A vertically-resolved atmospheric dust reanalysis for Mars Years 28-29 using Analysis Correction

This is a dataset of meteorological variables for the atmosphere of Mars, obtained by assimilating measurements (retrievals) of atmospheric temperature and dust opacity into a 3-dimensional, time-dependent numerical model of the Martian atmospheric circulation (known as a “reanalysis”).

The observations come from two spacecraft - the Mars Climate Sounder (MCS) instrument on board NASA’s Mars Reconnaissance Orbiter (e.g. Kleinboehl et al. 2009) and the Thermal Emission Imaging Spectrometer (THEMIS) on board NASA’s Mars Odyssey spacecraft, and cover the period from 21 September 2006 until  5 November 2009 (Mars Years 28:Ls=109.98 - 30:Ls=4.78). MCS observations include profiles of temperature and dust opacity from near the surface up to altitudes of around 80 km obtained from infrared limb-sounding (MCS version 3 retrievals, based on opacities at around 21.6 micron wavelengths), while THEMIS measurements are of column dust opacity in the infrared (centred around 9.3 micron wavelength). Further details can be found on the websites

https://pds-geosciences.wustl.edu/missions/odyssey/themis.html,
https://atmos.nmsu.edu/data and services/atmospheres data/MARS/aerosols.html

The model into which the observations are assimilated is the UK version of Laboratoire de Météorologie Dynamique Mars Global Circulation Model (LMDMGCM), a 3-dimensional, time-dependent numerical circulation model of the Martian atmosphere and near-surface environment, simulating the changing winds, temperature, pressure and dust content of the atmosphere across the whole planet. The model solves the equations of motion, mass and energy conservation using a spherical harmonic representation in the horizontal and finite difference formulation in the vertical direction, but outputs the data here on a regular longitude-latitude grid with 72 points in longitude, 36 points in latitude and 25 terrain-following sigma levels in the vertical direction (where sigma = pressure/surface pressure) on a stretched vertical grid that extends from the surface to an altitude of approximately 100 km. More details can be found in publications by Forget et al. (1999), Newman et al. (2001), Mulholland et al. (2013).

The observations and model are linked by an assimilation scheme, based on the Analysis Correction (AC) algorithm developed by Lorenc et al. (1991) and adapted for Mars by Lewis et al. (2007). Previous reanalyses of Mars observations using this scheme include the MACDA dataset (Montabone et al. 2014) and OPENMars (Holmes et al. 2020). This new dataset, however, makes use of an extension of the AC scheme to enable assimilation of both column integrated dust opacity measurements and dust opacity profiles in the vertical direction (see Ruan et al. 2021). This new dataset therefore provides a more realistic representation of the distribution of dust loading in the Martian atmosphere than previous work, which may also result in improved representation of other meteorological variables, notably temperature.

Data are provided as 2D and 3D fields of variables in netCDF format as generated by the numerical model on the (longitude, latitude, sigma) grid at 2-hourly intervals. Each file contains 360 time steps covering 30 Martian days or sols. The variables contained in each file are as follows:

 Variables and attributes
           0  lon:         FLOAT(72) = FLOAT(lon)
                 0  long_name: longitude
                 1  units: degrees_east
           1  lat:         FLOAT(36) = FLOAT(lat)
                 0  long_name: latitude
                 1  units: degrees_north
           2  sigma:       FLOAT(25) = FLOAT(sigma)
                 0  long_name: sigma
                 1  units: sigma_level = p/ps
           3  soil:        FLOAT(18) = FLOAT(soil)
                 0  long_name: soil levels (i.e. levels below the surface to represent thermal variations)
                 1  units: none
           4  time:        FLOAT(360) = FLOAT(time)
                 0  long_name: model time
                 1  units: days since 00:00:00 (the beginning of the file)
           5  controle:    FLOAT(100) = FLOAT(lentable)
                 0  long_name: Table of run parameters
                 1  description:  MGCM run    5.000
           6  Ls:          FLOAT(360) = FLOAT(time)
                 0  Physics_diagnostic: Solar longitude (such that Ls=0 is northern Spring equinox)
                 1  units: deg
           7  tsurf:       FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: Surface temperature
                 1  units: K
           8  ps:          FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: surface pressure
                 1  units: Pa
           9  co2ice:      FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: co2 ice thickness (column mass density)
                 1  units: kg.m-2
          10  fluxsurf_lw: FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: fluxsurf_lw (surface infrared radiative flux)
                 1  units: W.m-2
          11  fluxsurf_sw: FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: fluxsurf_sw (surface visible radiative flux)
                 1  units: W.m-2
          12  temp:        FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: temperature
                 1  units: K
          13  u:           FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: Zonal (east-west) wind
                 1  units: m.s-1
          14  v:           FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: Meridional (north-south) wind
                 1  units: m.s-1
          15  rho:         FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: density
                 1  units: kg.m-3
          16  udrag:       FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: Drag velocity
                 1  units: m/s
          17  udragt:      FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: Threshold velocity for dust lifting
                 1  units: m/s
          18  aerosol:     FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: dust opacity considering layer thickness
                 1  units: SI (opacity/m)
          19  taudustvis:  FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: Dust optical depth
                 1  units: SI
          20  q01:         FLOAT(72,36,25,360) = FLOAT(lon,lat,sigma,time)
                 0  Physics_diagnostic: mix. ratio
                 1  units: kg/kg
          21  dqsdevtot:   FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: dust devil lift rate
                 1  units: kg.m-2.s-1
          22  dqsstrtot:   FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: near surface wind stress dust lifting rate
                 1  units: kg.m-2.s-1
          23  dqssedtot:   FLOAT(72,36,360) = FLOAT(lon,lat,time)
                 0  Physics_diagnostic: dust sedimentation rate
                 1  units: kg.m-2.s-1