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81.
82.
Simulating the diurnal cycle of rainfall in global climate models: resolution versus parameterization 总被引:1,自引:1,他引:0
Paul A. Dirmeyer Benjamin A. Cash James L. Kinter III Thomas Jung Lawrence Marx Masaki Satoh Cristiana Stan Hirofumi Tomita Peter Towers Nils Wedi Deepthi Achuthavarier Jennifer M. Adams Eric L. Altshuler Bohua Huang Emilia K. Jin Julia Manganello 《Climate Dynamics》2012,39(1-2):399-418
The effects of horizontal resolution and the treatment of convection on simulation of the diurnal cycle of precipitation during boreal summer are analyzed in several innovative weather and climate model integrations. The simulations include: season-long integrations of the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) with explicit clouds and convection; year-long integrations of the operational Integrated Forecast System (IFS) from the European Centre for Medium-range Weather Forecasts at three resolutions (125, 39 and 16 km); seasonal simulations of the same model at 10 km resolution; and seasonal simulations of the National Center for Atmospheric Research (NCAR) low-resolution climate model with and without an embedded two-dimensional cloud-resolving model in each grid box. NICAM with explicit convection simulates best the phase of the diurnal cycle, as well as many regional features such as rainfall triggered by advancing sea breezes or high topography. However, NICAM greatly overestimates mean rainfall and the magnitude of the diurnal cycle. Introduction of an embedded cloud model within the NCAR model significantly improves global statistics of the seasonal mean and diurnal cycle of rainfall, as well as many regional features. However, errors often remain larger than for the other higher-resolution models. Increasing resolution alone has little impact on the timing of daily rainfall in IFS with parameterized convection, yet the amplitude of the diurnal cycle does improve along with the representation of mean rainfall. Variations during the day in atmospheric prognostic fields appear quite similar among models, suggesting that the distinctive treatments of model physics account for the differences in representing the diurnal cycle of precipitation. 相似文献
83.
Seiji Maruyama Masaki Watanabe Tak Kunihiro Eizo Nakamura 《Geochimica et cosmochimica acta》2009,73(3):778-793
Elemental and isotopic abundances of lithium in chondrule constituents in the Allende CV3 meteorite were determined using secondary ion mass spectrometry. Olivines and mesostasis dominated by a feldspathic phase are depleted in Li ( and , respectively). In contrast, low-Ca pyroxenes and mesostasis dominated by a Na-rich phase are enriched in Li ( and , respectively) and the interchondrule matrix is generally enriched in Li ( on average). The Li isotopic abundance of olivine ranges from to 21. The spatial distributions of elemental and isotopic abundances of Li in olivines within individual chondrules exhibit no systematic pattern. This suggests that the distribution of Li in olivine was not disturbed during aqueous alteration or thermal metamorphism on the Allende meteorite parent body. Although mesostasis is the last crystallizing phase from a chondrule melt and is expected to be enriched in Li, in the Allende meteorite it is generally depleted in Li. We suggest that during aqueous alteration on the CV asteroid, Li in mesostasis was leached out by aqueous fluids. The Li-enriched Na-rich mesostasis was probably produced later by infiltration of Na-rich fluids. It seems likely that aqueous fluids sequestered alkali elements from the Allende-chondrite region in the CV parent asteroid, although significant amounts of Li are preserved in ferrous olivine in the interchondrule matrix. 相似文献
84.
Aragonite and omphacite-bearing metapelite occurs in the albite–biotite zone of the Togu (Tohgu) area, Besshi region, Sambagawa metamorphic belt, central Shikoku, Japan. This metapelite consists of alternating graphite-rich and graphite-poor layers that contain garnet, phengite, chlorite, epidote, titanite, calcite, albite, and quartz. A graphite-poor layer contains a 1.5-cm ivory-colored lens that mainly consists of phengite, calcite, albite, and garnet. Aragonite, omphacite, and paragonite occur as inclusions in the garnet of the ivory lens. The aragonite has a composition that is close to the CaCO3 end-member: the FeCO3 and MnCO3 components are both less than 0.3 mol% and the SrCO3 component is about 1 mol%. The aragonite + omphacite + quartz assemblage in garnet indicates equilibrium conditions of P > 1.1–1.3 GPa and T = 430–550°C. Quartz grains sealed in garnet of the aragonite and omphacite-bearing sample and other metapelites in the Togu area preserve a high residual pressure that is equivalent to the Sambagawa eclogite samples. These facts suggest that: (i) the Togu area experienced eclogite facies metamorphism; and (ii) thus, eclogite facies metamorphism covered the Sambagawa belt more extensively than previously recognized. 相似文献
85.
Groundwater-wetland ecosystem interaction in the semiarid glaciated plains of North America 总被引:2,自引:2,他引:0
The prairie wetlands of northern USA and Canada exist in numerous topographical depressions within the glaciated landscape. The wetlands are disconnected from each other most of the time with respect to surface-water drainage. The wetland water balance is controlled by snowmelt runoff and snowdrift from the surrounding uplands, precipitation, evapotranspiration, groundwater exchange, and occasional “fill-spill” connections to other wetlands. Salinity of water and the seasonal variability of water level in these wetlands have a strong influence on the ecosystem. Clay-rich glacial tills, covering much of the region, have very low (0.001–0.01 m/yr) hydraulic conductivity, except for the top several meters where the factures and macropores increase conductivity up to 1,000 m/yr. Transpiration in the wetland margin induces infiltration and lateral flow of shallow groundwater from wetland ponds through the high-conductivity zone, which strongly affects the water balance of wetlands. In contrast, groundwater flow in the deeper low-conductivity till has minor effects on water balance, but has a strong influence on salinity because the flow direction determines if the salts accumulate in wetlands (upward flow) or are leached out (downward flow) under wetlands. Understanding of the roles of shallow and deep groundwater systems will improve the hydrological conceptual framework for the management of wetland ecosystems. 相似文献
86.
87.
88.
Pacific ocean circulation based on observation 总被引:2,自引:1,他引:1
A thorough understanding of the Pacific Ocean circulation is a necessity to solve global climate and environmental problems.
Here we present a new picture of the circulation by integrating observational results. Lower and Upper Circumpolar Deep Waters
(LCDW, UCDW) and Antarctic Intermediate Water (AAIW) of 12, 7, and 5 Sv (106 m3s−1) in the lower and upper deep layers and the surface/intermediate layer, respectively, are transported to the North Pacific
from the Antarctic Circumpolar Current (ACC). The flow of LCDW separates in the Central Pacific Basin into the western (4
Sv) and eastern (8 Sv) branches, and nearly half of the latter branch is further separated to flow eastward south of the Hawaiian
Ridge into the Northeast Pacific Basin (NEPB). A large portion of LCDW on this southern route (4 Sv) upwells in the southern
and mid-latitude eastern regions of the NEPB. The remaining eastern branch joins nearly half of the western branch; the confluence
flows northward and enters the NEPB along the Aleutian Trench. Most of the LCDW on this northern route (5 Sv) upwells to the
upper deep layer in the northern (in particular northeastern) region of the NEPB and is transformed into North Pacific Deep
Water (NPDW). NPDW shifts southward in the upper deep layer and is modified by mixing with UCDW around the Hawaiian Islands.
The modified NPDW of 13 Sv returns to the ACC. The remaining volume in the North Pacific (11 Sv) flows out to the Indian and
Arctic Oceans in the surface/intermediate layer. 相似文献
89.
Ohishi Masatoshi Kaifu Norio Suzuki Hiroko Morimoto Masaki 《Astrophysics and Space Science》1986,118(1-2):405-407
A molecular spectral line survey of the title source detected 166 molecular lines from 18 interstellar molecules in the frequency ranges of 34.25–50.00, 83.50–84.50, and 86.00–91.50 GHz. For each molecule, gaussian decomposition of the velocity components in the transition profiles gave consistent radial velocity and linewidth. Rotation diagrams were drawn for each velocity component.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
90.
Dynamic Structure of the Kuroshio South of Kyushu in Relation to the Kuroshio Path Variations 总被引:1,自引:1,他引:1
The variation of velocity and potential vorticity (PV) of the Kuroshio at the PN line in the East China Sea and the TK line
across the Tokara Strait were examined in relation to the path variations of the Kuroshio in the southern region of Japan,
using quarterly data from a conductivity-temperature-depth profiler and a shipboard acoustic Doppler current profiler during
1987–97. At the PN line the Kuroshio has a single stable current core located over the continental slope and a significant
maximum of PV located just onshore of the current axis in the middle part of the main pycnocline. On the other hand, the Kuroshio
at the TK line has double current cores over the two gaps in the Tokara Strait; the northern core has a much larger velocity
than the southern core on average during periods of the large meander of the Kuroshio, while the difference in strength between
the double cores is small during the non-large-meander (NLM) period. At the TK line, PV in the middle pycnocline is variable;
it is small and nearly uniform throughout the section for 40% of the total observations, while it has a significant maximum
near the northern core for 30% and two maxima corresponding to the double current cores for 23%. The small, nearly uniform
PV occurs predominantly during the NLM period, and is closely related to the generation of the small meander of the Kuroshio
southeast of Kyushu.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献