Annual and Seasonal Glacier-Wide Surface Mass Balance Quantified from Changes in Glacier Surface State: A Review on Existing Methods Using Optical Satellite Imagery

Abstract

Glaciers are one of the terrestrial essential climate variables (ECVs) as they respond very sensitively to climate change. A key driver of their response is the glacier surface mass balance that is typically derived from field measurements. It deserves to be quantified over long time scales to better understand the accumulation and ablation processes at the glacier surface and their relationships with inter-annual changes in meteorological conditions and long-term climate changes. Glaciers with in situ monitoring of surface mass balance are scarce at the global scale, and satellite remote sensing provides a powerful tool to increase the number of monitored glaciers. In this study, we present a review of three optical remote sensing methods developed to quantify seasonal and annual glacier surface mass balances. These methodologies rely on the multitemporal monitoring of the end-of-summer snow line for the equilibrium-line altitude (ELA) method, the annual cycle of glacier surface albedo for the albedo method and the mapping of the regional snow cover at the seasonal scale for the snow-map method. Together with a presentation of each method, an application is illustrated. The ELA method shows promising results to quantify annual surface mass balance and to reconstruct multi-decadal time series. The other two methods currently need a calibration on the basis of existing in situ data; however, a generalization of these methods (without calibration) could be achieved. The two latter methods show satisfying results at the annual and seasonal scales, particularly for the summer surface mass balance in the case of the albedo method and for the winter surface mass balance in the case of the snow-map method. The limits of each method (e.g., cloud coverage, debris-covered glaciers, monsoon-regime and cold glaciers), their complementarities and the future challenges (e.g., automating of the satellite images processing, generalization of the methods needing calibration) are also discussed.

Monitoring glacier albedo as a proxy to derive summer and annual surface mass balances from optical remote-sensing data

“…Larger-scale studies and multi-variable correlations in between morpho-topographic features could be for instance envisaged. Rabatel et al (2017) recently proposed an alternative approach to reconstruct the annual mass balance of unmonitored glacier on the basis of the albedo method. This approach relies on the ELA method (Rabatel et al, 2005), but using the remotely sensed monitored α min a together with the AAR, the glacier hypsometry, and the regional SMB elevation gradient (which is the annual SMB gradient in the vicinity of the glacier ELA).…”

“…This approach relies on the ELA method (Rabatel et al, 2005), but using the remotely sensed monitored α min a together with the AAR, the glacier hypsometry, and the regional SMB elevation gradient (which is the annual SMB gradient in the vicinity of the glacier ELA). For an exhaustive description of this approach, see Rabatel et al (2017).…”

“…To reach this objective, the development of methods complementary to the ground-based glaciological method is therefore required. Since the 1970s, several methods have taken advantage of satellite imaging to compute changes in glacier volume (Kääb et al, 2005;Rabatel et al, 2017;Racoviteanu et al, 2008). Several glacier surface properties have thus been used as proxies for volume fluctuations -changes in surface elevation from differencing digital elevation models (DEMs) (e.g.…”

Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations

“…The snow line is recognized as a valuable proxy for glacier mass balance (LaChapelle, 1962;Lliboutry, 1965;Braithwaite, 1984;Kulkarni, 2012;Rabatel et al, 2017). Different methods have been developed to use the end-of-summer snow line observed on air-and space-borne data, i.e.…”

Annual Glacier-Wide Mass Balance (2000–2016) of the Interior Tibetan Plateau Reconstructed from MODIS Albedo Products

“…In recent years, remote sensing techniques have proven to be useful for glacier monitoring, since the available satellite sensors are increasing and their spatial, radiometric and temporal resolutions are improved [11,12].Glacier mass fluctuations can be calculated by using several parameters derived from remote sensing images, e.g., the difference between two digital elevation models (DEMs) at different times [13][14][15][16], the equilibrium-line altitude (ELA) at the end of the hydrological year [12,17,18], the accumulation-area ratio (AAR) [19,20] over a glacier, and the average glacier surface albedo [21][22][23][24]. Among these glacier properties, recent studies have revealed that the variation of glacier-wide surface albedo has shown outstanding potentials in obtaining annual or seasonal mass balance, because minimum surface albedo was directly related to AAR and ELA.…”