scholarly journals The Role of Temperature Variability on Seasonal Electricity Demand in the Southern US

2021 ◽  
Vol 3 ◽  
Author(s):  
Dylan Cawthorne ◽  
Anderson Rodrigo de Queiroz ◽  
Hadi Eshraghi ◽  
Arumugam Sankarasubramanian ◽  
Joseph F. DeCarolis
Keyword(s):  
Time Scales ◽  
General Circulation ◽  
General Circulation Models ◽  
Electricity Demand ◽  
Temperature Variability ◽  
Seasonal Temperature ◽  
Power Demand ◽  
Southern Us ◽  
Demand Forecasts

The reliable and affordable supply of energy through interconnected systems represent a critical infrastructure challenge. Seasonal and interannual variability in climate variables—primarily precipitation and temperature—can increase the vulnerability of such systems during climate extremes. The objective of this study is to understand and quantify the role of temperature variability on electricity consumption over representative areas of the Southern United States. We consider two states, Tennessee and Texas, which represent different climate regimes and have limited electricity trade with adjacent regions. Results from regression tests indicate that regional population growth explains most of the variability in electricity demand at decadal time scales, whereas temperature explains 44–67% of the electricity demand variability at seasonal time scales. Seasonal temperature forecasts from general circulation models are also used to develop season-ahead power demand forecasts. Results suggest that the use of climate forecasts can potentially help to project future residential electricity demand at the monthly time scale.Capsule Summary: Seasonal temperature forecasts from GCMs can potentially help in predicting season-ahead residential power demand forecasts for states in the Southern US.

scholarly journals A Lagrangian-Based Approach for Determining Trajectories Taxonomy and Turbulence Regimes

2007 ◽  
Vol 37 (6) ◽  
pp. 1584-1609 ◽  
Author(s):  
Volfango Rupolo
Keyword(s):  
Time Scales ◽  
General Circulation ◽  
Eddy Diffusivity ◽  
General Circulation Models ◽  
Velocity Correlation ◽  
Velocity Correlation Function ◽  
Different Shapes ◽  
Surface Drifters ◽  
Current Systems

Abstract The use of the ratio between the acceleration and velocity time scales y = Ta/Tυ to separate Lagrangian trajectories in homogeneous classes is proposed. In fact, when analyzing subsurface floats data in the Atlantic Ocean and surface drifters data in the world’s ocean basins, it is observed that trajectories having different values of y are characterized by different shapes, correlation, and dispersal properties. In particular, trajectories having similar values of the acceleration and velocity time scales clearly show the influence of eddies and are characterized by an oscillating velocity correlation function. It is shown here that this trajectory screening is a useful procedure to rationalize the analysis of real Lagrangian trajectories and to avoid a mixture of different regimes, when averaging quantities. The mean statistical quantities computed averaging on quasi-homogeneous datasets put in evidence the role of the coherent structures in the dispersion properties, both in time and in the main oceanic current systems. These results are discussed in the context of the parameterization of eddy diffusivity in general circulation models.

scholarly journals On the role of Eurasian autumn snow cover in dynamical seasonal predictions 

2021 ◽  
Author(s):  
Paolo Ruggieri ◽  
Marianna Benassi ◽  
Stefano Materia ◽  
Daniele Peano ◽  
Constantin Ardilouze ◽  
...  
Keyword(s):  
Snow Cover ◽  
Northern Hemisphere ◽  
Land Surface ◽  
General Circulation ◽  
Dominant Role ◽  
General Circulation Models ◽  
The Arctic ◽  
Seasonal Forecasts ◽  
Eurasian Snow

