Recent Changes in the Climate At the Dead Sea – a Preliminary Study

In the last decade pan evaporation measured at the Southern Dead Sea has significantly increased. Wind, temperature and humidity measurements at the Dead Sea starting in the 1930s as well as 3-D model simulations all seem to indicate a statistically significant change in the local climate of the Dead Sea region. The potential contribution to this climatic change through the weakening of the local land-sea breeze circulation caused by the reduction in the Dead Sea surface area in 1979–1981, is examined. It is suggested that since the breeze tempers the Dead Sea climate, its weakening has caused the air temperature to increase, the relative humidity to decrease and thus increased the pan evaporation. The climatic changes as implied by the MM4 Mesoscale PSU/NCAR model simulations, seem to fit the observed changes and to suggest a local tendency to the more arid climate that now prevails to the south of the study region.     

Barometric pressure, dry bulb temperature and vapor pressure at the lowest terrestrial site on earth, Dead Sea basin, Neve Zohar, Israel

Summary The Dead Sea basin is located at the lowest terrestrial site on the earth and, thereby, has the tallest atmospheric air column above its surface. Consequently, the Dead Sea basin is expected, a priori, to have the highest terrestrial barometric pressure and, thereby, the highest molecular oxygen density on the earth. The barometric pressure and dry bulb temperature have been monitored continuously at Neve Zohar, located on the western shore of the Dead Sea, since January 1995. The monthly average daily barometric pressure values exceed normal atmospheric pressure by a maximum of 4.83 hPa (4.77%) and a minimum of 33.1 hPa (3.26%) for December and July, respectively. This increase in barometric pressure can serve as a simple way to improve arterial oxygenation in hypoxemic patients. As a result, a number of research projects have been initiated on the treatment of patients suffering from pulmonary and cardiac diseases at the Dead Sea basin. The hourly barometric pressure data with regard to both its diurnal and monthly variation and the correlation between barometric pressure and dry bulb temperature will be analyzed.     

Statistical analysis and inter-comparison of the solar UVB, UVA and global radiation for Beer Sheva and Neve Zohar (Dead Sea), Israel

Summary A statistical analysis and inter-comparison of the solar UVB, UVA and global radiation for Beer Sheva and Neve Zohar (Dead Sea) are presented utilizing data measured from January 1995 through December 2002. Beer Sheva is located approximately 65km to the west of and 700m above Neve Zohar. The monthly average hourly and daily values for all radiation types at both sites are reported. The standard errors of the monthly average daily values have been calculated in order to ascertain whether the average daily radiation intensities are representative, i.e. if the magnitude of the standard error is less than the inherent measurement uncertainty of the instruments, and, thereby, justify an inter-comparison between the two sites. The relative magnitude of the global, UVB and UVA radiation intensity at the two sites is attributed to the enhanced scattering of the incident solar radiation at the Dead Sea location due to the longer optical path length it must traverse to arrive at the Dead Sea, the lowest terrestrial point on earth. The degree of attenuation of solar radiation due to the scattering phenomena is inversely proportional to the wavelength raised to some power and, consequently, it is greatest for UVB and negligible for global radiation.     

Paleo-evolution of the Black Sea watershed: sea level and water transport through the Bosporus Straits as an indicator of the Lateglacial–Holocene transition

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.     

