bluuebunny/crossref_metadata_2025 huggingface dataset:
What can we learn about ship emission inventories from measurements of air pollutants over the Mediterranean Sea?
Authors: Marmer E. , Dentener F. , Aardenne J. v. , Cavalli F. , Vignati E. , Velchev K. , Hjorth J. , Boersma F. , Vinken G. , Mihalopoulos N. , Raes F.
Published: April 2010

Abstract. Ship emission estimates diverge widely for all chemical compounds for several reasons: use of different methodologies (bottom-up or top-down), activity data and emission factors can easily result in a difference from a factor of 1.5 to two orders of magnitude. Despite these large discrepancies in existing ship emission inventories for air pollutants very little has been done to evaluate their consistency with atmospheric measurements at open sea. Combining three sets of observational data – ozone and black carbon measurements sampled at three coastal sites and on board of a Mediterranean cruise ship, as well as satellite observations of atmospheric NO2 column concentration over the same area – we assess the accuracy of the three most commonly used ship emission inventories, EDGAR FT (Olivier et al., 2005), emissions described by Eyring et al. (2005) and emissions reported by EMEP (Vestreng et al., 2007). Our tool is a global atmospheric chemistry transport model which simulates the chemical state of the Mediterranean atmosphere applying different ship emission inventories. The simulated contributions of ships to air pollutant levels in the Mediterranean atmosphere are significant but strongly depend on the inventory applied. Close to the major shipping routes relative contributions vary from 10 to 50% for black carbon and from 2 to 12% for ozone in the surface layer, as well as from 5 to 20% for nitrogen dioxide atmospheric column burden. The relative contributions are still significant over the North African coast, but less so over the South European coast. The observations poorly constrain the ship emission inventories in the Eastern Mediterranean where the influence of uncertain land based emissions, the model transport and wet deposition are at least as important as the signal from ships. In the Western Mediterranean, the regional EMEP emission inventory gives the best match with most measurements, followed by Eyring for NO2 and ozone and by EDGAR for black carbon. Given the uncertainty of the measurements and the model, each of the three emission inventories could actually be right, implying that large uncertainties in ship emissions need to be considered for future scenario analysis.
Tropospheric water vapour above Switzerland over the last 12 years
Authors: Morland J. , Collaud Coen M. , Hocke K. , Jeannet P. , Mätzler C.
Published: April 2010

Abstract. Integrated Water vapour (IWV) has been measured since 1994 by the TROWARA microwave radiometer in Bern, Switzerland. Homogenization techniques were used to identify and correct step changes in IWV related to instrument problems. IWV from radiosonde, GPS and SPM was used in the homogenisation process as well as the IWV differences calculated between mountain and valley weather stations. The average IWV of the homogenised TROWARA time series was 14.4 mm over the 1996–2007 period, with maximum and minimum monthly average values of 22.4 mm and 8 mm occurring in August and January, respectively. A weak diurnal cycle in TROWARA IWV was detected with an amplitude of 0.32 mm, a maximum at 21:00 UT and a minimum at 11:00 UT. For 1996–2007, TROWARA trends were compared with those calculated from the Payerne radiosonde and the closest ECMWF grid point to Bern. The radiosonde midnight trend of +0.087 (standard error 0.046) mm/y was significant at the 90% level. The radiosonde trend for all measurement times, +0.098 (0.061) mm/y, and the TROWARA midday trends, 0.068 (0.043) mm/y, were significant at the 89% level. Seasonal Mann Kendall analysis revealed a significant positive trend in July of +0.19 (0.14) to +0.34 (0.25) mm/y for all three datasets. In December, the Payerne radiosonde showed a non-significant negative trend of −0.12 (0.13) mm/y, whilst ECMWF and TROWARA indicated a significant negative trend of −0.20 (0.14) and −0.36 (0.24) mm/y, respectively.
Measurement of acidic ions and their qualitative effects on snow crystal morphology and the quasi-liquid layer
Authors: Knepp T. N. , Renkens T. L. , Shepson P. B.
Published: April 2010

Abstract. A chamber was constructed within which snow crystals were grown on a string at various temperatures, relative humidities, and acetic acid gas phase mole fraction. The temperature, relative humidity, and acid mole fraction were measured for the first time at the point of crystal growth. Snow crystal morphological transition temperature shifts were recorded as a function of acid mole fraction, and interpreted according to the calculated acid concentration in the crystal's quasi-liquid layer, which increased in thickness as a function of acid mole fraction, thereby affecting the crystal's morphology according to the hypothesis of Kuroda and Lacmann. Deficiencies in the understanding of the quasi-liquid layer and its role in determining snow crystal morphology are briefly discussed.
Influence of meteorological variability on interannual variations of the springtime boundary layer ozone over Japan during 1981–2005
Authors: Kurokawa J. , Ohara T. , Uno I. , Hayasaki M. , Tanimoto H.
Published: April 2010

