Trends and Variability of Sea Surface Temperature in the Northwest Atlantic from Three Historical Gridded Datasets     

John W. Loder  Zeliang Wang 《大气与海洋》2015,53(5):510-528

ABSTRACT

Historical variability in sea surface temperature (SST) in the North Atlantic (NA) is examined using trend and Empirical Orthogonal Function (EOF) analyses of annual and summer means from three interpolated monthly datasets: Hadley Centre Sea Ice and Sea Surface Temperature (HadISST1), Extended Reconstruction of SST (ERSST), and Centennial in situ Observation-Based Estimates (COBE). Comparisons with time series of upper-ocean temperature from four monitoring sites off Atlantic Canada reveal substantial similarity in the interannual to multi-decadal variability but notable differences in the longer-term trends. The magnitude of decadal-scale variability is comparable to, or greater than, the long-term changes in all of the datasets; together with the trend discrepancies, this needs to be considered in climate change applications. Averaged over the NA, the annual means have a long-term increasing trend and a pronounced multi-decadal variation, resembling those in global mean (land-ocean) surface temperature and the Atlantic Multi-decadal Oscillation (AMO). There is remarkable similarity in the spatial and temporal variability of the three leading EOF modes from the different gridded datasets, with the first highly correlated with the AMO, the second modestly correlated with the winter North Atlantic Oscillation, and the third apparently related to ocean circulation variability. Trends since 1981 are generally two to three times larger than those since 1900 and 1950, which is at least partly related to the phase of the AMO. Trends in the summer means are generally larger than in the annual means. Overall, the results provide support for both anthropogenic global warming and decadal-scale natural variations making important contributions to ocean climate variability in the Northwest Atlantic.  相似文献   

地电化学方法技术研究现状及发展趋势   总被引：2，自引：0，他引：2  

孙彬彬  刘占元  周国华 《物探与化探》2015,(1):16-21

地电化学方法技术经过几十年的发展,已经发生了极大的变化,传统的低效率技术方法已被效率极高的新技术所替代。笔者回顾了地电化学发展历史,并对近年来国内外地电化学方法技术进展进行了总结。介绍了"独立供电偶极子地电化学技术"的方法原理及工作方式,并对地电化学方法应用推广过程中需要解决的技术装置商品化、技术体系规范化及异常形成机理等问题进行了探讨及展望。  相似文献   

Is flooding in South Asia getting worse and more frequent?     

Vishwas S. Kale 《Singapore journal of tropical geography》2014,35(2):161-178

South Asia is drained by some of the most flood‐prone rivers in the world. Flooding during the monsoon season is the most recurring, widespread and disastrous natural hazard in South Asia that results in enormous social, economic and environment consequences every year. Several massive floods have occurred in the recent decades causing huge economic losses and human suffering. On average, the total damage is close to USD 1 billion annually. To answer the question whether flooding in South Asia is getting worse and more frequent, all available data were considered: the annual peak discharge data for major rivers, post‐1985 information on floods from the global archive of large floods and palaeoflood records from nine Indian rivers. According to the global archive data, 372 large and 55 extreme flood events have occurred since 1985. Although there is no significant trend, all types of data point to clustering of large floods. Palaeoflood records show that modern floods (post‐1950) have higher flood levels than the late Holocene floods. Notwithstanding the limitations of data, there is enough evidence to conclude that (1) incidences of flood‐generating extreme rainfall event are rising and (2) human interventions have made the recent floods more destructive.  相似文献   

Trends in the near-zero range of the minimum air-temperature distribution     

Noriyuki Sato  Scott M. Robeson 《自然地理学》2014,35(5):429-442

This study estimated the trends in the number of days that fall within the near-zero (0?°C) range of the temperature continuum. This narrow range has importance for potential transportation hazards and freeze-thaw cycles. While the tails of the air-temperature distribution and their trends often are closely examined under the climate change context, the frequency and trend of other portions of the air-temperature distribution can be equally important, as many societal impacts are caused by events in the non-tail region, such as near-zero °C temperatures (NZT). Examining the trend of the number of NZT days over the conterminous USA for the period of 1948–1949 through 2010–2011, we found three distinct spatial clusters. The most distinctive spatial clusters are found along the West Coast (positive temperature trends leading to a decrease in NZT days), the High Plains and Northern Rockies (positive temperature trends leading to an increase in NZT days), and the southeastern USA (negative temperature trends leading to an increase in NZT days). While trends in the number of NZT days are linked to changes in mean minimum air temperature, increasing minimum temperature leads to a positive trend at NZT days only at some locations.  相似文献   

