activity : indicator-arctic-glacier-mass-balance-process-2021

indicator-arctic-glacier-mass-balance-process-2021

Methodology:

* Mass balance estimates were divided by 1,000 to convert millimeters to meters.
* Cumulative mass balance for each individual glacier was calculated by adding net balances from (or backwards from) 1970, which we've established as a consistent baseline (zero) point across all eight glaciers.
* The cumulative mean mass balance was determined by calculating the annual mean mass balance across the eight glaciers (or as many of the eight had data in a given year), then adding these mean net balances from year to year. The mean line was also adjusted to use 1970 as a common zero point.

Note: Glacier mass balance data are calculated based on a variety of measurements at the surface of a glacier, including measurements of snow depths and snow density. The net balance is the average mass balance of the glacier from data collected over a glaciological year, the time between the end of the summer ablation season from one year to the next. These measurements help glaciologists determine changes in snow and ice accumulation and ablation that result from snow precipitation, snow compaction, freezing of water, melting of snow and ice, calving (i.e., ice breaking off from the tongue or leading edge of the glacier), wind erosion of snow, and sublimation from ice (Mayo et al., 2004). Both surface size and density of glaciers are measured to produce net mass balance data. These data are reported in meters of water equivalent (mwe), which corresponds to the average change in thickness over the entire surface area of the glacier. Because snow and ice can vary in density (depending on the degree of compaction, for example), converting to the equivalent amount of liquid water provides a more consistent metric.

* The cumulative mass balance for each individual glacier was plotted as a time series, along with the eight-glacier average. * A map depicting the locations of each glacier was placed alongside the chart, accompanied by a color-coded legend.

Methodology Citation: * WGMS (World Glacier Monitoring Service). 2015. Global glacier change bulletin no. 1 (2012–2013). Zemp, M., I. Gärtner-Roer, S.U. Nussbaumer, F. Hüsler, H. Machguth, N. Mölg, F. Paul, and M. Hoelzle (eds.). ICSU (WDS)/IUGG (IACS)/UNEP/UNESCO/WMO. Zurich, Switzerland: World Glacier Monitoring Service * Østrem, G., and M. Brugman. 1991. Glacier mass-balance measurements: A manual for field and office work. National Hydrology Research Institute (NHRI), NHRI Science Report No. 4.

Methodology Contact: Michael Zemp, World Glacier Monitoring Serivce

Processes

How the source was modified: When extracting data (from the "Original Arctic Glacier Data" tab), if more than one result was provided for the same year for a given glacier, results in the row with Upper and Lower Bound = 9999 were used; these values refer to total glacier estimates, in contrast to other rows that give mass balance for only specific portions of a glacier.

Modified Source Location: World Glacier Monitoring Service, Zurich, Switzerland

The duration of this activity was 8 hours.

Interim artifacts generated by this activity :
REF-Glaciers_all_2018-11.xlsx,Arctic Glaciers - Figure 1 - 03-09-21.xlsx
Output artifacts generated by this activity :
ArcticGlaciers_052721.png
Tools

Computing environment : macOS Big Sur Version 11.3

Software used : Microsoft Excel

Visualization software used : SigmaPlot,Adobe Photoshop

Data Bounding

The input object was time bounded starting from January 01, 1945 (00:00 AM)

The input object was time bounded ending at October 14, 2019 (00:00 AM)

The input object was bounded spatially:

This activity resulted in the following :

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