Abstract. We investigated the influence of meteorological variability on the interannual variation of the springtime boundary layer ozone over Japan during 1981–2005 by multiyear simulations with the Models-3 Community Multiscale Air Quality (CMAQ) modeling system and the Regional Emission Inventory in Asia (REAS). CMAQ/REAS generally reproduced the observed interannual variability of springtime ozone over Japan, showing year-to-year variations larger than the annual rate of increase of the long-term trend. We then analyzed the influence of the interannual variation of meteorological fields in simulated results by using the fixed emissions for 2000 and meteorology data for each year. As a reference parameter, we calculated the area-weighted surface pressure anomaly over the Pacific Ocean east of Japan. When the anomaly has a large negative value, polluted air masses from continental Asia tend to be transported directly to Japan by westerly winds. In contrast, when the anomaly has a large positive value, the influences of the outflow from continental Asia tends to be small because the westerly components of wind fields around Japan are comparatively weak. Instead, southerly winds are relatively strong and transport clean air masses from the Pacific Ocean to Japan. Consequently, springtime ozone over Japan is higher (lower) than in ordinary years when the anomaly has a large negative (positive) value. In general, the interannual variation of springtime ozone over Japan is sensitive to the outflow from continental Asia. We also found some correlation between springtime ozone over Japan and the El Niño-Southern Oscillation, indicating that higher and lower springtime ozone over Japan are related to La Niña and El Niño, respectively. Differences in the meridional displacement and diversity of cyclone tracks near Japan between El Niño and La Niña years may be responsible for interannual variations in the springtime boundary layer ozone over Japan.
Characterization of methane retrievals from the IASI space-borne sounder
Authors: Razavi A. , Clerbaux C. , Wespes C. , Clarisse L. , Hurtmans D. , Payan S. , Camy-Peyret C. , Coheur P. F.
Published: April 2010

Abstract. Although the global methane (CH4) concentration has more than doubled since pre-industrial times, local emission sources are still poorly identified and quantified. Instruments onboard satellites can improve our knowledge about the methane global distribution owing to their very good spatial coverage. The IASI (Infrared Atmospheric Sounding Interferometer) instrument launched on the European MetOp platform is a Fourier transform spectrometer which measures the thermal infrared radiation emitted by the Earth and its atmosphere. In this paper, we present the first global distribution of methane total columns from the IASI spectra using the methane ν4 absorption band. The retrieval spectral range was set in order to minimize possible spectroscopic issues. Results are discussed in terms of error budget and vertical sensitivity. In addition, we study the gain of information on surface methane concentrations provided by using the ν3 band, which is partly covered by IASI on the short-wave end of the spectra (extending to 2760 cm−1), where solar reflection contributes significantly.
Global distributions of nitric acid from IASI/MetOP measurements
Authors: Wespes C. , Hurtmans D. , Clerbaux C. , Santee M. L. , Martin R. V. , Coheur P. F.
Published: April 2010

Abstract. This paper presents the first global distributions of HNO3 acquired by the Infrared Atmospheric Sounding Interferometer (IASI) instrument, launched onboard the MetOp platform in October 2006. IASI is an infrared nadir-looking Fourier transform spectrometer providing atmospheric radiance spectra at 0.5 cm−1 spectral resolution, from which temperature and infrared absorbing gas concentration profiles are retrieved with global Earth coverage twice a day. A first analysis of the IASI measurements in terms of information content demonstrates the possibility of retrieving a total column for HNO3 at all latitudes with a maximal sensitivity in the middle stratosphere. The retrievals are performed from IASI spectra in the atmospheric window using a fast radiative transfer model and inversion software relying on the Optimal Estimation Method. The operational processing of HNO3 is achieved since March 2008. The global distributions of the retrieved total columns for 10 months (from March to December 2008) are presented and discussed with emphasis given to seasonal and interhemispheric variations. Local trends at 6 specific locations are also described and discussed in comparison with MLS volume mixing ratios at 46.5 hPa. The seasonal cycle observed in Polar regions is highlighted, with maxima observed in fall and minima during spring-summer. The denitrification inside the Antarctic polar vortex during winter is clearly revealed with unprecedented horizontal resolution: HNO3 columns decreasing down to about 1×1016 molecules.cm−2 are observed, which is consistent with the lower values of temperature observed between 50 and 15 hPa (~20–25 km) and the resulting formation and sedimentation of polar stratospheric clouds. During the same period, the collar region of high quantities of HNO3 at the vortex edge is also observed around 65–60° S latitude. Preliminary correlations between IASI derived HNO3 and O3 columns inside the polar vortex are presented and discussed.
A review of Secondary Organic Aerosol (SOA) formation from isoprene
Authors: Carlton A. G. , Wiedinmyer C. , Kroll J. H.
Published: April 2010

