A GCM study of future climate response to aerosol pollution reductions     

Silvia Kloster  Frank Dentener  Johann Feichter  Frank Raes  Ulrike Lohmann  Erich Roeckner  Irene Fischer-Bruns 《Climate Dynamics》2010,34(7-8):1177-1194

We use the global atmospheric GCM aerosol model ECHAM5-HAM to asses possible impacts of future air pollution mitigation strategies on climate. Air quality control strategies focus on the reduction of aerosol emissions. Here we investigate the extreme case of a maximum feasible end-of-pipe abatement of aerosols in the near term future (2030) in combination with increasing greenhouse gas (GHG) concentrations. The temperature response of increasing GHG concentrations and reduced aerosol emissions leads to a global annual mean equilibrium temperature response of 2.18 K. When aerosols are maximally abated only in the Industry and Powerplant sector, while other sectors stay with currently enforced regulations, the temperature response is 1.89 K. A maximum feasible abatement applied in the Domestic and Transport sector, while other sectors remain with the current legislation, leads to a temperature response of 1.39 K. Increasing GHG concentrations alone lead to a temperature response of 1.20 K. We also simulate 2–5% increases in global mean precipitation among all scenarios considered, and the hydrological sensitivity is found to be significantly higher for aerosols than for GHGs. Our study, thus highlights the huge potential impact of future air pollution mitigation strategies on climate and supports the need for urgent GHG emission reductions. GHG and aerosol forcings are not independent as both affect and are influenced by changes in the hydrological cycle. However, within the given range of changes in aerosol emissions and GHG concentrations considered in this study, the climate response towards increasing GHG concentrations and decreasing aerosols emissions is additive.  相似文献   

Bi-decadal variability excited in the coupled ocean–atmosphere system by strong tropical volcanic eruptions     

D. Zanchettin  C. Timmreck  H.-F. Graf  A. Rubino  S. Lorenz  K. Lohmann  K. Krüger  J. H. Jungclaus 《Climate Dynamics》2012,39(1-2):419-444

Decadal and bi-decadal climate responses to tropical strong volcanic eruptions (SVEs) are inspected in an ensemble simulation covering the last millennium based on the Max Planck Institute—Earth system model. An unprecedentedly large collection of pre-industrial SVEs (up to 45) producing a peak annual-average top-of-atmosphere radiative perturbation larger than ?1.5 Wm^?2 is investigated by composite analysis. Post-eruption oceanic and atmospheric anomalies coherently describe a fluctuation in the coupled ocean–atmosphere system with an average length of 20–25 years. The study provides a new physically consistent theoretical framework to interpret decadal Northern Hemisphere (NH) regional winter climates variability during the last millennium. The fluctuation particularly involves interactions between the Atlantic meridional overturning circulation and the North Atlantic gyre circulation closely linked to the state of the winter North Atlantic Oscillation. It is characterized by major distinctive details. Among them, the most prominent are: (a) a strong signal amplification in the Arctic region which allows for a sustained strengthened teleconnection between the North Pacific and the North Atlantic during the first post-eruption decade and which entails important implications from oceanic heat transport and from post-eruption sea ice dynamics, and (b) an anomalous surface winter warming emerging over the Scandinavian/Western Russian region around 10–12 years after a major eruption. The simulated long-term climate response to SVEs depends, to some extent, on background conditions. Consequently, ensemble simulations spanning different phases of background multidecadal and longer climate variability are necessary to constrain the range of possible post-eruption decadal evolution of NH regional winter climates.  相似文献   

Interannual to decadal summer drought variability over Europe and its relationship to global sea surface temperature   总被引：4，自引：0，他引：4  