<p>Seasonal climate predictions leverage on many predictable or persistent components of the Earth system that can modify the state of the atmosphere and of relant weather related variable such as temprature and precipitation. With a dominant role of the ocean, the land surface provides predictability through various mechanisms, including snow cover, with particular reference to Autumn snow cover over the Eurasian continent. The snow cover alters the energy exchange between land surface and atmosphere and induces a diabatic cooling that in turn can affect the atmosphere both locally and remotely. Lagged relationships between snow cover in Eurasia and atmospheric modes of variability in the Northern Hemisphere have been investigated and documented but are deemed to be non-stationary and climate models typically do not reproduce observed relationships with consensus. The role of Autumn Eurasian snow in recent dynamical seasonal forecasts is therefore unclear. In this study we assess the role of Eurasian snow cover in a set of 5 operational seasonal forecast system characterized by a large ensemble size and a high atmospheric and oceanic resolution. Results are compemented with a set of targeted idealised simulations with atmospheric general circulation models forced by different snow cover conditions. Forecast systems reproduce realistically regional changes of the surface energy balance associated with snow cover variability. Retrospective forecasts and idealised sensitivity experiments converge in identifying a coherent change of the circulation in the Northern Hemisphere. This is compatible with a lagged but fast feedback from the snow to the Arctic Oscillation trough a tropospheric pathway.</p>

scholarly journals The potential benefit of the use of seasonal forecast during the agricultural economic year 2019-2020 in Bulgaria

2021 ◽  
Vol 13 (30) ◽  
pp. 64-73
Author(s):  
Ilian Gospodinov ◽  
◽  
Valentin Kazandjiev ◽  
Veska Georgieva ◽  
◽  
...  
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Seasonal Forecast ◽  
Ensemble Prediction ◽  
Seasonal Temperature ◽  
Current Standard ◽  
Middle Latitudes ◽  
Chaotic Nature ◽  
Seasonal Time Scale ◽  
Prediction Systems

Seasonal forecasting gained ground in the last decades by building up knowledge on the processes staying behind the climate variability at the seasonal time scale, constructing ever more sophisticated general circulation models and ensemble prediction systems and thus enhancing forecast skill. The seasonal forecast is a climate forecast and is therefore probabilistic in nature. The predictability of the atmospheric circulation at the seasonal scale is limited in the middle latitudes, where Europe and Bulgaria are situated, by its chaotic nature. The current standard is to give forecast of the potential anomalies of the mean seasonal temperature and the seasonal amount of precipitation. The National Institute of Meteorology and Hydrology of Bulgaria has been issuing operationally seasonal forecast for the country since 2005. The goal of this work is to discuss the seasonal forecast for the last agricultural year 2019-2020. The year was characterized by its drought conditions especially in Eastern Bulgaria. This work would show the extent to which it was successfully predicted and how the seasonal forecast could have been used for decision making. The use of agrometeorological indices for the analysis of the skill of the seasonal forecast has been shown.

scholarly journals Time scales of the European surface air temperature variability: The role of the 7–8 year cycle

2016 ◽  
Vol 43 (2) ◽  
pp. 902-909 ◽  
Author(s):  
Nikola Jajcay ◽  
Jaroslav Hlinka ◽  
Sergey Kravtsov ◽  
Anastasios A. Tsonis ◽  
Milan Paluš
Keyword(s):  
Time Scales ◽  
Air Temperature ◽  
Surface Air Temperature ◽  
Temperature Variability

scholarly journals Geophysical fluid dynamics: whence, whither and why?

2016 ◽  
Vol 472 (2192) ◽  
pp. 20160140 ◽  
Author(s):  
Geoffrey K. Vallis
Keyword(s):  
Fluid Dynamics ◽  
General Circulation ◽  
Condensed Matter ◽  
General Circulation Models ◽  
Condensed Matter Physics ◽  
Geophysical Fluid Dynamics ◽  
Emergent Phenomena ◽  
Interacting Systems ◽  
Geophysical System

This article discusses the role of geophysical fluid dynamics (GFD) in understanding the natural environment, and in particular the dynamics of atmospheres and oceans on Earth and elsewhere. GFD, as usually understood, is a branch of the geosciences that deals with fluid dynamics and that, by tradition, seeks to extract the bare essence of a phenomenon, omitting detail where possible. The geosciences in general deal with complex interacting systems and in some ways resemble condensed matter physics or aspects of biology, where we seek explanations of phenomena at a higher level than simply directly calculating the interactions of all the constituent parts. That is, we try to develop theories or make simple models of the behaviour of the system as a whole. However, these days in many geophysical systems of interest, we can also obtain information for how the system behaves by almost direct numerical simulation from the governing equations. The numerical model itself then explicitly predicts the emergent phenomena—the Gulf Stream, for example—something that is still usually impossible in biology or condensed matter physics. Such simulations, as manifested, for example, in complicated general circulation models, have in some ways been extremely successful and one may reasonably now ask whether understanding a complex geophysical system is necessary for predicting it. In what follows we discuss such issues and the roles that GFD has played in the past and will play in the future.

