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1.
Circulation over Bulgaria and its connection with NAO indices and Sea Surface Temperatures 总被引：1，自引：0，他引：1
Peter Nojarov 《Theoretical and Applied Climatology》2013,114(1-2):329-348
Trends in atmospheric pressure, circulation and some relationships between North Atlantic Oscillation (NAO) indices, sea surface temperatures, and atmospheric circulation over Bulgaria are discussed in this article. Data for measured atmospheric pressure at stations Burgas, Pleven, and Sandanski are used. Information about atmospheric circulation over Bulgaria was obtained using sea level pressure and 700 hPa Omega (vertical velocity) reanalysis daily data for grid cells covering the territory of Bulgaria for the period 1948–2010. Zonal and meridional indices for Bulgaria were also calculated based on the data for sea level pressure. NAO index calculated by NOAA and NCAR is correlated with atmospheric pressure and circulation. A total of 12 areas in three major water basins influencing Bulgarian climate—North Atlantic, Mediterranean, and Black Seas—were studied. Main methods employed in the article are statistical—trend analysis, multiple linear regression, correlation, nonparametric tests, etc. There is no change in the mean values of atmospheric pressure over Bulgaria. Circulation over Bulgaria during the research period increases its anticyclonal patterns mainly due to the decrease of the number of cyclones. Dynamics in zonal and meridional indices for Bulgaria result in an increase of the northwest transport in the winter and an increase of the northeast transport in the summer. Cyclones over Bulgaria determine the values of atmospheric pressure. Influence of the NAO on atmospheric pressure and circulation is stronger in winter. Atmospheric processes, expressed by the number of cyclones and anticyclones, are most active in spring. Current trends are towards increasing of sea surface temperatures (SSTs) at all investigated places. Temporally, the effect of SSTs on the number of cyclones, anticyclones, zonal and meridional indices for Bulgaria during the different seasons comes with a delay of 1 to 3 months. Constructed multiple linear regression (MLR) models with predictors SSTs adequately describe the atmospheric circulation over Bulgaria. There is a clear pattern of SSTs distribution, which leads to a higher number of cyclones over Bulgaria in winter—lower than normal temperatures in the Aegean Sea and higher than normal in the Black Sea. A decrease in the difference of temperatures between the Gulf Stream and western colder parts leads to higher values of winter zonal transport over Bulgaria. Higher than normal temperatures in Black Sea lead to a higher number of cyclones in spring. Higher difference in temperatures of the North Atlantic leads to a stronger cyclogenesis and enhanced zonal transport, which affects autumn circulation over Bulgaria. 相似文献
2.
P. M. Della-Marta J. Luterbacher H. von Weissenfluh E. Xoplaki M. Brunet H. Wanner 《Climate Dynamics》2007,29(2-3):251-275
We investigate the large-scale forcing and teleconnections between atmospheric circulation (sea level pressure, SLP), sea
surface temperatures (SSTs), precipitation and heat wave events over western Europe using a new dataset of 54 daily maximum
temperature time series. Forty four of these time series have been homogenised at the daily timescale to ensure that the presence
of inhomogeneities has been minimised. The daily data have been used to create a seasonal index of the number of heat waves.
Using canonical correlation analysis (CCA), heat waves over western Europe are shown to be related to anomalous high pressure
over Scandinavia and central western Europe. Other forcing factors such as Atlantic SSTs and European precipitation, the later
as a proxy for soil moisture, a known factor in strengthening land–atmosphere feedback processes, are also important. The
strength of the relationship between summer SLP anomalies and heat waves is improved (from 35%) to account for around 46%
of its variability when summer Atlantic and Mediterranean SSTs and summer European precipitation anomalies are included as
predictors. This indicates that these predictors are not completely collinear rather that they each have some contribution
to accounting for summer heat wave variability. However, the simplicity and scale of the statistical analysis masks this complex
interaction between variables. There is some useful predictive skill of summer heat waves using multiple lagged predictors.
