Arctic Land Surface Hydrology: Moving Towards a Synthesis Princeton University December 4-6, 2006

Session Overview Introduction Project Overviews –NEESPI: Terrestrial Water and Energy Cycles –NEESPI: Changing Lake/Wetland Extent and Carbon Balance –NSF: Arctic Synthesis Overarching science questions among projects?

An integrated understanding of the terrestrial water and energy cycles across the NEESPI domain through observations and modeling Eric Wood, Princeton University Laura Bowling, Purdue University Alexander Oltchev, Severtsov Institute of Evolution and Ecological Problems with N. Speranskaya, K. Tysentko, N. Lemeshko, A. Sogavchev, N. Tchevakova, J. Kurbatova, N. Vygodskaya, A. Varlagin, and O. Panferov

Primary Science Question How have changes in climate, land cover and water management in northern Eurasia over the last half- century affected the land surface hydrology and flood frequency, and what are the impacts at regional to continental scales?

Subsidiary Science Questions To what extent can observed changes in seasonal discharge be attributed to land use change and water management versus climate variability? What are the effects of anthropogenic activities such as water and land management on water and energy fluxes across the NEESPI domain and how are they compounded by the presence of permafrost, snow, and wetlands? How well can hydrologic processes related to permafrost, land and wetland hydrology, and impacts from land cover change and water management be represented by our VIC LSM and how can it be improved through the synthesis of local field data and remote sensing observations? How does the hydroclimatology of the NEESPI region relate to continental and global water and energy cycle processes?

Work Plan Model improvements Data preparation & analysis Model testing and evaluation Retrospective reconstruction of water & energy balance Large-scale diagnostic and teleconnection studies (Bartalev et al., 2003)

Modeling Improved modeling of wetlands and lakes to deal with thaw lakes Retrospective reconstruction of water and energy balance ( ) Project future water and energy balance and the implications for water resources

Data Sets Ground-based observations –Soil moisture, evaporation, snow melt –Tower flux data from the Upper Volga catchment in the Central Forest Biosphere Reserve Meteorological Forcing Data –50-year, 1-degree, observation-based data set developed at Princeton and the University of Washington –GLDAS for near real-time simulations –ERA-40 Reanalysis

Data Sets Satellite Data –Understand the state of the land surface (snow extent, freeze/thaw process) –Provide inputs to terrestrial water- energy modeling (land cover and its change) –Evaluate/validate the VIC model simulations through snow extent and its evolution

Large Scale Diagnostic & Teleconnection Studies Correlation of DJF average states with CRU NAO index TemperaturePrecipitation Soil MoistureSWE Strong positive correlation at high latitudes and southern US

Collaborative research: Understanding change in the climate and hydrology of the Arctic land region, synthesizing the results of the ARCSS Fresh Water Initiative Projects Eric Wood Dennis Lettenmaier John Cassano Charles Vörösmarty

Science Questions How do changes in arctic land processes affect the climate of the region? What are the implications of these changes for the arctic hydrologic cycle (including coupling and feedbacks with the atmosphere)? What are the impacts of changes in the arctic freshwater system on global climate?

Science Questions How can the results from the FWI studies be used to better understand the hydrologic processes affecting observed change in the freshwater balance of the pan arctic land system? To what extent are the observed changes in Arctic terrestrial hydrologic cycle due to imported change from other regions (via atmospheric processes), and to what extent are the observed terrestrial hydrologic changes exported to the atmosphere and to the ocean system?

Scientific Perspective Figure 1: Time series of discharge of the Yenesei and Ob Rivers over the last 50 years.

Conflicting Explanations for Discharge Trends Increased northward atmospheric moisture transport Nijssen et al. (2001), Wu et al. (2005), Arnel (2005) Human effects (reservoir construction) Yang et al. (2004), Ye et al. (2003), McClelland et al. (2004) Release of water from permafrost degradation Frauenfield et al. (2004), Zhang et al. (2003), Ye et al. (2003) Climate-induced changes to the land surface (increased fire frequency) McClelland et al. (2004), Conrad and Ivanova (1997) Changes in lake areal extent and storage Smith et al. (2005) Change in evapotranspirationGedney et al. (2006) Change in snow accumulation / ablation patterns Brown (2000), Groisman et al. (1994), Robinson et al. (1990)

FWI Projects of Interest Larry Hinzman (University of Alaska) Int’l observation system for key hydrologic fluxes & state variables; Used for parameterizations Doug Kane (University of Alaska) Compile data into electronic data base. Used to force model & evaluate model performance Dennis Lettenmaier (Univ. of Washington) Performed VIC runs over pan-arctic; assembled forcing & evaluation data sets Glen Liston (Colorado State Univ.) Field campaign to measure surface fluxes. Used to evaluate VIC sublimation algorithm Igor Semiletov (University of Alaska) Evaluate inter-annual and intra-seasonal variability of atmospheric forcings over Siberia. Mark Serreze Multi-model hindcast of pan-arctic land surface conditions.

FWI Projects of Interest Laurence Smith (UCLA) Disappearance of lakes over parts of Siberia over the last 30 years Charles Vörösmarty (UNH) Extension of Arctic-RIMS data set Daqing Yang (University of Alaska) Constructing bias-adjusted data, used for offline forcings Tingjun Zhang (Univ. of Colorado) Changes in freeze-thaw and permafrost dynamics, data used for evaluation of permafrost algorithm Tony England (Univ. of Michigan) Remote sensing estimates of active layer depth, used to evaluate model estimates Marika Holland Global coupled model results to evaluate UVic model

Approach Arctic-RIMS VIC with Cold Land Updates University of Washington Multi- Model Ensemble Prediction System Regional Climate Models –Polar MM5 / WRF UVic Earth System Climate Model

Work Plan Enhancement of Artic-RIMS with model integration output Workshops & Chapman Conference Evaluate and improve hydrologic parameterizations using FWI data Uncoupled, partially coupled, and fully coupled regional model feedback studies Global simulations to evaluate teleconnections associated with arctic freshwater change Exploratory 21 st century scenario analysis

Arctic-RIMS

Science Questions Where they intersect

Crossover Areas Lake/wetland extent and effect on hydrology Permafrost active layer depth –Effect on wetlands & carbon –Effect on land surface hydrology Changes in land surface hydrologic processes & their effect on the region’s climate Land cover changes