M. Ionita  G. Lohmann  N. Rimbu  S. Chelcea  M. Dima 《Climate Dynamics》2012,38(1-2):363-377

Interannual to decadal variability of European summer drought and its relationship with global sea surface temperature (SST) is investigated using the newly developed self calibrated Palmer drought severity index (scPDSI) and global sea surface temperature (SST) field for the period 1901–2002. A European drought severity index defined as the average of scPDSI over entire Europe shows quasiperiodic variations in the 2.5–5 year band as well as at 12–13 years suggesting a possible potential predictability of averaged drought conditions over Europe. A Canonical Correlation Analysis between summer scPDSI anomalies over Europe and global SST anomalies reveals the existence of three modes of coupled summer drought scPDSI patterns and winter global SST anomalies. The first scPDSI-SST coupled mode represents the long-term trends in the data which manifest in SST as warming over all oceans. The associated long-term trend in scPDSI suggests increasing drought conditions over the central part of Europe. The second mode is related to the inter-annual ENSO and decadal PDO influence on the European climate and the third one captures mainly the drought pattern associated to Atlantic Multidecadal Oscillation. The lag relationships between winter SST and summer drought conditions established in this study can provide a valuable skill for the prediction of drought conditions over Europe on interannual to decadal time scales.  相似文献   

Ein Beitrag zur Petrographie Melilith-führender Olivinnephelinite aus dem Gebiet Fritzlar—Naumburg (Nordhessen)     

Dr. Ludwig Lohmann 《Contributions to Mineralogy and Petrology》1964,9(6):533-584

Zusammenfassung Tertiäre Olivinnephelinite aus dem Gebiet zwischen Naumburg und Fritzlar südwestlich des Habichtswaldes bei Kassel wurden optisch, röntgenographisch und chemisch untersucht. Die Basalte gehören dem Stamm der Alkali-Olivin-Basalte an und zeigen bis auf Vorkommen im Nordteil des Untersuchungsgebietes ein in den Hauptgemengteilen petrographisch einheitliches Bild.Im Norden des Gebietes treten Limburgite sowie Basalte mit der Paragenese Analcim + Alkalifeldspat + Nephelin auf.Tuffe Bind nur im mittleren Teil des Untersuchungsgebietes aufgeschlossen, welches infolge seiner Morphologie als ein Haupteruptionszentrum anzusehen ist.In einem Teil der Basalte trio (örtlich im Bereich weniger m) Melilith stellen-Weise mit sanduhrförmig eingelagertem Pyroxen auf. Häufig ist der Melilith pseudomorphosiert zu Karbonat und Zeolith oder einer nicht näher bestimmbaren Tonmineralkomponente.Aus dem einheitlichen Bild dieser Basalte wird geschlossen, daß in sämtlichen Vorkommen außer im nördlichen Teil des Gebietes Melilith hätte gebildet werden können. Eine solche Möglichkeit lassen die in der Literatur angegebenen experimentellen Untersuchungen der jeweiligen Systeme zu. Gegen die Bildung von SiO₂-untersättigten Schmelzen durch Assimilation von Sedimenten werden petrographische und geochemische Beobachtungen angeführt. Die Frage nach der Bildung solcher Schmelzen kann jedoch an Hand des Untersuchungsmaterials nicht beantwortet werden. Es werden Reaktionen von Olivin, Pyroxen und Magnetit mit der Sehmelze beobachtet, die denen in experimentell untersuchten Systemen entsprechen.Für das sporadische Auftreten des Melilithes bzw. seiner Pseudomorphosen werden Reaktionen mit Restschmelzen angenommen. Ein Abquetschen dieser Restschmelzen vom Ort ihrer Entstehung kann für die Bildung von Analeim-Basalten im Norden des Untersuchungsgebietes verantwortlich sein.

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Tertiary olivine-nephelinites from the region between Naumburg and Fritzlar, southwest of the Habichtswald near Kassel were investigated by optical, x-ray, and chemical methods. The basalts belong to the alkali-olivine-type. They are petrographically uniform in terms of major constituents, except a few occurrences of limburgites and analcite-basalts in the northern part of the area. The latter contain the paragenesis analcite + alkali feldspar + nepheline. Pyroclastics are only exposed in the central part of the area. Because of its morphology this part may be considered as the main eruption center. Several of the basalt-masses contain melilite, locally in patches of a few meters in extent. Hour glass-shaped inclusions of pyroxene are observed in some of them. In many rocks melilite is replaced by carbonates and zeolites or a clay mineral which could not be precisely identified. It is concluded from the uniform character of these basalts that in all occurrences except the northern part of the area melilite could have been formed. This assumption is in accordance with the experimental results of the systems related to our problem (literature data). Petrological and geochemical observations in this area do not favour the formation of undersaturated liquids from the assimilation of sediments (hypothesis ofDaly andShand). Reactions are observed between the liquid and the minerals olivine, pyroxene and magnetite corresponding to those in experimentally investigated systems. The sporadic occurrence of melilite and its alteration products is derived from reactions with residual liquids. The analcite-basalts in the northern part of the area may originate from a separated residual liquid squeezed off its place of origin.

