bluuebunny/crossref_metadata_2025 huggingface dataset:
Manipulating marine stratocumulus cloud amount and albedo: a process-modelling study of aerosol-cloud-precipitation interactions in response to injection of cloud condensation nuclei
Authors: Wang H. , Rasch P. J. , Feingold G.
Published: May 2011

Abstract. We use a cloud-system-resolving model to study marine-cloud brightening. We examine how injected aerosol particles that act as cloud condensation nuclei (CCN) are transported within the marine boundary layer and how the additional particles in clouds impact cloud microphysical processes, and feedback on dynamics. Results show that the effectiveness of cloud brightening depends strongly on meteorological and background aerosol conditions. Cloud albedo enhancement is very effective in a weakly precipitating boundary layer and in CCN-limited conditions preceded by heavy and/or persistent precipitation. The additional CCN help sustain cloud water by weakening the precipitation substantially in the former case and preventing the boundary layer from collapse in the latter. For a given amount of injected CCN, the injection method (i.e., number and distribution of sprayers) is critical to the spatial distribution of these CCN. Both the areal coverage and the number concentration of injected particles are key players but neither one always emerges as more important than the other. The same amount of injected material is much less effective in either strongly precipitating clouds or polluted clouds, and it is ineffective in a relatively dry boundary layer that supports clouds of low liquid water path. In the polluted case and "dry" case, the CCN injection increases drop number concentration but lowers supersaturation and liquid water path. As a result, the cloud experiences very weak albedo enhancement, regardless of the injection method.
Springtime carbon episodes at Gosan background site revealed by total carbon, stable carbon isotopic composition, and thermal characteristics of carbonaceous particles
Authors: Jung J. , Kawamura K.
Published: May 2011

Abstract. In order to investigate the carbon episodes at Gosan background super-site (33.17° N, 126.10° E) in East Asia during spring of 2007 and 2008, total suspended particles (TSP) were collected and analyzed for particulate organic carbon, elemental carbon, total carbon (TC), total nitrogen (TN), and stable carbon isotopic composition (δ13C) of TC. The carbon episodes at the Gosan site were categorized as long-range transported anthropogenic pollutant (LTP) from Asian continent, Asian dust (AD) accompanying with LTP, and local pollen episodes. The stable carbon isotopic composition of TC (δ13CTC) was found to be lowest during the pollen episodes (range: −26.2 ‰ to −23.5 ‰, avg.: −25.2 ± 0.9 ‰), followed by the LTP episodes (range: −23.5 ‰ to −23.0 ‰, avg.: −23.3 ± 0.3 ‰) and the AD episodes (range: −23.3 to −20.4 %, avg.: −21.8 ± 2.0 ‰). The δ13CTC of the airborne pollens (−28.0 ‰) collected at the Gosan site showed value similar to that of tangerine fruit (−28.1 ‰) produced from Jeju Island. Based on the carbon isotope mass balance equation and the TN and TC regression approach, we found that ∼40–45 % of TC in the TSP samples during the pollen episodes was attributed to airborne pollens from Japanese cedar trees planted around tangerine farms in Jeju Island. The δ13C of citric acid in the airborne pollens (−26.3 ‰) collected at the Gosan site was similar to that in tangerine fruit (−27.4 ‰). The negative correlation between the citric acid-carbon/TC ratios and δ13CTC were obtained during the pollen episodes. These results suggest that citric acid emitted from tangerine fruit may be adsorbed on the airborne pollens and then transported to the Gosan site. Based on the thermal evolution pattern of organic aerosols during the carbon episodes, we found that organic aerosols originated from East China are more volatile on heating and are more likely to form pyrolized organic carbon than the pollen-enriched organic aerosols and organic aerosols originated from Northeast China. Since thermal evolution patterns of organic aerosols are highly influenced by their molecular weight, they can be used as additional information on the formation of secondary organic aerosols during the long-range atmospheric transport and the source regions of organics.
Examination of aerosol distributions and radiative effects over the Bay of Bengal and the Arabian Sea region during ICARB using satellite data and a general circulation model
Authors: Cherian R. , Venkataraman C. , Ramachandran S. , Quaas J. , Kedia S.
Published: May 2011

