Distribution of seasonal rainfall in the East Asian monsoon region   总被引：8，自引：1，他引：8  

W. Qian  H.-S. Kang  D.-K. Lee 《Theoretical and Applied Climatology》2002,73(3-4):151-168

Summary ?This study deals with the climatological aspect of seasonal rainfall distribution in the East Asian monsoon region, which includes China, Korea and Japan. Rainfall patterns in these three countries have been investigated, but little attention has been paid to the linkages between them. This paper has contributed to the understanding of the inter-linkage of various sub-regions. Three datasets are used. One consists of several hundred gauges from China and South Korea. The second is based on the Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP). The two sources of precipitation information are found to be consistent. The third dataset is the NCEP/NCAR reanalysis 850-hPa winds. The CMAP precipitation shows that the seasonal transition over East Asia from the boreal winter to the boreal summer monsoon component occurs abruptly in mid-May. From late March to early May, the spring rainy season usually appears over South China and the East China Sea, but it is not so pronounced in Japan. The summer monsoon rainy season over East Asia commonly begins from mid-May to late May along longitudes of eastern China, the Korean Peninsula, and Japan. A strong quasi-20-day sub-seasonal oscillation in the precipitation appears to be dominant during this rainy season. The end date of the summer monsoon rainy season in eastern China and Japan occurs in late July, while the end date in the Korean Peninsula is around early August. The autumn rainy season in the Korean Peninsula has a major range from mid-August to mid-September. In southern China, the autumn rainy season prevails from late August to mid-October but a short autumn rainy season from late August to early September is noted in the lower part of the Yangtze River. In Japan, the autumn rainy season is relatively longer from mid-September to late October. The sub-seasonal rainfall oscillation in Korea, eastern China and Japan are explained by, and comparable to, the 850-hPa circulation. The strong westerly frontal zone can control the location of the Meiyu, the Changma, and the Baiu in East Asia. The reason that the seasonal sea surface temperature change in the northwestern Pacific plays a critical role in the northward advance of the onset of the summer monsoon rainfall over East Asia is also discussed. Received October 5, 2001; revised April 23, 2002; accepted May 11, 2002  相似文献   

Observations Of Nocturnal Drainage Flow In A Shallow Gully     

M.R. Soler  C. Infante  P. Buenestado  Larry Mahrt 《Boundary-Layer Meteorology》2002,105(2):253-273

The formation of cold air drainage flows in a shallow gully is studied during CASES-99 (Cooperative Atmosphere-Surface Exchange Study). Fast and slow response wind and temperature measurements were obtained on an instrumented 10-m tower located in the gully and from a network of thermistors and two-dimensional sonic anemometers, situated across the gully. Gully flow formed on clear nights even with significant synoptic flow. Large variations in surface temperature developed within an hour after sunset and in situ cooling was the dominant factor in wind sheltered locations. The depth of the drainage flow and the height of the down-gully wind speed maximum were found to be largest when the external wind speed above the gully flow is less than 2 m s^-1. The shallow drainage current is restricted to a depth of a few metres, and is deepest when the stratification is stronger and the external flow is weaker. During the night the drainage flow breaks down, sometimes on several occasions, due to intermittent turbulence and downward fluxes of heat and momentum. The near surface temperature may increase by 6 ° C in less than 30 min due to the vertical convergence of downward heat flux. The mixing events are related to acceleration of the flow above the gully flow and decreased Richardson number. These warming events also lead to warming of the near surface soil and reduction of the upward soil heat flux. To examine the relative importance of different physical mechanisms that could contribute to the rapid warming, and to characterize the turbulence generated during the intermittent turbulent periods, the sensible heat budget is analyzed and the behaviour of different turbulent parameters is discussed.  相似文献   

Modelling Korean extreme rainfall using a Kappa distribution and maximum likelihood estimate   总被引：6，自引：0，他引：6  

J.-S. Park  H.-S. Jung 《Theoretical and Applied Climatology》2002,72(1-2):55-64

Summary Attempts to use the 4-parameter Kappa distribution (K4D) with the maximum likelihood estimates (MLE) on the summer extreme daily rainfall data at 61 gauging stations over South Korea have been made to obtain reliable quantile estimates for several return periods. A numerical algorithm for searching MLE of K4D by minimizing the negative log-likelihood function with penalty method has been described. The isopluvial maps of estimated design values corresponding to selected return periods have been presented. The highest return values are centered at sites in the south-western part of the Korean peninsula. The distribution of return values for annual maxima of 2-day precipitation (AMP2) is more similar to the climatological features of annual total precipitation of Korea than that of annual maxima of daily precipitation (AMP1). Our results of return values delineate well the horizontal patterns of the heavy precipitation over the Korean peninsula. Received January 15, 2001 Revised October 8, 2001  相似文献   

Hindsight and Foresight     

N. E. Busch  L. Kristensen 《Boundary-Layer Meteorology》2002,105(3):369-388

  相似文献   

‘Second time around’: Squatter removals in a democratic South Africa     

Maano Ramutsindela 《GeoJournal》2002,57(1-2):53-60

  相似文献   

Anhydrite Dissolution Phenomena: Three Case Histories of Anhydrite Karst Caused by Water Tunnel Operation     

M. Gysel 《Rock Mechanics and Rock Engineering》2002,35(1):1-21

Summary Dissolution (karstification) of anhydrite/gypsum due to water tunnel operation of hydroelectric schemes has been experienced sporadically in the past. Two cases which occurred in Switzerland and a very severe damage concerning the Chixoy power tunnel in Guatemala are treated in the paper. In conclusion, it is shown which combinations of geological and hydraulic conditions may lead to major dissolutions and therefore to great tunnel damage.  相似文献   

