Regional Energy Demand Responses To Climate Change: Methodology And Application To The Commonwealth Of Massachusetts

Climate is a major determinant of energy demand. Changes in climate may alter energy demand as well as energy demand patterns. This study investigates the implications of climate change for energy demand under the hypothesis that impacts are scale dependent due to region-specific climatic variables, infrastructure, socioeconomic, and energy use profiles. In this analysis we explore regional energy demand responses to climate change by assessing temperature-sensitive energy demand in the Commonwealth of Massachusetts. The study employs a two-step estimation and modeling procedure. The first step evaluates the historic temperature sensitivity of residential and commercial demand for electricity and heating fuels, using a degree-day methodology. We find that when controlling for socioeconomic factors, degree-day variables have significant explanatory power in describing historic changes in residential and commercial energy demands. In the second step, we assess potential future energy demand responses to scenarios of climate change. Model results are based on alternative climate scenarios that were specifically derived for the region on the basis of local climatological data, coupled with regional information from available global climate models. We find notable changes with respect to overall energy consumption by, and energy mix of the residential and commercial sectors in the region. On the basis of our findings, we identify several methodological issues relevant to the development of climate change impact assessments of energy demand.     

Coseismic and post-seismic signatures of the Sumatra 2004 December and 2005 March earthquakes in GRACE satellite gravity

The GRACE satellite mission has been measuring the Earth's gravity field and its temporal variations since 2002 April. Although these variations are mainly due to mass transfer within the geofluid envelops, they also result from mass displacements associated with phenomena including glacial isostatic adjustment and earthquakes. However, these last contributions are difficult to isolate because of the presence of noise and of geofluid signals, and because of GRACE's coarse spatial resolution (>400 km half-wavelength). In this paper, we show that a wavelet analysis on the sphere helps to retrieve earthquake signatures from GRACE geoid products. Using a wavelet analysis of GRACE geoids products, we show that the geoid variations caused by the 2004 December ( M _w= 9.2) and 2005 March ( M _w= 8.7) Sumatra earthquakes can be detected. At GRACE resolution, the 2004 December earthquake produced a strong coseismic decrease of the gravity field in the Andaman Sea, followed by relaxation in the area affected by both the Andaman 2004 and the Nias 2005 earthquakes. We find two characteristic timescales for the relaxation, with a fast variation occurring in the vicinity of the Central Andaman ridge. We discuss our coseismic observations in terms of density changes of crustal and upper-mantle rocks, and of the vertical displacements in the Andaman Sea. We interpret the post-seismic signal in terms of the viscoelastic response of the Earth's mantle. The transient component of the relaxation may indicate the presence of hot, viscous material beneath the active Central Andaman Basin.     

Comment on “Is there a paleolimnological explanation for ‘walking on water’ in the Sea of Galilee?”

In a recent paper, Nof et al. (J Paleolimnol 35:417–439, 2006) suggest a physical mechanism which could account for the formation of ice on Lake Kinneret (Sea of Galilee) in northern Israel. Based on the sea surface temperature record of sediment cores from the Mediterranean Sea the authors argue that centennial-scale cold events had the potential to trigger local ‘springs ice’ formation on the lake in the past. Here, we demonstrate that a closer inspection of the paleoceanographic record in combination with correlation and regression analyses of meteorological data provides no evidence for such cold events in the lake region during the last 10,000 years. Thus, the formation of ‘springs ice’ on Lake Kinneret was unlikely at least since the beginning of the Neolithic.     