A CCA using preceding winter North Atlantic SSTs and preceding January to May Mediterranean total precipitation results in
significant hindcast (1972–2003) Spearman rank correlation skill scores up to 0.55 with an average skill score over the domain
equal to 0.28 ± 0.28. In agreement with previous studies focused on mean summer temperature, there appears to be some predictability
of heat wave events on the decadal scale from the Atlantic Multidecadal Oscillation (AMO), although the long-term global mean
temperature is also well related to western European heat waves. Combining these results with the observed positive trends
in summer continental European SLP, North Atlantic SSTs and indications of a decline in European summer precipitation then
possibly these long-term changes are also related to increased heat wave occurrence and it is important that the physical
processes controlling these changes be more fully understood. 相似文献
3.
E. Xoplaki J. González-Rouco D. Gyalistras J. Luterbacher R. Rickli H. Wanner 《Climate Dynamics》2003,20(5):537-554
The interannual and decadal variability of summer (June to September) air temperature in the northeastern Mediterranean is analysed for the period 1950 to 1999. Extremely hot and cool summers are illustrated by means of composite analysis. The combined influence of the large-scale atmospheric circulation and thermic predictors on local temperature is assessed by means of an objective approach based on empirical orthogonal functions and canonical correlation analysis. Monthly values of sea level pressure, geopotential heights, atmospheric thickness and Mediterranean sea surface temperatures are used as predictor fields and air temperature from 24 observational sites spread over Greece and western Turkey constitute the predictand variable. Results indicate that more than 50% of the total summer temperature variability can be explained linearly by the combination of eight large-scale predictor fields on two canonical correlation modes. The first canonical mode is related to a more meridional circulation at the upper tropospheric levels, which favours local land-sea contrasts in the associated local temperature pattern. Variations of this mode are found to be responsible for the occurrence of extreme events and decadal trends in regional temperature, the latter being characterized by a cooling in the early 1960s and a warming in the early 1990s. The second canonical mode pictures variations in the intensity of the zonal circulation over the Atlantic area that drive temperature anomalies affecting mainly the Aegean Sea and the west of Greece. Our results suggest the potential of statistical downscaling for Greek summer temperature with reliable climate forecasts for planetary-scale anomalies. 相似文献
4.
To describe the spatial structure of hydrometeorological fields in the North Atlantic and in the Black Sea, the temperature
indices (sea surface temperature gradients) representing the difference in sea surface temperature anomalies averaged throughout
the water area and normalized by standard deviations are introduced. Temperature gradients between the Sargasso Sea and the
tropics (STI), the Sargasso Sea and the subpolar cyclonic gyre (SNI), the Sargasso Sea and the Black Sea (SBI) are considered.
The spatial structure of the sea surface temperature field anomalies in the North Atlantic and in the Black Sea at extreme
values of STI and SBI is discussed. A sign-variable structure of air temperature and precipitation anomalies in the Black
Sea area at extreme values of SBI is shown. Time scales of sign-variable variability of anomalies of hydrometeorological fields
in the Black Sea area are estimated. 相似文献
5.
Cem Iyigun Murat Türkeş İnci Batmaz Ceylan Yozgatligil Vilda Purutçuoğlu Elçin Kartal Koç Muhammed Z. Öztürk 《Theoretical and Applied Climatology》2013,114(1-2):95-106
In this study, the hierarchical clustering technique, called Ward method, was applied for grouping common features of air temperature series, precipitation total and relative humidity series of 244 stations in Turkey. Results of clustering exhibited the impact of physical geographical features of Turkey, such as topography, orography, land–sea distribution and the high Anatolian peninsula on the geographical variability. Based on the monthly series of nine climatological observations recorded for the period of 1970–2010, 12 and 14 clusters of climate zones are determined. However, from the comparative analyses, it is decided that 14 clusters represent the climate of Turkey more realistically. These clusters are named as (1) Dry Summer Subtropical Semihumid Coastal Aegean Region; (2) Dry-Subhumid Mid-Western Anatolia Region; (3 and 4) Dry Summer Subtropical Humid Coastal Mediterranean region [(3) West coast Mediterranean and (4) Eastern Mediterranean sub-regions]; (5) Semihumid Eastern Marmara Transition Sub-region; (6) Dry Summer Subtropical Semihumid/Semiarid Continental Mediterranean region; (7) Semihumid Cold Continental Eastern Anatolia region; (8) Dry-subhumid/Semiarid Continental Central Anatolia Region; (9 and 10) Mid-latitude Humid Temperate Coastal Black Sea Region [(9) West Coast Black Sea and (10) East Coast Black Sea sub-regions]; (11) Semihumid Western Marmara Transition Sub-region; (12) Semihumid Continental Central to Eastern Anatolia Sub-region; (13) Rainy Summer Semihumid Cold Continental Northeastern Anatolia Sub-region; and (14) Semihumid Continental Mediterranean to Eastern Anatolia Transition Sub-region. We believe that this study can be considered as a reference for the other climate-related researches of Turkey, and can be useful for the detection of Turkish climate regions, which are obtained by a long-term time course dataset having many meteorological variables. 相似文献
6.
