Physics
Scientific paper
May 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agusmsa41a..04l&link_type=abstract
American Geophysical Union, Spring Meeting 2004, abstract #SA41A-04
Physics
3319 General Circulation, 5409 Atmospheres: Structure And Dynamics, 5445 Meteorology (3346)
Scientific paper
A major problem in planetary atmospheric dynamics that remains elusive to our understanding is equatorial superrotation. Our neighboring planet Venus exhibits this trait: the solid planet has a very slow retrograde rotation of 243 days while the cloud top travels at speeds of 100 ms-1 at the equator, a feature known as the ``four-day" wind. In order to maintain equatorial superrotation on Venus, three-dimensional (non-axisymmetric) eddies must transport angular momentum to low latitudes (Hide 1969). Several models support the Gierasch mechanism in which Hadley cells pump angular momentum upward at the equator and wave instabilities transport it towards the equator. However, there is also support for solar thermal tides and for topographically excited gravity waves as alternative eddy sources. One of the challenges is to distinguish the contribution of these effects on a given altitude region. Yamamoto and Takahashi (2003) are the first to report a fully developed superrotation for Venus. They use a low-resolution model that employs simplified physics and a configuration for Newtonian cooling, which, as they point out, uses a vertical heating profile that has an altitude of maximum heating rate that is 10 km lower than that of the cloud-top heating maximum. As our first terrestrial-planet application of the EPIC model with its new hybrid isentropic/terrain-following vertical coordinate, we are experimenting with the Yamamoto and Takahashi configuration and are performing additional sensitivity tests regarding the horizontal resolution and the Newtonian cooling profile. By using a hybrid as opposed to a traditional sigma terrain-following vertical coordinate, the EPIC GCM is able to conveniently calculate the Eliassen-Palm flux divergence in isentropic coordinates to diagnose wave transience and nonconservative effects and avoids having the signature of the topography carried all the way to the top of the model. None of the published Venus GCM work to date includes topography, although several authors have noted its likely importance. In fact, Venus has tall mountains: Ishtar Terra covers an area similar to that of Australia and contains the highest mountain, Maxwell Montes (10 km), and Aphrodite Terra covers an area similar to that of South America. We are testing the effects of orographic waves by scaling the topography (obtained from high-resolution Magellan data) from zero to full height in a series of simulations.
Dowling Timothy E.
Lee Chong Gyu
No associations
LandOfFree
Application of the Isentropic/Terrain-Following Hybrid EPIC GCM to Venus with Topography does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Application of the Isentropic/Terrain-Following Hybrid EPIC GCM to Venus with Topography, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Application of the Isentropic/Terrain-Following Hybrid EPIC GCM to Venus with Topography will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1178460