Sodom,gomorrah and the other lost cities of the plain - a climatic perspective

Certain aspects of the biblical story of the Cities of the Plain have in recent years become widely accepted. Among them is the placing of those cities in the southern basin of the Dead Sea, the assumption that those cities are now covered by Dead Sea water and, in particular, the belief that their destruction was due to catastrophic geological causes, such as an earthquake. The Bible emphasizes the agricultural richness of the Jordan plain prior to the upheaval of Sodom and Gomorrah and its catastrophic transformation into a wasteland. Thus, stripped of ethical and religious overtones, the scenario is that of a rapid climatic change that converted a densely inhabited and richly watered area into an infertile salt playa. The region northeast and southeast of Jericho, which today is quite barren as a result of the upward movement of salty ground water but which contains some of the World's earliest known agricultural settlements, fits such a picture. Dating the Sodom event to approximately the 23rd-21st centuries B.C. supports the idea that a major climatic change that occurred between the Early and Middle Bronze Ages and which resulted in profound transformations in the Middle East such as the collapse of the Ancient Kingdom of Egypt, the invasion of the Fertile Crescent by the Semitic desert nomads, and the collapse of Early Bronze Age civilization in Palestine - is also responsible for the Sodom story. Although the data are far from complete, desiccation during this period is indicated by palynological evidence pointing to the decimation of forests in Northern Israel, paleobotanical evidence from Southern Israel, the deposition of salt layers in the Dead Sea, the abandonment of almost all settlements in the Negev Desert of Southern Israel, the Jordan valley and Southern Jordan, except those which were associated with perennial springs, and further afield the drastic lowering of the level of Lake Moeris in Lower Egypt. This scenario does not exclude the possibility that a major earthquake - which may have occurred during this period - was considered to be the cause of the final physical destruction of the Cities of the Plain, delivering a coup de grace to a collapsing society, and which became through the mists of time and legend, the only agent of destruction.     

基于拉格朗日方法的中国东部雨季水汽输送垂直特征

利用基于拉格朗日轨迹追踪模式(HYSPLIT),结合区域源汇归属法,追踪1961～2010年中国东部地区雨带推进过程中各雨季后向轨迹,定量确定各雨季不同垂直层上的水汽输送路径与水汽贡献.结果表明在南海夏季风爆发前的华南前汛期,低层最主要水汽通道为太平洋通道,轨迹占比达到52.3％,中高层最主要的水汽通道为印度洋通道,占...     

Regional and local climatic effects on the Dead-Sea evaporation

The natural evaporation in the Dead-Sea is a very important meteorological parameter to the local industries at Sdom. It was found that the pan evaporation in Sdom has recently increased by 20?C25%. In this paper we explore the reasons for this increase. It is found that both large-scale and local climatic changes have contributed to the evaporation increase in the Dead Sea Valley. The large-scale (global) change potentially associated with the global warming, resulted in changes of the frequencies of some synoptic systems in the region. The local change is a result of the recent Dead-Sea drying, which reduced the local Dead-Sea breeze while intensifying the Mediterranean-Sea breeze penetrating the Dead Sea Valley. It is suggested that while the local effect was the dominant climatic change factor in the Dead-Sea Valley in the 1970?C1990, the global effect becomes the dominant one in the more recent evaporation increase in the Dead-Sea.     

Chemistry of Halogen Oxides in the Troposphere: Comparison of Model Calculations with Recent Field Data

Reactive halogen species (RHS = X, XO, HOX, OXO; X = Cl, Br, I) are known to have an important influence on the chemistry in the polar boundary layer (BL), where they are responsible for ozone depletion events in spring. Recent field campaigns at Mace Head, Ireland, and the Dead Sea, Israel, identified for the first time iodine oxide (IO) at mixing ratios of up to 6.6 ppt and 90 ppt bromine oxide (BrO), respectively, by DOAS also at lower latitudes. These results intensified the discussion about the role of the RHS in the mid-latitude BL.Photochemical box model calculations show that the observed IO mixing ratios can destroy ~0.45 ppb ozone per hour. This is comparable to the rates of the known O₃-loss processes in the boundary layer. The model studies also reveal that IO, at these levels, has a strong influence on the BL photochemistry, increasing the OH/HO₂- and the NO₂/NO - ratios. In combination these changes lead to a reduction of the photochemical ozone formation, which - in addition - reduces ozone mixing ratios by up to 0.15 ppb/h.The studies for the Dead Sea case give no information on the heterogeneous process responsible for the bromine release, but they show that a total of 2 – 4 ppb of total bromine have to be released to explain the observed complete depletion of 60 ppb ozone in 2 – 3 hours.     

