TY - JOUR

T1 - Heat and Salt Flow in Subsea Permafrost Modeled with CryoGRID2

AU - Angelopoulos, Michael

AU - Westermann, Sebastian

AU - Overduin, Paul

AU - Faguet, Alexey

AU - Olenchenko, Vladimir

AU - Grosse, Guido

AU - Grigoriev, Mikhail N.

N1 - Publisher Copyright: ©2019. The Authors.

PY - 2019/4

Y1 - 2019/4

N2 - Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice-bearing permafrost table (IBPT) for ice-rich sand and an erosion rate of 0.25 m/year was 16.7 m below the seabed 350 m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15–20 m below the seabed at 350 m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas.

AB - Thawing of subsea permafrost can impact offshore infrastructure, affect coastal erosion, and release permafrost organic matter. Thawing is usually modeled as the result of heat transfer, although salt diffusion may play an important role in marine settings. To better quantify nearshore subsea permafrost thawing, we applied the CryoGRID2 heat diffusion model and coupled it to a salt diffusion model. We simulated coastline retreat and subsea permafrost evolution as it develops through successive stages of a thawing sequence at the Bykovsky Peninsula, Siberia. Sensitivity analyses for seawater salinity were performed to compare the results for the Bykovsky Peninsula with those of typical Arctic seawater. For the Bykovsky Peninsula, the modeled ice-bearing permafrost table (IBPT) for ice-rich sand and an erosion rate of 0.25 m/year was 16.7 m below the seabed 350 m offshore. The model outputs were compared to the IBPT depth estimated from coastline retreat and electrical resistivity surveys perpendicular to and crossing the shoreline of the Bykovsky Peninsula. The interpreted geoelectric data suggest that the IBPT dipped to 15–20 m below the seabed at 350 m offshore. Both results suggest that cold saline water forms beneath grounded ice and floating sea ice in shallow water, causing cryotic benthic temperatures. The freezing point depression produced by salt diffusion can delay or prevent ice formation in the sediment and enhance the IBPT degradation rate. Therefore, salt diffusion may facilitate the release of greenhouse gasses to the atmosphere and considerably affect the design of offshore and coastal infrastructure in subsea permafrost areas.

KW - Bykovsky Peninsula

KW - CryoGRID

KW - electrical resistivity

KW - Lena Delta

KW - salt diffusion

KW - subsea permafrost

KW - SEDIMENTS

KW - LENA RIVER DELTA

KW - NORTHERN SIBERIA

KW - LAPTEV SEA REGION

KW - SURFACE-ENERGY BALANCE

KW - THERMOKARST

KW - SUBMARINE PERMAFROST

KW - SHELF

KW - DEGRADATION

KW - POLYGONAL TUNDRA SITE

UR - http://www.scopus.com/inward/record.url?scp=85063957811&partnerID=8YFLogxK

U2 - 10.1029/2018JF004823

DO - 10.1029/2018JF004823

M3 - Article

C2 - 31423408

AN - SCOPUS:85063957811

VL - 124

SP - 920

EP - 937

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 0148-0227

IS - 4

ER -