Two types of El Niño-related Southern Oscillation and their different impacts on global land precipitation     

徐康  祝从文  何金海 《大气科学进展》2013,30(6):1743-1757

The contrast between the eastern and central responses of zonal and vertical circulation in the Pacific （EP- and CP-） E1 Nino is observed in the different tropics. To measure the different responses of the atmo- spheric circulation to the two types of E1 Nino, an eastern and a central Pacific southern oscillation index （EP- and CP-SOI） are defined based on the air-sea coupled relationship between eddy sea level pressure and sea surface temperature. Analyses suggest that while the EP-SOI exhibits variability on an interannual （2- 7-yr） time scale, decadal （10-15-yr） variations in the CP-SOI are more dominant; both are strongly coupled with their respective EP- and CP-E1 Nino patterns. Composite analysis suggests that, during EP-ENSO, the Walker circulation exhibits a dipole structure in the lower-level （850 hPa） and upper-level （200 hPa） velocity potential anomalies and exhibits a signal cell over the Pacific. In the case of CP-ENSO, however, the Walker circulation shows a tripole structure and exhibits double cells over the Pacific. In addition, the two types of ENSO events show opposite impacts on global land precipitation in the boreal winter and spring seasons. For example, seasonal precipitation across mainland China exhibits an opposite relationship with the EP- and CP-ENSO during winter and spring, but the rainfall over the lower reaches of the Yangtze River and South China shows an opposite relationship during the rest of the seasons. Therefore, the different relationships between rainfall and EP- and CP-ENSO should be carefully considered when predicting seasonal rainfall in the East Asian monsoon regions.  相似文献   

A quantitative assessment of changes in seasonal potential predictability for the twentieth century     

M. Azhar Ehsan  In-Sik Kang  Mansour Almazroui  M. Adnan Abid  Fred Kucharski 《Climate Dynamics》2013,41(9-10):2697-2709

Changes over the twentieth century in seasonal mean potential predictability (PP) of global precipitation, 200 hPa height and land surface temperature are examined by using 100-member ensemble. The ensemble simulations have been conducted by using an intermediate complexity atmospheric general circulation model of the International Center for Theoretical Physics, Italy. Using the Hadley Centre sea surface temperature (SST) dataset on a 1° grid, two 31 year periods of 1920–1950 and 1970–2000 are separated to distinguish the periods of low and high SST variability, respectively. The standard deviation values averaged for the (“Niño-3.4”; 5°S–5°N, 170°W–120°W) region are 0.71 and 1.15 °C, for the periods of low and high SST variability, respectively, with a percentage change of 62 % during December–January–February (DJF). The leading eigenvector and the associated principal component time series, also indicate that the amplitude of SST variations have positive trend since 1920s to recent years, particularly over the El Niño Southern Oscillation (ENSO) region. Our hypothesis states that the increase in SST variability has increased the PP for precipitation, 200 hPa height and land surface temperature during the DJF. The analysis of signal and noise shows that the signal-to-noise (S/N) ratio is much increased over most of the globe, particularly over the tropics and subtropics for DJF precipitation. This occurs because of a larger increase in the signal and at the same time a reduction in the noise, over most of the tropical areas. For 200 hPa height, the S/N ratio over the Pacific North American (PNA) region is increasing more than that for the other extratropical regions, because of a larger percentage increase in the signal and only a small increase in noise. It is also found that the increase in seasonal mean transient signal over the PNA region is 50 %, while increase in the noise is only 12 %, during the high SST variability period, which indicates that the increase in signal is more than the noise. For DJF land surface temperature, the perfect model notion is utilized to confirm the changes in PP during the low and high SST variability periods. The correlation between the perfect model and the other members clearly reveal that the seasonal mean PP changed. In particular, the PP for the 31 years period of 1970–2000 is higher than that for the 31 years period of 1920–1950. The land surface temperature PP is increased in northern and southern Africa, central Europe, southern South America, eastern United States and over Canada. The increase of the signal and hence the seasonal mean PP is coincides with an increase in tropical Pacific SST variability, particularly in the ENSO region.  相似文献   

The Asian summer monsoon: an intercomparison of CMIP5 vs. CMIP3 simulations of the late 20th century   总被引：4，自引：0，他引：4  

K. R. Sperber  H. Annamalai  I.-S. Kang  A. Kitoh  A. Moise  A. Turner  B. Wang  T. Zhou 《Climate Dynamics》2013,41(9-10):2711-2744

