# + # MAVEN IUVS L2 limb N2 density, MCD v5.3 density, mixing ratio, derived homopause altitude and inferred CO2 density at homopause # Maintained by Nao Yoshida, n.yoshida@pat.gp.tohoku.ac.jp # Generated on October 4 2020 # Parameters for additional FAIR ARCHIVE requested by JGR # in Yoshida et al., Seasonal and latitudinal variations of dayside N2/CO2 ratio in the Martian thermosphere derived from MAVEN IUVS observations # doi: TBD # We constrained the profile such that uncertainties of N2/CO2 are less than 50%. # To observe N2/CO2 ratio at 140 km, we interpolated the N2 number density and its uncertainties using those observed at 137 km and 153 km altitude. We assumed that densities vary exponentially with altitude. The error is weighted by the interval. # To compare the number density at 140 km derived from IUVS and MCD, number densities of CO2 and N2 at 140 km as well as N2/CO2 at 140 km are predicted by MCD. # To interpolate the homopause altitude, we used N2/CO2 ratio at 50 km predicted by MCD as mixing ratio in the homosphere. Homopause altitude and its CO2 density are derived from that N2/CO2 ratio observed at 140 km by IUVS limb, atmospheric temperature at 175 km derived from IUVS limb, and N2/CO2 ratio at 50 km predicted by MCD. We assumed an isothermal atmosphere and hydrostatic equilibrium. Homopause altitude was derived below 140 km altitude, whose resolution is 0.1 km. # The full version of MCD version 5.3 was used to get the predicted parameters. We applied the IUVS geometry as input parameters. # # PARAMETER # # Original Level-2 data file name # # Below parameters are arranged from left to right. # # Orbit number INT16 {I6} # Scan profiles number INT16 {I6} # Solar longitude, 0deg=Martian spring equinox, 90deg=solstice, etc [deg] FLOAT32 {F10.3} # Interpolated IUVS N2 density [cm-3] Float32 {E14.6} # Interpolated IUVS N2 density uncertainty [cm-3] Float32 {E14.6} # Predicted CO2 density at 140 km by MCD [cm-3] Real {E14.6} # Predicted N2 density at 140 km by MCD [cm-3] Real {E14.6} # Predicted N2/CO2 ratio at 140 km by MCD [] Real {F9.5} # Predicted N2/CO2 ratio at 50 km by MCD [] Real {F9.5} # Inferred homopause altitude [km] Float32 {F7.1} # Inferred CO2 density at homopause altitude [cm-3] Float32 {E14.6} # - mvn_iuv_l2_periapse-orbit03150_20160512T233604_v13_r01.fits 3150 4 151.633 3.994470e+08 1.517093e+08 6.258372e+09 9.732258e+08 0.15551 0.01984 115.1 1.060672e+11 3150 5 151.633 5.371313e+08 1.884775e+08 7.547378e+09 1.131004e+09 0.14985 0.01975 103.8 3.774024e+11 3150 8 151.633 7.824552e+08 1.538913e+08 1.143637e+10 1.345094e+09 0.11762 0.01942 111.5 2.505825e+11 3150 9 151.633 1.011833e+09 2.335983e+08 1.299970e+10 1.346270e+09 0.10356 0.01939 108.2 4.241460e+11 3150 10 151.633 9.593646e+08 2.220829e+08 1.461337e+10 1.331797e+09 0.09114 0.01940 109.2 3.313124e+11 3150 11 151.633 6.558778e+08 1.921732e+08 1.510628e+10 1.246635e+09 0.08252 0.01945 118.5 1.255751e+11 3150 12 151.633 9.963169e+08 2.494579e+08 1.422055e+10 1.105100e+09 0.07771 0.01955 102.0 4.714958e+11