Boundary-layer remote-sensing observations and modeling of foehn in the Dead Sea valley

The atmospheric dynamics in the Dead Sea (DS) Valley has been studied for decades. However, the studies relied mostly on surface observations and simple coarse-model simulations, insufficient to elucidate the complex flow in the area.&#160; I will present a first study using high resolution (temporal and spatial) and sophisticate both, measurements and modeling tools. We focused on afternoon hours during summer time, when the Mediterranean Sea (MS) breeze penetrates into the DS Valley and sudden changes of wind, temperature and humidity occur in the valley.An intense observations period , including ground-based remote sensing and in-situ observations, took place during August and November 2014. The measurements were conducted as part of the Virtual Institute DEad SEa Research Venue (DESERVE) project using the KITcube profiling instruments (wind lidars, radiometer and soundings) along with surface Energy Balance Station. These observations enabled analysis of the vertical profile of the atmosphere at one single location at the foothills of Masada, about 1 km west of the DS shore.High resolution (1.1 km grid size) model simulations were conducted using the WRF model. The simulations enabled analysis of the 3D flow at the DS Valley, information not provided by the observations at a single location. Sensitivity tests were run to determine the best model configuration for this study.Our study shows that foehn develops in the lee side of the Judean Mountains and DS Valley in the afternoon hours when the MS breeze reaches the area. The characteristics of the MS breeze penetration into the valley and of the foehn (e.g. their depth) and the impact they have on the boundary layer flow in the DS Valley (e.g. the changes in temperature, humidity and wind) are conditioned to the daily synoptic and mesosocale conditions. In the synoptic scale, the depth of the seasonal trough at sea level and the height of inversion layers play a significant role in determining the breeze and foehn characteristics. In the mesoscale, the intensity of the DS breeze and the humidity brought by it determines the outcomes at the time of MS breeze penetration and foehn development. Dynamically, the foehn is associated with a hydraulic jump.Hypothetical model simulations with modified terrain and with warmer MS surface temperature were conducted to reveal the relative contribution of each of these factors and of their synergism on the observed phenomena. The information provided by the factor separation study can be useful in future climate projections, when a warmer MS is expected.The forecasting feasibility of foehn and the sudden changes in the DS valley 24 hours in advance using WRF is suggested following the present study. These forecasts can be most valuable for the region affected by pollution penetration from the metropolitan coastal zone.

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Investigation of sea breeze and foehn in the Dead Sea valley with remote sensing observations and WRF model simulations

10.5194/egusphere-egu2020-1708 ◽

2020 ◽

Author(s):

Dorita Rostkier-Edelstein ◽

Pavel Kunin ◽

Pinhas Alpert

Keyword(s):

Remote Sensing ◽

High Resolution ◽

Mediterranean Sea ◽

Sea Breeze ◽

Dead Sea ◽

Modeling Tools ◽

Model Simulations ◽

Single Location ◽

The Mediterranean ◽

The Dead

The atmospheric dynamics in the Dead Sea Valley has been studied for decades. However, the studies relied mostly on surface observations and simple coarse-model simulations, insufficient to elucidate the complex flow in the area. In this seminar I will present a first study using high resolution (temporal and spatial) and sophisticate both, measurements and modeling tools. We focused on afternoon hours during summer time, when the Mediterranean Sea breeze penetrates into the Dead Sea Valley and sudden changes of wind, temperature and humidity occur in the valley.An intense observations period in the area, including ground-based remote sensing and in-situ observations, took place during August and November 2014. The measurements were conducted as part of the Virtual Institute DEad SEa Research Venue (DESERVE) project using the KITcube profiling instruments (wind lidars, radiometer and soundings) along with surface Energy Balance Station. These observations enabled analysis of the vertical profile of the atmosphere at one single location at the foothills of Masada, about 1 km west of the Dead Sea shore.High resolution (1.1 km grid size) model simulations were conducted using the Advanced Research Weather version of the Weather Forecast and Research mesoscale model (WRF). The simulations enabled analysis of the 3D flow at the Dead Sea Valley, information not provided by the observations at a single location. Sensitivity tests were run to determine the best model configuration for this study.Our study shows that foehn develops in the lee side of the Judean Mountains and Dead Sea Valley in the afternoon hours when the Mediterranean Sea breeze reaches the area. The characteristics of the Mediterranean Sea breeze penetration into the valley and of the foehn (e.g. their depth) and the impact they have on the boundary layer flow in the Dead Sea Valley (e.g. sudden changes in temperature, humidity and wind) are conditioned to the daily synoptic and mesosocale conditions. In the synoptic scale, the depth of the seasonal pressure trough at sea level and the height of inversion layers play a significant role in determining the breeze and foehn characteristics. In the mesoscale, the intensity of the Dead Sea breeze and the humidity brought by it determines the outcomes at the time of Mediterranean Sea breeze penetration and foehn development. Dynamically, the foehn is associated with a hydraulic jump.Hypothetical model simulations with modified terrain and with warmer Mediterranean Sea surface temperature were conducted to reveal the relative contribution of each of these factors and of their synergism on the observed phenomena. The information provided by the factor separation study can be useful in future climate projections, when a warmer Mediterranean Sea is expected.The forecasting feasibility of foehn and the sudden changes in the Dead Sea valley 24 hours in advance using WRF is suggested following the present study. These forecasts can be most valuable for the region affected by pollution penetration from the metropolitan coastal zone.