Abstract. In this paper we analyse aerosol loading and its direct radiative effects over the Bay of Bengal (BoB) and Arabian Sea (AS) regions for the Integrated Campaign on Aerosols, gases and Radiation Budget (ICARB) undertaken during 2006, using satellite data from the MODerate Resolution Imaging Spectroradiometer (MODIS) on board the Terra and Aqua satellites, the Aerosol Index from the Ozone Monitoring Instrument (OMI) on board the Aura satellite, and the European-Community Hamburg (ECHAM5.5) general circulation model extended by Hamburg Aerosol Module (HAM). By statistical comparison with large-scale satellite data sets, we firstly show that the ship-based ICARB observations are representative for the entire northern Indian Ocean during the pre-monsoon season. In a second step, the modelled aerosol distributions were evaluated by a comparison with the measurements from the ship-based sunphotometer, and the satellites. It was found that the model reproduces the observed spatial and temporal variability in aerosol optical depth (AOD) and simulated AODs to a large extent. However, AOD was systematically underestimated during high-pollution episodes, especially in the BoB leg. We show that this underprediction of AOD is mostly due to deficiencies in the coarse mode, where the model showed that dust was the dominant component. The analysis of simulated dust AOD along with the OMI Aerosol Index showed that the too low dust emissions from the Thar Desert in the model are the main cause for this deficiency. Thirdly, we analysed the spatio-temporal variability of AOD comparing the ship-based observations to the large-scale satellite observations and simulations. It was found that most of the variability along the track was due to geographical patterns, with minor influence by single events. Aerosol fields were homogeneous enough to yield a good statistical agreement between satellite data at a 1° spatial, but only twice-daily temporal resolution, and the ship-based sunphotometer data at a much finer spatial, but daily-average temporal resolution. Finally, we estimated the shortwave aerosol radiative forcing. We found that the cruise represents well the regional-seasonal mean forcings. Constraining simulated forcings using the observed AOD distributions yields a regional-seasonal mean aerosol forcing of −8.6, −21.4 and +12.9 W m−2 at the top of the atmosphere (TOA), at the surface (SUR) and in the atmosphere (ATM), respectively, for the BoB region, and over the AS, of, −6.8, −12.8, and +6 W m−2 at TOA, SUR, and ATM, respectively.
Ab initio studies of O2−(H2O)n and O3−(H2O)n anionic molecular clusters, n≤12
Authors: Bork N. , Kurtén T. , Enghoff M. B. , Pedersen J. O. P. , Mikkelsen K. V. , Svensmark H.
Published: May 2011

Abstract. An ab initio study of gaseous clusters of O2− and O2− with water is presented. Based on thorough scans of configurational space, we determine the thermodynamics of cluster growth. The results are in good agreement with benchmark computational methods and existing experimental data. We find that anionic O2−(H2O)n and O3−(H2O)n clusters are thermally stabilized at typical atmospheric conditions for at least n = 5. The first 4 water molecules are strongly bound to the anion due to delocalization of the excess charge while stabilization of more than 4 H2O is due to normal hydrogen bonding. Although clustering up to 12 H2O, we find that the O2 and O3 anions retain at least ca. 80 % of the charge and are located at the surface of the cluster. The O2− and O3− speicies are thus accessible for further reactions. Finally, the thermodynamics of a few relevant cluster reactions are considered.
Solar response in tropical stratospheric ozone: a 3-D chemical transport model study using ERA reanalyses
Authors: Dhomse S. , Chipperfield M. P. , Feng W. , Haigh J. D.
Published: May 2011

Abstract. We have used an off-line 3-D chemical transport model (CTM), to investigate the 11-year solar cycle response in tropical stratospheric ozone. The model is forced with European Centre for Medium-Range Weather Forecasts (ECMWF) (re)analysis (ERA-40/Operational and ERA-Interim) data for 1978–2005 time period. We have compared the modelled solar response in ozone to observational data from three satellite instruments, Solar Backscatter UltraViolet instrument (SBUV), Stratospheric Aerosol and Gas Experiment (SAGE) and Halogen Occultation Experiment (HALOE). A significant difference is seen between simulated and observed ozone during the 1980s, which is probably due to inhomogeneities in the ERA-40 reanalyses. In general, the model with ERA-Interim dynamics shows better agreement with the observations from 1990 onwards than ERA-40. Overall both standard model simulations are partially able to simulate a "double peak"-structured ozone solar response profile with a minimum around 30 km, and these are in better agreement with HALOE than SBUV or SAGE. The largest model-observation differences occur in the upper stratosphere where SBUV and SAGE show a significant (up to 4 %) solar response whereas the standard model and HALOE do not. This is partly due to a positive solar response in the ECMWF upper stratosphere analysed temperatures which reduces the modelled ozone signal. The large positive upper stratosphere response seen in SAGE/SBUV can be reproduced in a model run with fixed dynamical fields (i.e. no inter-annual meteorological changes). As this run effectively assumes no long-term temperature changes (solar-induced or otherwise) it should provide an upper limit of the ozone solar response. Overall, full quantification of the upper stratosphere ozone solar response is limited by differences in the observed dataset and by uncertainties in the solar response in the stratospheric temperatures. In the lower stratosphere we find that transport by analysed winds, which contain information about the Quasi-Biennial Oscillation (QBO), can lead to a large ozone solar response. However, the run with fixed dynamical fields also produces a positive solar response (up to 2 %) in line with the SAGE and SBUV observations.
Possible effect of extreme solar energetic particle event of 20 January 2005 on polar stratospheric aerosols: direct observational evidence
Authors: Mironova I. A. , Usoskin I. G. , Kovaltsov G. A. , Petelina S. V.
Published: May 2011