The paleo-evolution of the Black Sea level during the Lateglacial–Holocene transition is still unclear, which motivates us
to provide new estimates for that period based on the analysis of water budget. Hydrological conditions in the Black Sea catchment
area are reconstructed here using water balance equation, available data, and constraints based on simple theory relating
the runoff ratio with climatic characteristics. In order to estimate the impact of the aridity of climate we consider two
alternative scenarios: (1) climate change under constant in time gradient in precipitation and evaporation over land and sea,
and (2) climate change accounting for changes in the horizontal distribution of precipitation and evaporation. Hydrological
data are compiled from available present-day data and paleo-observations. A number of sensitivity experiments is carried out
revealing that the hydrological conditions in the Black Sea watershed should have evolved towards a very arid climate (similar
to the present-day climate in the Caspian Sea area) in order to initiate a drop of sea level of ∼100 m below the sill depth
of the Bosporus Straits, as speculated in some recent research. Estimates of sea level changes reveal a qualitative agreement
with the coast-line evolution inferred from paleo-observations. The Younger Dryas draw down of the Black Sea starts at about
13.3 to 13 kyr BP, with a maximum low-stand of 104 m at 11.5 kyr BP. In an arid climate scenario the sea level reaches the
outlet at about 8.8 to 7.4 kyr BP. Approximately at that time, Mediterranean sea level was about 10 m higher, making flooding
events of the Black Sea possible. However, the nature and exact timing of the Holocene reconnection depends also on other
(not well known) factors; one of them is the Bosporus sill depth, motivating further research in this field. Estimates of
the water transport through the Bosporus Straits are also provided for the time of Lateglacial–Holocene transition. 相似文献
7.
X. Lana M. D. Martínez A. Burgueño C. Serra 《Theoretical and Applied Climatology》2009,97(1-2):135-150
Spatial patterns and statistical models for hot and cold events affecting Catalonia (NE Spain) are obtained from series of daily maximum and minimum temperatures recorded at 65 meteorological stations throughout the period 1950–2004. The study is based on the crossing theory, taking care that daily temperatures are normally distributed and previous data treatments (removal of trends and periodicities) assure their stationary character. With the aim of facilitating comparisons among different thermometric records, hot and cold events are defined as large departures, given in standard deviations, of daily temperatures from daily averages. From the statistical point of view, the assumption of a normal distribution of the initial date of the events is questionable and a simple assignment of hot events to summer and cold events to winter must be discarded according to the averaged initial dates and their standard deviations. The event magnitudes, defined as the absolute value of their maximum departures, follow an exponential distribution and event lengths can be modelled by an autoregressive Markov process with a Gaussian noise component. The number of events per year fits a Poisson distribution well only for high departures and the whole number of hot and cold events decays exponentially with the increasing departure for every temperature series. This property permits an estimation of the expected maximum departure for every thermometric station during the recording period. Even though spatial features observed for the number of events, their mean initial date, average event magnitude and average event length depict quite complex patterns due to the orography of the country and the vicinity to the Mediterranean Sea, the results obtained improve the knowledge on the hot and cold events in Catalonia. 相似文献
8.