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Carbon isotopic changes in benthic foraminifera from the western South Atlantic: Reconstruction of glacial abyssal circulation patterns     

W.B. Curry  G.P. Lohmann 《Quaternary Research》1982,18(2):218-235

Oxygen- and carbon-isotopic analyses have been performed on the benthic foraminifer Planulina wuellerstorfi in seven Late Quaternary cores from the Vema Channel-Rio Grande Rise region. The cores are distributed over the water-depth interval of 2340 to 3939 m, which includes the present transition from North Atlantic Deep Water (NADW) to Antarctic Bottom Water (AABW).The carbon-isotopic records in the cores vary as a function of water depth. The shallowest and deepest cores show no significant glacial-interglacial difference in δ¹³C. Four of the five cores presently located in the NADW have benthic foraminiferal δ¹³C that is lower during glacial isotopic stages. Based on bathymetric gradients in δ¹³C, we conclude that, like today, there were two water masses present in the Vema Channel during glacial intervals: a water mass enriched in ¹³C overlying another water mass depleted in ¹³C. The largest gradient of change of δ¹³C with depth, however, occurred at 2.7 km, ～ 1 km shallower than the present position of this gradient.On the basis of paleontologic and sedimentologic evidence, we consider it unlikely that the NADW:AABW transition shallowed to this level. Reduced carbon-isotopic gradients between the deep basins of the North Atlantic and Pacific Oceans during the last glaciation suggest that production of NADW was reduced. Lower production of NADW may have modified the local abyssal circulation pattern in the Vema Channel region.  相似文献   

Acceleration technique for Milankovitch type forcing in a coupled atmosphere-ocean circulation model: method and application for the Holocene     

Stephan J. Lorenz  Gerrit Lohmann 《Climate Dynamics》2004,23(7-8):727-743

A method is introduced which allows the calculation of long-term climate trends within the framework of a coupled atmosphere-ocean circulation model. The change in the seasonal cycle of incident solar radiation induced by varying orbital parameters has been accelerated by factors of 10 and 100 in order to allow transient simulations over the period from the mid-Holocene until today, covering the last 7,000 years. In contrast to conventional time-slice experiments, this approach is not restricted to equilibrium simulations and is capable to utilise all available data for validation. We find that opposing Holocene climate trends in tropics and extra-tropics are a robust feature in our experiments. Results from the transient simulations of the mid-Holocene climate at 6,000 years before present show considerable differences to atmosphere-alone model simulations, in particular at high latitudes, attributed to atmosphere-ocean-sea ice effects. The simulations were extended for the time period 1800–2000 AD, where, in contrast to the Holocene climate, increased concentrations of greenhouse gases in the atmosphere provide for the strongest driving mechanism. The experiments reveal that a Northern Hemisphere cooling trend over the Holocene is completely cancelled by the warming trend during the last century, which brings the recent global warming into a long-term context.  相似文献   

Drop shape and erosivity part II: Splash detachment,transport and erosivity indices     

Hans Th. Riezebos  Gerrit F. Epema 《地球表面变化过程与地形》1985,10(1):69-74

The relevance of drop shape for erosivity was tested for different combinations of drop sizes and fall heights. For all test combinations together the introduction of the observed drop shape in erosivity parameters only produces minor improvements in the relation between erosivity and detachment and transport by splash. This result is attributed to the dominance of oblate shapes in high velocity conditions. Using small fall heights and low fall velocities as in many rainfall simulators and drop tests it is shown that prolate drops produce a splash detachment which is 2 to 3 times higher than that produced by drops with an oblate shape at impact. As drop production in rainulators or for aggregate stability drop tests may result in more or less uncontrolled variations of drop shape, it is concluded that in addition to other test conditions drop shape should be specified. Moreover it is noted that the erosive capability of prolate drops can explain partly the high splash erosion amounts below vegetation.  相似文献   

