Mass balance, often referring to glacier mass balance, is measured using a combination of methods providing a comprehensive picture of ice gain and loss. These methods broadly fall into two categories: direct and indirect measurements.
Direct Methods: Measuring Accumulation and Ablation Directly
Direct methods involve directly measuring the changes in snow and ice volume on a glacier's surface. These measurements focus on the surface mass balance (SMB), which is the difference between accumulation (snowfall and deposition) and ablation (melting, evaporation, and calving).
- Stake measurements: A network of stakes is installed across the glacier. Regular measurements of stake height changes indicate the accumulation or ablation at each point. This is a common approach in glaciological studies as referenced in multiple sources. (Glacier Mass Balance Methods - Measuring Glacier Change | U.S. ...) and (An introduction to Glacier Mass Balance).
- Snowpack depth measurements: In the accumulation zone, snowpack depth is measured using various techniques. These include probing, snow pits, and crevasse stratigraphy, which utilizes annual layers visible in crevasse walls. ([To determine mass balance in the accumulation zone, snowpack depth is measured using probing, snowpits or crevasse stratigraphy...](Reference provided in prompt))
- Buoys: In sea ice studies, mass balance is measured using buoys equipped to monitor various parameters, including temperature profiles. Data on heat and mass exchange across the ice surface are collected and analyzed. (Ice Mass Balance (IMB) Buoy Program > Engineer Research and ...) (Sea ice heat and mass balance measurements from four ...)
Indirect Methods: Using Remote Sensing and Modeling
Indirect methods use remote sensing data and modeling to estimate mass balance changes. These methods provide broader coverage but may be less precise than direct measurements.
- Geodetic methods: These utilize satellite data (e.g., from GPS and altimetry) to measure changes in glacier volume and surface elevation over time. These are then used to calculate overall mass balance changes. (Glacier mass balance is measured either by glaciological (stake) or geodetic methods...) (Geodetic and direct mass-balance measurements: comparison and ...)
Combining Methods for Comprehensive Analysis
Often, a combination of direct and indirect methods is used to achieve a more accurate and comprehensive understanding of glacier mass balance. Data from different methods can be compared and integrated, leading to improved estimates of overall mass balance changes and a deeper understanding of the processes driving them. (Reanalysing glacier mass balance measurement series - TC)
