Ross Ice Shelf Airstream Pre-RIME Studies of Transport Processes in the Ross Sea Sector
It is generally agreed that Antarctica plays a vital role in global climate, and will be an important indicator of global change events. An understanding of the critical linkages between Antarctica and more northerly latitudes, however, is still being developed. To meet this goal, the Ross Island Meteorology Experiment (RIME) has been proposed. RIME is a research program designed to examine atmospheric processes in the Ross Sea sector of Antarctica and the interaction between the meteorology of this region and more northerly latitudes. Previous work has shown that the Ross Sea region is of critical importance in the connection of Antarctic processes to the rest of the globe on a variety of time scales. RIME will incorporate an extensive set of field measurements, obtained by surface-based instrumentation, remote sensing and airborne observations, with comprehensive numerical modeling efforts to enhance our understanding of Antarctic meteorology and transports to and from the continent. As a prelude to RIME, Pre-RIME has been proposed as a means to enable efficient siting of instrumentation that will become part of the RIME program, conduct preliminary analyses of exiting data sets and evaluate the quality of current numerical simulations.
This Pre-RIME research program will deploy an array of seven automatic weather stations (AWSs) about the region to the east and south of Ross Island during January 2004. The AWS observational network will sample the surface environment accompanying the Ross Ice Shelf air stream (RAS), which has been shown to be a primary corridor for the transport of mass, heat and momentum between Antarctica and subpolar latitudes. The RAS has been identified as a key feature of the topographically forced motion fields that will be examined as part of RIME. Prior to the RIME field activities, it will be necessary to understand the basic physical characteristics of this air stream and its modulation by the frequent cyclonic activity in the Ross Sea to the north. In addition, the potential contribution to the RAS of flow through major glacier valleys in the Transantarctic Mountains, such as Byrd Glacier, needs to be established. Pre-RIME AWS deployment will allow these objectives to be met. Along with extensive evaluation of data collected by the AWSs, numerical simulations and analyses will be performed using the version of the Fifth Generation NCAR/Penn State Mesoscale Modeling System (MM5) that is currently being used for operational forecasts in the Antarctic (Polar MM5 or AMPS). Simulations will be run in a real-time mode to provide details as to the vertical structure of the RAS as well as the sensitivity to transient cyclonic storms in the Ross Sea. This will assist in planning for the airborne measurement programs that will be part of RIME.
This research project is a two-year study. AWS deployment, analysis of existing output sets and the initial phase of model simulations are scheduled for the first year. AWS analyses and extensive numerical simulation, including key case studies, will be conducted during the second year. This research will complement ongoing operational model development by colleagues at The Ohio State University and the National Center for Atmospheric Research and possibly be of assistance in operational forecasting efforts. This research will dovetail into Phase 1 of RIME, which is the initial field season. Based on results of this study, redeployment of individual AWSs and deployment of the remainder of the AWS network specified in the RIME science plan can be put in place during the first RIME field season scheduled from December 2005-February 2006.
RAS Automatic Weather Station (AWS) network