“The UK and CliC”, British Antarctic Survey, 6 August 2004The Legacy of the WCRP Arctic Climate System Study (ACSYS): “The UK and CliC”, British Antarctic Survey, 6 August 2004 The Legacy of the WCRP Arctic Climate System Study (ACSYS) Howard Cattle International CLIVAR Project Office Southampton Oceanography Centre University of Southampton


World Climate Research Programme Projects: World Climate Research Programme Projects Climate Variability and Predictability (CLIVAR) Global Water and Energy Experiment (GEWEX) Stratospheric Processes and Climate (SPARC) Cryosphere and Climate (CliC) Carbon Cycle, Water and Food and Fibre Projects (joint with IGBP/IHDP) Past projects: Arctic Climate System Study (ACSYS) Tropical Ocean-Global Atmosphere (TOGA) World Ocean Circulation Experiment (WOCE)


World Climate Research Programme: World Climate Research Programme Objective: to determine to what extent climate can be predicted and the extent of human influence on climate, aiming at the general goal of greatly improved understanding of the role of climate in the total Earth system Acts through its projects to coordinate international research effort on physical aspects of climate Links, in particular to the international Geosphere-Biosphere Programme (IGBP, the International Human Dimensions Programme (IHDP) and the biodiversity programme, Diversitas.


The WCRP Arctic Climate System Study : The WCRP Arctic Climate System Study Objectives : - understand the interactions between the Arctic ocean circulation, ice cover and the hydrological cycle - initiate long-term climate research and monitoring programmes for the Arctic - provide a scientific basis for an accurate representation of Arctic processes in global models 10 year programme with ‘sunset date’ of end 2003 ACSYS Science and Implementation Plans


The ACSYS Implementation Plan: The ACSYS Implementation Plan ACSYS Implementation Plan components: - Arctic Ocean circulation - Arctic sea ice - Arctic atmosphere - Hydrology - Modelling A “wish list” of science activities identified as needing to be done by Institutional and National funding. “Anyone working in the Arctic today is working for ACSYS” (Roger Colony)


ACSYS - structure: ACSYS - structure ACSYS led by it’s Scientific Steering Group and 4 panels Numerical Experimentation Group Polar Products from Re-analyses Observational Products Data Management and Information assisted by the IAPO the IACPO, now CIPO) located at the Norwegian Polar Institute


The ACSYS role: The ACSYS role ACSYS “value added” through: international coordination of specific projects (model intercomparisons, Arctic precipitation and runoff data bases, promotion of observational networks, assessment of atmospheric reanalyses over the Arctic etc) providing various fora for scientists to meet (through its panels, workshops and 2 conferences) data management and information and other support through its website and the IAPO/IACPO


ACSYS - Overall aim: ACSYS - Overall aim To determine the role and sensitivity of the Arctic in the global climate system. In particular: Is the Arctic climate as sensitive to global change as models seem to suggest? What is the sensitivity of global climate to Arctic processes


Slide9: 2xCO2 winter (DJF) temperature change from three early climate models (IPCC, 1990). High-latitude amplification is attributed to positive feedbacks involving sea-ice albedo over ocean and snow albedo over land. CCCma GFDL UKMO


Slide10: Walsh et al., J. Clim., 1998 Circulation biases, along with other errors, impact other quantities, such as precipitation … Range of observational estimates It is hard to isolate or identify shortcomings in process representation in a global model, particularly regionally …


Slide11: NH Ice Extent and its Change – CMIP2 model ensemble (CO2 increased at 1% per year for 80 years – the time of doubling Initial Ice Extent Ice Extent Change No obvious connection between error and ice model characteristics


ACSYS NEG Sea-Ice Model Intercomparison Project (SIMIP): ACSYS NEG Sea-Ice Model Intercomparison Project (SIMIP) Kreysher et al., JGR, 2000 Initial intercomparison focused on ‘dynamics’ Objective was to quantitatively evaluate performance of different dynamic schemes used in climate models. “viscous-plastic” model performed best; it is appearing in many of the new coupled models. A follow-on project, SIMIP2, focussed on ‘thermodynamics’, is underway now.