Abstract. Recent field and laboratory evidence indicates that the oxidation of isoprene, (2-methyl-1,3-butadiene, C5H8) forms secondary organic aerosol (SOA). Global biogenic emissions of isoprene (600 Tg yr−1) are sufficiently large that the formation of SOA in even small yields results in substantial production of atmospheric particulate matter, likely having implications for air quality and climate. Here we present a review of field measurements, experimental work, and modeling studies aimed at understanding the mechanisms, yield, and atmospheric importance of isoprene-derived SOA. SOA yields depend on a number of factors, including organic aerosol loading (Mo), NOx level (RO2 chemistry), and, because of the importance of multigenerational chemistry, the degree of oxidation. These dependences are not always included in SOA modules used in atmospheric transport models, and instead most yield parameterizations rely on a single set of chamber experiments (carried out over a limited range of conditions); this may lead to very different estimates of the atmospheric importance of isoprene SOA. New yield parameterizations, based on all available laboratory data (Mo=0−50 ug/m3), are presented here, so that SOA formation may be computed as a function of Mo, NOx level, and T. Current research needs and future research directions are identified.
Temporal and spatial variability of glyoxal as observed from space
Authors: Vrekoussis M. , Wittrock F. , Richter A. , Burrows P. J.
Published: April 2010

Abstract. Glyoxal, CHO.CHO, is produced during the oxidation of volatile organic compounds, VOC, released by anthropogenic activities, biogenic processes and biomass burning. It has a short chemical lifetime of a few hours in the boundary layer and lower troposphere and therefore serves as an indicator and a marker of photochemical hot-spots and their response to changing atmospheric conditions around the globe. For this reason more than five years of CHO.CHO observations (2002–2007), retrieved from the radiances measured by the satellite instrument SCIAMACHY, were obtained and analyzed both temporally and spatially. The largest columns of CHO.CHO (>6×1014 molec cm−2) are found in the tropical and sub-tropical regions, associated with high biological activity and the plumes from vegetation fires. The majority of the identified hot spots are characterized by a well-defined seasonality: the highest values being observed during the warm and dry periods as a result of the enhanced isoprene emissions and/or biomass burning from natural or man-made fires. The regions influenced by anthropogenic pollution also encounter enhanced amounts of CHO.CHO. The ratio ''CHO.CHO to HCHO, RGF'' over the biogenically influenced photochemical hot-spots is approximately 0.045. The presence of pyrogenic and anthropogenic emission seems to increase or decrease this number, respectively. Although the 2002–2007 period of observation is limited, over the northeastern Asia a significant annual increase in CHO.CHO in addition to a seasonal cycle is reported.
Carbon monoxide distributions from the IASI/METOP mission: evaluation with other space-borne remote sensors
Authors: George M. , Clerbaux C. , Hurtmans D. , Turquety S. , Coheur P.-F. , Pommier M. , Hadji-Lazaro J. , Edwards D. P. , Worden H. , Luo M. , Rinsland C. , McMillan W.
Published: April 2010

Abstract. The Infrared Atmospheric Sounding Interferometer (IASI) onboard the MetOp satellite measures carbon monoxide (CO) on a global scale, twice a day. CO total columns and vertical profiles are retrieved in near real time from the nadir radiance spectra measured by the instrument in the thermal infrared (TIR) spectral range. This paper describes the measurement vertical sensitivity of IASI. On the global scale, 0.8 to 2.4 independent pieces of information are available for the retrieval. At mid latitudes, the information ranges between 1.5 and 2, which enables the lower and upper troposphere to be distinguished, especially when thermal contrast is important. Global distributions of column CO are evaluated with correlative observations available from other nadir looking TIR missions currently in operation: the Measurements of Pollution in the Troposphere (MOPITT) onboard TERRA, the Atmospheric Infrared Sounder (AIRS) onboard AQUA and the Tropospheric Emission Spectrometer (TES) onboard AURA. On the global scale and on average, total column discrepancies ranging from 10 to 15% are found for latitudes above 45° N and lower than 15° S, but can reach 30% in cases of strong CO concentrations, e.g. when fires events occur. The choice of the a priori assumptions influences the retrievals and can explain some of the observed differences. Instrument specifications of IASI versus other missions are also discussed.
Ozone air quality during the 2008 Beijing Olympics – effectiveness of emission restrictions
Authors: Wang Y. , Hao J. , McElroy M. B. , Munger J. W. , Ma H. , Chen D. , Nielsen C. P.
Published: April 2010

Abstract. A series of aggressive measures was launched by the Chinese government to reduce pollutant emissions from Beijing and surrounding areas during the Olympic Games. Observations at Miyun, a rural site 100 km downwind of the Beijing urban center, show significant decreases in concentrations of O3, CO, NOy, and SO2 during August 2008, relative to August 2006–2007. The mean daytime mixing ratio of O3 was lower by about 15 ppbv, reduced to 50 ppbv, in August 2008. The relative reductions in daytime SO2, CO, and NOy were 61%, 25%, and 21%, respectively. Changes in SO2 and in species correlations from 2007 to 2008 indicate that emissions of SO2, CO, and NOx were reduced by 60%, 32%, and 36%, respectively, during the Olympics. Analysis of meteorological conditions and interpretation of observations using a chemical transport model suggest that restrictions on emissions during the Olympics were responsible for about 80% of the observed decreases in O3, with natural variations in meteorology accounting for the remaining 20%. Use of the Olympics emissions results in no significant biases between model and observations. The model predicts that emission restrictions such as those implemented during the Olympics can affect O3 far beyond the Beijing urban area, resulting in reductions in boundary layer O3 of 2–10 ppbv over a large region of the North China Plain and Northeastern China.
Space gravity spectroscopy: the benefits of Taylor-Karman structured criterion matrices
Authors: Marinkovice P. , Grafarend E. , Reubelt T.
Published: April 2010

