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S. P. Hayes, M. J. McPhaden, and J. M. Wallace

Abstract

Temporal correlations between near-equatorial surface wind and sea-surface temperatures (SST) at 11°W in the eastern Pacific Ocean are investigated using data from an array of moored sensors between 5°N and 5°S. The signature of tropical instability waves with periods of 20–30 days is apparent in time series of SST and both the meridional and zonal wind components. Results indicate the existence of a band of pronounced horizontal divergence in the surface wind field associated with the large meridional SST gradient (equatorial front) normally located just north of the equator. Perturbations of the equatorial front by the instability waves induce fluctuations in the overlying winds. Evidence of the air-sea coupling is stronger in time series of the meridional gradients of wind and SST than between time series of the variables themselves. The meridional differencing serves as a high-pass filter in the space domain, which removes planetary-scale wind fluctuations that are unrelated to the local SST perturbations. The wind fluctuations observed in association with tropical instability waves are on the order of 1–2 m s−1.

These results indicate that SST variability on weekly to monthly time scales forces perturbations in the surface wind field. It is suggested that the principal coupling mechanism in this region is the modification of the atmospheric boundary layer stratification. Over the equatorial cold SST tongue the vertical wind shear within the lowest 100 m of the atmosphere is strong and the surface winds are conspicuously weak. As the air flows northward across the equatorial front the boundary layer becomes destabilized, momentum is mixed downward, and the surface winds increase.

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S. P. Hayes, J. M. Toole, and L. J. Mangum

Abstract

An analysis of nine hydrographic sections collected in 1979–81 along 110°W in the equatorial Pacific Ocean is presented. Sections typically sampled the upper 500 m of the water column from 10°N to 3°S. Analysis concentrated on the repeated sections north of the equator. Examination of the variability of eastward transport indicates that the North Equatorial Countercurrent (NECC) and the Northern Subsurface Countercurrent (NSCC) cannot be distinguished solely on the basis of water-mass structure. However, using a potential density surface (σθ = 25.0) as a current boundary we find that on average the NSCC transports 13.7 × 106 m3 s−1 compared to only 8.3 × 106 m3 s−1 for the NECC. The NSCC flow is sufficiently stable so that meridional surface dynamic-height gradient remains a good index of zonal transport fluctuations. Variations in surface dynamic height observed in our data and in the EASTROPAC data indicate a seasonal cycle to the surface topography with large values for the equatorial and countercurrent depressions in boreal autumn and small values in spring. Broad meridional correlation scales for surface dynamic height were found; equatorial fluctuations were significantly positively correlated with variability at latitudes out to 5°N and significantly negatively correlated with variability at 9–10°N. The meridional and vertical structures or vertical displacement were reduced to two empirical orthogonal function (EOF) modes which contained 78% of the variance. These modes did not suggest simple dynamical interpretation in terms of first-vertical-mode linear waves.

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J. L. Hayes, R. T. Williams, and M. A. Rennick

Abstract

The growth of synoptic scale cyclones imbedded in a baroclinically unstable zonal flow over a long straight mountain range is investigated. Two different analytical models of the phenomenon are used.

The first model uses the linearized quasi-geostrophic equations. It allows a simple superposition of a steady state mountain forced solution and a transient Eady wave. There is no dynamic interaction between the two solutions, but the time evolution of the combined solution reproduces many characteristics of a disturbance passing over the Rocky Mountains.

The semigeostrophic equations are used in the second model. These equations allow a linear solution in transform space, but the transformation of the solution to physical space is nonlinear. This allows an interaction between the mountain forced and transient solutions. The minimum pressure developed by the semigeostrophic system is the same as that of the quasi-geostrophic system. However, the shape of the wave is distorted. This effect is caused by the divergent part of the mean flow over the mountain ridge.

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J. L. Hayes, R. T. Williams, and M. A. Rennick

Abstract

The effect of topography on the evolution of a disturbance in a baroclinically unstable mean flow is studied using a three-dimensional primitive equation model. A procedure is developed to compare control integrations with no topography with integrations that contain topography. It is found that lee cyclogenesis is caused primarily by the superposition of a growing baroclinic wave with a steady, orographically forced wave of the same scale. Some additional lee growth is found that may be orographically enhanced, or it may be related to certain small problems in the experimental set up. As the disturbances move over the ridge, they are deflected to the north on the upwind side Wore returning to their original latitudes on the lee side. The numerical results in this paper are in general agreement with the authors' previous analytic study.

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R. E. Pandya, D. R. Smith, M. K. Ramamurthy, P. J. Croft, M. J. Hayes, K. A. Murphy, J. D. McDonnell, R. M. Johnson, and H. A. Friedman

The 11th American Meteorological Society (AMS) Education Symposium was held from 13 to 15 January 2002 in Orlando, Florida, as part of the 82nd Annual Meeting of the AMS. The theme of the symposium was “creating opportunities in educational outreach in the atmospheric and related sciences.” Drawing from traditional strengths in meteorology and numerous national recommendations, the presentations and posters of the symposium highlighted three opportunities for reform. These opportunities build on partnerships between diverse educational stakeholders, efforts to make science education more like scientific practice, and strategies that place the atmospheric sciences within a larger, multidisciplinary context that includes oceanography, hydrology, and earth-system science.

