Examining Seasonal Trends of the Martian Polar Warming with the NASA Ames Mars Global Climate Model

The presented work focuses on polar warming as a diagnostic of the mean circulation to increase our understanding of processes that control the mean meridional circulation and transport in the Mars middle atmosphere. The NASA Ames Mars Global Climate Model is utilized to isolate physical processes to determine their impact on polar warming and its seasonal trends

Upper Boundary Extension of the NASA Ames Mars General Circulation Model

Extending the NASA Ames Mars General Circulation Model (MGCM) upper boundary will expand our understanding of the connection between the lower and upper atmosphere of Mars through the middle atmosphere. The extension's main requirements is incorporation of Non-local thermodynamic equilibrium (NLTE) heating (visible) and cooling (infrared). NLTE occurs when energy is exchanged more rapidly with the radiation field (or other energy sources) rather than collisions with other molecules. Without NLTE above approximately 80km/approximately 60km in Mars' atmosphere the IR/visible heating rates are overestimated. Currently NLTE has been applied successfully into the 1D RT code and is in progress for the 3D application

Modeled O 2 nightglow distributions in the Venusian atmosphere

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96410/1/jgre3128.pd

High-Resolution Modeling of the Dust and Water Cycles with the NASA Ames Mars Global Climate Model

NASAs Mars Climate Modeling Center at Ames Research Center is currently undergoing an exciting period of growth in personnel, modeling capabilities, and science productivity. We are transitioning from our legacy Arakawa C-grid finite-difference dynamical core to the NOAA/GFDL cubed-sphere finite-volume dynamical core for simulating the climate of Mars in a global framework. This highly parallelized core is scalable and flexible, which allows for significant improvements in the horizontal and vertical resolutions of our simulations. We have implemented the Ames water ice cloud microphysics package described in Haberle et al. (2018) into this new dynamical core. We will present high-resolution simulations of the dust and water cycles that show that sub-degree horizontal resolution improves the agreement between the vertical distribution of dust and water ice and observations. In particular, both water ice clouds and dust are transported to higher altitudes due to stronger topographic circulations at high resolution. Preliminary results suggest that high-resolution global modeling is needed to properly capture critical features of the dust and water cycles, and thus the current Mars climate

Tracing the Dynamics in Venus' Upper Atmosphere.

Venus is a unique planet because its atmospheric dynamics are mainly driven by thermal heating and its very low rotation rate. Many details of the middle and upper atmospheric dynamics can be determined from observing nightside airglow emissions, which serve as effective tracers of Venus' middle and upper atmosphere global wind system. The purpose of this dissertation is to use the National Center for Atmospheric Research (NCAR) Venus Thermospheric General Circulation Model (VTGCM) to examine the underlying processes that control the thermospheric circulation of Venus by comparing simulations to observations. Most recently, Venus Express (VEX) has been monitoring key atmospheric features (O2 IR nightglow, NO UV nightglow, and nightside temperatures) of Venus. Statistical maps have been created utilizing these nightglow observations from VEX. Moreover, the O2 IR statistical map has been used to deduce a three-dimensional atomic oxygen density map, which is used to examine the implications of atomic oxygen density distributions below 140 km on the nightside. The VTGCM model has been reconstructed and revised in order to address these key nightglow observations and provide diagnostic interpretation. Specifically, the VTGCM simulations capture the statistically averaged mean state of these three key observations. The correlation between the simulation results and the VEX data sets implies a weak retrograde superrotating zonal flow (RSZ) from ~80 km to 110 km with the emergence of modest RSZ winds approaching 60 m s-1 above ~130 km. This RSZ flow is superimposed upon a strong subsolar-antisolar flow from day-to-night. VTGCM sensitivity tests were subsequently performed using two tunable parameters (nightside eddy diffusion and wave drag) to examine corresponding variability within the VTGCM and these nightglow distributions. The VTGCM also reproduces a nightside atomic oxygen density map and vertical profiles across the nightside. Both the simulated map and vertical profiles are in close agreement with VEX observations within a ~30 degree contour of the anti-solar point. The atomic oxygen vertical profiles are comparable to the data above 90 km, consistent with the corresponding O2 IR nightglow intensities. The research performed for this dissertation has determined the parametric sensitivity of the thermospheric flow around Venus.Ph.D.Atmospheric and Space SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/84530/1/abrecht_1.pd

Venus Night Airglow Distibutions and Variability: NCAR VTGCM Simulations

audience: researcher, professionalThe National Center for Atmospheric Research (NCAR) thermospheric general circulation model for Venus (VTGCM) is producing results that are comparative to Pioneer Venus and Venus Express data. The model is a three dimensional model that can calculate temperatures, zonal winds, meridional winds, vertical winds, and concentration of specific species. The VTGCM can also compute the O[SUB]2[/SUB]-IR and NO-UV night airglow intensity distributions. With a lower boundary set at 70 Km and a range of sensitivity tests, the VTGCM is able to show consistent set of results with the nightside temperature and the night airglows. These results can show possible controlling parameters of the O[SUB]2[/SUB]-IR, NO-UV night airglow layers, and the nightside hot spot. Being able to understand the night airglow distribution and variability provides valuable insight into the changing circulation of Venusâ upper atmosphere and leads to an overall planetary perception of the atmospheric dynamics

Documentation of the NASA/Ames Legacy Mars Global Climate Model: Simulations of the present seasonal water cycle

International audienceWe describe and document the physics packages in the legacy NASA/Ames Mars Global Climate Model, present simulations of the seasonal water cycle and how it compares with observations, assess the role of radiatively active clouds on the water cycle and planetary eddies, and discuss the strengths and weakness of the model and the implication for future efforts. The physics packages we describe include the treatment of surface properties, the ground temperature model, planetary boundary layer scheme, sublimation physics, cloud microphysics, the use of a moment method for tracer transport, a semi-interactive dust tracking scheme, and a two-stream radiative transfer code based on correlated-k's. With virtually no tuning of the water cycle and assuming the north polar residual water ice cap is the only source of water we find the model gives a reasonably good simulation of the present seasonal water cycle. No persistent clouds form over the residual cap, seasonal variations in column vapor abundances are similar to those observed, the aphelion cloud belt has about the right opacity, and surface and air temperatures are in reasonably good agreement with observations. The radiative effect of clouds does not significantly alter the seasonal and spatial variation of the moisture fields, though the clouds are thicker and the atmosphere somewhat wetter. As others have found cloud radiative forcing amplifies the mean meridional circulation, transient baroclinic eddies, and global thermal tides. However, it also changes the characteristics of forced stationary waves in ways that are not straightforward to understand. The main weakness of the model, we believe, is sluggish vertical mixing. Water is not transported high enough in the model and as a consequence the water cycle is too dry, the aphelion cloud belt is too low, and the mean meridional circulation is too shallow. These, we feel, could be remedied by some combination of non-local mixing, deep mountain-induced circulations, better horizontal and vertical resolution, and/or gravity wave drag. Efforts are now underway to study these issues as we are transitioning away from our legacy code to one with a more modern dynamical core