Long time series (1984-2020) of albedo variations on the Greenland ice sheet from harmonized Landsat and Sentinel 2 imagery

TY - JOUR

T1 - Long time series (1984-2020) of albedo variations on the Greenland ice sheet from harmonized Landsat and Sentinel 2 imagery

AU - Feng, Shunan

AU - Cook, Joseph Mitchell

AU - Anesio, Alexandre Magno

AU - Benning, Liane G.

AU - Tranter, Martyn

PY - 2023/10

Y1 - 2023/10

N2 - Albedo is a key factor in modulating the absorption of solar radiation on ice surfaces. Satellite measurements have shown a general reduction in albedo across the Greenland ice sheet over the past few decades, particularly along the western margin of the ice sheet, a region known as the Dark Zone (albedo < 0.45). Here we chose a combination of Landsat 4-8 and Sentinel 2 imagery to enable us to derive the longest record of albedo variations in the Dark Zone, running from 1984 to 2020. We developed a simple, pragmatic and efficient sensor transformation to provide a long time series of consistent, harmonized satellite imagery. Narrow to broadband conversion algorithms were developed from regression models of harmonized satellite data and in situ albedo from the Program for Monitoring of the Greenland Ice Sheet (PROMICE) automatic weather stations. The albedo derived from the harmonized Landsat and Sentinel 2 data shows that the maximum extent of the Dark Zone expanded rapidly between 2005 and 2007, increasing to ∼280% of the average annual maximum extent of 2900 km2 to ∼8000 km2 since. The Dark Zone is continuing to darken slowly, with the average annual minimum albedo decreasing at a rate of ∼-0.0006+0.0004 a-1 (p = 0.16, 2001-2020).

AB - Albedo is a key factor in modulating the absorption of solar radiation on ice surfaces. Satellite measurements have shown a general reduction in albedo across the Greenland ice sheet over the past few decades, particularly along the western margin of the ice sheet, a region known as the Dark Zone (albedo < 0.45). Here we chose a combination of Landsat 4-8 and Sentinel 2 imagery to enable us to derive the longest record of albedo variations in the Dark Zone, running from 1984 to 2020. We developed a simple, pragmatic and efficient sensor transformation to provide a long time series of consistent, harmonized satellite imagery. Narrow to broadband conversion algorithms were developed from regression models of harmonized satellite data and in situ albedo from the Program for Monitoring of the Greenland Ice Sheet (PROMICE) automatic weather stations. The albedo derived from the harmonized Landsat and Sentinel 2 data shows that the maximum extent of the Dark Zone expanded rapidly between 2005 and 2007, increasing to ∼280% of the average annual maximum extent of 2900 km2 to ∼8000 km2 since. The Dark Zone is continuing to darken slowly, with the average annual minimum albedo decreasing at a rate of ∼-0.0006+0.0004 a-1 (p = 0.16, 2001-2020).

KW - albedo

KW - Arctic glaciology

KW - data harmonization

KW - snow/ice surface processes

UR - http://www.scopus.com/inward/record.url?scp=85150476633&partnerID=8YFLogxK

U2 - 10.1017/jog.2023.11

DO - 10.1017/jog.2023.11

M3 - Journal article

AN - SCOPUS:85150476633

SN - 0022-1430

VL - 69

SP - 1225

EP - 1240

JO - Journal of Glaciology

JF - Journal of Glaciology

IS - 277

ER -