VIC Land surface model overview Dennis P. Lettenmaier Department of Civil Engineering University of Washington for presentation at DOE ASM project meeting San Francisco December 14, 2007

VIC Modeling Framework Features specific to Cold-Land Processes: Two-layer energy balance snow model (Storck et al. 1999, Andreadis et al 2007) Frozen soil/permafrost algorithm (Cherkauer et al. 1999, 2003) Lakes and wetlands model (Bowling et al. 2004) Blowing snow algorithm (Bowling et al. 2004)

VIC Snow Algorithm Storck et al. 1999 Bowling et al. 2004 Andreadis et al 2007

VIC Frozen Soil Algorithm Cherkauer et al. 1999, 2003

Wetland Algorithm soil land surface runoff enters lake saturated evaporation depletes soil moisture lake recharges soil moisture Bowling et al. 2004

VIC River Network Routing Model Lohmann et. al. 1998

Snow Cover Extent Comparison NOAA-NESDIS weekly snow charts VIC

SWE, 1981 Thaw Depth, 1981

Fig. 9 Mean day of the year at when 5mm or less of SWE remained in the gridbox (final melt day) for 1980-2001. Slater, A.G., T.J. Bohn, J.L. McCreight, M.C. Serreze, and D.P. Lettenmaier, 2007: A Multi-Model Simulation of Pan-Arctic Hydrology, J. Geophys. Res. (accepted).

Lena at Kusur (Drainage Area: 2,430,000 km2)

Yenisey at Igarka (Drainage Area: 2,440,000 km2)

Digital river networks for the pan-Arctic drainage basins at the 100 km resolution, showing the watershed boundaries of the Lena, Yenisei, Ob, and Mackenzie. A routing scheme [Lohmann et al., 1996; 1998] was run offline using daily VIC surface and subsurface runoff as inputs to obtain simulated streamflows at the outlets of selected study basins. Eleven Regions were calibrated separately (not including Greenland) Calibration was focused on matching the shape of the monthly hydrograph and annual runoff. Parameter transfer to un-gauged basins was based on the hydro-climatology of the region.

WRF Software Architecture WRF system components Initialization WRF-Var Obs Data, Analyses, Forecast Dynamics Solvers ARW Solver NMM Solver … Standard Physics Interface Physics Packages Top-level Control, Memory Management, Nesting, Parallelism, External APIs Post processors, Verification Model coupling API enabling WRF to be coupled with other models such as ocean, and land models. WRF Software Architecture Hierarchical organization Multiple dynamical cores Plug compatible physics Abstract interfaces (APIs) to external packages Performance-portable Skamarock, W. C., J. B. Klemp, J. Dudhia, D. O. Gill, D. M. Barker, W. Wang and J. G. Powers, 2005: A Description of the Advanced Research WRF Version 2. Technical Note, NCAR/TN–468+STR.

Model Coupling subroutinization Componentization sequential concurrent ( http://www.mmm.ucar.edu/wrf/WG2/software_2.0/index.html ) subroutinization Componentization (maintains the component codes in close to their original forms) ( difficult to integrate with components developed independently by other groups ) sequential concurrent (Two-way coupling) (One-way coupling) For model coupling the API may be implemented using packages such as the Model Coupling Toolkit (MCT) or The Model Coupling Environment Library (MCEL) MCEL MCT (Single processor) (Parallel)

WRF I/O and Model Coupling API Subroutines ext_pkg_ioinit ext_pkg_ioexit ext_pkg_inquiry ext_pkg_open_for_read ext_pkg_open_for_read_begin ext_pkg_open_for_read_commit ext_pkg_open_for_write ext_pkg_open_for_write_begin ext_pkg_open_for_write_commit ext_pkg_inquire_opened ext_pkg_open_for_update ext_pkg_ioclose ext_pkg_read_field ext_pkg_write_field ext_pkg_get_next_var ext_pkg_end_of_frame ext_pkg_iosync ext_pkg_inquire_filename ext_pkg_get_var_info ext_pkg_set_time ext_pkg_get_next_time ext_pkg_get_var_ti_type set of routines ext_pkg_put_var_ti_type set of routines ext_pkg_get_var_td_type set of routines ext_pkg_put_var_td_type set of routines ext_pkg_get_dom_ti_type set of routines ext_pkg_put_dom_ti_type set of routines ext_pkg_get_dom_td_type set of routines ext_pkg_put_dom_td_type set of routines ext_pkg_warning_string ext_pkg_error_string