scholarly journals Radiative-Convective Equilibrium Model Intercomparison Project

2017 ◽  
Author(s):  
Allison A. Wing ◽  
Kevin A. Reed ◽  
Masaki Satoh ◽  
Bjorn Stevens ◽  
Sandrine Bony ◽  
...  
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Cloud Fraction ◽  
Model Intercomparison ◽  
Tropical Circulation ◽  
Cloud Feedbacks ◽  
Single Column ◽  
Intercomparison Project ◽  
Self Aggregation

Abstract. RCEMIP, an intercomparison of multiple types of models configured in radiative-convective equilibrium (RCE), is proposed. RCE is an idealization of the climate system in which there is a balance between radiative cooling of the atmosphere and heating by convection. The scientific objectives of RCEMIP are three-fold. First, clouds and climate sensitivity will be investigated in the RCE setting. This includes determining how cloud fraction changes with warming and the role of self-aggregation of convection. Second, RCEMIP will quantify the dependence of the degree of convective aggregation and tropical circulation regimes on temperature. Finally, by providing a common baseline, RCEMIP will allow the robustness of the RCE state, cloud feedbacks, and convective aggregation across the spectrum of models to be assessed. A novel aspect and major advantage of RCEMIP is the accessibility of the RCE framework to a variety of models, including cloud-resolving models, general circulation models, global cloud-resolving models, and single column models.

scholarly journals Gulf Stream Variability in Five Oceanic General Circulation Models

2006 ◽  
Vol 36 (11) ◽  
pp. 2119-2135 ◽  
Author(s):  
Gaëlle de Coëtlogon ◽  
Claude Frankignoul ◽  
Mats Bentsen ◽  
Claire Delon ◽  
Helmuth Haak ◽  
...  
Keyword(s):  
Time Scales ◽  
Gulf Stream ◽  
General Circulation ◽  
General Circulation Models ◽  
Meridional Overturning Circulation ◽  
Fast Time ◽  
Wind Stress Curl ◽  
Similar Time ◽  
The North ◽  
Basin Scale

Abstract Five non-eddy-resolving oceanic general circulation models driven by atmospheric fluxes derived from the NCEP reanalysis are used to investigate the link between the Gulf Stream (GS) variability, the atmospheric circulation, and the Atlantic meridional overturning circulation (AMOC). Despite the limited model resolution, the temperature at the 200-m depth along the mean GS axis behaves similarly in most models to that observed, and it is also well correlated with the North Atlantic Oscillation (NAO), indicating that a northward (southward) GS shift lags a positive (negative) NAO phase by 0–2 yr. The northward shift is accompanied by an increase in the GS transport, and conversely the southward shift with a decrease in the GS transport. Two dominant time scales appear in the response of the GS transport to the NAO forcing: a fast time scale (less than 1 month) for the barotropic component, and a slower one (about 2 yr) for the baroclinic component. In addition, the two components are weakly coupled. The GS response seems broadly consistent with a linear adjustment to the changes in the wind stress curl, and evidence for baroclinic Rossby wave propagation is found in the southern part of the subtropical gyre. However, the GS shifts are also affected by basin-scale changes in the oceanic conditions, and they are well correlated in most models with the changes in the AMOC. A larger AMOC is found when the GS is stronger and displaced northward, and a higher correlation is found when the observed changes of the GS position are used in the comparison. The relation between the GS and the AMOC could be explained by the inherent coupling between the thermohaline and the wind-driven circulation, or by the NAO variability driving them on similar time scales in the models.

