ASTER Datasets and Derived Products for Global Glacier Monitoring
This book investigates a wide selection of the world’s glaciers and the status of remote-sensing and GIS technologies designed to address their global monitoring in this age of rapid climate change impacts on glaciers and increasing awareness of the polic
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ASTER datasets and derived products for global glacier monitoring Bhaskar Ramachandran, John Dwyer, Bruce H. Raup, and Jeffrey S. Kargel
ABSTRACT This book investigates a wide selection of the world’s glaciers and the status of remote-sensing and GIS technologies designed to address their global monitoring in this age of rapid climate change impacts on glaciers and increasing awareness of the policy and economic relevance of glaciers in areas as diverse as water resources and geohazards. This chapter focuses on an important part of the data component, especially data from the Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) project, which also spawned the Global Land Ice Measurements from Space (GLIMS) project as an ASTER Science Team member project (see Foreword by Hugh Kieffer). ASTER’s combination of sensor systems, spanning the visible through thermal infrared and its stereo-imaging capability, the high radiometric and geometric fidelity of the cameras, combined with a liberal data dissemination policy for glacier images, have made it a favored instrument for glacier remote-sensing studies. Operational use of the instrument with on-demand targeting has also aided specific studies ranging from preplanned field campaigns to rapid response to glacier-related disasters. 6.1
INTRODUCTION
GLIMS is an international consortium established to facilitate the acquisition and analysis of remotely
sensed satellite images of glaciers worldwide. These images are used to monitor and evaluate changing glacier extent and dynamics, and the implications of these changes for people and the environment. Although GLIMS has benefited from data derived from many passive and active remote-sensing instruments, and ground-based observations as well, ASTER data remain a primary source. The instrument has three telescopes and associated sets of sensors, one for each of the wavelength ranges, VNIR, SWIR, and TIR (visible and near-infrared, shortwave infrared, and thermal infrared, respectively), an image swath width of 60 km, and ground resolutions of 15 m/pixel for VNIR, 30 m/pixel for SWIR, and 90 m/pixel for TIR. The instrument is described elsewhere in detail (Ramachandran et al. 2011), but hallmarks of its capabilities include its broad multispectral and thermal imaging range, its exquisite pointing stability (which partly stems from the Terra spacecraft’s high mass), and its systematic stereoscopic imaging in VNIR band 3. The multispectral response of the sensor system to glacier target materials is described theoretically in Chapter 3 of this book by Furfaro et al., in practice in Chapter 4 by Ka¨a¨b et al., and as used for glacier mapping in Chapter 2 by Bishop et al. Fig. 4.2 depicts ASTER’s spectral wavelengths for all three sensors juxtaposed alongside those of Landsat ETMþ and widely used radar bands. The on-demand nature of ASTER data acquisition and the ability to optimize acquisitions (via seasonality, telescope pointability, instrument gain
J. S. Kargel et al. (eds.), Global Land Ice Measurements from S
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