Antarctic Automatic Weather (AWS) Meeting 2005 - Abstracts


ATS Weather Sensor Network - AWS Section
Arthur Cayette
SPAWAR System Center

SPAWAR System Center, Charleston's Aviation Technical Services (ATS) Division weather sensors are fielded and maintained for support of operational meteorology. These systems include aviation support fixed based, aviations support portable, and automated weather stations for operational data collection. This presentation will provide information on equipment, applications, and updates to the location of the various systems.


ATS Weather Network - AMRC Section
Arthur Cayette
SPAWAR System Center

SPAWAR System Center, Charleston's Aviation Technical Services (ATS) Division weather network collects and distributes operational meteorological data through a series of programs and communication systems. The network data collection system has been designed to infuse meteorological information from multi-agency data sets and weather instruments from various vendor software configurations. This presentation will introduce the various software components, data collection architecture, and the present and planned distribution of Antarctic meteorological data sets. This design will allow the planned capability to provide remote forecasting without any restrictions or limits on data sets and allow a reduction of bandwidth usage on the McMurdo Internet communication pipe.


S-MAR Project: Actual OpMet and Scientific results
G. Clai (1), P. F. Coppola(2), A. Pellegrini (3)
(1) ENEA- Ente per le Nuove Tecnologie, Energia e Ambiente
(2) Italian Air Force Weather Service
(3) PNRA SCrl

The S-MAR Project involves an integrated atmosphere-cryosphere-ocean modelling study of the Antarctic environment through the use of MAR (Modéle Atmosphèrique Regional). This project is financed by the Italian PNRA. The Atmospheric Research principal themes of the project are:

  • Study and simulation of katabatic airflows on extra-fine grids.[ Priestley Glacier].
  • Study and simulation of the interaction of katabatic airflows of Reeves and Priestley Glaciers at their convergence and comparison with AWS, SODAR and Wind towers data.
The Oceanographic Research principal themes of research are:
  • Determination of the impact of katabatic airstreams on the vertical structure of the sea water column and on the thermoaline cell processes in the polynya.
  • Validation of energy and momentum fluxes model estimates through the comparison with RADAR in situ observations.
  • Determination of the polynya model sensitivity respect to the introduction of surface sea currents in the ocean mixing layer.
  • Feasibility study for coupling MAR and a mesoscale ocean model.
Computer science principal themes of research:
  • Determination of the LINUX Cluster High availability configuration for OpMet.
  • Determination of the LINUX Cluster High computing configuration for scientific simulations.
  • Feasibility study of code parallelization.
  • Code-parallelization: MAR now is written in serial FORTRAN 77 code.
Operational Meteorology principal themes of research: Setup and validation of MAR for operational meteorology issues for the area of responsability including DDU, TNB.
    Here the actual results referring to simulations performed over a wide area ([64° S-80°S],[135°E-175°E]) and on the Terra Nova Bay region as a spot area are shown. These results concern the simulation of katabatic airflows on extra-fine grids.[Priestley Glacier], the interaction of katabatic airflows of Reeves and Priestley Glaciers at their convergence, the simulation of the polynya and determination of the oceanograpfhy sub-model sensitivity on the same area and the Operational Meteorology and computational state of art.


Simulating Antarctic Precipitation Variability in Recent Decades
Andrew J. Monaghan, David H. Bromwich, and Sheng-Hung Wang
Ohio State University

Two 24-year simulations of Antarctic climate have been performed with an atmospheric model optimized for use at high latitudes, Polar MM5. The initial and boundary conditions for each simulation were derived from different datasets. One is the European Centre for Medium-Range Weather Forecasts 40-year Reanalysis (ERA-40). This is the newest global atmospheric dataset and thus has employed the most modern assimilation techniques, especially exploiting the wealth of satellite data available during the past two decades. The other is the National Centers for Environmental Prediction / Department of Energy Reanalysis II (NN2). This U.S. dataset extends back to 1979 and is meant to be an improvement over the groundbreaking NCEP/NCAR Reanalysis, which had a few data assimilation problems that make analyzing climate change difficult (especially over Antarctica). The motivation for this work is to understand how climate variability, especially the hydrologic cycle, differs between the two simulations.

