Antarctic Meteorological Research Center: 1996–2000. Charles R. Stearns and John T. Young, University of Wisconsin at Madison. The Antarctic Meteorological Research Center (AMRC), one of three research centers in the Science and Engineering Technology Center at McMurdo, is a resource for meteorological research and a test bed for improving operational synoptic forecasting.
The Man-Computer Interactive Data Access System (McIDAS), a versatile computer-based system for organizing, manipulating, and integrating antarctic environmental data, forms the basis of AMRC. It captures the flow of meteorological information from polar-orbiting satellites, automatic weather stations (AWSs), operational station synoptic observations, and research project reports. It also receives environmental data products, such as weather forecasts, from outside Antarctica and acts as a repository for existing archived databases.
Phase I began in the 1992–1993 summer season and consisted of the installation and operation of work stations capable of manipulating and displaying Advanced Very High Resolution Radiometer (AVHRR) data based on the existing satellite imagery acquisition system. This effort was followed by the acquisition and integration of a system that provided data collection, data display and archiving, scientific applications, network communications, and remote-user access.
The McIDAS system, developed at the University of Wisconsin in the mid-1970s, receives meteorological data from various sources: standard synoptic observations, radiosonde profiles, satellite-based visible and infrared imagery, atmospheric profiles inverted from multispectral scanning sensors, and nonstandard data such as thematic ozone mapping spectrometer (TOMS) data, synthetic aperture radar (SAR) sea-ice information, and the AWS network observations. The system automatically registers, calibrates, and locates (by geographical coordinates) the input information and allows a user at a work station to manipulate the database. The manipulations include sectorization, false color, enhancements, brightness stretching, overlays, looping, and differencing and are quite definitely keyed to synoptic meteorological research and weather forecasting. The antarctic system is based primarily on data streams provided by polar orbiters (AVHRR/HRPT and DMSP), since the look angles from geostationary satellites are so extremely low. The full utilization of McIDAS capabilities in producing meteorological data products useful in both forecasting and research will include a data transfer and communications capability to, for example, the Australian Bureau of Meteorology (ABOM), the University of Wisconsin Space Science and Engineering Center (SSEC), the Fleet Numerical Oceanography Center (FNOC) in Monterey, and the European Center for Medium Range Weather Forecasts (ECMRWF) in Reading, U.K. (OO-202-O)
Atmospheric oxygen variability in relation to annual-to-decadal variations in terrestrial and marine ecosystems. Ralph F. Keeling, Scripps Institution of Oceanography. In this project, we will continue measuring the concentration of molecular oxygen and carbon dioxide in air samples. The samples are collected at a series of baseline sites around the world. The data will lead to improved estimates of the net exchange of carbon dioxide with land biota and the oceans, marine photosynthesis rates, and atmospheric mixing rates. These results are needed to improve our understanding of the processes regulating the buildup of carbon dioxide in the atmosphere as well as our understanding of the processes regulating marine and terrestrial ecological functions in relation to various agents of change, especially climate changes. In support of the measurement program, we will develop absolute standards for oxygen in air to ensure stable long-term calibration. We will conduct a survey of the oxidative oxygen/carbon ratios of terrestrial and marine organic carbon to improve the quantitative basis for linking the oxygen and carbon dioxide geochemical cycles. (OO-204-O)
Chlorine- and bromine-containing trace gases in the Antarctic. Reinhold A. Rasmussen and M.A.K. Khalil, Oregon Graduate Institution of Science and Technology. We will collect a year-long suite of air samples at Palmer Station to investigate the seasonal trend of the trace gas concentration. At the Oregon Graduate Center, we will analyze the samples for a number of trace components, especially chlorine- and bromine-containing species. These trace constituents have come from both biogenic and anthropogenic sources, and they have the capacity to alter the Earth's climate and to deplete the ozone layer in the way it has recently been depleted above Antarctica. This work is considered vital for a better understanding of the buildup of trace constituents, particularly those of high-latitude marine origin. (OO-254-O)
South Pole monitoring for climate change. Amundsen–South Pole Station: David Hofman, Climate Monitoring and Diagnostics Laboratory; Palmer Station: James T. Peters, Environmental Research Laboratories, National Oceanic and Atmospheric Administration. The National Oceanic and Atmospheric Administration (NOAA) Climate Monitoring and Diagnostic Laboratory team will continue long-term measurements of trace atmospheric constituents that influence climate and the ozone layer. Four scientists will work at the Amundsen–Scott South Pole Station observatory during the austral summer, and two NOAA personnel will stay over the winter to measure carbon dioxide, methane, carbon monoxide, aerosols, water vapor, surface and stratospheric ozone, chlorofluorocarbons, wind, pressure, air and snow temperatures and atmospheric moisture and other trace constituents from the Atmospheric Research Observatory. These measurements are part of NOAA's effort to determine and assess the long-term buildup of global pollutants in the atmosphere. The measurements will be used for time-series analyses of multiyear data records that focus on
We will also determine the rates at which concentrations of these atmospheric constituents change and will examine their sources, sinks, and budgets. Working with climate modelers and diagnosticians, we will use these data to determine how the rates of change of these parameters affect climate, particularly when the data are included in climate model studies. In support of this project, Palmer Station personnel also will collect carbon dioxide samples. (OO-257-O and OO-264-O)
