WIMPs and solar evolution code     

Yannick Giraud-Héraud  Jean Kaplan  François De Volnay Martin  Charling Tao  Sylvaine Turck-Chièze 《Solar physics》1990,128(1):21-33

The Saclay solar evolution code is used to check the effect of WIMPs on solar evolution. In this paper we study the effects of various types of Cosmion-matter interactions, give constraints on the crosssections compatible with the measured neutrino rate of 2 SNU on chlorine, and relate these constraints to ongoing dark matter detection experiments.Unité associée au CNRS UA 280, F-75251 Paris Cedex 05, France.On leave from LPC, Collège de France.  相似文献   

Vertical and lateral transport of organic carbon and the carbon budget in Santa Monica Basin, California     

M.I. Venkatesan  I.R. Kaplan 《Progress in Oceanography》1992,30(1-4)

The flux and compositions of solvent-extractable lipid fractions were measured in particulate matter collected periodically by moored sediment traps in the Santa Monica Basin from 1985–1988. The purpose was to assess the compositional changes during settling, the carbon dynamics in the basin and to estimate the impacts of energy-related by-products on the surface sediments. Sediment traps recorded consistently high lipid fluxes in the eastern slope relative to the central basin, reflecting elevated terrigenous carbon inputs possibly from land-based human activities. Generally, lipid fluxes decrease offshore but increase vertically with water depth below 500m, implying lateral transport of particles. The steep decline of flux in the top 500m of the water is related to the rapid decomposition and mineralization of the marine-derived cellular carbon compounds. Less than 5% of the marine lipid components reach the seabed. In contrast, preferential preservation of terrigenous lipid is clearly evident from the chemistry of deeper traps and surface sediments.The lateral transport of particles is reflected in the presence of higher plant-derived lignin phenols and sewage-derived coprostanol and epicoprostanol in the deep trap material as well as in surface sediment throughout the basin. Petroleum triterpanes characteristic of natural seepage also permeates through the entire basin. Based on the data collected from both the trap particulte matter and surface sediments, a carbon budget for the Santa Monica Basin has been constructed.  相似文献   

Remote sensing and surface POC concentration in the South Atlantic   总被引：1，自引：0，他引：1  

Alexey V. Mishonov  Wilford D. Gardner  Mary Jo Richardson 《Deep Sea Research Part II: Topical Studies in Oceanography》2003,50(22-26):2997

Several SeaWiFS products have been compared with shipboard data to assess the possibility of using remote sensing to estimate particulate organic carbon (POC) concentration in surface waters. Transmissometer data were collected during six South Atlantic Ventilation Experiment (SAVE) hydrographic expeditions conducted between November 1987 and March 1989 from R/V Knorr, and Melville. A total of 361 beam attenuation profiles were made with a SeaTech transmissometer interfaced with a CTD/rosette. In order to calculate the POC concentration from transmissometer profiles, a regression between beam attenuation and POC for open Atlantic Ocean waters derived from our research in the North Atlantic (North Atlantic Bloom Experiment, NABE) and enhanced by data from the Bermuda Atlantic Time Series Station (BATS) was applied. The profiles were processed and examined as vertical sections of the surface 250 m. The data were collected in two successive years, during the same season, which allowed us to compile a combined data set over the austral summer for examination. Beam attenuation/POC concentrations were integrated down to one attenuation depth with the intent of making comparisons with satellite optical data. No satellite optical data were available for 1987–1989, so the only option was to compare our integrated data with SeaWiFS-derived variables from later years averaged over the same season as SAVE data. Analysis of four SeaWiFS products acquired from 1997 to 2002 demonstrated very low variations from year to year for seasonally averaged data, suggesting that making comparisons of the beam attenuation/POC fields with averaged satellite optical products from later years is a valid (though not optimal) approach for this area. The highest correlation between beam attenuation/POC concentration and remotely derived products was found with normalized water-leaving radiance at 555 nm. Other SeaWiFS-derived variables—chlorophyll concentration, diffuse attenuation coefficient at 490 nm and integral chlorophyll (integrated over one attenuation depth)—were also compared but showed a slightly less satisfactory correlation.  相似文献   

Meso-beta scale numerical simulations of terrain drag-induced along-stream circulations. Part II: Concentration of potential vorticity within dryline bulges     

