Search Results

You are looking at 1 - 5 of 5 items for

  • Author or Editor: R. C. Bales x
  • Refine by Access: All Content x
Clear All Modify Search

CONFIDENCE BUILDERS

Evaluating Seasonal Climate Forecasts from User Perspectives

Holly C. Hartmann
,
Thomas C. Pagano
,
S. Sorooshian
, and
R. Bales

Water managers, cattle ranchers, and wildland fire managers face several barriers to effectively using climate forecasts. Repeatedly, these decision makers state that they lack any quantitative basis for evaluating forecast credibility. That is because the evaluations currently available typically reflect forecaster perspectives rather than those of users, or are not available in forms that users can easily obtain or understand. Seasonal climate forecasts are evaluated from the perspective of distinct user groups, considering lead times, seasons, and criteria relevant to their specific situations. Examples show how results targeted for different user perspectives can provide different assessments of forecast performance.

The forecasts evaluated are the official seasonal temperature and precipitation outlooks issued by the NOAA Climate Prediction Center, produced in their present format since December 1994. It is considered how forecast formats can affect the ease, accuracy, and reliability of interpretation, and suggest that the “climatology” designation be modified to better reflect complete forecast uncertainty. A graphical product is presented that tracks time evolution of the forecasts and subsequent observations. The framework for evaluation has multiple quantitative forecast performance criteria that allow individuals to choose the level of sophistication of analysis that they prefer.

Full access
K. A. Dressler
,
S. R. Fassnacht
, and
R. C. Bales

Abstract

Temporal and spatial differences in snow-water equivalent (SWE) at 240 snow telemetry (SNOTEL) and at 500 snow course sites and a subset of 93 collocated sites were evaluated by examining the correlation of site values over the snow season, interpolating point measurements to basin volumes using hypsometry and a maximum snow extent mask, and variogram analysis. The lowest correlation at a point (r = 0.79) and largest interpolated volume differences (as much as 150 mm of SWE over the Gunnison basin) occurred during wet years (e.g., 1993). Interpolation SWE values based on SNOTEL versus snow course sites were not consistently higher or lower relative to each other. Interpolation rmse was comparable for both datasets, increasing later in the snow season. Snow courses correlate over larger distances and have less short-scale variability than SNOTEL sites, making them more regionally representative. Using both datasets in hydrologic models will provide a range of predicted streamflow, which is potentially useful for water resources management.

Full access
R. C. Bales
,
D. M. Liverman
, and
B. J. Morehouse

Managing the effects of climate change requires new approaches to develop and deliver relevant climate information to regional and local decision makers, and to infuse that knowledge into their decision support systems. In the southwestern United States an alternative approach to integrated climate assessment is changing how both researchers and stakeholders view climate information and vulnerability. In this region, climate assessment is an ongoing, sustained process to improve climate awareness, change scientific research on climate, build effective research–applications partnerships around climate variability and change, and maintain those partnerships. The multiple activities in this regional climate assessment serve as a pilot for a broader climate services organization in the United States, and both highlight the crucial need for regional climate services and provide important lessons for implementation.

Full access
T. J. Smyth
,
J. R. Fishwick
,
C. P. Gallienne
,
J. A. Stephens
, and
A. J. Bale

Abstract

A buoy system has been developed to continually monitor the operationally demanding coastal and open-shelf environment of the western English Channel. The buoys measure a range of physical and biogeochemical parameters on an hourly basis at two established long-term monitoring sites and the data are relayed to shore in near–real time using radio communications. This paper describes the technological challenges faced in such long-term marine deployments including the mooring design, warning systems, command and control, and radio communications, and how each were overcome. The fine temporal frequency data are used within an operational oceanography context, will underpin the long-term sustained observations in the western English Channel, and will form the basis of improvements to finescale ecosystem modeling to better predict any changes in the U.K. shelf seas.

Full access
J. Jin
,
X. Gao
,
Z.-L. Yang
,
R. C. Bales
,
S. Sorooshian
,
R. E. Dickinson
,
S. F. Sun
, and
G. X. Wu

Abstract

A comparative study of three snow models with different complexities was carried out to assess how a physically detailed snow model can improve snow modeling within general circulation models. The three models were (a) the U.S. Army Cold Regions Research and Engineering Laboratory Model (SNTHERM), which uses the mixture theory to simulate multiphase water and energy transfer processes in snow layers; (b) a simplified three-layer model, Snow–Atmosphere–Soil Transfer (SAST), which includes only the ice and liquid-water phases;and (c) the snow submodel of the Biosphere–Atmosphere Transfer Scheme (BATS), which calculates snowmelt from the energy budget and snow temperature by the force–restore method. Given the same initial conditions and forcing of atmosphere and radiation, these three models simulated time series of snow water equivalent, surface temperature, and fluxes very well, with SNTHERM giving the best match with observations and SAST simulation being close. BATS captured the major processes in the upper portion of a snowpack where solar radiation provides the main energy source and gave satisfying results for seasonal periods. Some biases occurred in BATS surface temperature and energy exchange due to its neglecting of liquid water and underestimating snow density. Ice heat conduction, meltwater heat transport, and the melt–freeze process of snow exhibit strong diurnal variations and large gradients at the uppermost layers of snowpacks. Using two layers in the upper 20 cm and one deeper layer at the bottom to simulate the multiphase snowmelt processes, SAST closely approximated the performance of SNTHERM with computational requirements comparable to those of BATS.

Full access