The boreal summer Asian monsoon has been evaluated in 25 Coupled Model Intercomparison Project-5 (CMIP5) and 22 CMIP3 GCM simulations of the late twentieth Century. Diagnostics and skill metrics have been calculated to assess the time-mean, climatological annual cycle, interannual variability, and intraseasonal variability. Progress has been made in modeling these aspects of the monsoon, though there is no single model that best represents all of these aspects of the monsoon. The CMIP5 multi-model mean (MMM) is more skillful than the CMIP3 MMM for all diagnostics in terms of the skill of simulating pattern correlations with respect to observations. Additionally, for rainfall/convection the MMM outperforms the individual models for the time mean, the interannual variability of the East Asian monsoon, and intraseasonal variability. The pattern correlation of the time (pentad) of monsoon peak and withdrawal is better simulated than that of monsoon onset. The onset of the monsoon over India is typically too late in the models. The extension of the monsoon over eastern China, Korea, and Japan is underestimated, while it is overestimated over the subtropical western/central Pacific Ocean. The anti-correlation between anomalies of all-India rainfall and Niño3.4 sea surface temperature is overly strong in CMIP3 and typically too weak in CMIP5. For both the ENSO-monsoon teleconnection and the East Asian zonal wind-rainfall teleconnection, the MMM interannual rainfall anomalies are weak compared to observations. Though simulation of intraseasonal variability remains problematic, several models show improved skill at representing the northward propagation of convection and the development of the tilted band of convection that extends from India to the equatorial west Pacific. The MMM also well represents the space–time evolution of intraseasonal outgoing longwave radiation anomalies. Caution is necessary when using GPCP and CMAP rainfall to validate (1) the time-mean rainfall, as there are systematic differences over ocean and land between these two data sets, and (2) the timing of monsoon withdrawal over India, where the smooth southward progression seen in India Meteorological Department data is better realized in CMAP data compared to GPCP data.  相似文献   

Surface mean temperature from the observational stations and multiple reanalyses over the Tibetan Plateau     

Yan  Yuping  You  Qinglong  Wu  Fangying  Pepin  Nick  Kang  Shichang 《Climate Dynamics》2020,55(9-10):2405-2419

The Tibetan Plateau (TP), also called the “Third pole”, is sensitive to climate change due to extensive areas at high elevation presently dominated by snow and ice. In this study, observed surface temperature trends at 150 stations over the TP during 1979–2018 are analyzed and compared with surface temperatures from multiple reanalyses (NCEP1, NCEP2, ERA-Interim, MERRA, JRA55). Observed warming at the stations has a mean annual rate of 0.46 °C/decade during 1979–2018. Although all reanalyses underestimate observed temperatures (cold bias), most reproduce much of the inter-decadal variations of surface temperature shown in the observations. Absolute errors of mean surface temperature (reanalysis minus observation) are closely correlated with elevation errors, suggesting that parts of the cold bias can be interpreted by elevation errors of reanalysis. After elevation-temperature correction, about half of the cold bias is typically eliminated, more for both ERA-Interim and JRA55. Compared with the observations, corrected NCEP2 surface temperatures still have larger cold biases, and fail to capture the overall warming over the TP. Since the elevation-temperature correction fails to improve trend magnitudes even when a significant proportion of the bias has been removed, this suggests that a more sophisticated modeling of the lapse rate in each reanalysis is required to realistically model warming trends across complex topography.

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个旧锡石一赤铁矿一方解石脉型矿体地质特征及其研究意义     

钱志宽  武俊德  康德明  陆荣宇  杨宝富  胡勇  罗泰义  黄智龙 《矿物学报》2011,31(3):328-337

报道了在个旧锡矿松树脚矿区发现的脉状锡石一赤铁矿一方解石新型矿体,认为该新型矿体很可能是成矿流体运移的通道,同时对其成因进行了初步探讨。通过与红海型热水沉积矿床的特征进行对比分析,提出个旧锡矿“层间氧化矿”以及红海型热水沉积矿床中铁氧化物型矿床可能存在2种成因模式：第一种是热卤水自海水向海底沉积物、从上到下的热卤水分层氧化模式;第二种是成矿流体自地下深部向海底的从下到上逐步氧化模式。  相似文献   

Simulation of a groundwater fall caused by geological discontinuities     

Wenping Li  Zhenying Liu  Haipeng Guo  Ning Li  Weidong Kang 《Hydrogeology Journal》2011,19(6):1121-1133

