MODIS Image-derived ice surface temperature assessment in the southern patagonian icefield

Abstract

Ice surface temperature (IST) is one of the most relevant parameters when it comes to estimating the effects of climate change on glaciers. This study aims to estimate the IST for the Southern Patagonian Icefield (SPI) during the 2001–2016 period and, in so doing, to contribute to the assessment of the MOD11A1 product in this area. We evaluated IST performance by comparing it with that of automatic weather stations (AWSs). In addition, the glaciological significance of the results is presented through 1) IST trends, 2) annual IST anomalies, 3) IST behavior at different altitudes and orientations and 4) a comparison with Santa Cruz River flow records. The correlation coefficients obtained between the IST and AWSs ranged between 0.66 and 0.85. In addition, we report on the mean absolute differences between them, ranging between 0.6 ± 3.6°C and 9.4 ± 1.9°C. In this sense, we observed the lowest differences at the AWSs that were located in a homogeneous environment. Stated in glaciological terms: 1) only 1% of the pixels had a statically significant IST trend (p-value ≤ 0.05): between 0.01 and 0.05°C/month; 2) we found that most of the IST anomalies ranged between –1 and 1°C throughout the period of this study; 3) the results suggest that the altimetric gradient was the most influential variable of the IST, mostly in north-oriented glaciers; and 4) the SPI IST showed an annual periodicity, which, in turn, shows a high correlation with the Santa Cruz River flow (R = 0.86). This study is the first in estimating the SPI’s IST and contributes to enhance our knowledge of glacier dynamics and, therefore, the management of the water resource. Despite this, some MOD11 filtering is required in regions with high cloud cover frequency.