Hydrodynamics and associated sediment transport over coastal wetlands in Quanzhou Bay,China     

王爱军 《中国海洋工程》2011,25(1):59-72

Coastal salt marshes represent an important coastal wetland system.In order to understand the differences between boundary layer parameters of vegetated and unvegetated areas,as well as the mechanisms of sediment transport,several electromagnetic current meters (AEM HR,products of Alec Electronics Co.Ltd.) were deployed in coastal wetlands in Quanzhou Bay,China,to measure current velocity.During the low tide phase,the surficial sediment was collected at 10 m intervals.In situ measurements show that the current velocities on the bare flat were much higher than those in the Spartina alterniflora marsh.Current velocity also varied with distance from marsh edge and plant canopy height and diameter.Around 63% of the velocity profiles in the tidal creek can be described by a logarithmic equation.Over the bare flat and Spartina alterniflora marsh,a logarithmic profile almost occurs during the flood tide phase.Sediment analysis shows that mean grain size was 6.7 Φ along the marsh edge,and surface sediments were transported from bare flat to marsh;the tidal creeks may change this sediment transport pattern.The hydrodynamics at early flood tide and late ebb tide phases determined the net transport direction within the study area.  相似文献   

A Modeling Study on the Mechanism of Convective Initiation of a Squall Line over Northeastern China     

张哲  周玉淑  邓国 《热带气象学报(英文版)》2020,26(3):336-347

High-resolution numerical simulation results of a squall line initiated along a convergence zone in northeast China on 26 June 2014 were presented in this study. The simulation was performed by a convection-permitting model with coarse and fine grids of 4 and 1.33 km, respectively, and the simulation results were validated against the observation. Results showed that the simulation adequately reproduced the life cycle of the squall line, which allowed detailed investigation of the mechanism of convective initiation in this case. The synoptic condition was favorable for convective initiation and the convection was triggered in a convergence zone, where a branch of dry and cold air and a branch of moist and warm air collided. The water vapor flux divergence was inhomogeneous and some cores of water vapor convergence existed in the convergence zone. These cores were the spots where water vapor converged intensely and the air there was forced to rise, creating favorable spots where the convection was initially triggered. A series of quasi-equally spaced vortices near the surface, which themselves were the result of horizontal shear instability, were accountable for the inhomogeneity of the surface water vapor flux divergence. These vortices rotated the moist air into their north and dry air into their south, thus creating more favorable spots for convective initiation in their north. After initiation, the updraft turned the horizontal vorticity into vertical vorticity in the mid-level. The vortices near the surface collaborated with the vorticity maxima in the mid-level and enhanced the development of convection by providing water vapor.  相似文献   