Remarkably different trends in the Antarctic hydrologic cycle result from the two runs. The precipitation trends averaged over Antarctica from 1979-2001 are of opposite sign. The Polar MM5 runs driven with ERA-40 indicate a downward trend in precipitation of about 6 mm over the past two decades, while the runs driven with NN2 yield an upward trend of about 14 mm over the same period. The differences are not caused from within the model domain, but through the side boundaries of Polar MM5, which are set at about 50 degrees south latitude. Thus, the differences between ERA-40 and NN2 in the mid-latitudes and perhaps even the tropics are causing the disagreement in the precipitation trends over Antarctica. Detailed moisture budget calculations are performed on both datasets in order to isolate the cause of the differences. Components of the moisture budget are compared to observations at mid-latitudes in order to determine the accuracy of ERA-40 and NN2.

WRF Simulations of the May 2004 Extreme Wind Event at McMurdo, Jordan G. Powers

Mesoscale and Microscale Meteorology Division, NCAR

The Weather Research and Forecasting (WRF) Model is a next-generation mesoscale model designed for both operational forecasting and research. WRF is in the process of being ported into the Antarctic Mesoscale Prediction System and ultimately is slated to replace the MM5. This study examines WRF's behavior in Antarctica in the context of simulations of the extreme wind event at McMurdo in May 2004. The model's performance in the event is examined and sensitivity tests are performed. The latter focus on the impact of MODIS wind assimilation, as this data type has shown promise in improving forecasts in the polar regions. The presentation will offer WRF simulations and results, including some comparisons to AMPS MM5 for the case.


2004-05 Iceberg Status Report
Shelley L. Knuth(1), Douglas R. MacAyeal(2), Jonathan E. Thom(1), Linda M. Keller(1), and Matthew A. Lazzara(1)
(1) University of Wisconsin
(2) University of Chicago

In the past year, the icebergs in the Ross Sea have undergone many important changes. The most important of these has been the significant movement of B-15A toward the Drygalski Ice Tongue. B-15J and C-16 have also been moving, but not as significantly. A new iceberg in the Weddell Sea was also discovered. An overview of the past year's movements will be analyzed, including new movies of the icebergs. We will examine not only the Ross Ice Shelf, but the Ronne and Larsen Ice Shelves as well, and will also look at the importance that building sea ice has held for the past year in the Ross Sea.


An Evaluation of Clouds Forecast by AMPS
Ryan L. Fogt and David H. Bromwich
Ohio State University

The 12 and 24-hour cloud forecasts from the 3.3 km AMPS 00Z initialization time during austral summer 2004-2005 are evaluated using observations. The relative humidity data from the McMurdo radiosonde record are used to provide an overall validation in the skill of AMPS prediction of clouds. Through cluster analysis, forecasts with similar skill are examined throughout the whole column to discern the variation in forecast skill with height, and if clouds in one layer have significant impacts upon cloud formation / model depiction in other layers. The validation is first performed on monthly mean data to observe any model biases. Similarly, using the model cloud parameters (cloud liquid water, cloud ice, cloud rain water, snow, etc.), comparisons are made with the synoptic visual observations from the local runways and a contingency table is constructed to observe the overall prediction of clouds within the model at these locations. The forecast clouds are further evaluated using the same methodologies described earlier by employing a case study to observe the temporal performance in cloud prediction. The period for the case study was chosen to be the first few weeks of January 2005, when a persistent low pressure center entered the Ross Sea region, resulting in the passage of several shortwave troughs with accompanying snow. Operations were disrupted during this system due to the persistent snow and cloud cover, and the runways and associated roads were often at weather condition 2. Findings from the study will help to understand how AMPS predicts clouds, leading to increased forecast accuracy during the height of the operational season. Additionally, the findings will aid a future study that will examine clouds in the McMurdo region (encompassing the Ross Sea and Ross Ice Shelf) using satellite composites and other observations.