This study aims to explore the relative role of oceanic dynamics and surface heat fluxes in the warming of southern Arabian Sea and southwest Indian Ocean during the development of Indian Ocean Dipole (IOD) events by using National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) daily reanalysis data and Global Ocean Data Assimilation System (GODAS) monthly mean ocean reanalysis data from 1982 to 2013, based on regression analysis, Empirical Orthogonal Function (EOF) analysis and combined with a 2? layer dynamic upper-ocean model. The results show that during the initial stage of IOD events, warm downwelling Rossby waves excited by an anomalous anticyclone over the west Indian Peninsula, southwest Indian Ocean and southeast Indian Ocean lead to the warming of the mixed layer by reducing entrainment cooling. An anomalous anticyclone over the west Indian Peninsula weakens the wind over the Arabian Sea and Somali coast, which helps decrease the sea surface heat loss and shallow the surface mixed layer, and also contributes to the sea surface temperature (SST) warming in the southern Arabian Sea by inhibiting entrainment. The weakened winds increase the SST along the Somali coast by inhibiting upwelling and zonal advection. The wind and net sea surface heat flux anomalies are not significant over the southwest Indian Ocean. During the antecedent stage of IOD events, the warming of the southern Arabian Sea is closely connected with the reduction of entrainment cooling caused by the Rossby waves and the weakened wind. With the appearance of an equatorial easterly wind anomaly, the warming of the southwest Indian Ocean is not only driven by weaker entrainment cooling caused by the Rossby waves, but also by the meridional heat transport carried by Ekman flow. The anomalous sea surface heat flux plays a key role to damp the warming of the west pole of the IOD. 相似文献
9.
M. J. OrtizBeviá F. J. Alvarez-García A. M. Ruiz de Elvira G. Liguori J. H. Carretero 《Climate Dynamics》2012,39(12):3103-3120
The anomalous climatic variability of the Western Mediterranean in summer, its relationships with the large scale climatic teleconnection modes and its feedbacks from some of these modes are the targets of this study. The most important trait of this variability is the recurrence of warm and cold episodes, that take place at 2–4 year intervals, and which are monitored in the Western Mediterranean Index. We find that the Western Mediterranean events are part of a basin scale mode, and are related to the previous spring atmospheric anomalies. These anomalies are related mainly to the Pacific North America teleconnection pattern and the North Atlantic Oscillation, but also to a number of other climatic modes, connected with the previous two, as the Southern Oscillation, the Indian Core Monsoon and the Scandinavian teleconnection pattern. We identify the main spatial and temporal traits of the Western Mediterranean summer variability, the physical mechanisms at play in the generation of the events and their impacts. Considering the Atlantic Ocean, the Mediterranean events influence the sea surface temperature in the southeastern part of the North Atlantic Gyre. Additionally, they are significantly related to summer precipitation anomalies of the opposite sign in the Baltic basin (Central Germany and Poland) and near the Black Sea. We then estimate the mutual influence that the anomalous previous state of the Western Mediterranean, of the Pacific North America teleconnection pattern and of the North Atlantic Oscillation have on their summer conditions using a simple stochastic model. As the summer Western Mediterranean events have an influence on a part of the Baltic basin, we propose a second stochastic model in order to investigate if thereafter the Baltic basin variability will feedback on the Western Mediterranean sea surface temperature anomalies. Among the variables included in the second model are, in addition to the Western Mediterranean previous state, that of the Baltic Sea and of the Scandinavian teleconnection pattern. From each of the feedback matrices, a linear statistical analysis extracts spatial patterns whose evolution in time exhibits predictive capabilities for the Western Mediterranean evolution in summer and autumn that are above those of persistence, and that could be improved. 相似文献
10.
