 347° in MY 37; approx. May 2021–October 2024]. Results are stored as a self describing NetCDF4 file (https://www.unidata.ucar.edu/software/netcdf/).

The root group contains retrieval output for each spectrum. Variable descriptions are included in the file archive. Coordinate variables associated with the observation are latitude, longitude, solar longitude, local true solar time, emission angle of the observation, solar incidence angle of the observation, and the spacecraft clock timestamp when the observation was made. Output from the aerosol retrieval are stored as data variables and include the surface temperature, water-ice optical depth, water-ice optical depth uncertainty, surface anisothermality "slope" correction parameter, surface emissivity correction parameter, and estimated water condensation level. Spectra included in this dataset are those observations which passed quality checks for the water-ice optical depth retrieval.

Additional uncertainty weighted mean values for water-ice optical depth averaged across various coordinate dimensions are included as NetCDF4 groups. These groups correspond to selected figures shown in the accompanying manuscript for this dataset, and can be used to reconstruct the figures or compare against other datasets or results.

As an example, the full dataset can be opened using python and xarray (v2024.10.0 or greater) as an xarray DataTree with the following:
import xarray as xr
emirs_data = xr.open_datatree('EMIRS_tauice_dataset.nc')

Description of the retrieval and data in this archive can be found in the accompanying manuscript for this dataset:
"The Full Diurnal Cycle of Mars Water-Ice Cloud Optical Depth in EMIRS Observations" by Samuel A. Atwood, Michael D. Smith, Michael J. Wolff, and Christopher S. Edwards, submitted to JGR-Planets.