Permafrost

1. Permafrost Andrew G. Slater

2. Permafrost in the News

3. What is Permafrost? Near-Surface Permafrost IPA Permafrost Distribution Map Continuous Discontinuous Continuous (90 – 100% coverage) Discontinuous (50 – 90%) Sporadic (10 – 50%) Isolated (0 – 10%) Brown et al., 1998

4. Observations

5. Deep Soil Temperatures (Alaska) Temperature at 20m Depth Photo: A. Slater Hinzman et al., 2005

6. Deep Soil Temperatures (Alaska) CHANDALER SHELF Data/Images Courtesy V. Romanovsky, UAF

7. Deep Soil Temperatures (Russia) 10m temperatures 15m temperatures 10m temperatures Oberman, 2008; Romanovsky et al., 2008

8. Active Layer Thickness Image:Slater, Data: Circum-Polar Active Layer Monitoring (CALM) Network

9. Why does Permafrost matter? • Impacts on the landscape • Impacts to hydrology • Infrastructure • Vegetation changes • Carbon cycle

10. Landscape Changes & Ice-Rich Permafrost Caribou-Poker Creek, AK, July 1999

11. Siberian Lake Appearance and Disappearance Smith et al., 2005

12. Damage to Infrastructure?

13. Engineering: Salekhard, Russia

14. Vegetation Changes – Shrubs & Treeline • Changes: • Albedo • Insulation • Snow trapping • Transpiration 1950 2002 Sturm et al., 2005

15. Shrubs??

16. Trace Gas Emission – an unknown!

17. Permafrost Organic Carbon Content New estimates of carbon in frozen soils (NH) Tarnocai et al., 2009

18. Sea Ice – Permafrost Interactions Lawrence, Slater, Tomas, Holland and Deser, 2008

19. LSM LSM Land Surface Models – what are they? • Traditionally, an atmospheric boundary condition • Energy, Mass and Momentum transfer • Albedo, Radiant Temperature • Sensible and Latent (Evap.) Heat fluxes • Coupled moisture and energy ATM ATM ATM LSM

20. Fluxes are main aim Feedbacks important Coupled Hydrology Global/Continent scale Less than 10 layers 5-30min time step Meteorology forcing Temp / Thaw is main aim No feedbacks Hydrology optional (?) Point & Local scale Up to +100 layers Daily time step (?) Temperature & snow forcing Model Purpose and Philosophy Land Surface Model Permafrost Model

21. Where have we been? (где мы были?) • 1970’s : Example: Simple ‘bucket’ case • No temperature adjustment for soil freezing • No infiltration in presence of snow Ks KL* L H evaporation precipitation q: surface moisture content a G

22. Where have we been? (где мы были?) • 1980’s : First generation LSM’s • Little accounting for soil fusion term • Infiltration a function of soil temperature • Simple snow models included q1 T1 q2 T2 q3 T3

23. Where have we been? (где мы были?) • 1990’s : More Physics • Inclusion of explicit soil ice more common • Soil columns still shallow (<5m) • “Tiled” vegetation representation • Bulk and multi-layer snow models • Impacts of frozen ground receives recognition • NWP (Viterbo et al., 1998) • GCM’s (Slater et al, 1998)

24. Where are we now? (где мы сейчас?) • 2000’s and beyond: Earth System Models • Most models include explicit soil ice • Carbon cycle modeling • Dynamic Vegetation • Better snow models (?) • Still a wide variety of complexity in models.

25. Momentum flux Wind speed 0 ua Surface energy fluxes Biogeochemical cycles Hydrology BVOCs Photosynthesis Precipitation Diffuse solar Fire Downwelling longwave Direct solar Autotrophic respiration Transpiration Sensible heat flux Evaporation Latent heat flux Reflected solar Emitted longwave Phenology Vegetation C/N Throughfall Absorbed solar Dust Evaporation Sublimation Aerosol deposition N dep N fixation Surface runoff Heterotrophic respiration Infiltration Melt Litterfall SCF Soil heat flux Saturated fraction Soil C/N Root litter Soil Soil (sand, clay, organic) Denitrification N leaching Aquifer recharge N uptake N mineralization Water table Sub-surface runoff Unconfined aquifer Bedrock Glacier Runoff Disturbance Lake Competition Wetland River Routing Vegetation Dynamics Land Use Change River discharge Wood harvest Urban Growth

26. Mean Annual Temperature vs. Reanalysis

27. Winter Normalized Snow Depth vs. Reanalysis

28. Indirect Measure • Surface Frost Index • Nelson & Outcalt (1987) • Climate Only • Steady-State • Empirical Estimate

29. Range of Near-Surface Permafrost Area (1900-2100) Slater & Lawrence, 2013

30. Mean Soil Temperature @ 3.3m (RCP 8.5) Slater & Lawrence, 2013

31. Direct vsIndirectDiagnosis • Impact of Land Model • Common result across RCPs Slater & Lawrence, 2013

32. Climate Change in the Permafrost Region Slater & Lawrence, 2013

33. One Estimate of Change in Permafrost Area Slater & Lawrence, 2013

34. SFI in Yr 2000

35. SFI in Yr 2099

36. Where are we now? (где мы сейчас?) SNOW MODELS • Can’t model permafrost without modeling snow • Many different model structures • Has a big impact on model ability Slater et al., 2001

37. Where are we now? (где мы сейчас?) Koven et al., 2013

38. Where are we now? • Different: • Number of soil layers • Depths per layer • Hydrologiaclly active layers • Which is sufficient? • Which is best? CMIP5 Models Slater & Lawrence, 2013

39. Where are we going? (куда мы идем?) • Organic Soils • Improved Hydrology • Excess Soil Ice • Thermokarst • Numerical Methods • Vegetation Interactions • Sub-grid permafrost • Heterogeneity

40. Organic Mat

41. Organic Soil and Deep Soils Lawrence & Slater, 2008; Lawrence et al., 2008

42. Improved Hydrology Transient Layer NEW OLD Swenson & Lawrence, 2012

43. Improved Hydrology OLD NEW Swenson & Lawrence, 2013

44. Excess Soil Ice & Projected Subsidence Lee, Swenson, Lawrence & Slater, 2013

45. Excess Ice

46. Ice Wedge: Permafrost Tunnel, Fairbanks, AK Photos: A. Hurley; A.Slater

47. Spatial Heterogeneity July, 1999 – Council, AK

48. σ2 Parameterizing Thermokarst Microtopography PDF σ1 High relief: e.g. after thermokarst Height above mean surface (m)

49. Data • Still many gaps • Getting much better ? ? ? Romanovsky et al., 2010

50. Thanks. Any questions? Спасибо. Есть вопросы? Photo: Tom Douglas