H. Toros A. Deniz L. Şaylan O. Şen M. Baloğlu 《Meteorology and Atmospheric Physics》2005,88(1-2):107-118
Summary Air temperature, absolute humidity and wind speed are the most important meteorological parameters that affect human thermal comfort. Because of heat loss, the human body feels air temperatures different to actual temperatures. Wind speed is the most practical element for consideration in terms of human comfort. In winter, due to the strong wind speeds, the sensible temperature is generally colder than the air temperature. This uncomfortable condition can cause problems related to tourism, heating and cooling. In this study, the spatial and temporal distributions of cooling temperatures and Wind Chill Index (WCI) are analyzed for Turkey, and their effect on the human body is considered. In this paper, monthly cooling temperatures between October and March in the years 1929 to 1990 are calculated by using measured temperature and wind speed at 79 stations in Turkey. The influence of wind chill is especially observed in the regions of the Aegean, west and middle Black Sea and east and central Anatolia. The wind chill in these regions has an uncomfortable effect on the human body. Usually, the WCI value is higher in western, northern and central Anatolia than in other regions. 相似文献
11.
Results from high resolution 7-km WRF regional climate model (RCM) simulations are used to analyse changes in the occurrence frequencies of heat waves, of precipitation extremes and of the duration of the winter time freezing period for highly populated urban areas in Central Europe. The projected climate change impact is assessed for 11 urban areas based on climate indices for a future period (2021–2050) compared to a reference period (1971–2000) using the IPCC AR4 A1B Scenario as boundary conditions. These climate indices are calculated from daily maximum, minimum and mean temperatures as well as precipitation amounts. By this, the vulnerability of these areas to future climate conditions is to be investigated. The number of heat waves, as well as the number of single hot days, tropical nights and heavy precipitation events is projected to increase in the near future. In addition, the number of frost days is significantly decreased. Probability density functions of monthly mean summer time temperatures show an increase of the 95th percentile of about 1–3 °C for the future compared with the reference period. The projected increase of cooling and decrease of heating degree days indicate the possible impact on urban energy consumption under future climate conditions. 相似文献
12.
2021年秋季(9—11月)北半球大气环流特征为:极涡整体呈单极型,中高纬环流呈5波型分布,欧亚地区西风带环流形势季节内调整大,副热带高压(以下简称“副高”)偏强,西伸明显。秋季我国近海大风过程主要由冷空气、温带气旋和热带气旋影响造成。在12次8级以上大风过程中,冷空气影响8次,温带气旋影响6次,台风影响4次。西北太平洋和南海共生成9个台风,其中5个台风进入我国近海,在东西带状分布的副高影响下,近海台风主要活跃于南部海域;全球其他海域共命名热带气旋18个。我国出现2 m以上大浪过程的日数为74 d,约占总日数的81%,大浪过程与大风过程联系密切。秋季我国近海海面温度整体偏高,随着冷空气的逐渐活跃,北部海区和沿岸海域海面降温迅速,沿岸海面温度梯度加大,我国近海海域中,海面温度梯度最大的区域出现在东海。 相似文献
13.
极端高温事件是我国南方夏季频发的天气灾害,区域性明显,持续性高温事件的环流背景及其影响机理值得深入研究。基于台站观测资料和欧洲中期天气预报中心的再分析资料,对1961—2010年广西东南部贵港地区发生的高温事件的时间变化规律及持续性高温天气过程对应的大气环流场演变进行了统计诊断分析。(1)广西东南部贵港地区的高温日主要出现在6—9月,其中7—8月是高温日频发的月份;3天以上的持续高温日数占总高温日数的6成;8—9月的高温日数具有明显的增加趋势。(2)桂东南在6—9月的持续性高温天气与一些特定的天气系统的存在有紧密联系。持续的下沉运动是造成广西东南部升温的主要原因,而导致垂直下沉运动的主要原因又与大陆高压、副热带高压或南海-菲律宾海出现的热带低压系统的北移路径偏东有关,持续时间较长的高温过程还与热带气旋的活动时间较长和强度偏强有关。(3)高压控制的晴空少云天气可导致地表接收更多的太阳辐射,使得地表温度的升高,从而导致地表向上的长波辐射及感热通量增强,加热近地面空气,这些有利于近地面升温的热力过程以及垂直下沉绝热加热过程的增强,使得高温天气过程得以维持。 相似文献
14.
