Fengge Su

Current Research

1. Modeling of land surface processes in La Plata Basin

The La Plata Basin is the second largest river (in discharge) in the Americas. Its mean discharge exceeds that of the Mississippi by about 20%, with a drainage area that is slightly smaller. The basin covers parts of five South American countries and plays a critical role in energy production, water resources, transportation, agriculture, and livestock production of the region. Significant changes in precipitation and discharge of many tributaries of La Plata have raised questions as to the relative roles of remote climate forcings (e.g., Atlantic and Pacific Ocean conditions) and land cover change as the proximate causes. Macroscale hydrology models provide a useful approach for understanding the nature and cause of these changes. We describe an application of the Variable Infiltration Capacity (VIC) macroscale hydrology model to simulate the land surface water balance of La Plata basin and its major tributaries, and to diagnose long-term changes. A 0.125°×0.125° river network based on 1 km DEM is the basis for routing VIC surface and subsurface runoff to produce simulated streamflows. The modeled water balance was evaluated with streamflow records from the three major subbasins of La Plata: the Parana, Paraguay, and Uruguay Rivers.

2. Streamflow Simulations of the Terrestrial Arctic Domain

A set of simulations with the land surface scheme VIC (Variable Infiltration Capacity) implemented at 100 km EASE-Grid across the pan-Arctic domain was conducted to evaluate the model's representation of various hydrologic processes in the Arctic land region, and to provide a consistent baseline hydroclimatology for the region. The pan-Arctic drainage basin system was partitioned into twelve regions for purposes of model implementation and testing. Streamflow observations at various basin outlets, satellite-based snow cover extent, observed dates of lake freeze-up and break-up, and sited monitored summer permafrost maximum active layer thickness were used to evaluate various simulated hydrologic variables. The results indicate that the VIC model was able to reproduce these hydrologic processes in the Arctic region. A 21-year average river inflow (1979-1999) to the Arctic Ocean from the AORB (Arctic Ocean River Basin) illustrated in Prowse et al. [2000], was estimated with the simulated streamflow as 3354 km3/yr, and 3596 km3/yr with the inclusion of the Arctic Archepelago, which are comparable to the previous estimates derived from the observed data.

3. Surface water and energy fluxes of the pan-Arctic land region based on a land surface model and ERA-40 reanalysis

One difficulty in evaluating simulated water and energy budgets over the pan-Arctic domain is the paucity of observations of land surface variables over large regions for long time periods. Reanalysis products have the advantage of being consistent and continuous in space and time, and provide the research community with new opportunities to understand the continental water and energy budgets, and to diagnose the performance of land surface parameterizations. In this paper we examine the depictions of land surface water and energy fluxes over the Arctic basin based on the VIC model and ERA-40 reanalysis. Specific objectives of present study are: 1) to evaluate the estimates of evaporation from the VIC model over the Arctic with observed P and the P-E derived from the ERA-40 wind and humidity fields ; 2) to know how well the VIC simulations and ERA-40 reanalysis agree with each other; 3) to identify apparent biases in both the VIC model and the ERA-40; 4) to understand how well we can model the latitudinal, seasonal, and interannual variation of the surface energy and hydrological balances of the Arctic land region.

Related Presentations

Hydrological evaluation of statellite precipitation products in La Plata Basin