Abstract. Energetic cosmic rays are the main source of ionization of the low-middle atmosphere, leading to associated changes in atmospheric properties. Via the hypothetical influence of ionization on aerosol growth and facilitated formation of cloud condensation nuclei, this may be an important indirect link relating solar variability to climate. This effect is highly debated, however, since the proposed theoretical mechanisms still remain illusive and qualitative, and observational evidence is inconclusive and controversial. Therefore, important questions regarding the existence and magnitude of the effect, and particularly the fraction of aerosol particles that can be formed and grow large enough to influence cloud condensation nuclei (CCN), are still open. Here we present empirical evidence of the possible effect caused by cosmic rays upon polar stratospheric aerosols, based on a case study of an extreme solar energetic particle (SEP) event of 20 January 2005. Using aerosol data obtained over polar regions from different satellites with optical instruments that were operating during January 2005, such as the Stratospheric Aerosol and Gas Experiment III (SAGE III), and Optical Spectrograph and Infrared Imaging System (OSIRIS), we found a significant simultaneous change in aerosol properties in both the southern and northern polar regions in temporal association with the SEP event. We speculate that ionization of the atmosphere, which was abnormally high during this extreme SEP event, might have led to formation of new particles and/or growth of preexisting ultrafine particles up to the size of CCN. However, a detailed interpretation of the effect is left for subsequent studies. This is the first time high vertical resolution measurements have been used to provide evidence for the probable production of stratospheric CCN from cosmic ray induced ionization.
Characterisation of a new Fast CPC and its application for atmospheric particle measurements
Authors: Wehner B. , Siebert H. , Hermann M. , Ditas F. , Wiedensohler A.
Published: May 2011

Abstract. A new Fast CPC (FCPC) using butanol as working fluid has been built based on the setup described by Wang et al. (2002). In this study, we describe the new instrument. The functionality and stable operation of the FCPC in the laboratory, as well as under atmospheric conditions, is demonstrated. The counting efficiency was measured for three temperature differences between FCPC saturator and condenser, 25, 27, and 29 K, subsequently resulting in a lower detection limit between 6.1 and 8.5 nm. Above 25 nm the FCPC reached 98–100% counting efficiency compared to an electrometer used as the reference instrument. The FCPC demonstrated its ability to perform continuous measurements over a few hours in the laboratory with respect to the total particle counting. The instrument has been implemented into the airborne measurement platform ACTOS to perform measurements in the atmospheric boundary layer. Therefore, a stable operation over two hours is required. The mixing time of the new FCPC was estimated in two ways using a time series with highly fluctuating particle number concentrations. The analysis of a sharp ramp due to a concentration change results in a mixing time of 5 ms while a spectral analysis of atmospheric data demonstrates that for frequencies up to 10 Hz coherent structures can be resolved before sampling noise dominates.
Empirical analysis and modeling of errors of atmospheric profiles from GPS radio occultation
Authors: Scherllin-Pirscher B. , Steiner A. K. , Kirchengast G. , Kuo Y.-H. , Foelsche U.
Published: May 2011

Abstract. The utilization of radio occultation (RO) data in atmospheric studies requires precise knowledge of error characteristics. We present results of an empirical error analysis of GPS radio occultation (RO) bending angle, refractivity, dry pressure, dry geopotential height, and dry temperature. We find very good agreement between data characteristics of different missions (CHAMP, GRACE-A, and Formosat-3/COSMIC (F3C)). In the global mean, observational errors (standard deviation from "true" profiles at mean tangent point location) agree within 0.3 % in bending angle, 0.1 % in refractivity, and 0.2 K in dry temperature at all altitude levels between 4 km and 35 km. Above ≈20 km, the observational errors show a strong seasonal dependence at high latitudes. Larger errors occur in hemispheric wintertime and are associated mainly with background data used in the retrieval process. The comparison between UCAR and WEGC results (both data centers have independent inversion processing chains) reveals different magnitudes of observational errors in atmospheric parameters, which are attributable to different background fields used. Based on the empirical error estimates, we provide a simple analytical error model for GPS RO atmospheric parameters and account for vertical, latitudinal, and seasonal variations. In the model, which spans the altitude range from 4 km to 35 km, a constant error is adopted around the tropopause region amounting to 0.8 % for bending angle, 0.35 % for refractivity, 0.15 % for dry pressure, 10 m for dry geopotential height, and 0.7 K for dry temperature. Below this region the observational error increases following an inverse height power-law and above it increases exponentially. The observational error model is the same for UCAR and WEGC data but due to somewhat different error characteristics below about 10 km and above about 20 km some parameters have to be adjusted. Overall, the observational error model is easily applicable and adjustable to individual error characteristics.
Determination of field scale ammonia emissions for common slurry spreading practice with two independent methods
Authors: Sintermann J. , Ammann C. , Kuhn U. , Spirig C. , Hirschberger R. , Gärtner A. , Neftel A.
Published: May 2011

