Data accompanying "Retreat and Frontal Ablation Rates for Alaska's Lake-Terminating Glaciers: Investigating Potential Physical Controls with Implications for Future Stability" by Noah Caldwell and others, published in Journal of Glaciology in 2025.
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Readme for data from "Retreat and Frontal Ablation Rates for Alaska’s Lake-Terminating Glaciers: Investigating Potential Physical Controls with Implications for Future Stability" by Noah Caldwell, William Armstrong, and others, published in Journal of Glaciology in 2025. Readme written by William Armstrong (armstrongwh@appstate.edu) on 18 April 2025. contact: armstrongwh@appstate.edu This folder contains 5 files: 0) this readme1) caldwell2025_terminusPositiosn_final.zip2) caldwell2025_lakeMasterData_paperReRevisions_20241007.csv3) caldwell2025_marineMasterData_paperReRevisions_20241007.csv4) caldwell2025_minowa_patagonia_glacierArea_frontalAblation.csv Details on each file is found below.---------------------------------------------1) Filename: caldwell2025_terminusPositiosn_final.zip Summary: A zipped shapeile (EPSG:4326) containing manually digitized ~annual terminus positions for all lake-terminating study glaciers from 1984 - 2021. Digitization accomplished using GEEDiT: https://liverpoolgee.wordpress.com/geedit-geedit-reviewer/ Variables:Name = study-assigned glacier name. This can be matched to an RGI ID using file #2.Date = date of image used for terminus digitation. Form = YYYY-MM-DDYear = year of date field Other fields largely null. ---------------------------------------------2) Filename: caldwell2025_lakeMasterData_paperReRevisions_20241007.csv Summary: A table containing results & attributes of each Alaska lake-terminating study glacier. Variables:RGI-ID = glacier ID number from the Randolph Glacier Inventory (RGI) v6Name_y = study-assigned glacier name > this can be used to map file 1 terminus positions to RGI IDsLat_y & lon_y = glacier centroid latitude and longitudearea(km2)_y = glacier area in square kmO2Region = sub-region within RGI Region 01 (Alaska & NW Canada)A_xsec_med_m2 = cross-sectional area of the glacier @ flux gate, units of square mA_below_xsec_m2_y = planform surface area of glacier between flux gate and RGI terminus, units of square mQ_med_m3a = estimate of ice discharge through flux gate (integral of thickness & surface velocity over width), units of cubic m per yearTotaldL_m_y = total glacier length change between first & last positions, units of m, with negative = retreat** Retreat rates below estimated using the slope of Theil-Sen robust fit. Negative = retreat. **allRetreatRate_ma(1984-2018)_y = retreat rate in m/an estimated over 1984-2018mcnabbRetreatRate(1985-2013) = retreat rate over the same time span as McNabb marine-terminating dataset (file #3)earlyRetreatRate(1984-1999)_y = retreat rate over 1984-1999midRetreatRate(1999-2009)_y = '' for 1999 - 2009lateRetreatRate(2009-2018)_y = '' for 2009 - 2018Fsen_gt_84-21_y = frontal ablation rate estimated via manuscript Eqn #2 using the allRetreatRate retreat values. Units of Gt/a.Fsen_gt_09-18_y = frontal ablation rate estimated via manuscript Eqn #2 using the lateRetreatRate retreat values. Units of Gt/a. *These are the main results presented in the text.*zs_lake = lake surface elevation manually read from ESA GLO90 DEM. Units of m height above ellipsoidarea_2018_ = lake area estimate in 2018 from Rick et al. (2022) https://doi.org/10.5194/tc-16-297-2022medLakeDepth_termZone_m_y = median lake depth (estimated via manuscript Eqn #7) in the terminal 2 km of the glacier's RGI extent. Units = m.lakeLen_medH_y = length between most recent glacier terminus and point @ which glacier bed rises above lake surface elevation. Units = km. The _lowH and _highH variations account for ice thickness uncertainty as shown on manuscript Fig 3.lakeTimeRecentRetreat_y = time for terminus to retreat lakeLen_medH_y at lateRetreatRate. Units of years (a).dmdt_2010-2020 = glacier-wide mass change over 2010-2020 in units of Gt/a from Hugonnet 2022. https://doi.org/10.1038/s41586-021-03436-zela_2018-2022-avg = equlibrium line altitude averaged over 2018-2022 in units of m height above ellipsoid from Zeller et al. (2025) - https://doi.org/10.1017/jog.2024.65aar_2018-2022-avg = accumulation area ratio (unites) averaged over 2018-2022 from Zeller et al. (2025) - https://doi.org/10.1017/jog.2024.65Zmed = median glacier elevation (min and max defined similarly) pulled from RGI v6. Units of heigh above ellipsoid? ---------------------------------------------3) Filename: caldwell2025_marineMasterData_paperReRevisions_20241007.csv Summary: A table containing results & attributes of Alaska marine-terminating study glaciers for comparison. Variables:All variables defined for File #2. This is a subset of data previously published in "Variations in Alaska tidewater glacier frontal ablation, 1985–2013" by Bob McNabb and others, published in JGR Earth Surface in 2015. https://doi.org/10.1002/2014JF003276 ---------------------------------------------4) Filename: caldwell2025_minowa_patagonia_glacierArea_frontalAblation.csv Summary: A table containing results & attributes of Patagonia lake-terminating study glaciers for comparison. Variables:Name = glacier nameArea = glacier area in square kmF_neg = frontal ablation in Gt/a where values <0 indicate mass loss (convention of Minowa study)F = frontal ablation in Gt/a where values >0 indicate mass loss (convention of Caldwell study) This is a subset of data previously published in "Frontal ablation and mass loss of the Patagonian icefields" by Masahiro Minowa and others, published in Earth and Planetary Science Letters in 2021. https://doi.org/10.1016/j.epsl.2021.116811