M. L. Kaplan  V. M. Karyampudi 《Meteorology and Atmospheric Physics》1992,49(1-4):157-185

Summary Hydrostatic and nonhydrostatic simulation models are employed to study the intensification of a terrain drag-induced dryline. The study develops a multi-stage theory for the evolution of the dryline including the concentration of potential vorticity accompanying meso-gamma scale dryline bulges.The numerical simulations indicate three fundamental stages of dryline intensification all of which are either directly or indirectly a result of the terrain-drag on the mid/upper-tropospheric jet stream by the Front Range of the Colorado Rocky Mountains. The first stage involves the downward momentum flux accompanying a large amplitude hydrostatic mountain wave which induces a downslope windstorm along the lee slopes. The surge of momentum (i.e., the dry, warm air associated with the downslope windstorm) propagates down the leeslope and modifies an existing weak dryline boundary. As the downslope windstorm initiates an undular bore along the lee slopes, the high momentum gradient which propagates downstream accompanying the bore, as well as the strong lower tropospheric sinking motions ahead of the bore, contract the scale of the surface moisture boundary between the dry air from above the leeslope and the moist air over the High Plains. This process further strengthens the dryline.The second stage involves the coupling of the terrain drag-induced along-stream ageostrophic front within the midtroposphere to the boundary layer through a thermally-indirect circulation. As the along-stream ageostrophic circulation intensifies within the middle troposphere down-stream from the mountain wave, sinking air parcels originating above 40 kPa descend to below 60 kPa over the High Plains where surface pressures are, only 85 kPa. These descending air parcels within the upstream branch of the along-stream ageostrophic thermally-indirect circulation contain high values of momentum and very low dewpoint values. As the planetary boundary layer (PBL) deepens due to surface warming during the morning hours, momentum and dry air from the midtropospheric along-stream ageostrophic front are entrained into the PBL. This process amplifies the bore-induced hydrostatic dryline bulge via low-level ageostrophic confluence.Finally, regions of low Richardson number (arising from strong vertical shears) within the amplifying midtropospheric along-stream ageostrophic thermally-indirect circulation become preferred regions for the development of non-hydrostatic evanescent internal gravity waves. These waves are embedded within the hydrostatic along-stream front above the low-level dryline and are accomapanied by very significant values of vertical momentum flux which act to focus the meso-gamma scale structure of the dryline into smaller scale bulges where low-level winds and vorticities are very high. This meso-gamma scale process follows the hydrostatic tilting and vortex tube stretching which creates meso-beta scale maxima of mid-lower tropospheric vorticity. The turbulent momentum fluxes accompanying wavebreaking within the nonhydrostatic dryline bulge create very large (i.e., stratospheric values of) potential vorticity near 70 kPa due to the nonconservation of potential vorticity on isentropic surfaces.With 30 Figures  相似文献   

Spatial and temporal variability of Holocene temperature in the North Atlantic region   总被引：1，自引：0，他引：1  

Michael R. Kaplan  Alexander P. Wolfe 《Quaternary Research》2006,65(2):223-231

The early Holocene climate of the North Atlantic region was influenced by two boundary conditions that were fundamentally different from the present: the presence of the decaying Laurentide Ice Sheet (LIS) and higher than present summer solar insolation. In order to assess spatial and temporal patterns of Holocene climate evolution across this region, we collated quantitative paleotemperature records at sub-millennial resolution and synthesized their temporal variability using principal components analysis (PCA). The analysis reveals considerable spatial variability, most notably in the time-transgressive expression of the Holocene thermal maximum (HTM). Most of the region, but especially areas peripheral to the Labrador Sea and hence closest to the locus of LIS disintegration, experienced maximum Holocene temperatures that lagged peak summer insolation by 1000-3000 years. Many sites from the northeastern North Atlantic sector, including the Nordic Seas and Scandinavia, either warmed in phase with maximum summer insolation (11,000-9000 years ago) or were less strongly lagged than the Baffin Bay-Labrador Sea region. These spatially complex patterns of Holocene climate development, which are defined by the PCA, resulted from the interplay between final decay of the LIS and solar insolation forcing.  相似文献   

Impact of the North Atlantic Oscillation on Middle Eastern Climate and Streamflow   总被引：6，自引：0，他引：6  

Heidi M. Cullen  Alexey Kaplan  Phillip A. Arkin  Peter B. deMenocal 《Climatic change》2002,55(3):315-338

Interannual to decadal variations in Middle Eastern temperature, precipitationand streamflow reflect the far-field influence of the North Atlantic Oscillation (NAO), a dominant mode of Atlantic sector climate variability. Using a new sea surface temperature (SST) based index of the NAO and availablestreamflow data from five Middle Eastern rivers, we show that the first principal component of December through March streamflow variability reflects changes in the NAO. However, Middle East rivers have two primary flooding periods.The first is rainfall-driven runoff from December through March, regulated on interannual to decadal timescales by the NAO as reflected in local precipitation and temperature.The second period, from April through June, reflects spring snowmelt and contributes in excess of 50% of annual runoff.This period, known locally as the khamsin, displays no significantNAO connections and a less direct relationship with local climatic factors, suggesting that streamflow variability during this period reflects land-cover change, possibly related to agriculture and hydropower generation, and snowmelt.  相似文献   