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Rajul E. Pandya, David R. Smith, Donna J. Charlevoix, Wayne Hart, Marianne J. Hayes, Shirley T. Murillo, Kathleen A. Murphy, Diane M. Stanitski, and Thomas M. Whittaker
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P. A. Phoebus, D. R. Smith, R. A. McPherson, M. J. Hayes, J. M. Moran, P. J. Croft, J. T. Snow, E. S. Takle, R. L. Fauquet, L. M. Bastiaans, and J. W. Zeitler

The American Meteorological Society (AMS) held its Seventh Symposium on Education in conjunction with the 78th AMS Annual Meeting. The theme of the symposium was “Atmospheric and Oceanographic Education: Advancing Our Awareness.” Thirty-six oral presentations and 47 poster presentations summarized a variety of educational programs or examined educational issues relevant for both the precollege and university levels.

There were also joint sessions held with the Second Conference on Coastal Atmospheric and Oceanic Prediction and Processes and the Ninth Conference on Interaction of the Sea and Atmosphere, as well as the 10th Symposium on Meteorological Observations and Instruments. Over 200 people representing a wide spectrum of the Society attended one or more of the sessions during this two-day event.

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Ikrom Artikov, Stacey J. Hoffman, Gary D. Lynne, Lisa M. Pytlik Zillig, Qi Hu, Alan J. Tomkins, Kenneth G. Hubbard, Michael J. Hayes, and William Waltman

Abstract

Results of a set of four regression models applied to recent survey data of farmers in eastern Nebraska suggest the causes that drive farmer intentions of using weather and climate information and forecasts in farming decisions. The model results quantify the relative importance of attitude, social norm, perceived behavioral control, and financial capability in explaining the influence of climate-conditions information and short-term and long-term forecasts on agronomic, crop insurance, and crop marketing decisions. Attitude, serving as a proxy for the utility gained from the use of such information, had the most profound positive influence on the outcome of all the decisions, followed by norms. The norms in the community, as a proxy for the utility gained from allowing oneself to be influenced by others, played a larger role in agronomic decisions than in insurance or marketing decisions. In addition, the interaction of controllability (accuracy, availability, reliability, timeliness of weather and climate information), self-efficacy (farmer ability and understanding), and general preference for control was shown to be a substantive cause. Yet control variables also have an economic side: The farm-sales variable as a measure of financial ability and motivation intensified and clarified the role of control while also enhancing the statistical robustness of the attitude and norms variables in better clarifying how they drive the influence. Overall, the integrated model of planned behavior from social psychology and derived demand from economics, that is, the “planned demand model,” is more powerful than models based on either of these approaches alone. Taken together, these results suggest that the “human dimension” needs to be better recognized so as to improve effective use of climate and weather forecasts and information for farming decision making.

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Vikram M. Mehta, Cody L. Knutson, Norman J. Rosenberg, J. Rolf Olsen, Nicole A. Wall, Tonya K. Bernadt, and Michael J. Hayes

Abstract

Many decadal climate prediction efforts have been initiated under phase 5 of the World Climate Research Programme Coupled Model Intercomparison Project. There is considerable ongoing discussion about model deficiencies, initialization techniques, and data requirements, but not much attention is being given to decadal climate information (DCI) needs of stakeholders for decision support. Here, the authors report the results of exploratory activities undertaken to assess DCI needs in water resources and agriculture sectors, using the Missouri River basin as a case study. This assessment was achieved through discussions with 120 stakeholders.

Stakeholders’ awareness of decadal dry and wet spells and their societal impacts in the basin are described, and stakeholders’ DCI needs and potential barriers to their use of DCI are enumerated. The authors find that impacts, including economic impacts, of decadal climate variability (DCV) on water and agricultural production in the basin are distinctly identifiable and characterizable. Stakeholders have clear notions about their needs for DCI and have offered specific suggestions as to how these might be met. However, while stakeholders are eager to have climate information, including decadal climate outlooks (DCOs), there are many barriers to the use of such information. The first and foremost barrier is that the credibility of DCOs is yet to be established. Second, the nature of institutional rules and regulations, laws, and legal precedents that pose obstacles to the use of DCOs must be better understood and means to modify these, where possible, must be sought. For the benefit of climate scientists, these and other stakeholder needs are also articulated in this paper.

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Qi Hu, Lisa M. Pytlik Zillig, Gary D. Lynne, Alan J. Tomkins, William J. Waltman, Michael J. Hayes, Kenneth G. Hubbard, Ikrom Artikov, Stacey J. Hoffman, and Donald A. Wilhite

Abstract

Although the accuracy of weather and climate forecasts is continuously improving and new information retrieved from climate data is adding to the understanding of climate variation, use of the forecasts and climate information by farmers in farming decisions has changed little. This lack of change may result from knowledge barriers and psychological, social, and economic factors that undermine farmer motivation to use forecasts and climate information. According to the theory of planned behavior (TPB), the motivation to use forecasts may arise from personal attitudes, social norms, and perceived control or ability to use forecasts in specific decisions. These attributes are examined using data from a survey designed around the TPB and conducted among farming communities in the region of eastern Nebraska and the western U.S. Corn Belt. There were three major findings: 1) the utility and value of the forecasts for farming decisions as perceived by farmers are, on average, around 3.0 on a 0–7 scale, indicating much room to improve attitudes toward the forecast value. 2) The use of forecasts by farmers to influence decisions is likely affected by several social groups that can provide “expert viewpoints” on forecast use. 3) A major obstacle, next to forecast accuracy, is the perceived identity and reliability of the forecast makers. Given the rapidly increasing number of forecasts in this growing service business, the ambiguous identity of forecast providers may have left farmers confused and may have prevented them from developing both trust in forecasts and skills to use them. These findings shed light on productive avenues for increasing the influence of forecasts, which may lead to greater farming productivity. In addition, this study establishes a set of reference points that can be used for comparisons with future studies to quantify changes in forecast use and influence.

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