超强与普通厄尔尼诺海-气特征差异及对西太平洋副热带高压的不同影响 总被引：1，自引：0，他引：1
利用NCEP/NCAR再分析资料、GODAS海洋资料、哈得来中心海表温度（SST）以及中国国家气候中心（NCC）环流指数数据,依据美国气候预测中心的厄尔尼诺事件标准筛选出1980-2016年的超强与普通厄尔尼诺事件,对比了两类事件的不同生命阶段内海表及次表层温度特征的差异,并探讨了其对西太平洋副热带高压（西太副高）的不同影响。结果表明,对超强厄尔尼诺事件而言,海表温度正距平发展早且迅速,其大值中心偏东,纬向梯度强,但对普通厄尔尼诺事件而言,海表温度正距平中心偏西,纬向梯度小。厄尔尼诺事件的发展源于次表层海温距平（SOTA）随开尔文波东传并沿温跃层上升到达海表,其波动前部区域异常垂直海流对次表层海温距平的变化起重要作用;当海气激烈耦合时,可在温跃层激发出更强的海洋波动,使得次表层变暖更明显,激发出强的厄尔尼诺事件。海温异常强迫出的大气异常环流的强度与强迫源的强度关系密切。两类厄尔尼诺均能通过异常的沃克环流引起大气Gill型响应,使得西太副高偏强、西伸,且当超强厄尔尼诺发生时,异常沃克环流更强,海洋性大陆区域上空的异常强辐散导致Gill型响应而产生的反气旋更强,对西太副高的影响更甚。印度洋海表温度对厄尔尼诺的滞后变暖所带来的影响在上述亚太大气环流的持续异常中起重要作用。这些结果有利于加深对不同类型厄尔尼诺事件及影响西太副高机理的认识。 相似文献
15.
2018年7月北半球天气气候显著异常,极端事件高发。欧洲、北非、东亚以及北美的大部分地区均遭受严重的高温热浪侵袭;印度、东南亚、中国西南部以及日本西部等地出现极端降水;西太平洋台风活动异常活跃,移动路径偏北。初步诊断表明,北半球中高纬度,由低层到高层稳定维持的异常高压系统是导致北半球中高纬度大部分地区高温热浪持续发生的直接原因。其中异常偏强、偏北的副热带高压,以及增强、东伸的南亚高压与东亚地区持续高温和极端降水事件直接相关;低层菲律宾周围异常活跃的对流活动和强盛的西南水汽输送共同导致南亚、东南亚地区极端降水发生。热带太平洋大部分地区偏暖的海温条件和菲律宾附近异常气旋性环流则与异常活跃的台风活动有关。更需要关注的是,北半球尤其是东亚地区大气环流的异常主要受海洋表面热力状况以及其他区域大气环流遥相关的影响。 相似文献
16.
Summary Air temperatures in the Western Mediterranean area exhibited a positive trend during the last 40 years, whilst the Eastern Mediterranean area showed a decrease. The mean temperature of the surface/500 hPa layer exhibited a positive trend in both the Western and Eastern Mediterranean. This almost continuous increase of mean temperature is partly due to horizontal thermal advection and mainly to diabatic warming. Sea surface temperatures show a negative trend throughout the Mediterranean area. The time series of sea surface temperatures in the Eastern Mediterranean show evidence of 48- and 54-month harmonics, while the time series in the Western Mediterranean show evidence of 28- or 30-month harmonics.With 9 Figures 相似文献
17.