Citation for presentation of 2001 Alfred E. Treibs award to John W. Smith May 22, 2001     

Isaac Ian Kaplan 《Geochimica et cosmochimica acta》2002,66(4):545-546

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Amplitude—Phase Characteristics of the Annual Cycle of Surface Air Temperature in the Northern Hemisphere   总被引：2，自引：0，他引：2  

Alexey V.ELISEEV  Igor I. MOKHOV 《大气科学进展》2003,20(1):1-16

The amplitude-phase characteristics(APC)of surface air temperature(SAT)annual cycle(AC)in the Northern Hemisphere are analyzed.From meteorological observations for the 20th century and meteorological reanalyses for its second half,it is found that over land negative correlation of SAT ACamplitude with annual mean SAT dominates.Nevertheless,some exceptions exist.The positive correlationbetween these two variables is found over the two desert regions:in northern Africa and in Central America.Areas of positive correlations are also found for the northern Pacific and for the tropical Indian and PacificOceans.Southward of the characteristic annual mean snow-ice boundary (SIB) position,the shape ofthe SAT AC becomes more sinusoidal under climate warming.In contrast,northward of it,this shapebecomes less sinusoidal.The latter iS also found for the above-mentioned two desert regions.In theFar East(southward of about 50°N),the SAT AC shifts as a whole:here its spring and autumn phasesoccur earlier if the annual  相似文献   

Prolonged postcollisional shoshonitic magmatism in the southern Svecofennian domain – a case study of the Åva granite–lamprophyre ring complex     

Olav Eklund  Alexey Shebanov 《Lithos》2005,80(1-4):229-247

The Åva ring complex is one of four Paleoproterozoic postcollisional shoshonitic ring complexes in southwestern Finland. It is composed of ring dykes of K-feldspar megacryst-bearing granite, mingled in places with a shoshonitic monzonite, and lamprophyre dykes crosscutting all the rocks in a radial pattern. A survey was undertaken to trace the magma chamber beneath the ring complex to date it and measure some intensive parameters to clarify the crystallisation conditions at depth before the granite was emplaced in the upper crust. Mineral separates were extracted from the core zones of K-feldspar megacrysts in the granite, heavy mineral fractions (including zircons) from these separates were used for P-T assessment and age determinations, and the results were compared to data obtained from bulk rock samples. It appears that magma differentiation took place in a midcrustal magma chamber (at 4 to 7 kbar) possibly 30 Ma before the emplacement of the ring complex in the upper crust (deep assemblage 1790 Ma, shallow assemblage 1760 Ma). Relatively high activity of the alkalies and a low oxygen fugacity characterised the midcrustal chamber. The juvenile Svecofennian crust was invaded by shoshonitic magmas from an enriched lithospheric mantle over a long period of time. Some of these magmas were stored and differentiated in the middle crust before transportation to the upper crust. The results also show that coarse-grained granites may provide evidence for several magmatic evolutionary episodes, e.g., differentiation and crystallisation in different environments prior to final emplacement.  相似文献   

Flooding of the continental shelves as a contributor to deglacial CH4 rise     

Andy Ridgwell  Mark Maslin  Jed O. Kaplan 《第四纪科学杂志》2012,27(8):800-806

The transition from the last glacial and beginning of Bølling–Allerød and Pre‐Boreal periods in particular is marked by rapid increases in atmospheric methane (CH₄) concentrations. The CH₄ concentrations reached during these intervals, ～650–750 ppb, is twice that at the last glacial maximum and is not exceeded until the onset of industrialization at the end of the Holocene. Periods of rapid sea‐level rise as the Last Glacial Maximum ice sheets retreated and associated with ‘melt‐water pulses’ appear to coincide with the onset of elevated concentrations of CH₄, suggestive of a potential causative link. Here we identify and outline a mechanism involving the flooding of the continental shelves that were exposed and vegetated during the glacial sea‐level low stand and that can help account for some of these observations. Specifically, we hypothesize that waterlogging (and later, flooding) of large tracts of forest and savanna in the Tropics and Subtropics during the deglacial transition and early Holocene would have resulted in rapid anaerobic decomposition of standing biomass and emission of methane to the atmosphere. This novel mechanism, akin to the consequences of filling new hydroelectric reservoirs, provides a mechanistic explanation for the apparent synchronicity between rate of sea‐level rise and occurrence of elevated concentrations of ice core CH₄. However, shelf flooding and the creation of transient wetlands are unlikely to explain more than ～60 ppb of the increase in atmospheric CH₄ during the deglacial transition, requiring additional mechanisms to explain the bulk of the glacial to interglacial increase. Similarly, this mechanism has the potential also to play some role in the rapid changes in atmospheric methane associated with the Dansgaard–Oeschger cycles. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献