Status of the SIO Arctic and Antarctic Research Center
Dan Lubin
Scripps Institution of Oceanography

Since 1994, the Arctic and Antarctic Research Center (AARC) has worked with AMRC to provide customized and timely satellite remote sensing services to Antarctic research programs and field expeditions. The operational focus of the AARC has been mainly on sea ice and oceanographic support, although researchers in all polar-related disciplines have utilized the AARC's archive of NOAA and DMSP polar orbiter data tracked by the NSF facilities at Palmer and McMurdo Stations. The AARC has recently reorganized its operations, motivated by the realization that more than half of the researchers requesting AARC satellite data are interested in the most recent field season. The AARC maintains the ability to copy, reduce, and analyze data from magnetic tape dating back to 1987. However, we have now set up a 1.2 Terabyte RAID storage device that will allow interested parties to acquire data instantaneously. This facility, the Recently Acquired Satellite Telemetry Archive (RASTA), will host satellite data from the most recent field season in three formats: original raw Terascan data format, full resolution JPG images, and calibrated and geolocated data in hierarchical data format (HDF). Initial data migration to RASTA will come from the Palmer Station antenna. RASTA will be accessible to interested parties for instantaneous data retrieval, by password after straightforward registration with the AARC as a user. We anticipate that this RAID storage device will steadily expand in capacity in the coming years, to eventually hold a substantial multiyear portion of the NSF-supported satellite data collection.


Climatology and Variability of Mesoscale Cyclones in the Western Antarctic Peninsula Region
Dan Lubin(1), Rob Wittenmyer(2), Gareth Marshall(3)
(1) Scripps Institution of Oceanography
(2) Department of Astronomy, University of Texas
(3) British Antarctic Survey

A proposed mechanism for the Western Antarctic Peninsula (WAP) warming, recently supported by GCM simulations, involves a strengthening of westerlies during high Southern Annular Mode (SAM) conditions, which blocks cold air outbreaks from the continent and allows warmer air masses to propagate into the WAP region. One possible avenue of investigation to test this hypothesis involves analyzing a multiyear record of mesoscale cyclone frequency and trajectories. Since 1989, the USAP satellite tracking facility at Palmer Station has collected and archived NOAA and U.S. Air Force polar orbiter data, at a rate of ~10 overpasses per day, that provide moderate spatial resolution (~1 km) of meteorological conditions in the WAP and Weddell Sea regions. The time resolution and spatial coverage of this multiyear satellite data set are sufficient to develop a climatology of polar mesoscale cyclones. Preliminary analysis of this imagery indicates that the WAP region experiences a normalized weekly average of 7.1 mesoscale cyclones, and that the Weddell Sea experiences a slightly smaller normalized weekly average of 5.1. However, there is substantial interannual variability in these cyclone frequencies, of order 30% for the WAP region and a factor of two for the Weddell Sea. There are noticeable correlations with the SAM in WAP cyclone frequency and trajectory. In a high SAM index, more cyclones are seen in the WAP region. However, their trajectories are altered to be mainly circumpolar within Southern Ocean latitudes, as opposed to moving into the region from lower latitudes.


The Meteorology of High NO Episodes Observed in the 2003 ANTCI Field Program and Relation to Past Experiments in 1998 and 2000
W.D. Neff and ANTCI Colleagues

High NO-Episodes have been observed at various times at the South Pole and correlate in a general fashion with the state of the Antarctic Oscillation and systematic downslope flows. In this talk we will describe the phenomenology of these episodes as observed with both sodars and surface meteorological data. In addition, in 1998 and 2000 AWS stations Henry adn Nico were in observation and provided additional insight into the regional nature of these episodes.


Relative performance of self-organizing maps and principal component analysis in pattern extraction from synthetic climatological data
David Reusch
Penn State University

Based on a comparison of their ability to identify known patterns of variability in synthetic datasets, Self-Organizing Maps (SOMs) provide information not available from principal component analysis (PCA), suggesting SOMs offer an advantage for application in climatological and other studies. Positive and negative modes of four idealized North Atlantic sea-level-pressure fields provide eight known variability targets for analysis by SOMs and PCA tools. The synthetic datasets combine the patterns randomly, with and without noise components. PCA, both standard and with rotation of components, fails to adequately extract the known spatial patterns, mixes patterns into single components, and incorrectly partitions the variance among the components. The SOMs-based analyses are more robust and, with a sufficiently large map (set of generalized patterns), are able to isolate all the known patterns with correct attribution of variance. Smaller maps produce more-generalized versions of the input patterns more suited to grouping similar patterns than for identification of specific patterns. The transition between pattern grouping and pattern classification is readily discovered if the recommended practice of examining different size SOMs is followed. With PCA, it is difficult, if not impossible, to detect pattern mixing without prior knowledge of the patterns being mixed.