Abstract. As soon as a space gravity spectroscopy was successfully performed, for instance by means of semicontinuous ephemeris of LEO - GPS tracked satellites, the problem of data validation appeared. It is for this purpose that a stochastic model for the homogeneous and isotropic analysis of measurements, obtained as “directly" measured values in LEO satellite missions (CHAMP, GRACE, GOCE), is studied. An isotropic analysis is represented by the homogeneous distribution of measured values and the statistical properties of the model are calculated. In particular, a correlation structure function is defined by the third order tensor (Taylor-Karman tensor) for the ensemble average of a set of incremental differences in measured components. Specifically, Taylor-Karman correlation tensor is calculated with the assumption that the analyzed random function is of a “potential type". The special class of homogeneous and isotropic correlation functions is introduced. Finally, a successful application of the concept is presented in the case study CHAMP and a comparison between modeled and estimated correlations is performed.Key words. data validation, 3D correlation tensor, homogeneous and isotropic correlation functions, Taylor-Karman structure, CHAMP
The possibility of the calibration/validation of the GOCE data with the balloon-borne gradiometer
Authors: Zieliński J. B. , Petrovskaya M. S.
Published: April 2010

Abstract. A new calibration/validation experiment for GOCE mission is proposed. Simultaneously with the satellite mission another gradiometer will be flown on the board of the stratospheric balloon on the altitude 20–40 km. The measurements can be compared with satellite data. The advantage of this method is that the same functionals are compared – gravity gradients. The post-mission external calibration/ validation is possible more directly than through the comparison with the ground truth gravity anomalies or geoid undulation. The calibrating gradiometer is less sensitive, but thanks to the altitude difference, compatible in precision with the orbiting GOCE gradiometer. Analytical procedure of the downward continuation is presented which permits comparison of these observables, supported by numerical examples. The threshold for the precision of the calibrating gradiometer is indicated. Similar comparison can be done between GOCE and GRACE missions.
GOCE gradients in various reference frames and their accuracies
Authors: Müller J. , Wermut M.
Published: April 2010

Abstract. The objective of GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) is the determination of the Earth’s gravity field with high spatial resolution. The main science sensor (the gradiometer) measures differential accelerations, from which the gravitational gradients, i.e. the matrix of the second derivatives of the gravitational potential, are derived. Some of them (the diagonal components of the gravitational tensor) are observed with highest accuracy, 4 mE/√Hz in a frequency range from 5 mHz to 100 mHz, whereas the off-diagonals are obtained less accurately. The gradients will be observed in the instrument frame, which approximates the along-track oriented, local orbital frame. For the transformation of the gradients in other frames (e.g. in the strictly earth-pointing frame or a local geodetic frame), the transformation parameters (orientation angles) and all components of the gravity tensor have to be known with sufficient accuracy. We show how the elements of the gravitational tensor and their accuracies look like in the various frames as well as their spectral behaviour, if only the GOCE observations are used for the transformation. Only V'zz keeps approximately its original accuracy in all frames discussed, except in the earth-fixed frame ITRF (International Terrestrial Reference Frame). Therefore we recommend to analyse the gradients as ‘close’ as possible in the observation frame.Key words. Satellite gradiometry, GOCE mission, reference frames, transformation errors
Kinematic and reduced-dynamic precise orbit determination of low earth orbiters
Authors: Švehla D. , Rothacher M.
Published: April 2010

Abstract. Various methods for kinematic and reduced-dynamic precise orbit determination (POD) of Low Earth Orbiters (LEO) were developed based on zero- and double-differencing of GPS carrier-phase measurements with and without ambiguity resolution. In this paper we present the following approaches in LEO precise orbit determination: – zero-difference kinematic POD, – zero-difference dynamic POD, – double-difference kinematic POD with and without ambiguity resolution, – double-difference dynamic POD with and without ambiguity resolution, – combined GPS/SLR reduced-dynamic POD. All developed POD approaches except the combination of GPS/SLR were tested using real CHAMP data (May 20-30, 2001) and independently validated with Satellite Laser Ranging (SLR) data over the same 11 days. With SLR measurements, additional combinations are possible and in that case one can speak of combined kinematic or combined reduced-dynamic POD. First results of such a combined GPS/SLR POD will be presented, too. This paper shows what LEO orbit accuracy may be achieved with GPS using different strategies including zerodifference and double-difference approaches. Kinematic versus dynamic orbit determination is presently an interesting issue that will also be discussed in this article.Key words. POD, kinematic orbit, dynamic orbit, LEO, CHAMP, ambiguity resolution, GPS, SLR
CHAMP gravity field recovery using the energy balance approach
Authors: Gerlach Ch. , Sneeuw N. , Visser P. , Švehla D.
Published: April 2010