Eigenshape analysis of microfossils: A general morphometric procedure for describing changes in shape     

G. P. Lohmann 《Mathematical Geosciences》1983,15(6):659-672

A general morphometric procedure is described that organizes collections of microfossil outlines according to their shape. It involves representing the greatest proportion of variation observed among a collection of shapes by the least number of different shapes. Since these are determined as empirical orthogonal shape functions—eigenfunctions—of the observed shapes, the procedure is termed eigenshape analysis. Observed shapes are arranged and their shape differences systemized by reference to these determined eigenshape functions. The well-known ecophenotypic shape variation with latitude exhibited by the Pleistocene planktonic foraminifer Globorotalia truncatulinoides (d'Orbigny)serves as an example.  相似文献   

Atmospheric bridge on orbital time scales     

Gerrit?LohmannEmail author 《Theoretical and Applied Climatology》2017,128(3-4):709-718

Large-scale atmospheric patterns are examined on orbital timescales using a climate model which explicitly resolves the atmosphere–ocean–sea ice dynamics. It is shown that, in contrast to boreal summer where the climate mainly follows the local radiative forcing, the boreal winter climate is strongly determined by modulation of circulation modes linked to the Arctic Oscillation/North Atlantic Oscillation (AO/NAO) and the Northern/Southern Annular Modes. We find that during a positive phase of the AO/NAO the convection in the tropical Pacific is below normal. The related atmospheric circulation provides an atmospheric bridge for the precessional forcing inducing a non-uniform temperature anomalies with large amplitudes over the continents. We argue that this is important for mechanisms responsible for multi-millennial climate variability and glacial inception.  相似文献   

A comparison of ASCE and FAO-56 reference evapotranspiration for a 15-min time step in humid climate conditions     

Ayman A. Suleiman  Gerrit Hoogenboom   《Journal of Hydrology》2009,375(3-4):326-333

Many applications in diverse disciplines require estimates of evapotranspiration (ET) at hourly or smaller time steps. The primary objectives of this study were to compare the American Society of Civil Engineers (ASCE) and FAO-56 Penman–Monteith equations for 15-min ET₀ (ET_{0,15-min,ASCE} and ET_0,15-min,FAO) estimations for humid climate conditions and to compare the 24 h sum of ASCE (ET_0,24 h,ASCE) and FAO-56 15-min ET₀ (ET_0,24 h,FAO) with the daily ET₀ (ET_0,d,FAO) computed from the daily FAO-56 equation, which is identical to ASCE daily ET₀ equation. Ten-year, i.e., 1997–2006 continuous 15-min and daily weather data for 11 representative and well-distributed sites throughout Georgia, USA were used. It was evident that during the day, ET_{0,15-min,ASCE} was higher than ET_0,15-min,FAO due to a lower surface resistance parameter value, while at night ET_{0,15-min,ASCE} was lower than ET_0,15-min,FAO due to a higher surface resistance parameter value. The ET_0,15-min,FAO was about 5% less than ET_{0,15-min,ASCE} and ET_0,24 h,FAO was about 5% lower than ET_0,24 h,ASCE. The difference between ET_{0,15-min,ASCE} and ET_0,15-min,FAO during the day and night was highly dependent on wind speed. During the three summer months, i.e., June, July and August, on average, ET_0,24 h,FAO was only 1% higher than ET_0,d,FAO while ET_0,24 h,ASCE was 5% higher than ET_0,d,FAO. For the entire year, ET_0,24 h,FAO was 8% higher than ET_0,d,FAO while ET_0,24 h,ASCE was 13% higher than ET_0,d,FAO. The ET_0,24 h,FAO and ET_0,d,FAO had a better agreement than ET_0,24 h,ASCE and ET_0,d,FAO throughout the year and during the summer months. It is also worth noting that the daily calculations for FAO-56 and ASCE were identical. These results demonstrated that for applications that require 15-min time steps or daily ET₀ for the entire year, the use of ET_0,15-min,FAO and ET_0,24 h,FAO, respectively, will yield more consistent outcomes. The use of ET_0,d,FAO during the summer months can be as accurate as the use of ET_0,24 h,FAO for applications that require daily time steps, such as irrigation scheduling.  相似文献