北半球冬季110°—120°E垂直经向环流的年际变化及其与中国东部同期降水的关系     

王玉 《气象与减灾研究》2013,36(2):14-20

利用NCEP／NCAR再分析月平均风场资料和中国东部120个站的降水资料,分析了1951--2010年北半球冬季110°-120°E经向环流的气候特征,定义了北半球冬季110°-120°E低纬Hadley环流和中高纬气流强度指数,并分析了其强度的长期变化趋势以及对中国东部同期降水的影响。结果表明：（1）北半球冬季110°-120°E经向环流主要包括低纬Hadley环流和中高纬度从高层到低层较-致的偏北下沉气流。（2）北半球冬季110°-120°EHadley环流和中高纬气流强度有明显的年际和年代际变化,二者在长期变化趋势上表现-致,即在1990年以前呈约20a的振荡周期,且波动更大,而在1990年以后呈约10a的振荡周期,波动相对较小。（3）北半球冬季110°-120°E经向环流强度指数对中国东部同期降水的年际变率具有较高的解释率,二者在统计上呈显著的负相关关系。北半球冬季110°-120°EHadley环流强度和中国东部同期降水相关程度大值区集中在江南、华南及江淮地区,中高纬气流强度和中国东部同期降水相关程度大值区集中在西北、江淮及江南地区。（4）东亚地区冬季经向环流异常的显著差异主要表现在中高纬度反向的异常气流和中低纬度反向异常环流圈的变化。强（弱）经向风年,北半球中高纬度从高层到低层为异常的偏北（南）气流,中低纬度对流层存在顺时针（逆时针）方向闭合的异常经向环流,对应中国东部降水显著减少（增多）。  相似文献   

REGIONAL TRENDS IN ELECTORAL SUPPORT IN BRITAIN, 1950–1983*     

Andrew R. Bodman 《The Professional geographer》1985,37(3):288-295

Analyses of the geography of British elections have typically stressed the continuity in patterns of party support. This paper challenges that conclusion. Employing an alternative method of analysis, it identifies significant regional trends in the Conservative and Labour vote between 1950 and 1983. Pro-Labour trends in Scotland and Northwest England are contrasted with secular changes favoring the Conservatives in non-metropolitan Southern England. These long-term trends have not been associated with growing regional polarization in party support. While the findings are specific to Britain, the method of assessing electoral change might be usefully applied to patterns in other countries.  相似文献   

新冠肺炎疫情背景下日本应急避难场所运营管理新动向     

金英淑 《中国地震》2022,38(2):322-337

通过梳理日本防控传统传染病视角下的应急避难场所运营管理方法,对比分析新冠肺炎疫情下日本应急避难场所运营管理面临的困境,总结出新冠肺炎疫情下日本应急避难场所运营管理新动向,以及日本政府针对新冠肺炎疫情下应急避难场所运营管理实施的具体措施,如应急避难场所的布局与防止感染对策、日常运营管理对策等,以期为我国新冠肺炎疫情常态化防控下应急避难场所的运维提供借鉴。  相似文献   

An Analysis of the Discontinuity in Chinese Radiosonde Temperature Data Using Satellite Observation as a Reference     

Yanjun GUO  Chengzhi ZOU  Panmao ZHAI  Guofu WANG 《Journal of Meteorological Research》2019,(2):289-306

Reconciling upper-air temperature trends derived from radiosonde and satellite observations is a necessary step to confidently determine the global warming rate. This study examines the raw and homogenized radiosonde observations over China and compares them with layer-mean atmospheric temperatures derived from satellite microwave observations for the lower-troposphere(TLT), mid-troposphere(TMT), upper-troposphere(TUT), and lower-stratosphere(TLS) by three research groups. Comparisons are for averages over China, excluding the Tibetan Plateau, and at individual stations where metadata contain information on radiosonde instrument changes. It is found that major differences between the satellite and radiosonde observations are related to artificial systematic changes. The radiosonde system updates in the early 2000 s over China caused significant discontinuities and led the radiosonde temperature trends to exhibit less warming in the middle and upper troposphere and more cooling in the lower stratosphere than satellite temperatures. Homogenized radiosonde data have been further adjusted by using the shift-point adjustment approaches to match with satellite products for China averages. The obtained trends during 1979–2015 from the re-adjusted radiosonde observation are respectively 0.203 ± 0.066, 0.128 ± 0.044, 0.034 ± 0.039, and –0.329 ± 0.135 K decade^–1 for TLT, TMT, TUT, and TLS equivalents. Compared to satellite trends, the re-adjusted radiosonde trends are within 0.01 K decade^–1 for TMT and TUT, 0.054 K decade^–1 warmer for TLT, and 0.051 K decade^–1 cooler for TLS. The results suggest that the use of satellite data as a reference is helpful in identifying and removing inhomogeneities of radiosonde temperatures over China and reconciling their trends to satellite microwave observations. Future efforts are to homogenize radiosonde temperatures at individual stations over China by using similar approaches.  相似文献