Long‐term satellite passive microwave brightness temperature trends, supported by short‐term automatic weather station (AWS) temperature data, show that the Greenland Summit area experiences secondary warm periods in the late fall and/or winter as well as primary midsummer warmth. High‐resolution isotope profiles from snow pits dug in 1989, 1990, and 1991 near the Greenland Ice Sheet Project II; (GISP2) site reveal that stable isotope ratios (δ18O and δD) preserve this distinctive temperature cycle. This indicates that snow accumulation occurs frequently through the year at the Greenland Summit and that the isotope record initially contains temperature information from many times of the year. Through an empirically derived emissivity model using AWS air temperature data and satellite microwave brightness temperatures, our approach allows isotope values preserved in the snow to be related to estimated near‐surface air temperatures. Density‐corrected profiles allow the amounts and timing of accumulation to be determined as well. Our results indicate that stable isotope ratios from the near‐surface snow at the Greenland Summit are currently a reliable, high‐resolution temperature proxy. This result increases confidence in the paleoclimatic interpretation of isotope signal variations in the GISP2 and Greenland Ice Core Project (GRIP) deep ice cores.

No abstract

No abstract

No abstract

No abstract

A detailed description of the characteristics of the three-dimensional wind flow for the Ross Island region of Antarctica is presented. This region of Antarctica has complex topographic features, and the wind flow is dependent on the topography and the local meteorological conditions. High-resolution nonhydrostatic numerical simulations are conducted over a high-resolution domain in the Ross Island region. Two simulations are performed corresponding to the two dominant wind flow patterns in the Ross Island region. The first simulation is a light wind case with a stable lower atmosphere and the second is a high wind speed event. Froude number calculations, along with a study of the equation of motion, are included for a more complete understanding of the dynamics of the wind flow. The results of the simulations show a favorable correlation to past research results and observations, and provide a more complete understanding of the three-dimensional wind flow in the region. In addition to a more thorough understanding of the wind flow, the results indicate the usefulness and future applicability of nonhydrostatic simulations to understanding the unique meteorological conditions and features in the Antarctic.

No abstract

The purpose of our research is to analyze surface pressure and temperature patterns in Antarctica for relationships with the E1 Nifio/Southern Oscillation (ENSO). Using monthly anomalies of surface pressure and temperature in Antarctica, lag correlations are made to the Southern Oscillation index (SO1) and annual composites are created for years where ENSO is in a warm phase. Comparisons are made to annual composites for nonwarm phase years and to six individual ENSO warm phases occurring between 1957 and 1984. We found a sharp change in the sign of the pressure and temperature anomalies between the year before and the year after the minimum in the SO1. We hypothesize that the temperature and pressure anomaly patterns are related, through a thickness argument, to the 500-mbar southern hemispheric flow and the Australian branch of the Southern Oscillation. 1. teleconnections and were some of the first authors whose results indicated a possible link between the SO and the southern polar latitudes. Mo and White found high teleconnectivity values in the summer SLP field over Antarctica and even though they discounted their results because they felt the SLP data over Antarctica were suspect, their work revealed that an Antarctic-ENSO link may exist. Since Me and White [1985], other authors have pointed out possible links between ENSO and higher southern latitudes. Van Loon and Shea [1985, 1987] found reversals in the seasonal SLP anomalies between yr_l and yr 0 of an ENSO warm event. Van Loon and Shea [1987] concluded that the area of Australasia and the subtropical South Pacific Ocean likely play the major role in forcing the SO. Carleton [1988] found similar pressure reversals in the Weddell Sea sector and also revealed associated anomalies in sea ice concentrations between yr_• and yr 0 of an ENSO warm event. Bremwich et al. [1991] briefly reviewed other papers involving possible ENSO relationships to the snow accumulation rates on the Ross Ice Shelf of Antarctica and the horizontal extent of Antarctic sea ice. Savage et al. [1988] found, using lagged correlation statistics, temperatures at the Amundsen-Scott South Pole Station to be anomalously cold one year after a warm phase of ENSO. Wind data for the same time period showed enhanced downslope flow from the Antarctic ice dome one year after an ENSO warm phase. Savage et al. concluded that these anomalous temperature and wind patterns were maintained by a large-scale circulation pattern dynamically linked to the ENSO system. A dynamic link between Antarctica and the large-scale circulation of the southern hemisphere was suggested by James [1988] and Trenberth [1980]. Both authors found the topography of Antarctica to be important in forcing the planetary scale, tropospheric flow patterns of the southern hemisphere. Furthermore, Trenberth [1980] discussed a link between the topography of Antarctica and the amplitude and phase of a blocking ridge common to the New Zealand area [Streten and Zillman, 1984, Figure 28]. The New Zealand block is important since Trenbert...