PNNL-13501 - Pacific Northwest National Laboratory

Application of a Crop Model
The resolution of global climate models is far too coarse
to drive crop models, particularly in regions with
topography as complex as in the Pacific Northwest. The
high spatial resolution meteorology simulated by the
PNNL RCM provides the opportunity to drive crop
models directly at the farm levels. The Erosion
Productivity Impact Calculator was driven by
meteorology simulated by the regional climate model to
assess the impact of a 2xCO2 “greenhouse” scenario of
climate change on winter wheat production in the Palouse
region in eastern Washington and portions of Oregon and
Idaho. The climate scenarios were extracted from the
regional climate model baseline and 2xCO2 simulations
for each 90 km grid cell of the regional climate model,
with differentiation by elevation. Winter wheat crop
yields for the baseline climate averaged 4.52 Mg ha -1
across the study region. The lowest yields (0 Mg ha -1 )
occurred at the higher elevations where temperatures were
not sufficient to allow for crop maturity. The highest
yields (7.32 Mg ha -1 ) occurred at intermediate elevations
with sufficient precipitation and mild temperatures.
Winter wheat mean yield increased to 5.45 Mg ha -1 for the
2xCO2 climate, which was markedly warmer and wetter
than baseline. Yield increases were principally explained
by decreases in both cold temperature and water stress.
Development of a Problem-Solving Environment
The collaboration center modeling system must be
intuitive and convenient if it is to be useful to the climate
impact assessment community. This will require
integration and coordination of each of the steps involved
in using the modeling system. A user interface for the
modeling system has been designed to guide the user
through the process of defining the regional domain and
resolution, selecting and interpolating the boundary
conditions, compiling and running the regional climate
model, mapping the regional climate simulation to the
selected resolution, and displaying the data. As a proof of
concept, a graphical user interface is being developed to
facilitate the preprocessing of information that provides
all data necessary for performing regional climate
simulations. The model preprocessing is a very
straightforward procedure masked by repetitive steps of
script editing, source code editing, and data file renaming.
By wrapping this process with Java codes to do the
nonintuitive and repetitive parts, the user will be given a
friendly, simple interface to the model.
240 FY 2000 Laboratory Directed Research and Development Annual Report
Summary and Conclusions
Major accomplishments have been achieved toward the
development of a prototype Collaboration Center. A twodimensional
decomposition parallel version of the
Laboratory’s regional climate model has been developed
and tested on various supercomputing platforms. The
hydrologic model has been enhanced to represent river
basins of different spatial scales. A reservoir model and
an optimization routine can be used to evaluate the
impacts of climate change using realistic water
management strategies for the altered climate conditions.
The procedures of using regional climate model outputs to
assess climate change impacts on crop yields have been
demonstrated using regional climate model simulations of
the control and 2xCO2 conditions to drive a crop model
over the Pacific Northwest Palouse region. A prototype
graphical user interface is being developed to facilitate the
preprocessing of information for performing regional
climate simulations. With the completion of these tasks,
we will be ready to operate an Collaboration Center to
deliver information of relevance to the climate change
impact assessment community.
References
Leung LR and SJ Ghan. 1995. “A subgrid
parameterization of orographic precipitation.” Theoretical
and Applied Climatology 52:95-118.
Leung LR and SJ Ghan. 1998. “Parameterizing subgrid
orographic precipitation and surface cover in climate
models.” Mon Wea Rev. 3271-3291.
Leung LR, MS Wigmosta, SJ Ghan, DJ Epstein, and LW
Vail. 1996. “Application of a subgrid orographic
precipitation/surface hydrology scheme to a mountain
watershed.” J. Geophys. Res. 101:12,803-12,817.
Wigmosta MS, LW Vail, and DP Lettenmaier. 1994. “A
distributed hydrology-vegetation model for complex
terrain.” Water Resour. Res. 30:1665-1679.
Publications
Contributor 1999. “Impacts of climate variability and
change in the Pacific Northwest.” A Regional Report for
the USGCRP National Assessment. Pacific Northwest
Regional Assessment Group, pp 109.