Spatiotemporal variations of snowmelt in Antarctica derived from satellite scanning multichannel microwave radiometer and Special Sensor Microwave Imager data (1978–2004)

Abstract

We derived the extent, onset date, end date, and duration of snowmelt in Antarctica from 1978 to 2004 using satellite passive microwave scanning multichannel microwave radiometer (SMMR) and Special Sensor Microwave Imager (SSM/I) data. A wavelet‐transform‐based method was developed to determine and characterize melt occurrences. About 9–12% of the Antarctic surface experiences melt annually. This is more than twice the surface melt extent measured in Greenland. Seasonally, surface melt primarily takes place in December, January, and February and peaks in early January. Regression analysis over the 25 year period of study reveals a negative interannual trend in surface melt. Nevertheless, the trend inference is not statistically significant. Large year‐to‐year fluctuations characterize the interannual variability. Extremely high melt occurred in the 1982/1983 and 1991/1992 summers, while extremely weak melt occurred in the 1999/2000 summer. A strong correlation with air temperature suggests that the melt index can serve as a diagnostic indicator for regional temperature variations. Periodic melting has been observed over Ross Ice Shelf, Ronne‐Filchner Ice Shelf, the West Antarctic ice streams, and outlet glaciers in the Transantarctic Mountains. The Antarctic Peninsula, West Ice Shelf, Shackleton Ice Shelf, Amery Ice Shelf, and the ice shelf along the Princess Ragnhild Coast experienced the most persistent and intensive melt and should be closely monitored for their stability in the future, given the recent disintegration of the Larsen Ice Shelf A and B.

Snow physics as relevant to snow photochemistry

“…In active mode, the increased absorption decreases the backscattering coefficient coming from the soil. Various techniques were developed for both passive and active, for Greenland (Albdalati and Steffen, 1997 andWiesmann, 2000), Antarctica (Torinesi et al, 2003;Picard and Fily, 2006;Liu et al, 2006) and boreal regions (Kimball et al, 2004). These methods have been successful to detect the presence/absence of water and the next step in the future may be to derive quantitatively the liquid water content.…”

Persistent surface snowmelt over Antarctica (1987–2006) from 19.35 GHz brightness temperatures

“…The strong positive correlation with the near surface air temperature and the melting index [e.g., Liu et al, 2006] suggests that the latter can be used as an indicator of changing climate. In this paper, we update the results of previous investigations by studying the presence of persistent melting in Antarctica between 1987 and 2006 by means of a more sensitive method, using nighttime and daytime microwave brightness temperatures at 19.35 GHz, horizontal polarization.…”

Rise in Frequency of Surface Melting at Siple Dome Through the Holocene: Evidence for Increasing Marine Influence on the Climate of West Antarctica

“…[18] Surface melting is a rare phenomenon across most of West Antarctica, including the Siple Dome region [Liu et al, 2006;Das and Alley, 2005;Zwally and Fiegles, 1994]. Melt layers record ''extreme events'' in a statistical sense, occurring in response to air temperatures exceeding a certain threshold (Figure 4).…”

“…Most valuable are $25 years of passive microwave records, which provide daily brightness temperatures from the surface of the ice sheet that are highly sensitive to the onset of melting [e.g., Zwally and Fiegles, 1994;Fahnestock et al, 2002;Torinesi et al, 2003;Liu et al, 2006]. Because of the rarity of melt events, the large interannual variations in extent, and the short length of the satellite time series (1978 -present), spatial and temporal trends of melt in Antarctica are not statistically significant [Liu et al, 2006].…”

“…Most valuable are $25 years of passive microwave records, which provide daily brightness temperatures from the surface of the ice sheet that are highly sensitive to the onset of melting [e.g., Zwally and Fiegles, 1994;Fahnestock et al, 2002;Torinesi et al, 2003;Liu et al, 2006]. Because of the rarity of melt events, the large interannual variations in extent, and the short length of the satellite time series (1978 -present), spatial and temporal trends of melt in Antarctica are not statistically significant [Liu et al, 2006]. At the same time, a strong correlation between melt events and elevated air temperature (as was found by Liu et al [2006]) demonstrates that variation in melt could serve as a diagnostic indicator for regional temperature change, especially on longer timescales, if records of past melt are available [Das and Alley, 2005].…”