Drake Passage expendable bathythermograph program. Ray Peterson, University of California. In this project, we will analyze data from bottom pressure gauges deployed across chokepoints for the southern ocean flow. Bottom pressure gauges were deployed between South Africa and the antarctic coast close to the Greenwich Meridian and at two locations spanning the Antarctic Circumpolar Current (ACC) south of Tasmania. Simultaneously, the British deployed similar instruments in the Drake Passage. The main scientific goal of these deployments was to determine the fluctuations in the transport of the ACC and to relate it to those in the subtropical and subpolar gyres and to the wind field over the southern oceans. (OO-260-O)
Katabatic winds in eastern Antarctica and their interaction with sea ice. Gerd Wendler, University of Alaska Fairbanks. Our project is the continuation of an internationally collaborative (U.S.–French–Australian) study of katabatic winds along the coast of East Antarctica. It is based on two lines of automatic weather stations, one from Dumont d'Urville, the French station, inland to Dome C at an altitude of greater than 3,200 meters, the other along the coast. The coastal array includes stations at Cape Denison and Port Martin, which have recorded the highest average surface wind speeds on the globe (a monthly average of 27.8 meters per second). One additional automatic weather station will be installed 15 kilometers inland where model results predict even higher average wind speeds. These winds drive the sea ice offshore and are responsible for extremely high heat fluxes from the ocean to the atmosphere. Satellite-based active microwave imagery (synthetic aperture radar) will be combined with the observed meteorological data to analyze the formation persistence and size of offshore polynyas as a function of wind speed. The effort to produce a numerical model of the regional atmospheric structure will continue, with the incorporation of a more detailed terrain map, and a new mesoscale model developed by our French colleagues. In conjunction with the Australian and Japanese station networks to the west of this study area, this work will allow an assessment of the influence of cyclonic storm systems on the drainage flow along the antarctic coast. (OO-263-O)
Investigation of Sulfur Chemistry in the Antarctica Troposphere (ISCAT). Douglas D. Davis and Fred L. Eisele,Georgia Institute of Technology. During this 4-year study, we will examine the sulfur chemistry in the antarctic atmosphere, working at Amundsen–Scott South Pole Station for two field seasons, 1998–1999 and 2000–2001. The study, which includes 10 principal and senior investigators at five institutions with seven additional contributing investigators, has two broad-based goals:
The South Pole was selected because at this site, the atmospheric boundary layer presents a homogeneous and relatively simple environment from which to unravel the photochemically driven oxidation chemistry of dimethyl sulfide.
Atmospheric sulfur chemistry is an important component in climate change issues because both naturally (i.e., from volcanic emissions and oceanic phytoplankton production) and anthropogenically emitted sulfur compounds form minute particles in the atmosphere—the so-called aerosols—that reflect solar radiation, produce atmospheric haze and acid rain, and affect ozone depletion. Sulfate particles in the atmosphere may also act as condensation nuclei for water vapor and enhance global cloudiness. On the millennial timescale, the variability and natural background level of atmospheric aerosols can be reconstructed from the preserved paleorecords of sulfur oxidation products in ice cores. It is necessary, however, to understand how the physical and chemical environment of the oxidation process affects the relative concentrations of the oxidation products that become buried in the ice.
This study requires simultaneous observations of a wide-ranging suite of sulfur species such as DMS and its oxidation products: sulfur dioxide, dimethyl sulfoxide, dimethyl sulfone, methane sulfonic acid, and sulfuric acid, as well as photochemically important compounds such as carbon monoxide, nitrous oxide, water vapor, and nonmethane hydrocarbons.
Secondary objectives will be
This study will provide, for the first time, a quantitative picture of exactly which atmospheric sulfur compounds are advected into the antarctic interior and a detailed picture of the sulfur chemistry that is active in the antarctic atmosphere. (OO-270-O)
Operation of an aerosol sampling system at Palmer Station. Gail dePlannque and Colin G. Sanderson, Environmental Measurements Laboratory, U.S. Department of Energy. In 1990, a team from the U.S. Department of Energy, Environmental Measurements Laboratory (EML) in New York City, installed a high-volume aerosol sampler, a gamma-ray spectrometer, and satellite data transmission system at Palmer Station. This installation is part of EML's Remote Atmospheric Measurements Program, which is an extension of its worldwide surface air-sampling program. The system transmits data through the National Oceanic and Atmospheric Administration's ARGOS satellite system. The sampling station at Palmer provides significant input for EML's database. (OO-275-O)
Particulate organic carbon production and export in the Indian sector of the Southern Ocean: A United States–China collaborative research project. Cynthia Pilskaln, University of Maine at Orono. As part of a collaboration between the University of Maine and the Chinese Antarctic Research Expedition (CINARE), we will study the biological production and export flux of biogenic matter in response to ventilation of intermediate and deep water masses within the Polar Front Zone. The shipboard work will be done aboard the Chinese antarctic resupply vessel off Prydz Bay in the Indian Ocean sector. In the austral spring, this region experiences phytoplankton blooms that scientists believe are the result of nutrient transport by the ventilation of intermediate and deep water masses. Researchers believe that each year such blooms are the primary source of particulate organic carbon and biogenic silica flux to the ocean bottom. At this time, however, no data exist on the amount of particulate organic matter that sinks through the water column, leaving the quantitative relationships between production and export largely undefined in this region. The initial phase of our work consists of setting out a time-series sediment-trap mooring at approximately 64° S 73° E to take advantage of the historical data set that CHINARE has obtained in this area over the past decade. The biweekly to monthly trap samples will be analyzed for their organic constituents and, in conjunction with primary productivity observations, will provide the basic data from which export values can be derived.
