Work Description

Title: Venus-like Exoplanet Simulations: Temperature, Wind and Energy Balance Datasets Using the VTGCM Open Access Deposited

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Methodology
  • This numerical model study makes use of the Venus Thermospheric General Circulation Model (VTGCM) to predict the state of the upper atmosphere of a Venus-like exoplanet orbiting and M-dwarf star (GJ436). The VTGCM is a fluid model that solves the Navier-Stokes equations to compute temperatures, winds, and species distributions in the upper atmosphere of Venus above the cloud tops (44 mbar near 70 km). Heating and cooling terms are added that capture EUV heating, CO2 15-micron cooling, near IR heating, molecular thermal conduction and the impact of global winds. Species distributions are simulated utilizing ion-neutral chemical reactions and rates for a CO2 dominated neutral atmosphere (lower altitudes) that gives way to atomic O at the top of the thermosphere. Solar EUV-UV fluxes are now taken from remote measurements from an M-dwarf star (GJ436), along with specific stellar-planet distances that are varied. Computed temperatures, winds, and species distributions are subsequently obtained for this Venus-like exoplanet and compared to the current Venus upper atmosphere for solar minimum conditions . Datasets are produced for this repository so that modern day Venus conditions can be compared with Venus-like exoplanet conditions for a variety of star-planet distances. Heat balance terms from the VTGCM are also provided to understand the processes responsible for the predicted temperatures. This study is the first of several that will serve to predict the possible state of a terrestrial like planet orbiting around GJ436.
Description
  • Understanding the state and composition of an exoplanetary atmosphere depends upon several parameters such as heating, cooling, mixing and reactions between constituent chemical species. Only a few types of atmospheric species can be detected remotely spectroscopically and only if their abundance is large enough to be detectable. In this initial study, we model the atmosphere of a Venus-like planet orbiting the M-type star GJ 436 to determine the global neutral temperature structure, winds, and energy balance as the radial distance of the planet from the star decreases.
Creator
Depositor
  • bougher@umich.edu
Contact information
Discipline
Funding agency
  • National Aeronautics and Space Administration (NASA)
Keyword
Citations to related material
  • C. D. Parkinson, S. W. Bougher, F. P. Mills, R. Hu, G. Gronoff, J. Li, A. Brecht, D. Adams, and Y. L. Yung. Venus as an Exoplanet: I. An Initial Exploration of the 3-D Energy Balance for a CO2 Exoplanetary Atmosphere Around an M-Dwarf Star, J. Geophysical Research, X, (2022). doi:....
Resource type
Last modified
  • 11/26/2022
Published
  • 08/29/2022
Language
DOI
  • https://doi.org/10.7302/vtaz-tw05
License
To Cite this Work:
Bougher, S. W., Parkinson, C. D. (2022). Venus-like Exoplanet Simulations: Temperature, Wind and Energy Balance Datasets Using the VTGCM [Data set], University of Michigan - Deep Blue Data. https://doi.org/10.7302/vtaz-tw05

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Files (Count: 25; Size: 6.08 MB)

Venus -like Exoplanet Simulations Utilizing the VTGCM numerical code.
S. W. Bougher (8/29/2022)
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List of Files and Contents:

Section #1
----------
There are 2-ascii files (*.dat), and 2-plots (*.pdf) for each of 4-simulation sets. One complete set contains both VTGCM state variables (2-D slices), and the
corresponding heat balance (HTBAL) terms (1-D profiles). These 7-state variables are found in vtgcm.VEN*.ZP.FLDS7.dat and *.pdf files; the 5-heat balance terms
are found in vtgcm.HTBAL.VEN*.dat and *.pdf files.

These state variables are as follows:
(1) Height (km)
(2) Neutral Temperature (K)
(3) Atomic O mixing ratio
(4) Atomic CO mixing ratio
(5) Atomic CO2 mixing ratio
(6) Atomic O2 mixing ratio
(7) Zonal winds (m/sec)

These heat balances ternms are as follows:
(1) EUV heating rate (k/day)
(2) Near-IR heating rate (K/day)
(3) CO2 15-micron cooling rate (K/day)
(4) Molecular thermal conduction rate (K/day)
(5) Total dynamical heating/cooling rate (K/day)

The Domain and Grid structure for these 2-D tables is as follows: all at LAT = 2.5N
(1) Fast variable: Longitude (0.0 to 180 to 360, by 5.0 degree intervals)
Local time (LT = 0.0 to 12.0 to 24.0, by 0.33 hour intervals)

(2) Slow variable: Log pressure (Zp): -16.0 to 18.0, by 0.5 intervals

The Grid structure for these 1-D profiles is as follows: all at LT = 12.0, and LAT = 2.5N
(1) Only variable: Altitude (km): 70.0 to 200.0, by 2.0 km intervals