Abstract. At a cropland and a grassland site field scale ammonia (NH3) emissions from slurry application were determined simultaneously by two approaches based on (i) eddy covariance (EC) flux measurements using high temperature Chemical Ionisation Mass Spectrometry (HT-CIMS) and on (ii) backward Lagrangian Stochastic (bLS) dispersion modelling using concentration measurements by three optical open path Fourier Transform Infrared (FTIR) systems. Slurry was spread on the fields in sequential tracks over a period of one to two hours. In order to calculate field emissions, measured EC/HT-CIMS fluxes were combined with flux footprint analysis of individual slurry spreading tracks to parameterise the NH3 volatilisation with a bi-exponential time dependence. Accordingly, track-resolved concentration footprints for the FTIR measurements were calculated using bLS. Comparison of concentrations calculated from the parameterised fluxes with concentrations measured by impingers showed that the EC/HT-CIMS emissions on the two fertilisations corresponded to the impinger concentrations within 10 % while the bLS/FTIR results showed larger deviations. For both events, the period during fertilisation and the subsequent two hours contributed by more than 80 % to the total field emissions. Averaged over the two measurement methods, the cumulated emissions of the first day amounted to 17 ± 3 % loss of applied total ammoniacal nitrogen over the cropland and 16 ± 3 % over the grassland field.
Polar cap ion beams during periods of northward IMF: Cluster statistical results
Authors: Maggiolo R. , Echim M. , De Keyser J. , Fontaine D. , Jacquey C. , Dandouras I.
Published: May 2011

Abstract. Above the polar caps and during prolonged periods of northward IMF, the Cluster satellites detect upward accelerated ion beams with energies up to a few keV. They are associated with converging electric field structures indicating that the acceleration is caused by a quasi-static field-aligned electric field that can extend to altitudes higher than 7 RE (Maggiolo et al., 2006; Teste et al., 2007). Using the AMDA science analysis service provided by the Centre de Données de la Physique des Plasmas, we have been able to extract about 200 events of accelerated upgoing ion beams above the polar caps from the Cluster database. Most of these observations are taken at altitudes lower than 7 RE and in the Northern Hemisphere. We investigate the statistical properties of these ion beams. We analyze their geometry, the properties of the plasma populations and of the electric field inside and around the beams, as well as their dependence on solar wind and IMF conditions. We show that ~40 % of the ion beams are collocated with a relatively hot and isotropic plasma population. The density and temperature of the isotropic population are highly variable but suggest that this plasma originates from the plasma sheet. The ion beam properties do not change significantly when the isotropic, hot background population is present. Furthermore, during one single polar cap crossing by Cluster it is possible to detect upgoing ion beams both with and without an accompanying isotropic component. The analysis of the variation of the IMF BZ component prior to the detection of the beams indicates that the delay between a northward/southward turning of IMF and the appearance/disappearance of the beams is respectively ~2 h and 20 min. The observed electrodynamic characteristics of high altitude polar cap ion beams suggest that they are closely connected to polar cap auroral arcs. We discuss the implications of these Cluster observations above the polar cap on the magnetospheric dynamics and configuration during prolonged periods of northward IMF.
Technical note on measuring run-off dynamics from pavements using a new device: the weighable tipping bucket
Authors: Nehls T. , Nam Rim Y. , Wessolek G.
Published: May 2011

Abstract. Due to climate change, cities need to adapt to changing rainfall and rainwater run-off dynamics. In order to develop an corresponding process based run-off model for pavements, we had to improve the measurement technique to detect run-off dynamics in an appropriate high resolution. Traditional tipping buckets (TB) have a comparable low volume resolution, capable to quantify the highest intensities in a range of expected flows. This results in varying temporal resolutions for varying flow intensities, especially in low resolutions for small flow events. Therefore, their applicability for run-off measurements and other hydrological process studies is limited, especially when the dynamics of both small and big flow events shall be measured. We improved a TB by coupling it to a balance and called it weighable tipping bucket (WTB). This paper introduces the device set up and the according data processing concept. The improved volume and temporal resolution of the WTB are demonstrated. A systematic uncertainty of TB measurements compared to WTB measurements is calculated. The impact of that increased resolution on our understanding of run-off dynamics from paved urban soils are discussed, exemplary for the run-off and the surface storage of a paved urban soil. The study was conducted on a permeably paved lysimeter situated in Berlin, Germany. Referring to the paved surface, the TB has a resolution of 0.1 mm, while the WTB has a resolution of 0.001 mm. The temporal resolution of the WTB is 3 s, the TB detects individual tippings with 0.4 s between them. Therefore, the data processing concept combines both the benefits of the balance to measure small intensities with that of the TB to measure high flow intensities. During a five months period (July to November 2009) 154 rain events were detected. Accordingly, the TB and WTB detected 47 and 121 run-off events. The total run-off was 79.6 mm measured by the WTB which was 11 % higher than detected by the TB. 95 % of that difference can be appointed to water, which evaporated from the TB. To derive a surface storage estimation, we analyzed the WTB and TB data for rain events without run-off. According to WTB data, the surface storage of the permeable pavement is 1.7 mm, while using TB data leads to an overestimation of 47 % due to low volume resolution of the TB. Combining traditional TB with modern, fast, high resolution digital balances offers the opportunity to upgrade existing TB systems in order to improve their volume detection limit and their temporal resolution, which is of great advantage for the synchronization of water balance component measurements and the investigation of hydrological processes. Furthermore, we are able to quantify the uncertainty of flow measurements gained with traditional tipping buckets.
An objective approach for feature extraction: distribution analysis and statistical descriptors for scale choice and channel network identification
Authors: Sofia G. , Tarolli P. , Cazorzi F. , Dalla Fontana G.
Published: May 2011

