Development of global distribution of debris thermal resistance on glaciers at 90m resolution derived from multi-temporal satellite measurements

• Main Authors: 佐々木織江, Orie Sasaki, 野口淡海, Omi Noguchi, 張 勇, Yong Zhang, 平林由希子, Yukiko Hirabayashi, 鼎信次郎, Shinjiro Kanae
• Format: Conference Object
• Language: English
• Published: 2017
• Subjects: Greenland; Svalbard; Antarc*; Antarctica; glacier
• Online Access: http://t2r2.star.titech.ac.jp/cgi-bin/publicationinfo.cgi?q_publication_content_number=CTT100745928

Estimating glaciers’ response to climate change is an important issue, since meltwater from glaciers makes contributions to global sea level change and regional streamflow. Several research groups therefore developed global glacier models that estimate glacier behavior in the past and projected future. Such researches, however, did not consider the effects of debris cover on glaciers due to the limited input information of debris. Debris-covered glaciers widely present in high relief mountain regions. The debris affects glacier evolution by accelerating (if debris layer is this) or suppressing (if debris layer is thick) melting rate. In order to consider the debris effect in numerical model for calculating glacier mass balance, information about debris thickness and thermal conductivity are required. Because debris thickness and thermal conductivity were usually obtained through in-situ measurements, it is difficult to obtain the parameters on a global scale. Here, in this study, we developed a global distribution data set of debris information by using a parameter, thermal resistance, to account for debris effects in global glacier models. Thermal resistance is a parameter that enables to calculate energy balance of debris surface, which obtained from satellite measurement. We calculated thermal resistance of debris layer at 90m horizontal resolution on a global scale by utilizing ASTER and CERES products, excluding Greenland and Antarctica. Result indicated that 16.8% of total glacier area was covered by supraglacial debris, and regional differences are apparent from region to region. When we classified debris into thin debris and thick debris, it was found that thick debris-covered area was larger than thin debris-covered area, with the exception of Svalbard and Scandinavia. Uncertainties in debris thermal resistance due to downward radiation data were assessed to be up to 23% at global mean. Although uncertainties was quantified relatively high, our estimation provides a necessary basis to calculate the ...