*************************************************************************************** Date: 21-June-2022 Who: S. W. Bougher General Details of MGITM datasets for Dayside Exospheric Temperature Variation Project ***************************************************************************************** Description: The NASA MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft, which is currently in orbit around Mars, has been taking systematic measurements of the densities and deriving temperatures in the upper atmosphere of Mars between about 140 to 240 km above the surface since late 2014. Wind measurement campaigns are also conducted once per month for 5-10 orbits. These densities, temperatures and winds change with time (e.g. solar cycle, season, local time) and location, and sometimes fluctuate quickly. Global dust storm events are also known to significantly impact these density, temperature and wind fields in the Mars thermosphere. For the current project, the derived temperatures and O plus CO2 densities are used to characterize the upper atmosphere dayside thermal and density structure. Presently, more than 6 years of Neutral Gas and Ion Mass Spectrometer (NGIMS) measurements of neutral densities have been obtained by the MAVEN team (e.g. Mahaffy et al. 2015; Bougher et al 2015; Elrod et al., 2017; 2021; Stone et al. 2018; Gupta et al., 2021). Measured neutral density distributions are compared to simulations from a computer model of the Mars atmosphere called M-GITM (Mars Global Ionosphere-Thermosphere Model), developed at U. of Michigan. Since the global circulation plays a role in the structure, variability, and evolution of the atmosphere, understanding the processes that drive the winds in the upper atmosphere of Mars also provides the needed context for understanding density and temperature distributions and how the atmosphere behaves as a whole system. Three dimensional M-GITM simulations for extreme Mars seasonal and solar cycle conditions were conducted for detailed comparisons with NGIMS derived temperatures and O/CO2 ratio distributions (Bougher et al. 2022). Extracted model densities and temperatures along the MAVEN inbound trajectory of each orbit path (between ~300 km and periapsis) are provided in this Deep Blue Data archive. Corresponding M-GITM heat balance terms are also provided in vertical 1-D tabulated formats. README files are included for each suite of 1-D "flythru" tables, detailing the contents of each file. In addition, a general README file is provided that summarizes the inputs and outputs of the M-GITM code simulations for this study. Finally, a basic version of the M-GITM code can be found on Github at https:/github.com/dpawlows/MGITM. ***************************************************************************************** Four Extreme Solar Cycle and Seasonal conditions for M-GITM simulations of this project (Bougher et al., 2022) -------------------------------------------------------------------------------------------- Interval Date Range Season (Ls) Narrative -------------------------------------------------------------------------------------------- 1 17-April to 13-May, 2015 328-341 DD2 (extended) sampling period 2 17-22 April, 2015 328-331 DD2 (only) sampling period 3 16-22 October, 2017 75-77 DD8 sampling period 4 16-30 September, 2019 84-86 PC19 sampling period ***************************************************************************************** MGITM results are presented along spacecraft orbital trajectories making use of GEO grid (Longitude-Latitude vs Altitude): ------------------------------------------------------------------------- LST and LAT varying slowly along the orbital trajectory ALT = ~300 km to periapsis altitudes along the orbit path (see note **) Fields (7): -- Temperatures (neutral) : Tn -- Major neutral densites : [CO2], [N2], [CO], [O], [He] -- Mass density : Rho -- Major plasma densities : none here Units = All Temperatures (K), All neutral densities (#/m3), Mass density (kg/km3) 13-Files in the respository for downloading: ----------------------------------------------------------------------------------- README.MGITM.General.txt Bundled Orbital File Batches: ------------------------------ Interval 1: DD2E.MGITM_UATM_Extraction_csv.zip README.DD2E.MGITM_UATM_Extraction Interval 2: DD2only.MGITM_UATM_Extraction_csv.zip README.DD2only.MGITM_UATM_Extraction Interval 3: DD8.MGITM_UATM_Extraction_csv.zip README.DD8.MGITM_UATM_Extraction_csv Interval 4: PC19.MGITM_UATM_Extraction_csv.zip README.PC19.MGITM_UATM_Extraction ** Note. The irregular altitude grid dislayed in these UATM model extracted atmospheres (along each orbit trajectory) has a few peculiar attributes. Most of these can be overcome with variable interpolation to a regular altitude grid. First, since the M-GITM vertical resolution is 2.5 km, sometimes the same density value can appear in a few adjacent altitude cells. This becomes increasingly the case as periapsis is approached, and the regular cadence by the NGIMS instrument sampling spans smaller and smaller altitude intervals as the spacecraft trajectory becomes more horizontal and less vertical. In addition, the "stair-step" appearance of the 1-D density and temperature profiles will be smoothed out once proper interpolation to a regular altitude grid is made, and campaign averaged density and temperature profiles are computed and displayed. Secondly, data-model density comparisons along the orbit track are reasonable, again once a common sampling (regular altitude) grid is used. However, data-model temperature comparisons are best made at least a scale height above periapsis. Temperature extractions (like those performed in the supported jounral paper) for exospheric conditions largely satisfy this requirement. However, model heat balance term extraction requires vertical profiles (only), so that molecular thermal conduction and gravity wave effects can be properly studied as computed in the vertical. Here we use 2.5 km vertical grid at a single (low SZA) location for comparing heat balance terms for both DD2 and DD8 conditions. We note that tabulated HTBAL_Extraction term values do not exactly match those plotted in Figures 5 and 7, especially at low altitudes near periapsis. This does not impact the major conclusions about these heat balance terms and their relative importance as a function of altitude. Heat Balance Term Files: ------------------------------ Interval 1: DD2E.MGITM_HTBAL_Extraction_cvs.zip README.DD2E.MGITM_HTBAL_Extraction Interval 4: PC19.MGITM_HTBAL_Extraction_csv.zip README.PC19.MGITM_HTBAL_Extraction FISM-Mars daily averaged solar EUV-UV fluxes (1-195 nm) used based upon MAVEN Extreme Ultraviolet Monitor (EUVM) instrument: Thiemann et al. (2017). ------------------------------------------------------------------------------------- Level 3 EUVM daily products used: v14_r03 (all intervals) ***************************************************************************************** Specific Key References pertaining to MGITM Simulations plus MAVEN NGIMS and EUVM Datasets: -------------------------------------------------------------------------------------- Bougher et al. (2015), J. Geophys. Res., 120, 311-342. doi:10.1002/2014JE004715. Thiemann et al. (2017), J. Geophys. Res., 122, 2748-2767. doi:10.1002/2016JA023512. Benna and Elrod (2020), NGIMS Software Interface Specification (SIS).Version 1.12 , DOC Number MAVEN605 NGIMS-SIS-0001. Citation for this dataset: ------------------------- Bougher, S. W., (2022) M-GITM Simulated Temperature and Density Distributions for Extreme Conditions: Comparions to MAVEN Neutral Gas and Ion Mass Spectrometer (NGIMS) Measurements. University of Michigan - Deep Blue Data. https://doi.org/......... *****************************************************************************************