Abstract. Since the early days of satellite geodesy energy balance based methods for gravity field determination have been considered. If non-conservative forces are known the Hamiltonian along the orbit is a constant of the motion. Thus the gravity field can be determined if position and velocity of the satellite are known and accelerometer measurements are available to model the non-conservative part. CHAMP is the first satellite that provides the user with those three kinds of data nearly continuously. Numerical investigations using real CHAMP data are presented to show the feasibility of the method. Using a semi-analytical approach the gravity field can be determined efficiently by a 2D-Fourier method. Those fast computations also give way to application of the method not only to a full gravity field recovery but also, e.g. for quick-look and validation of SST observations for satellite missions like CHAMP, GRACE or GOCE. The method can also be used for estimation of accelerometer calibration parameters.Key words. gravity field, energy balance, Jacobi-integral, non-conservative forces, accelerometer calibration, CHAMP
Freezing precipitation in Russia and the Ukraine
Authors: Khomenko I. A. , Ivanova A. R. , Chakina N. P. , Skriptunova E. N. , Zavyalova A. A.
Published: April 2010

Abstract. Conditions for freezing precipitation (FP), including freezing rain (FR) and freezing drizzle (FZ) for 8 airports in Russia and 4 in the Ukraine are studied on the basis of 10 to 20-year series of surface observations, radiosonde and objective analysis data. Statistical characteristics are presented of the FP episode durations and of occurrence frequency dependences on surface air temperature, wind direction and speed and cloud base height. From the radiosonde data, it is found that the "classical mechanism" of FP generation (for which, stratification of "warm nose" type in the cloud layer is necessary) is not frequent: most of FP cases are associated with "all cold" conditions in the lower 3-km layer, that is, with negative temperatures in and below the clouds.
Fine-scale precipitation structure of a cold front and the problem of the representativeness error
Authors: Ivanov S. , Palamarchuk J.
Published: April 2010

Abstract. The proper knowledge of spatial precipitation structure is important as much as that of microphysics processes for reliable quantitative precipitation forecasts. This study considers some aspects of how precipitation is organized on meso- and fine-scales, within a cold front line and how moisture transport is driven by these structures. Also, a spectral space vision of the representativeness error is proposed, which highlights uncertainties arising on the scales lying between resolutions of different networks. This approach is used to explain an improper simulation of humidity and precipitation fields in models whose resolution is coarser than the scales being considered.
Spatiotemporal monthly rainfall reconstruction via artificial neural network – case study: south of Brazil
Authors: Lucio P. S. , Conde F. C. , Cavalcanti I. F. A. , Serrano A. I. , Ramos A. M. , Cardoso A. O.
Published: April 2010

Abstract. Climatological records users, frequently, request time series for geographical locations where there is no observed meteorological attributes. Climatological conditions of the areas or points of interest have to be calculated interpolating observations in the time of neighboring stations and climate proxy. The aim of the present work is the application of reliable and robust procedures for monthly reconstruction of precipitation time series. Time series is a special case of symbolic regression and we can use Artificial Neural Network (ANN) to explore the spatiotemporal dependence of meteorological attributes. The ANN seems to be an important tool for the propagation of the related weather information to provide practical solution of uncertainties associated with interpolation, capturing the spatiotemporal structure of the data. In practice, one determines the embedding dimension of the time series attractor (delay time that determine how data are processed) and uses these numbers to define the network's architecture. Meteorological attributes can be accurately predicted by the ANN model architecture: designing, training, validation and testing; the best generalization of new data is obtained when the mapping represents the systematic aspects of the data, rather capturing the specific details of the particular training set. As illustration one takes monthly total rainfall series recorded in the period 1961–2005 in the Rio Grande do Sul – Brazil. This reliable and robust reconstruction method has good performance and in particular, they were able to capture the intrinsic dynamic of atmospheric activities. The regional rainfall has been related to high-frequency atmospheric phenomena, such as El Niño and La Niña events, and low frequency phenomena, such as the Pacific Decadal Oscillation.
Assignment of rainfall confidence values using multispectral satellite data at mid-latitudes: first results
Authors: Nauss T. , Kokhanovsky A. A.
Published: April 2010

Abstract. The authors propose a new method for the assignment of rainfall confidences on a pixel basis using cloud properties derived from optical satellite data during daytime. This approach is based on the concept model that the probability for precipitation is a function of the liquid water path, which in turn can be computed using the satellite-retrieved cloud optical thickness and the cloud effective droplet radius. In order to evaluate the principal potential of this idea, scenes from the Terra-MODIS sensor during the severe European summer floods in 2002 have been analysed in order to derive a corresponding regression function that interlinks the liquid water path with the rainfall probability or better with the confidence that a pixel which is classified as raining does actually rain. A first evaluation against ground-based radar data during March 2004 shows good skill of this new method.
Quasi 2D hydrodynamic modelling of the flooded hinterland due to dyke breaching on the Elbe River
Authors: Huang S. , Vorogushyn S. , Lindenschmidt K.-E.
Published: April 2010