渤黄东海40年水位模拟与分析

基于1980—2019年数值模拟的水位和ERA5的风速数据,使用EOF分析方法,研究了渤黄东海40年的水位变化特征和动力机制,分析了气候变化和极端天气对水位变化产生的影响。EOF分析主要模态结果显示,东海东北部海域的水位变化受黑潮路径改变的影响比较明显,并存在一定的时间延迟;台湾岛东北部的水位变化受到黑潮入侵影响,与ENSO变化呈现一定相关性。研究区风速的EOF分析结果显示,年际变化受ENSO的影响显著,并影响了渤黄东海部分区域的水位变化。      

广东后汛期季风槽暴雨天气形势特征分析

对1981-2002年广东后汛期季风槽暴雨期间的环流形势和天气系统进行了统计分析,结果发现,广东后汛期的季风槽暴雨多数发生在西太平洋副高位置偏东或偏南的情况下,并与中纬西风槽或ITCZ有直接联系;季风槽多数位于华南地区上空或华南沿岸海面;高层辐散覆盖广东全部或大部,中心在华南近海。西南季风向北推进源于西南和华南地区低压槽发展,或由于热带气旋登陆后北上而牵动西南季风深入华南陆地,也有些过程是副高西端的偏南气流引导南海季风北进。对流活动有从南海北部或北部湾附近向华南移动的趋势,并有昼夜变化。     

局地海啸对我国南海影响的数值模拟分析

选取了一组代表性的南海海啸源,并分别使用COMCOT海啸模式,以数值模拟的方法对南海局地海啸源进行了数值模拟,从海啸的传播影响时间、波高和能量分布等角度,分析了如果南海发生地震海啸,不同海啸源将会对我国南海沿岸地区和南海岛礁造成的影响。通过敏感性试验证实,海啸波的强度受地震震级变化影响较大,因此,如果南海发生强震引发局地海啸,不同海啸源将会给我国南海周边及岛礁等不同区域造成严重损害。     

南海近海面风场变化特征及其与ENSO的相关性研究

利用1979—2017年共39 a欧洲中期天气预报中心（ECMWF）海表面10 m风场资料,采用经验正交函数方法（EOF）、小波时频特征分析等方法分析了南海近海面风场变化特征及其对ENSO的响应。结果表明：南海近海面风场第一模态海表面平均风速呈减小趋势, 呈现年代际变化,且与ENSO相关,但相关性在1990年后趋于减小;第二模态中南海北部和南部平均风速呈减小趋势,中部增大;第三模态中南海中部海表面平均风速趋于减小,北部和南部增大,第二和第三模态均表现为年际变化,且均与ENSO显著相关,近年来ENSO与第三模态的相关性逐渐增强。春季南海表面平均风速从南到北逐渐增加;夏季在越南沿岸部分海域仍有一个风速极大值中心,从该海域向四周逐渐减小,整片海域风向均是西南风;秋季由南向北依次增加;冬季南海整片海域风速都较大,越南沿岸和我国东沙群岛海域存在两个极大值中心。     

Interannual variability of water discharge through the Korea (Tsushima) Strait and its influence on the dissolved oxygen content in the Sea of Japan

The interannual variations of the sea level at the coastal stations of the Sea of Japan and of the water discharge through the Korea (Tsushima) Strait are studied. It is demonstrated that the interannual variations of the water discharge through this strait are determined by the water discharge of the Oyashio (in the subarctic Pacific) and the Kuroshio (in the East China Sea) currents and by the zonal wind stress component over the Sea of Japan in winter period. It is revealed that the variations in the East China Sea water transport through the Korea (Tsushima) Strait cause the interannual variations of the dissolved oxygen content in intermediate (500 m) and deep (1000 m and more, σ_θ = 27.35) waters of the Sea of Japan.     

Studying the influence of cyclonic activity on suspension distribution in the sea water of the northwestern Black Sea

Processes of roiling, transport-diffusion, and deposition of fine disperse bottom sediments are studied in the northwestern shelf of the Black Sea in different synoptic situations connected with the passage of cyclones. Movement of atmospheric disturbances with velocities of 5 and 15 m/s along three trajectories typical of this region is considered. A nonlinear sigma-coordinate numerical model is used to calculate hydrodynamic and suspension concentration fields. The bottom areas, most sensitive to erosion, and the areas of maximum accumulation of depositions due to their sedimentation are determined. The change in suspension distribution in the surface layer with time is studied.     

南海和孟加拉湾热带气旋的对比分析

本文着重对夏季风盛行时期,7—9月份的孟加拉湾热带气旋与南海热带气旋活动规律、以及某些结构特征作比较,以期加深对这两个地区气旋系统的认识。      

River Runoff and Probabilistic Forecast of the Caspian Sea Level

The main components ofthe Caspian Sea water balance and water level are assessed. Stochastic models of time series of the water balance components are proposed ustng morphometric dependences specified by creating and processing digital elevation models for the flooded areas. The sea level forecast is obtained by the method of simulation modeling based on algorithms for the generation of Markovian random sequences with non-Gaussian marginal distributions.     

