A Vapor Pressure Database for Modeling Exoplanet Atmospheres
Abstract
Understanding the validity of vapor pressure and latent heat equations for a given temperature range is of great importance to a variety of researchers across the planetary science community. Applications include photochemical modeling, microphysical modeling, energy balance models, general circulation models, planetesimal formation models, and interpreting spacecraft observations. In the ever growing field of exoplanet research, knowledge of clouds is becoming more important to the interpretation of observations. Clouds are important to all aspects of a planetary atmosphere, from the transport of radiation, to atmospheric chemistry, to dynamics. They also affect surface temperature and habitability. The atmospheres of hot Jupiters, hot Neptunes, Super Earths, as well as brown dwarfs are much warmer and so the volatiles are likely more metal-rich than found in the planetary atmospheres of our solar system. . In order to model the formation and evolution of these clouds, the vapor pressure and latent heat of each condensing species must be known at the relevant atmospheric temperatures. This project will provide the planetary science community with a set of reference equations for calculating vapor pressure and latent heat as a function of temperature. These equations are included from an extensive literature search as well as some new derivations and presented through the creation of both Fortran 90 and Python modules for each condensing species. These modules are available to the community on NASA's GitHub site . A Fortran 90 module for each chosen species was written so that these equations can be called directly from existing code. Each reference equation is coded into a separate function within the module, named with the condensing species and the specific reference name (e.g., nist, author's name). The complete citation and temperature range (if available) cited from the original source is listed. A wrapper function is then used to access the specific reference equation for a given species, providing an input argument of phase and reference ID. There is a similar looking wrapper function with calls to the collected latent heat equations. Additionally, a similar set of functions are coded in Python. These functions also take temperature as an input argument, as well as a string for pressure units for the output value. The Python dictionary tool allows for the creation of a simple plotting program, where all relevant equations can be accessed simply by giving the species' chemical formula. This work is funded by the NASA PDART program.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.530B