Abstract. A statistical approach to LiDAR derived topographic attributes for the automatic extraction of channel network and for the choice of the scale to apply for parameter evaluation is presented in this paper. The basis of this approach is to use distribution analysis and statistical descriptors to identify channels where terrain geometry denotes significant convergences. Two case study areas with different morphology and degree of organization are used with their 1 m LiDAR Digital Terrain Models (DTMs). Topographic attribute maps (curvature and openness) for various window sizes are derived from the DTMs in order to detect surface convergences. A statistical analysis on value distributions considering each window size is carried out for the choice of the optimum kernel. We propose a three-step method to extract the network based (a) on the normalization and overlapping of openness and minimum curvature to highlight the more likely surface convergences, (b) a weighting of the upslope area according to these normalized maps to identify drainage flow paths and flow accumulation consistent with terrain geometry, (c) the standard score normalization of the weighted upslope area and the use of standard score values as non subjective threshold for channel network identification. As a final step for optimal definition and representation of the whole network, a noise-filtering and connection procedure is applied. The advantage of the proposed methodology, and the efficiency and accurate localization of extracted features are demonstrated using LiDAR data of two different areas and comparing both extractions with field surveyed networks.
Rank ordering multifractal analysis of the auroral electrojet index
Authors: Consolini G. , De Michelis P.
Published: May 2011

Abstract. In the second half of the 90s interest grew on the complex features of the magnetospheric dynamics in response to solar wind changes. An important series of papers were published on the occurrence of chaos, turbulence and complexity. Among them, particularly interesting was the study of the bursty and fractal/multifractal character of the high latitude energy release during geomagnetic storms, which was evidenced by analyzing the features of the Auroral Electrojet (AE) indices. Recently, the multifractal features of the small time-scale increments of AE-indices have been criticized in favor of a more simple fractal behavior. This is particularly true for the scaling features of the probability density functions (PDFs) of the AE index increments. Here, after a brief review of the nature of the fractal/multifractal features of the magnetospheric response to solar wind changes, we investigate the multifractal nature of the scaling features of the AE index increments PDFs using the Rank Ordering Multifractal Analysis (ROMA) technique. The ROMA results clearly demonstrate the existence of a hierarchy of scaling indices, depending on the increment amplitude, for the data collapsing of PDFs relative to increments at different time scales. Our results confirm the previous results by Consolini et al. (1996) and the more recent results by Rypdal and Rypdal (2010).
On the freshening of the northwestern Weddell Sea continental shelf
Authors: Hellmer H. H. , Huhn O. , Gomis D. , Timmermann R.
Published: May 2011

Abstract. We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.
Utility of late summer transient snowline migration rate on Taku Glacier, Alaska
Authors: Pelto M.
Published: May 2011

Abstract. On Taku Glacier, Alaska a combination of field observations of snow water equivalent (SWE) from snowpits and probing in the vicinity of the transient snowline (TSL) are used to quantify the mass balance gradient. The balance gradient is determined from the difference in elevation and SWE from the TSL to snowpits at 1000 m from 1998–2010 and ranges from 2.6–3.8 mm m−1. Probing transects from 950 m–1100 m directly measure SWE and yield a slightly higher balance gradient of 3.3–3.8 mm m−1. TSL is identified in MODIS and Landsat 4 and 7 Thematic Mapper imagery for 31 dates during the 2004–2010 period on Taku Glacier to assess the consistency of its rate of rise and usefulness in assessing mass balance. In 2010, the TSL rose from 750 m on 28 July, 800 m on 5 August, 875 m on 14 August, 925 m on 30 August, and to 975 m on 20 September. The mean observed probing balance gradient was 3.3 mm m−1 and TSL rise was 3.7 m day−1, yielding an ablation rate of 12.2 mm day−1 on Taku Glacier from mid-July to mid-September. A comparison of the TSL rise in the region from 750–1100 m on Taku Glacier during eleven different periods of more than 14 days during the ablation season with repeat imagery indicates a mean TSL rise of 3.7 m day−1 on Taku Glacier, the rate of rise is relatively consistent ranging from 3.0 to 4.8 m day−1. This is useful for ascertaining the final ELA if imagery or observations are not available within a week or two of the end of the ablation season. From mid-July-mid-September the mean ablation from 750–1100 m determined from the TSL rise and the observed balance gradient varied from 11 to 18 mm day−1 on Taku Glacier during the 2004–2010 period.
Spatio-temporal measurements and analysis of snow depth in a rock face
Authors: Wirz V. , Schirmer M. , Gruber S. , Lehning M.
Published: May 2011