Hydrodynamic modeling of floods in Saint Petersburg considering the operating dam

The Baltic Sea level is computed from the BALT-P three-dimensional hydrodynamic model at the grid with the horizontal resolution of 2 nautical miles, and the computation for the top of the Gulf of Finland is provided at the grid with the spatial resolution of 90 m. The sea motion is induced by the air pressure gradients and wind stress values from the HIRLAM model forecast specified on the sea surface. The sea level is calculated for three floods in Saint Petersburg with account that each of eight spillways of the dam closed and opened not instantly but during the prescribed period of time. It is revealed that the BALT-P model simulates the sea level well during three floods in Saint Petersburg considering the operating dam. The model can be used for the sea level forecasting in Saint Petersburg based on the HIRLAM atmospheric model data with the lead time of 60 hours.     

Investigation of effects of spatially and temporally variable wind on currents, surges, and admixture spread in the Sea of Azov

The analysis of surges in the Sea of Azov is carried out on the basis of three-dimensional nonlinear model using the prognostic fields of near-water wind and atmospheric pressure. Carried out is the comparison of the results of numerical computations with the data of direct measurements of the sea level at a number of coastal stations. Studied is an effect of atmospheric impact intensity variations on the maximum values of sea level deviations and current velocities, as well as on the admixture transformation features. The analysis of results of numeric computations enabled to make a conclusion on the dependence of the pollution dissipation time on the wind speed and on the location of pollution areas.     

基于Copula函数的中国南方干旱风险特征研究

利用1961—2012年1710个地面气象台站观测的逐日降水资料,对中国大陆雨季特征进行了分析。结果表明,雨季最早到来的地方是藏东南、滇西北的横断山脉中西部地区;接着江南地区进入雨季;之后随着夏季风的爆发,全国大部分地区进入雨季。而雨季结束最早的地区在江南地区,较迟结束的地区在华西地区、南海地区,最迟是在新疆西北部地区。就雨季持续时间而言,华北地区和西藏西部及其与新疆南部相接的部分地区雨季持续时间最短,横断山脉中西部地区、华西地区和南海地区雨季较长。通过对多年平均逐候降水进行经验正交函数(EOF)分解,能较好地将主要的降水季节演变特征分离出来,分析发现,第1、第2和第3模态分别反映了夏季、春季和秋季降水为主要特征的降水空间结构。     

Effects of salinity upon evaporation from pans and shallow lakes near the Dead Sea

Summary Evaporation was evaluated for three shallow lakes near the Dead Sea with specific gravities (s.g.) of 1.26, 1.31 and 1.34, and for a hypothetical fresh lake of similar depth. The annual march of lake temperature was adequately predicted with an equilibrium temperature model. Predicted temperatures were only slightly affected by neglecting heat exchange between the lake and the underlying sediments. Modeled lake temperatures were then used in a modified Penman-type model and an alpha ratio model to generate evaporation estimates. The evaporation models were verified by comparison against 1950'ies water balance estimates of evaporation from the Dead Sea (s.g. about 1.18). Annual totals of evaporation predicted by the models for the shallow lakes declined from 2125 mm for fresh water (s.g. = 1.0) down to 588 mm for the most saline conditions (s.g. = 1.34). Evaporation was also measured from sunken pans in which s.g. was maintained at 1.0, 1.26, 1.31 and 1.34. Mean monthly pan coefficients (from lake/pan evaporation for equal s.g. values) ranged from 0.63 up to 1.03 as s.g. increased from 1.00 up to 1.34. The variations in coefficients are attributed to effects of salinity on the mechanisms that control the gain and loss of heat to the ponds and evaporation pans. The temperatures of the saline lakes were always somewhat warmer than the temperatures measured in the sunken pans, ranging from + 0.7 °C for s.g. of 1.26 up to + 1.3 °C for s.g. of 1.34; the corresponding value for the fresh condition was — 0.4 °C. The pan coefficients defined here for saline conditions will be useful for estimating actual water loss from brine-filled ponds used in commercial extraction of potash and other chemicals.With 2 Figures