Decadal-Length Composite Inland West Antarctic Temperature Records

Abstract

Decadal-length, daily average, temperature records have been generated for four inland West Antarctic sites by combining automatic weather station (AWS) and satellite passive microwave brightness temperature records. These records are composites due to the difficulty in maintaining continuously operating AWS in Antarctica for multiyear to multidecade periods. Calibration of 37-GHz, vertical polarization, brightness temperature data during periods of known air temperature by emissivity modeling allows the resulting calibrated brightness temperatures (TC) to be inserted into data gaps with constrained errors. By the same technique, but with reduced constraints, TC data were also developed through periods before AWS unit installation or after removal.

The resulting composite records indicate that temperature change is not consistent in sign or magnitude from location to location across the West Antarctic region. Linear regression analysis shows an approximate 0.9°C increase over 19 yr at AWS Byrd (0.045 yr⁻¹ ±0.135°C), a 0.9°C cooling over 12 yr at AWS Lettau (−0.078 yr⁻¹ ±0.178°C), a 3°C cooling over 10 yr at AWS Lynn (−0.305 yr⁻¹ ±0.314°C), and a 2°C warming over 19 yr at AWS Siple (0.111 yr⁻¹ ±0.079°C). Only the Siple trend is statistically significant at the 95% confidence level however. The temperature increases at Siple and possibly Byrd are suggestive of a broader regional warming documented at sites on the Antarctic Peninsula. The cooling suggested by the shorter records in the vicinity of the Ross Ice Shelf is consistent with results recently reported by Comiso and suggests that significant regional differences exist. Continued data acquisition should enable detection of the magnitude and direction of potential longer-term changes.