Abstract. In flood modeling, many 1D and 2D combination and 2D models are used to simulate diversion of water from rivers through dyke breaches into the hinterland for extreme flood events. However, these models are too demanding in data requirements and computational resources which is an important consideration when uncertainty analysis using Monte Carlo techniques is used to complement the modeling exercise. The goal of this paper is to show the development of a quasi-2D modeling approach, which still calculates the dynamic wave in 1D but the discretisation of the computational units are in 2D, allowing a better spatial representation of the flow in the hinterland due to dyke breaching without a large additional expenditure on data pre-processing and computational time. A 2D representation of the flow and velocity fields is required to model sediment and micro-pollutant transport. The model DYNHYD (1D hydrodynamics) from the WASP5 modeling package was used as a basis for the simulations. The model was extended to incorporate the quasi-2D approach and a Monte-Carlo Analysis was used to conduct a flood sensitivity analysis to determine the sensitivity of parameters and boundary conditions to the resulting water flow. An extreme flood event on the Elbe River, Germany, with a possible dyke breach area was used as a test case. The results show a good similarity with those obtained from another 1D/2D modeling study.
Evaluation of evapotranspiration methods for model validation in a semi-arid watershed in northern China
Authors: Schneider K. , Ketzer B. , Breuer L. , Vaché K. B. , Bernhofer C. , Frede H.-G.
Published: April 2010

Abstract. This study evaluates the performance of four evapotranspiration methods (Priestley-Taylor, Penman-Monteith, Hargreaves and Makkink) of differing complexity in a semi-arid environment in north China. The results are compared to observed water vapour fluxes derived from eddy flux measurements. The analysis became necessary after discharge simulations using an automatically calibrated version of the Soil and Water Assessment Tool (SWAT) failed to reproduce runoff measurements. Although the study area receives most of the annual rainfall during the vegetation period, high temperatures can cause water scarcity. We investigate which evapotranspiration method is most suitable for this environment and whether the model performance of SWAT can be improved with the most adequate evapotranspiration method. The evapotranspiration models were tested in two consecutive years with different rainfall amounts. In general, the simple Hargreaves and Makkink equations outmatch the more complex Priestley-Taylor and Penman-Monteith methods, although their performance depended on water availability. Effects on the quality of SWAT runoff simulations, however, remained minor. Although evapotranspiration is an important process in the hydrology of this steppe environment, our analysis indicates that other driving factors still need to be identified to improve SWAT simulations.
Global modelling of continental water storage changes – sensitivity to different climate data sets
Authors: Fiedler K. , Döll P.
Published: April 2010

Abstract. Since 2002, the GRACE satellite mission provides estimates of the Earth's dynamic gravity field with unprecedented accuracy. Differences between monthly gravity fields contain a clear hydrological signal due to continental water storage changes. In order to evaluate GRACE results, the state-of-the-art WaterGAP Global Hydrological Model (WGHM) is applied to calculate terrestrial water storage changes on a global scale. WGHM is driven by different climate data sets to analyse especially the influence of different precipitation data on calculated water storage. The data sets used are the CRU TS 2.1 climate data set, the GPCC Full Data Product for precipitation and data from the ECMWF integrated forecast system. A simple approach for precipitation correction is introduced. WGHM results are then compared with GRACE data. The use of different precipitation data sets leads to considerable differences in computed water storage change for a large number of river basins. Comparing model results with GRACE observations shows a good spatial correlation and also a good agreement in phase. However, seasonal variations of water storage as derived from GRACE tend to be significantly larger than those computed by WGHM, regardless of which climate data set is used.
The rainfall regime and its uncertainty in Valencia and Larnaca
Authors: Reiser H. , Kutiel H.
Published: April 2010

Abstract. The Most Expected Rainfall Regime – MERR in a certain region is composed of various parameters regarding the annual rainfall regime in that region. The present study examines several parameters of the MERR, such as: the rainfall TOTAL, the Date of Accumulated Percentage-DAP, the Rainy Season Length-RSL, the Number of Rain-Spells-NRS, the Rain-Spell Yield-RSY, the ratio between Average and Median rainfall-AMED, the relationship between accumulated precipitation and the number of rain-spells and the Dry-Spell Distribution-DSD. Two stations at the two sides of the Mediterranean basin, Valencia and Larnaca, have been used to illustrate the distribution of the above parameters across the Mediterranean. The main conclusion of the study is that the rainfall regime at Larnaca is less uncertain as compared with the regime in Valencia. This is probably due to the fact that rainfalls are completely absent during the summer in Larnaca, which better suits the definition of a Mediterranean climate than that of Valencia.
Synoptic climatological analysis of Red Sea Trough and non-Red Sea Trough rain situations over Israel
Authors: Tsvieli Y. , Zangvil A.
Published: April 2010