Slide13: Arctic Regional Climate Model Intercomparison Project (ARC-MIP) Joint project of ACSYS/CliC NEG and GEWEX Working Group on Polar Clouds RCM experiments using common domain and boundary conditions. 5 RCM groups participating. Comparing with observations from SHEBA year: Oct/97 – Oct/98 http://cires.colorado.edu/lynch/arcmip/background.html


Slide14: Arctic Ocean Model Intercomparison Project (AOMIP) Initial evaluation of existing Arctic ocean model output. Coordinated model experiments underway now. Example shows transport streamfunction from various Arctic Ocean models, forced in various ways. Steiner et al., Ocean Modelling, 2003 http://fish.cims.nyu.edu/project_aomip/overview.html


Ice drift & atmospheric pressure changes: Ice drift & atmospheric pressure changes - Beaufort High decreased &shifted east in the 1990s. - Transpolar drift of ice shifted axis counterclockwise producing a more cyclonic motion in the 1990s


Slide16: The ACSYS Panel on Polar Products from Reanalysis (PPOR) was established in June 1997. It was tasked with the following: 1) Promote the evaluation and assessment of reanalysis products for polar regions, working with the reanalysis centers as appropriate. 2) Promote the development and implementation of techniques for blending modeled and in-situ data sources to provide optimal gridded products. 3) Give particular attention to precipitation fields, with the aim of providing data sets at spatial and temporal resolutions suitable for input to hydrologic models. 4) Maintain awareness of the work of reanalysis centers, liasing with them as appropriate on the representation of polar processes in future reanalysis efforts.


Slide17: PPOR involvement with ERA-40 Much of the effort by the Panel focused on NCEP-1 and ERA-15 evaluation and ERA-40 development: 1) Use of improved sea ice boundary conditions that include realistic sea ice concentrations. ERA-15 essentially used a “slab” depiction. 2) Use of a multi-layer formulation to improve depiction of 2-m air temperature over sea ice. 3) Improved treatments of the land surface (albedo, frozen soil hydrology) Over half of improved surface treatments in ERA-40 were driven by high-latitude concerns!


Slide18: Stand-alone sea-ice models, forced with historical analyses of atmospheric quantities, have provided insight into aspects of sea-ice behaviour that we cannot observe.


Slide19: Hilmer and Jung, 2000


Through the ACSYS decade a number of clear trends in Arctic climate began to emerge…: Through the ACSYS decade a number of clear trends in Arctic climate began to emerge… Extensive land areas show a warming trend in air temperature of as much as 5 deg C; warming over sea ice; precipitation has increased (less certain) Arctic sea ice extent has decreased over the satellite era; sea ice has thinned; there are now more melt days in summer Decreasing snow cover, (which can be correlated to surface temperature changes)


…trends in Arctic climate began to emerge: …trends in Arctic climate began to emerge Atlantic layer water in the Arctic has warmed; the mixed layer in the Beaufort Sea has become less saline Permafrost temperatures in the intermittent permafrost region of Alaska and the permafrost region of the Russian Arctic have been rising (falls over eastern Canada) Increased summer melt area over Greenland


Slide22: Arctic climate links to AO/NAO Rising AO lowers atmospheric pressure over the Arctic. (Thompson and Wallace, 1998) Low pressure spins up Polar Vortex, brings warm air to Greenland Sea and Russian Arctic Warm air over Greenland Sea allows warmer Atlantic Water in Arctic Ocean Warm air advection increases SAT warms permafrost Increase in Polar Vortex - More cyclonic ocean circulation Shift in front and Transpolar Drift Russian shelf water to Beaufort Increase in Polar Vortex - Weakens Beaufort High Increases open water Decreases Albedo Increases radiative heating & melt Freshens upper Beaufort Sea Cyclonic Arctic Ocean Circulation - Increases export of fresh water Increases stratification in Greenland Sea


Maximal temperature of Atlantic Water layer averaged for 1950-70s (a), 1990s (b) and difference between (b) and (a) (Alekseev et al., 2003, submitted to DSR): Maximal temperature of Atlantic Water layer averaged for 1950-70s (a), 1990s (b) and difference between (b) and (a) (Alekseev et al., 2003, submitted to DSR) a b c