Abstract. Snow in rock faces plays a key role in the alpine environment for permafrost distribution, snow water storage or run off in spring. However, a detailed assessment of snow depths in steep rock walls has never been attempted. To understand snow distribution in rock walls a high-resolution terrestrial laser scanner (TLS), including a digital camera, was used to obtain snow depth (HS) data with a resolution of one metre. The mean HS, the snow covered area and their evolution in the rock face were compared to a neighbouring smoother catchment and a flat field station at similar elevation. Further we analyzed the patterns of HS distribution in the rock face after different periods and investigated the main factors contributing to them. In a first step we could show that with TLS reliable information on surface data of a steep rocky surface can be obtained. In comparison to the flatter sites in the vicinity, mean HS in the rock face was lower during the entire winter, but trends of snow depth changes were similar. We observed repeating accumulation and ablation patterns in the rock face, while maximum snow depth loss always occurred at those places with maximum snow depth gain. Further analysis of the main factors contributing to the snow depth distribution in the rock face revealed terrain-wind-interaction processes to be dominant. Processes related to slope angle seem to play a role, but no linear function of slope angle and snow depth was found. Further analyses should involve measurements in rock faces with other characteristics and higher temporal resolutions to be able to distinguish individual processes better. Additionally the relation of spatial and temporal distribution of snow depth to terrain-wind interactions should be tested.
Energy Policy: An Economist’s Confessions
Authors: Schlesinger James R.
Published: May 2011

It is a particular pleasure to be addressing an association of professional colleagues. I must concede it is the first time that I have done so since I was on the faculty at the University of Virginia. The atmosphere here is a little bit chilly; you can rest assured that when our rulemaking on temperature control takes effect on July 1, you will not have this experience.
The World Oil Market: An Exporter’s View
Authors: Parra Alirio A.
Published: May 2011

I am deeply honored to be part of this distinguished panel and to address my professional colleagues on the occasion of the first annual meeting of the International Association of Energy Econo- mists.
The U.S. Outlook for Supplemental Gas
Authors: Tussing Arlon R.
Published: May 2011

Current forecasts of natural gas demand in the United States through the turn of the century are lower than projections made only a few years ago, and fall far short of the volumes the economy is technically capable of absorbing even with its existing stock of energy-using equipment.
Coal Policy and Energy Economics
Authors: Gordon Richard L.
Published: May 2011

With the flurry of legislation in 1977 further inhibiting coal consumption and production, it became apparent to many observers that coal had joined oil, gas, and nuclear energy as a tightly regulated industry. Since by now this observation has been widely dissemi- nated, it seems most appropriate here only to summarize the nature of the barriers and their obvious implications. Then emphasis can be placed on the perspectives that economic analyses can provide for evaluating the issues.
Energy Prices and the U.S. Economy in 1979-1981
Authors: Mork Knut Anton , Hail Robert E.
Published: May 2011

For the second time in the decade, the U.S. economy is absorbing a large sudden shock in the world price of oil. From late in 1978 to June 1979, OPEC raised the world price of oil by close to $9 per barrel. Western industrial nations could face a repetition of the serious recession of 1974-75 on close to the same scale. The increase in the total cost of energy inputs induced by this oil price increase is about two-thirds of the increase in 1974. The potential disruption to the U.S. economy and others is a similar fraction of what occurred in the earlier episode.
Simulation of World Oil Market Shocks: A Markov Analysis of OPEC and Consumer Behavior
Authors: Kosobud Richard F. , Stokes Houston H.
Published: May 2011

One major determinant of crude oil price will be the question of whether or not OPEC can resolve its internal conflicts and act effectively as a coalition in restricting the quantities it will supply. For the economist, this question stands at the center of the energy problem; unfortunately, economic analysis has little that is definite to say about the question, and consequently little to say about how OPEC determines its posted price policies and the quantities of oil to be placed on the market. Economic analysis has also failed to provide any definite explanation of the fact that individual OPEC members have not been prone to seek net revenue increases through additional sales, even during periods of declining sales or during oil gluts such as the 1975 recession in OECD countries.
Energy Prices, Inflation, and Recession, 1974-1975
Authors: Mork Knut Anton , Hall Douglas E.
Published: May 2011

The rapid escalations of energy prices, in late 1973 and early 1974 and again in mid- and late-1979, have had major adverse impacts on the U.S. economy. The energy price shock of 1973-1974 played a dominant role, by most accounts, in bringing about the deep recession and high inflation of the mid-1970s. In the most recent period, the full impact is yet to be seen, but it does not appear to be minor. In a previous paper published in this journal, (volume 1, number 2, April 1980), we presented the results of our efforts to quantify the economic impact on the U.S. economy of the July 1979 oil price increases.
Crude Oil Resource Appraisal in the United States
Authors: Uri Noel D.
Published: May 2011