The world''s large lake basins as denudation-accumulation systems and implications for their lifetimes

The mechanical denudation rates of 81 large lake basins (lake area > 500 km²) were determined from long-term river loads and erosion maps. Using the drainage area/lake area ratios the mean sedimentation rates of the lakes were calculated for a porosity of 0.3. The mean sedimentation rates of different lake types vary between 0.1 mm/a (glacial lakes, lowland) and 5.4 mm/a (mostly sag basin lakes). The calculated lifetimes of the lakes are based on the lake volumes and mean sedimentation rates, assuming steady-state conditions and solely clastic material. On average, glacial lakes in highlands and fault-related lakes show the shortest lifetimes (c. 70 ka), glacial lakes in lowlands and rift lakes have the longest lifetimes (c. 1 Ma). Some lakes remain unfilled for very long time spans due to rapid subsidence of their basin floors. The calculated lifetimes are compared with those derived from sediment core studies. Most core studies indicate lower mechanical sedimentation rates than the calculated ones because a major part of the incoming sediment is trapped in deltas. However, a number of lakes (e.g., the Great Lakes of North America) show the opposite tendency which is largely caused by extensive shoreline erosion and resuspension. The lifetimes of large glacial lakes often exceed the duration of interglacials. Hence, their lifetimes are restricted by glaciation and not by sediment infill. Rift lakes persist for long time periods which exceed the calculated lifetimes in some cases. Time-dependent subsidence, basin extension, as well as the impact of climate change are briefly described.     

Ein weiterer Beitrag zur Vereinfachung der graphischen Integration der barotropen Wirbelgleichung

Zusammenfassung In einer früheren Arbeit konnte gezeigt werden, daß das durchFjörtoft bei der graphischen Integration des barotropen Modells zur Rückermittlung des Isohypsenfeldes aus der Vorticityverteilung angewandte Näherungsverfahren, dem gewisse die Allgemeinheit einschränkende Voraussetzungen zugrunde liegen, durch eine statistische Methode mit Erfolg ersetzt werden kann. Der vorliegende Bericht beruht auf den gleichen statistischen Grundlagen, es kommen jedoch zusätzlich noch kinematische Überlegungen hinzu, die schließlich zu einer weiteren Vereinfachung des Arbeitsvorganges führen. Auswertungen an einer konkreten Wetterlage zeigen, daß sowohl die statistische wie die statistisch-kinematische Methode darüber hinaus eine gewisse Verbesserung der Resultate der Integration herbeiführen.

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Summary In a previous paper it was shown that the computation of the geopotential field from a given vorticity distribution by means of theFjörtoft method of graphical integration of the barotropic model may be improved by the introduction of statistical considerations. The present paper deals with the same subject, however expanded by kinematical considerations which eventually lead to a further simplification of the routine procedure. The application to an actual weather situation indicates that the statistical as well as the statistical-kinematical method render a certain improvement of the results.

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Résumé Dans une précédente étude, on avait montré que le processus d'approximation deFjörtoft permettant par intégration graphique de restituer le champ d'isohypses et qui supposait certaines restrictions, peut être remplacé avec succès par une méthode statistique. On ajoute ici à cette dernière des considérations d'ordre cinématique qui conduisent à simplifier encore le procédé. Un exemple pratique démontre que l'intégration proposée conduit à des résultats encore meilleurs.

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Bemerkungen zu W. Dammann „Untersuchung über Schwankungen der Winterniederschläge in Deutschland”

Zusammenfassung An der Methode wird die physikalische Unwirklichkeit der Zusammenfassung der Monate Januar, Februar, März und November und Dezember des gleichen Kalenderjahres als Winter und die Unterdrückung wesentlicher Zusammenhänge mit dem Sonnenfleckenzyklus durch Bildung übergreifender Fünfjahresmittel bemängelt. Hinsichtlich des Ergebnisses wird die behauptete Ähnlichkeit der erhaltenen Kurven mit der Sonnenfleckenwelle widerlegt.

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Summary It is shown that the practice to define the months of January, February, March and November, December of the same calendar year as winter is not justifiable, from a physical point of view. By using running 5-yearly means important relations to the cycle of sun-spots are suppressed. A proposed similarity of the curves obtained byDammann with the solar cycle is disproved.

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Résumé L'auteur montre que l'hiver défini par la période de janvier à mars et de novembre à decembre de la même année est une irréalité physique et que l'emploi de la moyenne mobile de cinq ans masque le cycle des taches solaires; les courbes obtenues parDammann ne correspondent pas rythme des taches.