Improving the Prediction of Winter Precipitation and Temperature over the Continental United States: Role of the ENSO State in Developing Multimodel Combinations

2010 ◽  
Vol 138 (6) ◽  
pp. 2447-2468 ◽  
Author(s):  
Naresh Devineni ◽  
A. Sankarasubramanian
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Winter Precipitation ◽  
Skill Levels ◽  
Higher Weights ◽  
Atmospheric General Circulation Models ◽  
Multimodel Ensembles ◽  
Precipitation And Temperature

Abstract Recent research into seasonal climate prediction has focused on combining multiple atmospheric general circulation models (GCMs) to develop multimodel ensembles. A new approach to combining multiple GCMs is proposed by analyzing the skill levels of candidate models contingent on the relevant predictor(s) state. To demonstrate this approach, historical simulations of winter (December–February, DJF) precipitation and temperature from seven GCMs were combined by evaluating their skill—represented by mean square error (MSE)—over similar predictor (DJF Niño-3.4) conditions. The MSE estimates are converted into weights for each GCM for developing multimodel tercile probabilities. A total of six multimodel schemes are considered that include combinations based on pooling of ensembles as well as on the long-term skill of the models. To ensure the improved skill exhibited by the multimodel scheme is statistically significant, rigorous hypothesis tests were performed comparing the skill of multimodels with each individual model’s skill. The multimodel combination contingent on Niño-3.4 shows improved skill particularly for regions whose winter precipitation and temperature exhibit significant correlation with Niño-3.4. Analyses of these weights also show that the proposed multimodel combination methodology assigns higher weights for GCMs and lesser weights for climatology during El Niño and La Niña conditions. On the other hand, because of the limited skill of GCMs during neutral Niño-3.4 conditions, the methodology assigns higher weights for climatology resulting in improved skill from the multimodel combinations. Thus, analyzing GCMs’ skill contingent on the relevant predictor state provides an alternate approach for multimodel combinations such that years with limited skill could be replaced with climatology.

Filtering of Milankovitch Cycles by Earth's Geography

1991 ◽  
Vol 35 (2) ◽  
pp. 157-173 ◽  
Author(s):  
David A. Short ◽  
John G. Mengel ◽  
Thomas J. Crowley ◽  
William T. Hyde ◽  
Gerald R. North
Keyword(s):  
Time Series ◽  
General Circulation ◽  
Climate Model ◽  
Temperature Response ◽  
General Circulation Models ◽  
Complex Model ◽  
Milankovitch Cycles ◽  
Seasonal Temperature ◽  
Orbital Forcing ◽  
Model Response

AbstractEarth's land-sea distribution modifies the temperature response to orbitally induced perturbations of the seasonal insolation. We examine this modification in the frequency domain by generating 800,000-yr time series of maximum summer temperature in selected regions with a linear, two-dimensional, seasonal energy balance climate model. Previous studies have demonstrated that this model has a sensitivity comparable to general circulation models for the seasonal temperature response to orbital forcing on land. Although the observed response in the geologic record is sometimes significantly different than modeled here (differences attributable to model limitations and feedbacks involving the ocean-atmosphere-cryosphere system), there are several results of significance: (1) in mid-latitude land areas the orbital signal is translated linearly into a large (>10°C) seasonal temperature response; (2) although the modeled seasonal response to orbital forcing on Antarctica is 6°C, the annual mean temperature effect (<2°C) is only about one-fifth that inferred from the Vostok ice core, and primarily restricted to periods near 41,000 yr; (3) equatorial regions have the richest spectrum of temperature response, with a 3000-yr phase shift in the precession response, plus some power near periods of 10,000–12,000 yr, 41,000 yr, 100,000 yr, and 400,000 yr. Peaks at 10,000–12,000 yr and 100,000 and 400,000 yr result from the twice-yearly passage of the sun across the equator. The complex model response in equatorial regions has some resemblance to geologic time series from this region. The amplification of model response over equatorial land masses at the 100,000-yr period may explain some of the observed large variance in this band in geologic records, especially in pre-Pleistocene records from times of little or no global ice volume.

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