Search Results

You are looking at 1 - 4 of 4 items for :

  • Author or Editor: J. Roads x
  • Bulletin of the American Meteorological Society x
  • Refine by Access: All Content x
Clear All Modify Search
J. Roads

Since 27 September 1997, the Scripps Experimental Climate Prediction Center (ECPC) has been making near real-time experimental global and regional dynamical forecasts with the National Centers for Environmental Prediction (NCEP) global spectral model (GSM) and the corresponding regional spectral model (RSM), which is based on the GSM, but which provides higher-resolution simulations and forecasts for limited regions. The global and regional forecast skill of the GSM was previously described in several papers. The purpose of this paper is to describe the RSM-based U.S. regional forecast system, various biases and errors in these regional U.S. forecasts, as well as the significant skill of the of temperature, precipitation, soil moisture, relative humidity, wind speed, and planetary boundary layer height forecasts at weekly to seasonal time scales. The skill of these RSM forecasts is comparable to the skill of the GSM forecasts.

Full access
R. G. Lawford
,
R. Stewart
,
J. Roads
,
H.-J. Isemer
,
M. Manton
,
J. Marengo
,
T. Yasunari
,
S. Benedict
,
T. Koike
, and
S. Williams

Over the past 9 years, the Global Energy and Water Cycle Experiment (GEWEX), under the auspices of the World Climate Research Programme (WCRP), has coordinated the activities of the Continental Scale Experiments (CSEs) and other related research through the GEWEX Hydrometeorology Panel (GHP). The GHP contributes to the WCRP'S objective of “developing the fundamental scientific understanding of the physical climate system and climate processes [that is] needed to determine to what extent climate can be predicted and the extent of man's influence on climate.” It also contributes to more specific GEWEX objectives, such as determining the hydrological cycle and energy fluxes, modeling the global hydrological cycle and its impacts, developing a capability to predict variations in global and regional hydrological processes, and fostering the development of observing techniques, data management and assimilation systems. GHP activities include diagnosis, simulation, and experimental prediction of regional water balances and process and modeling studies aimed at understanding and predicting the variability of the global water cycle, with an emphasis on regional coupled land–atmosphere processes. GHP efforts are central to providing a scientific basis for assessing critical science issues, such as the consequences of climate change for the intensification of the global hydrological cycle and its potential impacts on regional water resources. This article provides an overview of the role and evolution of the GHP and describes scientific issues that the GHP is seeking to address in collaboration with the international science community.

Full access
E. S. Takle
,
J. Roads
,
B. Rockel
,
W. J. Gutowski Jr.
,
R. W. Arritt
,
I. Meinke
,
C. G. Jones
, and
A. Zadra

A new approach, called transferability intercomparisons, is described for advancing both understanding and modeling of the global water cycle and energy budget. Under this approach, individual regional climate models perform simulations with all modeling parameters and parameterizations held constant over a specific period on several prescribed domains representing different climatic regions. The transferability framework goes beyond previous regional climate model intercomparisons to provide a global method for testing and improving model parameterizations by constraining the simulations within analyzed boundaries for several domains. Transferability intercomparisons expose the limits of our current regional modeling capacity by examining model accuracy on a wide range of climate conditions and realizations. Intercomparison of these individual model experiments provides a means for evaluating strengths and weaknesses of models outside their “home domains” (domain of development and testing). Reference sites that are conducting coordinated measurements under the continental-scale experiments under the Global Energy and Water Cycle Experiment (GEWEX) Hydrometeorology Panel provide data for evaluation of model abilities to simulate specific features of the water and energy cycles. A systematic intercomparison across models and domains more clearly exposes collective biases in the modeling process. By isolating particular regions and processes, regional model transferability intercomparisons can more effectively explore the spatial and temporal heterogeneity of predictability. A general improvement of model ability to simulate diverse climates will provide more confidence that models used for future climate scenarios might be able to simulate conditions on a particular domain that are beyond the range of previously observed climates.

Full access
E. S. Takle
,
J. Roads
,
B. Rockel
,
W. J. Gutowski Jr.
,
R. W. Arritt
,
I. Meinke
,
C. G. Jones
, and
A. Zadra
Full access