Hydrographic cruises and SCICEX tracks through the ACSYS decade: Hydrographic cruises and SCICEX tracks through the ACSYS decade


BarKode: the Barents and Kara Seas oceanographic data base: BarKode: the Barents and Kara Seas oceanographic data base 2-year project, IAPO/IACPO and MMBI (1998 – 2000) Funding: European Polar Board, Norwegian Transport & Fate Program T-S profiles, 1898 – 1998, good coverage after 1920 206 300 stations from 11 institutions and 6 countries, civil and military original plus 9 standard layers (0 – 300 m depth) Cumulative station distribution:


Slide26: Average monthly SST, and data coverage: SST [°C]


Slide28: April 1866 April 2002 ACSYS Historical Ice Chart Archive (quicklook samples)


ACSYS Hydrological Programme: ACSYS Hydrological Programme Aimed towards understanding and quantifying the Arctic ocean freshwater budget Main components: Compilation of an Arctic Hydrological data base, in particular: - an Arctic precipitation data archive (GPCC, Offenbach) - an Arctic runoff database (GRDC, Koblenz) with the aim of determining the freshwater input from high latitude rivers into the Arctic basin Validation and use of reanalysis datasets of P, P-E


Slide31: & thanks to Mark Serreze Since 1936 there has been an upward trend in annual average discharge from Siberian rivers This may relate to both increased temperature and increased precipitation, but at present the link is not clear. Changing active layer thickness and permafrost may play a role. Increasing river discharge


Slide32: Mean Annual Cycles for the Major Eurasian Watersheds: Observed, NCEP-1, ERA-15 and ERA-40 Observations show July maxima and cold season minima. This basic pattern is reproduced by each model, but with warm-season precipitation too high in NCEP-1. ERA-40 and ERA-15 look quite good, and closely track each other.


Slide33: Aerological P-E: A Success Story Aerological estimates of precipitation minus evaporation (P-E, computed from wind and moisture profiles) from both NCEP-1 and ERA-15 look pretty good [Cullather et al., 2000; Rogers et al., 2001]. This is a strong point of reanalysis. The plots at right show mean January and July P-E (mm) from NCEP-1.


Slide34: ACSYS Data Management and Information Panel DMIP initial meeting March 1998 (St. Petersburg) DMIP active for 6 years Developed the ACSYS Data and Information System (ADIS) as a clearinghouse for project data and information Provided data management coordination with other WCRP projects Assisted other ACSYS Panels with data management related activities Provided recommendations to SSG on project data management International ACSYS/CliC Project Office (IACPO) and DMIP provided team support for data issues


Slide35: Functions of the ACSYS Data and Information System (ADIS) Provide information about and access to ACSYS and related datasets and information (location, discipline, time, archive source, author, contact information, etc) Establish single point of contact for information on ACSYS Develop and maintain meta-database describing datasets and related information, keeping current on the status of data collection campaigns and the status of ACSYS data projects Facilitate communication between user groups, information providers, and collaborating scientists Remain reference site for ACSYS Project legacy


Slide37: ADIS Holdings and Reference Materials Available 17 reports for ACSYS Project (Past issues of ACSYS Arctic Forecast and Ice and Climate News) 418 links to other archive centers, organizations, institutions and others involved in arctic research or activities 6130 publication references on research and activities in the Arctic (Journals, Conference volumes, etc.) 1012 datasets from ACSYS and ACSYS related projects during the 10 year lifetime 61 Reports from ACSYS meetings and sponsored gatherings


Slide39: ACSYS Project Legacy CDs: To include abstracts, publications, reports, organization, etc. A second CD will be the proceedings of the finasl ACSYS conference (St Petersburg, November 2003) including extended abstracts and presentations


Closing remarks: Closing remarks Demonstrated that there is a legacy from ACSYS in terms of e.g: Bringing people together (panels, workshops, conferences) Joint activities (modelling intercomparisons, promotion of observational networks, joint papers, data activities and input to global reanalyses etc.) Datasets ACSYS also encouraged coordinated national and international efforts in the Arctic SP and IP acted as a guide but were not constraining - much of what was achieved was dependent on the scientific opportunities and the individuals involved. ACSYS also laid the foundations for CliC as a global cryospheric component for WCRP


Slide42: Thank you