Abstract. Winter (October to April) rainfall in Israel is caused mostly by migrating Mediterranean cyclones but certain rain situations are accompanied by a low pressure trough extending northward from the southern Red Sea towards the Eastern Mediterranean (EM) and the Levant. This system, the Red Sea Trough (RST) is one of the most frequent surface atmospheric circulation patterns over the southeastern Mediterranean, but most of the RSTs are not accompanied by rain. This paper presents a synoptic climatological comparative analysis between rain situations associated with RSTs, and those not connected with RSTs (non-RST rain, NRR). The RST situations were identified objectively with the aid of a new algorithm applied to the GEOS-1 reanalysis gridded data set from NASA, for the period of March 1985–November 1995. Results show that RST rain is accompanied by a relatively narrow 500-hPa trough, located west of the Israeli coast-line and characterized by a deep southward penetration, while Non-RST-associated rain (NRR) is accompanied by a wider upper trough, located over the Israeli coast-line with a shallower southward penetration. We found a south-southwesterly wind vector anomaly at 200 hPa over Israel during RST rains, while during NRRs a similar wind vector anomaly pattern is observed east of Israel. There is a divergence center over, or a few degrees east of Israel during RST rains, while NRR is associated with a divergence value of nearly zero over Israel and a maximum divergence center located east of Israel. The moisture flux during NRR at 700 and 900 hPa is from the Mediterranean, while during RST rain there is a south-westerly moisture flux at 700 hPa from equatorial Africa to Israel and vicinity. A steeper temperature lapse-rate between 950–500 hPa was found during RST rain compared with NRR, resulting from a combination of cooling aloft together with heating near the surface.
Winter precipitation and cyclones in the Mediterranean region: future climate scenarios in a regional simulation
Authors: Lionello P. , Giorgi F.
Published: April 2010

Abstract. Future climate projections show higher/lower winter (Dec-Jan-Feb) precipitation in the northern/southern Mediterranean region than in present climate conditions. This paper analyzes the results of regional model simulations of the A2 and B2 scenarios, which confirm this opposite precipitation change and link it to the change of cyclone activity. The increase of the winter cyclone activity in future climate scenarios over western Europe is responsible for the larger precipitation at the northern coast of the basin, though the bulk of the change is located outside the Mediterranean region. The reduction of cyclone activity inside the Mediterranean region in future scenarios is responsible for the lower precipitation at the southern and eastern Mediterranean coast.
Toward a climate downscaling for the Eastern Mediterranean at high-resolution
Authors: Hahmann A. N. , Rostkier-Edelstein D. , Warner T. T. , Liu Y. , Vandenberghe F. , Swerdlin S. P.
Published: April 2010

Abstract. As a first step toward downscaling global model simulations of future climates for the eastern Mediterranean Sea and surrounding land area, mesoscale-model simulations with the Pennsylvania State University – National Center for Atmospheric Research (NCAR) mesoscale model, version 5 (MM5) are verified in the context of precipitation amount. The simulations are driven with January NCAR-NCEP reanalysis project (NNRP) lateral-boundary conditions and assimilate surface and upper air observations. The results of the simulations compare reasonably well with rain gauge and satellite estimates of monthly total precipitation, and the model reproduces the overall trends in inter-annual precipitation variability for one test region. Cyclones during the period were tracked, and their properties identified.
Development of a daily gridded precipitation data set for the Middle East
Authors: Yatagai A. , Xie P. , Alpert P.
Published: April 2010

Abstract. We show an algorithm to construct a rain-gauge-based analysis of daily precipitation for the Middle East. One of the key points of our algorithm is to construct an accurate distribution of climatology. One possible advantage of this product is to validate high-resolution climate models and/or to diagnose the impact of climate changes on local hydrological resources. Many users are familiar with a monthly precipitation dataset (New et al., 1999) and a satellite-based daily precipitation dataset (Huffman et al., 2001), yet our data set, unlike theirs, clearly shows the effect of orography on daily precipitation and other extreme events, especially over the Fertile Crescent region. Currently the Middle-East precipitation analysis product is consisting of a 25-year data set for 1979–2003 based on more than 1300 stations.
Predictability of intense rain storms in the Central Mediterraneanbasin: sensitivity to upper-level forcing
Authors: Federico S. , Avolio E. , Bellecci C. , Lavagnini A. , Walko R. L.
Published: April 2010

Abstract. This study investigates the sensitivity of a moderate-intense storm that occurred over Calabria, southern Italy, to upper-tropospheric forcing from a Potential Vorticity (PV) perspective. A prominent mid-troposheric trough can be identified for this event, which occurred between 22–24 May 2002, and serves as the precursor agent for the moderate-intense precipitation recorded. The working hypothesis is that the uncertainty in the representation of the upper-level disturbance has a major impact on the precipitation forecast and we test the hypothesis in a two-step approach. First, we examine the degree of uncertainty by comparing five different scenarios in a Limited area model Ensemble Prediction System (LEPS) framework which utilizes the height of the dynamical tropopause as the discriminating variable. Pseudo water vapour images of different scenarios are compared to the corresponding METEOSAT 7 water vapour image at a specific time, antecedent to the rain occurrence over Calabria, in order to evaluate the reliability of the different precipitation scenarios simulated by the LEPS. Second, we examine the impact of upper tropospheric PV variations on precipitation by comparing model simulations with slightly different initial PV fields. Initial velocity and mass fields in each case are balanced with the chosen PV perturbation using a PV inversion technique. The results of this study support the working hypothesis.
A simple atmospheric electrical instrument for educational use
Authors: Bennett A. J. , Harrison R. G.
Published: April 2010