Prior to the Arab oil embargo that began in October 1973, the general feeling was that U.S. oil resources were almost limitless. Certainly there were some who were aware that the rate of crude oil production was falling and costs were increasing, but these perceptions were relegated to the background. Past experience supported the explorer's optimistic outlook concerning potential discoveries. The United States never seemed in danger of being less than the world's foremost producer of crude oil.
Petroleum Policy and Mexican Domestic Politics: Left Opposition, Regional Dissidence, and Official Apostasy
Authors: Williams* Edward J.
Published: May 2011

The impact of the petroleum industry on oil-producing countries has frequently emphasized the intimate interconnection and reciprocal influences of economic and political change. The agony of contemporary Iran is a dramatic example, but only one of many that help prove the point. In Nigeria's recent history, the competition for control of petroleum resources was one factor instigating a brutal civil war. In Venezuela, a new era of constitutional stability flowed from an expanded economic base provided by petroleum export earnings. In the United States, the rise to national prominence of the Texas politicos reflected the economic changes that evolved from petroleum discoveries.
Economic Effects of Increased Penetration of Solar Energy
Authors: Hudson Edward A.
Published: May 2011

Recent energy policy proposals have given an important place to solar energy, and other new-technology energy sources, in the projected development of the U.S. energy system over the rest of the century. For example, the Domestic Policy Review of Solar Energy (U.S. Department of Energy, 1979), presented to the President in February 1979, raised the possibility that 20 percent of primary energy input in the year 2000 could be supplied from solar and other renewable sources. Since these technologies now provide only a small fraction of total energy input, changes of the magnitude involved in these proposals imply a major restructuring of the energy system.
The Real Price of Imported Oil
Authors: Dunkerley Joy , Jankowski John E.
Published: May 2011

The continual upward adjustment since 1973 in international quoted oil prices has been accompanied by two countervailing developments. The first is the weakening of the dollar against many national currencies. Since transactions in the international oil market are conducted in dollars, many countries were able to offer less of their national currency for each dollar of oil purchased. Second, sharply rising prices of all other goods and services in many oil-importing countries diminished the impact of the relative rise in oil prices. Thus oil appeared as only one of a host of rising prices, perhaps rising more strongly than other prices but otherwise indistinguishable from a multitude of inflationary pressures. In other words, the real price of oil to importing countries may not have been rising as strongly in real terms as is suggested by price quotations from internationally traded crude oil. If this is the case, pressures for limiting oil imports and oil conservation generally would be weakened.
Energy Price Increases and Macroeconomic Policy
Authors: Pindyck Robert S.
Published: May 2011

A rising world price of energy imposes a macroeconomic cost on the United States in two different ways. First, to the extent that energy is both an important input to production and a consumption good, with limited elasticities of substitution and demand, the economy's production and consumption possibilities are necessarily reduced as energy becomes more scarce. Thus, even if an expansionary monetary and fiscal policy were successful in pushing the economy close to its full capacity level, the resulting real national income would be lower than if energy prices had not An earlier version of this paper was presented at the CEPR Conference on Energy Prices, Inflation and Economic Activity, Cambridge, November 9, 1979. Work leading to this paper was supported by the Center for Energy Policy Research of the M.I.T. Energy Laboratory, and that support is gratefully acknowledged. In writing this paper, I benefited considerably from conversations with and comments from Olivier Blanchard, Stanley Fischer, Benjamin Friedman, Robert Hall, Franco Modigliani, Robert Solow, and an anonymous referee.
Economic Implications of Mandated Efficiency in Standards for Household Appliances
Authors: Khazzoom J. Daniel
Published: May 2011

In the discussion of energy conservation, a great deal of attention has focused on mandated efficiency standards for cars and energy-using household appliances. (In this article, I will use the term "appliance" in a generic sense to cover household durables). Unfortunately, the estimates of energy savings predicted to result from these mandated standards are derived mechanically.' When mandated standards raise the appliance efficiency by 1 percent, demand is predicted to drop by 1 percent; when they raise efficiency by 2 percent, demand is predicted to drop by 2 percent; and so on. Examples of such results are found in reports by the Department of Energy (1979a, 1980) and by the Staff of the California Energy Commission (1979) on energy demand in California in the coming two decades.
Long-Term Contracts for Crude Oil Imports into Costa Rica: A General Equilibrium Analysis
Authors: Dufournaud Christian , Gutierrez Carlos Raul , Berlage Lodewijk , Rogers Peter P.
Published: May 2011