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Simulation descriptions and associated files:
-------------------------------------------
1. Simulation #1: VTGCM case VEN1: Baseline modern solar mninimum conditions (like that for late Venus Express mission)
a. State variables (2-D): *.dat and *.pdf
b. Heat balances (1-D): *.dat and *.pdf

2. Simulation #2: case VEN2: Baseline conditions (now using GJ436 solar fluxes, at D = 0.72 AU)
a. State variables (2-D): *.dat and *.pdf
b. Heat balances (1-D): *.dat and *.pdf

3. Simulation #3: case VEN3: Baseline conditions (now using GJ436 solar fluxes, at D = 0.38 AU)
a. State variables (2-D): *.dat and *.pdf
b. Heat balances (1-D): *.dat and *.pdf

4. Simulation #4: case VEN4: Baseline conditions (now using GJ436 solar fluxes, at D = 0.175 AU)
a. State variables (2-D): *.dat and *.pdf
b. Heat balances (1-D): *.dat and *.pdf

Section #2
----------
There are 2-ascii files (*.dat), only, for each of 4-simulation sets. One set contains both 7-state variables (2-D slices), and
the other corresponding 5-heat balances (HTBAL) terms. Some HTBAL come from 2-D slices from which 1-D profiles can be extracted;
others come straight from 1-D profiles (at LT = 12 and LAT = 2.5N). Same 2-D and 1-D grid structure is used as above.

5. Simulation #5: case VEN4(0p7): Baseline conditions (now using GJ436 solar fluxes, at D = 0.175 AU, near-IR scaled by 0.7)
a. State variables (2-D): *.dat
b. Heat balances (2-D): *.dat

6. Simulation #6: case VEN4(1p3): Baseline conditions (now using GJ436 solar fluxes, at D = 0.175 AU, near-IR scaled by 1.3)
a. State variables (2-D): *.dat
b. Heat balances (2-D): *.dat

7. Simulation #7: case VEN4(2XIR): Baseline conditions (now using GJ436 solar fluxes, at D = 0.175 AU, near-IR scaled by 2.0)
a. State variables (2-D): *.dat
b. Heat balances (1-D): *.dat

8. Simulation #8: case VEN4(4XIR): Baseline conditions (now using GJ436 solar fluxes, at D = 0.175 AU, near-IR scaled by 4.0)
a. State variables (2-D): *.dat
b. Heat balances (1-D): *.dat

Repository Files and Connections:
------------------------
* vtgcm.VEN1.ZP.FLDS7.dat (VEN1: 2-D slices of state variables)
vtgcm.VEN1.ZP.FLDS7.pdf

* vtgcm.VEN2.ZP.FLDS7.dat (VEN2: 2-D slices of state variables)
vtgcm.VEN2.ZP.FLDS7.pdf

* vtgcm.VEN3.ZP.FLDS7.dat (VEN3: 2-D slices of state variables)
vtgcm.VEN3.ZP.FLDS7.pdf

* vtgcm.VEN4.ZP.FLDS7.dat (VEN4: 2-D slices of state variables)
vtgcm.VEN4.ZP.FLDS7.pdf

* vtgcm.HTBAL.VEN1.dat (VEN1: 1-D Profiles of heat balances)
vtgcm.HTBAL.VEN1.pdf

* vtgcm.HTBAL.VEN2.dat (VEN2: 1-D Profiles of heat balances)
vtgcm.HTBAL.VEN2.pdf

* vtgcm.HTBAL.VEN3.dat (VEN3: 1-D Profiles of heat balances)
vtgcm.HTBAL.VEN3.pdf

* vtgcm.HTBAL.VEN4.dat (VEN4: 1-D Profiles of heat balances)
vtgcm.HTBAL.VEN4.pdf

* vtgcm.VEN4.QNIR0p7.FLDS7.dat (VEN4(0p7): 2-D slices of state variables)

* vtgcm.VEN4.QNIR1p3.FLDS7.dat (VEN4(1p3): 2-D slices of state variables)

* vtgcm.VEN4.2XIR.FLDS7.dat (VEN4(2XIR): 2-D slices of state variables)

* vtgcm.VEN4.4XIR.FLDS7.dat (VEN4(4XIR): 2-D slices of state variables)

* vtgcm.VEN4.QNIR0p7.Flds5.HTBAL.dat (VEN4(0p7): 2-D slices of heat balances)

* vtgcm.VEN4.QNIR1p3.Flds5.HTBAL.dat (VEN4(1p3): 2-D slices of heat balances)

* vtgcm.VEN4.2XIR.HTBAL1D.100SOLb.dat (VEN4(2XIR): 1-D slices of heat balances)

* vtgcm.VEN4.4XIR.HTBAL1D.100SOLb.dat (VEN4(4XIR): 1-D slices of heat balances)
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