Abstract. Electricity in the atmosphere provides an ideal topic for educational outreach in environmental science. To support this objective, a simple instrument to measure real atmospheric electrical parameters has been developed and its performance evaluated. This project compliments educational activities undertaken by the Coupling of Atmospheric Layers (CAL) European research collaboration. The new instrument is inexpensive to construct and simple to operate, readily allowing it to be used in schools as well as at the undergraduate University level. It is suited to students at a variety of different educational levels, as the results can be analysed with different levels of sophistication. Students can make measurements of the fair weather electric field and current density, thereby gaining an understanding of the electrical nature of the atmosphere. This work was stimulated by the centenary of the 1906 paper in which C. T. R. Wilson described a new apparatus to measure the electric field and conduction current density. Measurements using instruments based on the same principles continued regularly in the UK until 1979. The instrument proposed is based on the same physical principles as C. T. R. Wilson's 1906 instrument.
InSAR processing for the recognition of landslides
Authors: Riedel B. , Walther A.
Published: April 2010

Abstract. Synthetic Aperture Radar Interferometry (InSAR) is an established method for the detection and monitoring of earth surface processes. This approach has been most successful where the observed area fulfills specific requirements, such as sufficient backscattering, flat slope gradients or very slow changes of vegetation. We investigated the capability of two different InSAR techniques and achieved good results for the recognition of landslides in China and Greece that compared well with geodetic derived movement rates. This demonstrates the strong potential of SAR Interferometry for the detection of landslides and earth surface movements.
Extreme precipitation events in the Czech Republic in the context of climate change
Authors: Květoň V. , Žák M.
Published: April 2010

Abstract. As an introduction, short survey of two analyses of long-term fluctuations of annual precipitation totals in the Czech Republic is presented. The main focus of this paper is to contribute to investigation of precipitation trends in the Czech Republic by another point of view. For every pixel of 1 km2 size, annual maxima of daily precipitation were obtained for time period of 112 years (1895–2006). Based on these time series, we were trying to answer question if there are some changes of area size/distribution of annual maximum of daily precipitation totals. Courses and trends are analyzed for some parameters of area distribution of annual maximum of daily precipitation totals in the area of the Czech Republic. No significant climate changes of tested precipitation characteristics were found.
The critical role of volcano monitoring in risk reduction
Authors: Tilling R. I.
Published: April 2010

Abstract. Data from volcano-monitoring studies constitute the only scientifically valid basis for short-term forecasts of a future eruption, or of possible changes during an ongoing eruption. Thus, in any effective hazards-mitigation program, a basic strategy in reducing volcano risk is the initiation or augmentation of volcano monitoring at historically active volcanoes and also at geologically young, but presently dormant, volcanoes with potential for reactivation. Beginning with the 1980s, substantial progress in volcano-monitoring techniques and networks – ground-based as well space-based – has been achieved. Although some geochemical monitoring techniques (e.g., remote measurement of volcanic gas emissions) are being increasingly applied and show considerable promise, seismic and geodetic methods to date remain the techniques of choice and are the most widely used. Availability of comprehensive volcano-monitoring data was a decisive factor in the successful scientific and governmental responses to the reawakening of Mount St. elens (Washington, USA) in 1980 and, more recently, to the powerful explosive eruptions at Mount Pinatubo (Luzon, Philippines) in 1991. However, even with the ever-improving state-of-the-art in volcano monitoring and predictive capability, the Mount St. Helens and Pinatubo case histories unfortunately still represent the exceptions, rather than the rule, in successfully forecasting the most likely outcome of volcano unrest.
Satellite-based detection of volcanic sulphur dioxide from recent eruptions in Central and South America
Authors: Loyola D. , van Geffen J. , Valks P. , Erbertseder T. , Van Roozendael M. , Thomas W. , Zimmer W. , Wißkirchen K.
Published: April 2010

Abstract. Volcanic eruptions can emit large amounts of rock fragments and fine particles (ash) into the atmosphere, as well as several gases, including sulphur dioxide (SO2). These ejecta and emissions are a major natural hazard, not only to the local population, but also to the infrastructure in the vicinity of volcanoes and to aviation. Here, we describe a methodology to retrieve quantitative information about volcanic SO2 plumes from satellite-borne measurements in the UV/Visible spectral range. The combination of a satellite-based SO2 detection scheme and a state-of-the-art 3D trajectory model enables us to confirm the volcanic origin of trace gas signals and to estimate the plume height and the effective emission height. This is demonstrated by case-studies for four selected volcanic eruptions in South and Central America, using the GOME, SCIAMACHY and GOME-2 instruments.