Energy is critical for all human activity. Many countries import a major proportion of essential energy resources such as oil, for which the ability to substitute alternative inputs is difficult in both the short and long run. A possible response to the prospect that energy prices can fluctuate is for governments to negotiate long-term contracts with suppliers to mitigate sudden price shocks. This strategy is, however, not cost-free. It is equally rational for suppliers to negotiate high prices which protect them from the prospect of having to supply their oil at a lower price than they could anticipate in the future. A country seeking long-term protection from unstable oil prices via long-term contracts, therefore, faces higher current prices.
Electricity Exports and Hydro-Québec’s 1986-2000 Development Plan
Authors: Belanger Danny , Bernard Jean-Thomas
Published: May 2011

Between 1980 and 1986. Hydro-Quebec's electricity exports to neighboring utilities in the United States and Canada posted an average annual growth rate of 7.3 percent while regular electricity sales in Quebec increased by only 3.8 percent.' Exports accounted for 18.7 percent of the electricity sold by Hydro-Quebec and 13.9 percent of its income in 1986. The Premier of Quebec, Robert Bourassa, is strongly committed to a policy of promoting further firm electricity exports. mostly to the U.S. Northeast region.
The Effect of Energy Aggregation on Energy Elasticities: Some Evidence from U.S. Manufacturing Data
Authors: Nguyen Sang V. , Andrews Stephen H.
Published: May 2011

Measuring energy input plays an important role in many empirical studies, such as analyses of energy demand, efficiency, and productivity. Yet energy is a complex concept and difficult to measure. As a result, energy studies have used energy aggregates constructed based on different aggregation methods. Different aggregates could lead to significantly different results, thus affecting the evaluation of alternative energy policies as well as other economic inferences.
Noisy Data and Uncertain Coefficients: A Comment
Authors: Herbert John H.
Published: May 2011

Noisy data are frequently used to estimate regression coefficients for energy demand equations. Although analysts new to the area might expect reported coefficients and forecasts to reflect this source of uncertainty, reported numbers, in general, do not reflect it. Recently, Kher et al. (1987, hereinafter KSS) confronted the problem and proposed a new technique for reporting forecasts based on the estimation of bounds for regression coefficients. Regression coefficient bounds reflect the uncertainty in an estimated model stemming from the use of noisy data. In this comment I identify additional studies that have addressed the estimation of such bounds and also present an example of a more common use of them.
Noisy Data and Uncertain Coefficients: A Reply
Authors: Sorooshian Soroosh , Kher Lov , Sioahansi F. P.
Published: May 2011

[N]o one (except KSS, as far as I know) has recommended using the bonds approach for forecasting. KSS however, does not reply on a well-founded statistical basis for their forecasting procedure: it is decidedly ad hoc. We are pleased that Herbert has recognized the potential of "the bounds approach for forecasting" as a viable alternative for forecasting. His major concern is with the "ad hoc" nature of our forecasting procedure. This apparent occurs because forecasts generated by the NVM do not come with confidence intervals similar to those placed on forecasts generated by classical regression techniques. We wish to reply.
The Economics of Strategic Choice: U.S. Uranium Enrichment in the World Market: A Comment
Authors: Combs George F.
Published: May 2011

In an earlier paper in The Energy Journal, Bodde, Quasebarth, and Thomasian (1986) discussed two pricing options that the U.S. government could pursue in selling enrichment services to the market, and noted the likely outcomes that adherence to each strategy would produce. While the authors considered the structure of the enrichment market and the cost advantages of new enrichment technology, they failed to take into account enrichment's role in the nuclear fuel cycle, particularly the degree to which enrichment and uranium can be substituted for one another. This omission is particularly significant, given the potential for the relative economics of enrichment and uranium to be affected due to the cost improvements and technological advances being made in enrichment.
Talks: Energy and Growth: Beyond the Myths and Myopia*
Authors: Pachauri R.K.
Published: May 2011

This annual international conference of the IAEE, being the tenth of a series, assumes special significance. It presents, therefore, a good opportunity to introspect on how these conferences, which receive increasing attention every year (as indeed does the Association of which this is the major annual meeting), have really fared in addressing the challenges confronting the energy economics profession. This is an association whose interests span perhaps a wider range of activities than other economics associations, particularly those dealing with other sectoral subjects. Our resources and strengths place us in a unique position to make contributions far beyond the range of most professional organizations. Not only has this association in its fold several luminaries drawn from the economics profession, but we are also uniquely endowed with a range of other disciplines and skills which supplement and support the economics profession. We have leaders of business, physical scientists, engineers, lawyers, politicians and others drawn from diverse field of learning and knowledge. It is indeed laudable and heartening that we have in this conference for the first time representation from the Soviet Union. I hope their participation marks the beginning of a relationship that will grow in the years to come, and culminate very soon in the organization of an annual international meeting in the USSR.
Energy Economists in the 21st Century*
Authors: Desprairies Pierre
Published: May 2011

Ladies and gentlemen, when I asked what the customary procedure was for this ceremony, I was told that the person receiving the award habitually gave a little talk on the subject of his choice. Since futurology is familiar to me, I have chosen to speak of energy economists in the twenty-first century.