Severe heat waves in Southern Australia: synoptic climatology and large scale connections 总被引：1，自引：0，他引：1
This paper brings a new perspective on the large scale dynamics of severe heat wave (HW) events that commonly affect southern Australia. Through an automatic tracking scheme, the cyclones and anticyclones associated with HWs affecting Melbourne, Adelaide and Perth are tracked at both the surface and upper levels, producing for the first time a synoptic climatology that reveals the broader connections associated with these extreme phenomena. The results show that a couplet (or pressure dipole) formed by transient cyclones and anticyclones can reinforce the HW similarly to what is observed in cold surges (CS), with an obvious opposite polarity. Our results show that there is a large degree of mobility in the synoptic signature associated with the passage of the upper level ridges before they reach Australia and the blocking is established, with HW-associated surface anticyclones often initiating over the west Indian Ocean and decaying in the eastern Pacific. In contrast to this result the 500?hPa anticyclone tracks show a very small degree of mobility, responding to the dominance of the upper level blocking ridge. An important feature of HWs is that most of the cyclones are formed inland in association with heat troughs, while in CS the cyclones are typically maritime (often explosive), associated with a strong cold front. Hence the influence of the cyclone is indirect, contributing to reinforce the blocking ridge through hot and dry advection on the ridge’s western flank. Additional insights are drawn for the record Adelaide case of March 2008 with fifteen consecutive days above 35°C breaking the previous record by 7?days. Sea surface temperatures suggest a significant air-sea interaction mechanism, with a broad increase in the meridional temperature gradient over the Indian Ocean amplifying the upstream Rossby waves that can trigger HW events. A robust cooling of the waters close to the Australian coast also contributes to the maintenance of the blocking highs locally, which is a fundamental ingredient to sustain the HWs. 相似文献
18.
The reanalysis ofthree-dimensional fields of water temperature and velocity ofcurrents in the Black Sea in January–March in 1971–1991 is used for studying the spatial distribution of sea surface temperature, heat content of the upper layer, and heat fluxes on the sea surface near the Caucasian coast and the southern coast of Crimea. It is demonstrated that a warm current in the upper layer of the sea and the high values of the heat flux from the sea to the atmosphere are observed in these areas in winter. The possible effect of the above features on the interannual variability of winter air temperature in Sochi and Yalta is assessed. 相似文献
19.
Gridded monthly evaporation data for 1958–2006 from the Woods Hole Oceanographic Institution data set are used to investigate interannual variability of Mediterranean evaporation during cold and hot seasons and its relation to regional atmospheric dynamics, sea surface temperature and atmospheric elements of the hydrological cycle. The first EOF mode of Mediterranean evaporation, explaining more than 50% of its total variance, is characterized by the monopole pattern both in winter and summer. However, despite structural similarity, the EOF-1 of Mediterranean evaporation is affected by different climate signals in cold and hot seasons. During winter the EOF-1 is associated with the East Atlantic teleconnection pattern. In summer, there is indication of tropical influence on the EOF-1 of Mediterranean evaporation (presumably from Asian monsoon). Both in winter and summer, principal components of EOF-1 demonstrate clear interdecadal signals (with a stronger signature in summer) associated with large sea surface temperature anomalies. The results of a sensitivity analysis suggest that in winter both the meridional wind and the vertical gradient of saturation specific humidity (GSSH) near the sea surface contribute to the interdecadal evaporation signal. In summer, however, it is likely that the signal is more related to GSSH. Our analysis did not reveal significant links between the Mediterranean evaporation and the North Atlantic Oscillation in any season. The EOF-2 of evaporation accounts for 20% (11%) of its total variance in winter (in summer). Both in winter and summer the EOF-2 is characterized by a zonal dipole with opposite variations of evaporation in western and eastern parts of the Mediterranean Sea. This mode is associated presumably with smaller scale (i.e., local) effects of atmospheric dynamics. Seasonality of the leading modes of the Mediterranean evaporation is also clearly seen in the character of their links to atmospheric elements of the regional hydrological cycle. In particular, significant links to precipitation in some regions have been found in winter, but not in summer. 相似文献
20.
Obtained are the estimates of the Black Sea level trends for the period of 1992–2005 as derived from the tide-gage and satellite altimetry data. An estimated rate of the mean sea level rate calculated from the averaged altimetry data is 7.6 ± 0.3 mm/year that is by 2–3 times higher than the estimates for the previous periods. Such high values of the trend are evidently associated with the sea level variability features at the 10-year temporal scale. The Black Sea level trend is characterized by the high spatial variability: it amounts to 8–9.5 mm/year in the coastal areas of the Black Sea basin that exceeds the trend in the deep-water part by 1.5–2 times (4.5–6 mm/year). Such distribution is an effect of the cyclonic Rim Current intensification. Based on the difference in the sea level trends obtained from in-situ and altimetry measurements, the velocity of the vertical crustal motion is estimated for the Ukrainian coastal stations of the Black Sea. 相似文献