Chlorophyll modulation of mixed layer thermodynamics in a mixed-layer isopycnal General Circulation Model — An example from Arabian Sea and equatorial Pacific     

S. Nakamoto  S. Prasanna Kumar  J. M. Oberhuber  H. Saito  K. Muneyama  R. Frouin 《Journal of Earth System Science》2002,111(3):339-349

Western tropical Indian Ocean, Arabian Sea, and the equatorial Pacific are known as regions of intense bio-chemical-physical interactions: the Arabian Sea has the largest phytoplankton bloom with seasonal signal, while the equatorial Pacific bloom is perennial with quasi-permanent upwelling. Here, we studied three dimensional ocean thermodynamics comparing recent ocean observation with ocean general circulation model (OPYC) experiment combined with remotely sensed chlorophyll pigment concentrations from the Coastal Zone Color Scanner (CZCS). Using solar radiation parameterization representing observations that a higher abundance of chlorophyll increases absorption of solar irradiance and heating rate in the upper ocean, we showed that the mixed layer thickness decreases more than they would be under clear water conditions. These changes in the model mixed layer were consistent with Joint Global Ocean Flux Study (JGOFS) observations during the 1994-1995 Arabian Sea experiment and epi-fluorescence microscopy (EFM) on samples collected during Equatorial Pacific Ocean Climate Study (EPOCS) in November, 1988. In the Arabian Sea, as the chlorophyll concentrations peak in October (3 mg/m³) after the summer plankton bloom induced by coastal upwelling, the chlorophyll induced biological heating enhanced the sea surface temperature (SST) by as much as 0.6‡C and sub-layer temperature decreases and sub-layer thickness increases. In the equatorial Pacific, modest concentrations of chlorophyll less than 0.3 mg/m³ is enough to introduce a meridional differential heating, which results in reducing the equatorial mixed layer thickness to more than 20 m. The anomalous meridional tilting of the mixed layer bottom enhances off equatorial westward geostrophic currents. Consequently, the equatorial undercurrent transports more water from west to east. We proposed that these numerical model experiments with use of satellite andin situ ocean observations are consistent under three dimensional ocean circulation theory combined with solar radiation transfer process.  相似文献   

Volatiles in Submarine Basaltic Glasses from the Northern Kerguelen Plateau (ODP Site 1140): Implications for Source Region Compositions, Magmatic Processes, and Plateau Subsidence   总被引：1，自引：4，他引：1  

WALLACE  PAUL J. 《Journal of Petrology》2002,43(7):1311-1326

Submarine pillow basalts (34 Ma) recovered from the NorthernKerguelen Plateau at ODP Site 1140 contain abundant unalteredglass, providing the first opportunity to measure the volatilecontents of tholeiitic basaltic magmas related to the Kerguelenmantle plume. The glasses have La/Sm and Nb/Zr ratios that varyfrom values similar to Southeast Indian Ridge (SEIR) MORB (Unit1), to slightly more enriched (Unit 6), to values transitionalbetween SEIR MORB and basaltic magmas formed by melting of theKerguelen plume (Units 2 and 3). Volatile contents for glassesin Units 1 and 6 are similar to depleted mid-ocean ridge basalt(MORB) values (0·25–0·27 wt % H₂O, 1240–1450ppm S, 42–54 ppm Cl). In contrast, H₂O contents are higherfor the enriched glasses (Unit 2, 0·44 wt % H₂O; Unit3, 0·69 wt %), as are S (1500 ppm) and Cl (146–206ppm). Cl/K ratios for all glasses are relatively low (0·03–0·04),indicating that assimilation of hydrothermally altered materialdid not occur during shallow-level crystallization. H₂O/Ce forthe enriched glasses (Units 2 and 3) is significantly lowerthan Pacific and South Atlantic MORB values, suggesting thatlow H₂O/Ce may be an inherent characteristic of the Kerguelenplume source. Vapor saturation pressures calculated using theH₂O and CO₂ contents of the glasses indicate that  相似文献   

A comparison of early juvenile red drum densities among various habitat types in Galveston Bay, Texas     

Gregory W. Stunz  Thomas J. Minello  Phillip S. Levin 《Estuaries and Coasts》2002,25(1):76-85

Seagrass meadows are often cited as important nursery areas for newly settled red drum even though many estuaries, such as Galveston Bay, Texas, support large numbers of red drum and have limited seagrass cover, suggesting the use of alternate nursery areas. We examined patterns of habitat use for newly settled red drum at six sampling areas in Galveston Bay; two areas had seagrass beds and four areas had no seagrass. We measured densities in different habitat types using epibenthic sleds and enclosure samplers. Peak recruitment of young red drum to the estuary occurred during September through December. Highest densities of new settlers were found in seagrass meadows (primarilyHalodule wrightii), but when seagrass was absent, the highest densities of red drum occurred along theSpartina alterniflora marsh edge interface. Densities were relatively low on nonvegetated bottom away from the marsh edge. We also examined density patterns in other habitat types at selected sampling areas and found no red drum within marsh vegetation away from the marsh edge interface (5 and 10 m into the marsh interior). Oyster reefCrassostrea virginica was sampled using lift nets, and we found no red drum using this habitat, although adjacent seagrass and marsh interface habitats were used. Even though red drum densities in marsh edge were low relative to seagrass, the large areal extent of marshes in the bay complex probably makes marsh edge the most important nursery habitat for red drum in Galveston Bay.  相似文献   

Fuller's earth (bentonite) in the Lower Cretaceous (Upper Aptian) ofShanklin (Isle of Wight, southern England)     

A.H. RuffellS.P. Hesselbo  G.D. Wach  M.I. SimpsonD.S. Wray 《Proceedings of the Geologists' Association. Geologists' Association》2002,113(4):281-290

  相似文献