In some areas close to a reverse fault with significant vertical displacement, or the boundary of a mining area in multi-layer rock and the boundary of perched water, the phreatic water-level changes abruptly from one side of the fault or boundary to the other. There is no direct hydraulic connection between the two sides and a groundwater fall occurs across the fault or boundary. This groundwater fall cannot be easily handled by the modules available in MODFLOW. Semi-analytical solutions were derived for water discharge from the upstream to the downstream side of the fault or boundary, and verified by air-water two-phase numerical simulation. The numerical results show that the derived semi-analytical solutions can be used to accurately estimate the groundwater flux at the fault even though the unsaturated zone is not considered. A module package, GWF, was developed to simulate the groundwater fall, which can be embedded directly into MODFLOW. A theoretical example is presented to show how the package GWF is used to simulate perched water. This package was also applied successfully to build a regional groundwater model of the Urumqi River Basin, Xinjiang, China, and the simulation results showed good agreement with the local hydrogeologic conditions.  相似文献   

大同煤田构造控煤特征研究     

袁远  曹代勇  林中月  刘亢 《中国煤炭地质》2011,(8):63-65,77

大同煤田位于山西省北部,主要含煤地层为石炭系太原组、二叠系山西组和侏罗系大同组。依据大同煤田构造发育特点,分析了区域构造对煤田构造格局的控制作用。研究认为,大同煤田主体为一向斜构造,控制了煤系的分布范围。区内控煤构造样式包括压缩构造和伸展构造两大类,前者分布于煤田边界,主要包括逆冲前锋构造、逆冲叠瓦构造、双冲构造、叠瓦扇构造等类型;后者主要分布在煤田内部,以正断层控制的堑垒构造类型为主,构成井田边界或采区边界。  相似文献   

中国东部超深超高温碳酸盐岩潜山油气藏的发现及关键技术——以渤海湾盆地冀中坳陷牛东1潜山油气藏为例   总被引：4，自引：1，他引：3  

赵贤正  金凤鸣  王权  李勖  康如坤  常建华  袁胜辉 《海相油气地质》2011,16(4):1-10

冀中坳陷霸县凹陷牛东1井于2011年1月钻探发现了超深层蓟县系雾迷山组碳酸盐岩潜山油气藏,油气藏底部钻达深度6027m尚未见油水界面,温度已达201℃,酸压测试获日产油642.9m3和气56.3×104m3,为渤海湾盆地乃至中国东部目前发现的深度最大、温度最高的特高产油气藏.回顾了油气藏初战失利、再战搁浅、重燃希望、重...  相似文献   

Biofilm: A crucial factor affecting the settlement of seaweed on intertidal rocky surfaces     

Sang Rul Park  Yun Hee Kang  Chang Geun Choi 《Estuarine, Coastal and Shelf Science》2011

We hypothesized that the presence of biofilm accelerated the settlement of dominant seaweed species and maintained high levels of species richness by regulating the blooming of particular species on an intertidal rocky shore. The coverage and species richness of macroalgae on sterile and cleared substrates (225 cm²) were measured to investigate the effects of biofilm on the settlement of macroalgae in intertidal zones at Noryang, Songmoon, and Sangnam in Gawngyang Bay on the southern coast of the Korean peninsula. Green algae coverage on cleared substrates was significantly higher than that on sterile substrates at both Noryang and Songmoon during the study period. This suggests that the presence of biofilm enhances the settlement of green algae by providing various habitat structures and, consequently, may lead to serious ‘green tide’ events. However, the coverage of algae other than green algae and algal species richness on cleared substrates remained high at Sangnam during the experimental period. Biofilm facilitated the settlement of macroalgae and inhibited the blooming of specific algae by inducing inter-specific space competition. Therefore, biofilm plays an important role on seaweed assemblages on intertidal rocky shores by accelerating the settlement of seaweed.  相似文献   

Application of potentiometric method using a cell without liquid junction to underway pH measurements in surface seawater     

Pavel Ya. TishchenkoDong-Jin Kang  Ruslan V. ChichkinAlexander Yu. Lazaryuk  Chi Shing WongWilliam Keith Johnson 《Deep Sea Research Part I: Oceanographic Research Papers》2011,58(7):778-786

This study evaluated a method to carry out underway pH measurements of surface seawater by means of a cell without liquid junction using glass electrodes for hydrogen and sodium ions as follows: