短时间尺度周期性热力强迫下流型的低频振荡

本文在正压涡度方程中引进短时间尺度周期性热力强迫项。在一定的参数范围内,该强迫项可以引起环流指数准两至三周的低频振荡。     

NUMERICAL EXPERIMENT OF THE INFLUENCES OF HEAT AND WIND STRESS ON THE EQUATORIAL OCEAN CIRCULATION

A time-dependent linear model on the equatorial beta plane is developed in this paper.Its verticalstructure consists of two active layers with equal density and temperature above the thermocline and aquasi-stationary layer with constant density below the thermocline.The results of nurnericat experiments show that the direct influence of heat on the equatorial ocean ismuch smaller than that of wind stress.Nevertheless,through the tropical ocean-atmosphere interaction,the change of wind stress resulting from the thermal forcing may set a determinant effect on the equilibriumand anomalous development of the ocean-almosphere circulation.     

Numerical experiments on the generation of long ocean waves in coastal waters of the Buenos Aires province,Argentina

A numerical model (two horizontal dimensions, vertically integrated) is used to investigate the generation of long ocean waves, ranging from 20 min to almost 2 h, at Buenos Aires continental shelf. The domain includes the Río de la Plata estuary and the continental shelf together and extends from 33.5° to 40.5°S latitude, and from 51° to 63°W longitude. Sea-level oscillations are modeled by forcing with passage of atmospheric cold fronts and atmospheric gravity waves. Both forcing mechanisms, which have been present during high activity lapses of long ocean waves, are mathematically implemented. After several numerical simulations, it is concluded that the pressure and wind fields associated to cold fronts do not generate long ocean waves in the area, though they do produce disturbances with periods longer than the tidal ones. On the other hand, it is so concluded that atmospheric gravity waves are an effective mechanism to force long ocean waves. Results obtained show that generation of long ocean waves is highly sensitive depending on the propagation direction and the phase speed of the atmospheric gravity waves. The long ocean wave event detected during the large-amplitude gravity-wave event of 13 October 1985 is successfully simulated. Finally, all our results suggest that atmospheric gravity waves are a highly effective mechanism forcing for the generation of long ocean waves in Buenos Aires coastal waters.     

THE IMPACT OF RELATIVE HUMIDITY ON THE RADIATIVE PROPERTY AND RADIATIVE FORCING OF SULFATE AEROSOL

With the data of complex refractive index of sulfate aerosol,the radiative properties of theaerosol under 8 relative humidity conditions are calculated in this paper.By using the concentrationdistribution from two CTM models and LASG GOALS/AGCM,the radiative forcing due tohygroscopic sulfate aerosol is simulated.The results show that:(1)With the increase of relativehumidity,the mass extinction coefficiency factor decreases in the shortwave spectrum;singlescattering albedo keeps unchanged except for a little increase in longwave spectrum,andasymmetry factor increases in whole spectrum.(2)Larger differences occur in radiative forcingsimulated by using two CTM data,and the global mean forcing is—0.268 and—0.816 W/m~2,respectively.(3)When the impact of relative humidity on radiative property is taken into account,the distribution pattern of radiative forcing due to the wet particles is very similar to that of drysulfate,but the forcing value decreases by 60%.     

生石灰桩及水泥注浆法在地基加固纠偏中的应用

某礼堂综合楼受浸水损坏，采用生石灰桩及高压水泥注浆综合法加固建筑物沉陷部分地基，获得成功。     

青藏高原地面热力异常对夏季江淮流域持续暴雨形成作用的数值试验

本文采用OSU-AGCM大气环流模式，对青藏高原下垫面热力异常与夏季江淮流域暴雨形成的关系进行了数值试验。模拟结果表明，青藏高原下垫面热力状况的异常对东亚环流形势及云量分布异常的影响是形成1991年夏季江淮流域持续性降水的重要原因之一。青藏高原异常热力强迫还可以引起大范围云量的异常分布和云量异常区类似于二维Rossby波列没大圆路径传播的特征。     

Response of Atmospheric Low-frequency Wave to Oceanic Forcing in the Tropics

1. IntroductionInvestigations about atmospheric LFW have been a focus of research since Madden andJulian/s outstanding analysis works (1971, 1972). Many dynamical and thermal mechanisms(Chao et al., 1996; Fu et al., 1998; Hendon et al., 1998; Krishnamurti et al., 1988; Lau andChan, 1988) have been advised to explain LFW. Among them are oceanic effects, such as SSTeffect, thermal forcing and others. Usually atmosphere and ocean are taken as a coupled system, which is used to explain ENS…     

Sea level,climate change and coastal evolution in Morar,northwest Scotland

Analyses of geomorphologically contrasting sites in Morar, NW Scotland, describe the forcing mechanisms of coastal change. Isolation basins (i.e. basins behind rock sills and now isolated from the sea following isostatic uplift) accumulated continuous marine and freshwater sediments from c.12 to 2 ka BP. Raised dune, marsh and wetland sites register breaching, migration and stability of dunes from c. 9 to 2 ka BP. High-resolution methods designed to address issues of macroscale and microscale sea-level changes and patterns of storminess include 1-mm sampling for pollen, dinocyst and diatom analyses, infra-red photography, X-ray photography and thin-section analysis. The data enhance the record of relative sea-level change for the area. Major phases of landward migration of the coast occurred during the period of low sea-level rise in the mid-Holocene as the rate of rise decreased from c. 3 to < 1 mm/year. Relative sea-level change controls the broad pattern of coastal evolution at each site; local site-specific factors contribute to short-term process change. There is no record of extreme events such as tsunami. Within a system of dynamic metastable equilibrium, the Holocene records show that site-specific factors determine the exact timing of system breakdown, e.g. dune breaching, superimposed on regional sea-level rise. The global average sea-level rise of 3 to 6 mm/yr by AD 2050 predicted by IPCC would only partly be offset in the Morar area by isostatic uplift of about 1 mm/yr. A change from relative sea-level fall to sea-level rise, in areas where the regional rate of uplift no longer offsets global processes, is a critical factor in the management of coastal resources.     

探讨气候变化的新热点:大气气溶胶的气候效应

气溶胶的气候效应是近年来研究的热点问题。针对这一问题已开展过许多观测研究和模式研究。但是由于气溶胶问题的复杂性以及对气溶胶的观测历史短,至今尚缺少全球范围的气溶胶系统观测资料,所以目前气溶胶的辐射强迫仍是个很不确定的量。这直接影响对全球气候变化的预测。目前国内外正在加强这方面的研究工作,并且有了一些初步的结果。概述了近期国内外对气溶胶的气候效应的研究状况及结果,介绍了今后国际上将要在这一领域开展的研究工作。