In situ and satellite surface temperature records in Antarctica

Abstract

Air-temperature records (Tᴀ) during 1992 from five inland Antarctic automatic weather station (AWS) sites were compared with the best available infrared temperatures (Tıʀ) from the Advanced Very High Resolution Radiometer (AVHRR) as well as calibrated passive-microwave temperatures (Tᴄ) from the Special Sensor Microwave/Imager (SSM/I). Daily and monthly average Tᴀ, Tıʀ, and Tᴄ data indicate that each approach captures generally similar trends at each site but each approach also has limitations. AWS Tᴀ data are considered the most accurate but represent spatially restricted areas and may have long gaps due to sensor or transmission problems. AVHRR TIR data have daily variability similar to the TA record but have numerous small gaps due to cloud cover or observation interruptions. An offset between Tᴀ and Tıʀ (>4 K) at the South Pole site was identified that may be due to the inclusion of data with large satellite scan angles necessary to cover this area. SSM/I Tᴄ data have the most continuity but exhibit calibration problems, a significantly damped daily response and do not cover all of Antarctica. Individual daily differences between Tᴀ and Tıʀ as well as Tᴀ and Tᴄ can exceed 17 K, but all sites have mean daily differences of about 1 K or better, after compensating for the offset at South Pole, and standard deviations of <6 K. Monthly temperature differences are typically 5 K or better, with standard deviations generally <3 K. And finally, using the available data, the 1992 average temperature differences are <1 K.