Our work will be carried out in collaboration with the State Oceanic Administration (SOA) of the People's Republic of China and the Chinese Antarctic Research Expedition. In addition to providing time on the antarctic resupply vessel, the SOA will sponsor the shipboard primary productivity experiments and the supporting hydrographic measurements. The collaborating American scientists will provide both guidance in making these observations to standards developed for the Joint Global Ocean Flux Study and the hardware for the moored sediment trap. There will be a mutual sharing between the U.S. and Chinese investigators of all samples and data sets, and the data analysis will be carried out jointly. (OO-278-O)
Antarctic automatic weather station program: 1998–2001. Charles Stearns, University of Wisconsin at Madison. Our project will maintain and augment, as necessary, the network of nearly 50 automatic weather stations established on the antarctic continent and on several surrounding islands. These weather stations measure surface wind, pressure, temperature, humidity, and in some instances, other atmospheric variables, such as snow accumulation and incident solar radiation, and report these readings via satellite to a number of ground stations. The data are used for operational weather forecasting in support of the U.S. Antarctic Program, for climatological records, and for research purposes. The AWS network, which began as a small-scale program in 1980, has been extremely reliable and has proven indispensable for both forecasting and research purposes. (OO-283-O)
Research on Ocean–Atmosphere Variability and Ecosystem Response in the Ross Sea. Robert B. Dunbar, Rice University. This interdisciplinary study, "Research on Ocean, Atmosphere and Ecosystem Response in the Ross Sea" (ROAVERRS), focuses on atmospheric forcing, ocean hydrography, sea-ice dynamics, primary productivity, and pelagic-benthic coupling in the southwestern Ross Sea. The primary goal is to examine how changes in aspects of the polar climate system, in this case wind and temperature, combine to influence marine productivity on a large antarctic continental shelf. In the Ross Sea, katabatic winds and mesocyclones influence the spatial and temporal distribution of sea ice, as well as the upper ocean mixed-layer depth, and thus control primary production in the sea ice and in the open water system. The structure, standing stock, and productivity of bottom-dwelling biological communities are also linked to meteorological processes through interseasonal and interannual variations in horizontal and vertical fluxes of organic carbon produced in the upper ocean.
During this 3-year study, we will investigate links among the atmospheric, oceanic, and biological systems of the southwestern Ross Sea ecosystem. Direct measurements will include
Based on archived meteorological data, we expect that the atmospheric variability during the study period will allow us to monitor changes in air-flow patterns and their influence on oceanographic and biological patterns and to deduce the direct and indirect links, which are the focus of the research. Results from this study will contribute to our knowledge of atmospheric and oceanic forcing of marine ecosystems and lead to a better understanding of marine ecosystem response to climatic variations.
During the 1998–1999 research season, the following researchers will conduct studies as part of the ROAVERRS project:
Dynamic/thermodynamic processes and their contribution to the sea-ice thickness distribution and radar backscatter in the Ross Sea. Martin O. Jeffries and Shusun Li, University of Alaska Fairbanks. We will study the effects of antarctic sea ice in the global climate system through an examination of how the spatial distribution of ice and snow thickness and of open water is reflected in satellite-based synthetic aperture radar (SAR) imagery. The field investigations, which will be carried out from the R/V Nathaniel B. Palmer in winter 1998 and summer 1999, will produce observations of the snow and ice distribution; the crystal structure, stable isotopes, salinity and temperature structure of ice cores; and the stratigraphy, grain size, and water content of the snow cover. The SAR images from ERS-2 and RADARSAT will be acquired at the McMurdo ground station and processed at the Alaska SAR Facility. These images will provide information about the large-scale ice-motion field and the small-scale ice-deformation field, both of which contribute to the observed ice-thickness distribution. In addition, a study of the spatial and temporal variation of the backscattered microwave energy will contribute to the development of numerical models that simulate the dynamic and thermodynamic interactions among the sea ice, ocean, and atmosphere. The surface data are vital for the extraction of environmental information from the radar data, and for the ultimate validation of interactive models. (OX-286-O)