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Bathymetry and uplift rate of the Gulf of Aqaba, Dead Sea Fault.

10.5194/egusphere-egu21-10905 ◽

2021 ◽

Author(s):

Matthieu Ribot ◽

Yann Klinger ◽

Edwige Pons-Branchu ◽

Marthe Lefevre ◽

Sigurjón Jónsson

Keyword(s):

High Resolution ◽

Tectonic Evolution ◽

Active Faults ◽

Major Change ◽

Dead Sea ◽

Fault System ◽

Arabian Plate ◽

Gulf Of Aqaba ◽

Uplift Rate ◽

The Dead

Initially described in the late 50&#8217;s, the Dead Sea Fault system connects at its southern end to the Red Sea extensive system, through a succession of left-stepping faults. In this region, the left-lateral differential displacement of the Arabian plate with respect to the Sinai micro-plate along the Dead Sea fault results in the formation of a depression corresponding to the Gulf Aqaba. We acquired new bathymetric data in the areas of the Gulf of Aqaba and Strait of Tiran during two marine campaigns (June 2018, September 2019) in order to investigate the location of the active faults, which structure and control the morphology of the area. The high-resolution datasets (10-m posting) allow us to present a new fault map of the gulf and to discuss the seismic potential of the main active faults.We also investigated the eastern margin of the Gulf of Aqaba and Tiran island to assess the vertical uplift rate. To do so, we computed high-resolution topographic data and we processed new series of U-Th analyses on corals from the uplifted marine terraces.Combining our results with previous studies, we determined the local and the regional uplift in the area of the Gulf of Aqaba and Strait of Tiran.Eventually, we discussed the tectonic evolution of the gulf since the last major change of the tectonic regime and we propose a revised tectonic evolution model of the area.&#160;

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An assessment of the Dead Sea level change using remotely sensed data

10.5194/egusphere-egu21-12906 ◽

2021 ◽

Author(s):

Musab Mbideen ◽

Balázs Székely

Keyword(s):

Remote Sensing ◽

Water Level ◽

Surface Area ◽

Dead Sea ◽

Spectral Radiance ◽

Water Volume ◽

Surface Model ◽

Atmospheric Effects ◽

Level 1 ◽

The Dead

Remote Sensing (RS) and Geographic Information System (GIS) instruments have spread rapidly in recent years to manage natural resources and monitor environmental changes. Remote sensing has a vast range of applications; one of them is lakes monitoring. The Dead Sea (DS) is subjected to very strong evaporation processes, leading to a remarkable shrinkage of its water level. The DS is being dried out due to a negative balance in its hydrological cycle during the last five decades. This research aims to study the spatial changes in the DS throughout the previous 48 years. Change detection technique has been performed to detect this change over the research period (1972-2020). 73 Landsat imageries have been used from four digital sensors; Landsat&#160;1-5 MSS C1 Level-1, Landsat&#160;4-5 TM C1 Level-1, Land&#160;sat&#160;7&#160;ETM+ C1 &#160;Level-1, and Landsat&#160;8 OLI-TIRS C1 Level. After following certain selection criteria , the number of studied images decreased. Furthermore, the Digital Surface Model of the Space Shuttle Radar Topography Mission and a bathymetric map of the Dead Sea were used. The collected satellite imageries were pre-processed and normalized using ENVI 5.3 software by converting the Digital Number (DN) to spectral radiance, the spectral radiance was converted to apparent reflectance, atmospheric effects were removed, and finally, the black gaps were removed. It was important to distinguish between the DS lake and the surrounding area in order to have accurate results, this was done by performing classification techniques. The digital terrain model of the DS was used in ArcGIS (3D) to reconstruct the elevation of the shore lines. This model generated equations to detect the water level, surface area, and water volume of the DS. The results were compared to the bathymetric data as well. The research shows that the DS water level declined 65&#160;m (1.35&#160;m/a) in the studied period. The surface area and the water volume declined by 363.56&#160;km2 (7.57&#160;km2/a) and 53.56&#160;km3 (1.11&#160;km3/a), respectively. The research also concluded that due to the bathymetry of the DS, the direction of this shrinkage is from the south to the north. We hypothesize that anthropogenic effects have contributed in the shrinkage of the DS more than the climate. The use of the DS water by both Israel and Jordan for industrial purposes is the main factor impacting the DS, another factor is the diversion of the Jordan and Yarmouk rivers. Our results also allow to give a prediction for the near future of the DS: the water level is expected to reach &#8211;445&#160;m in 2050, while the surface area and the water volume is expected to be 455&#160;km2 and 142&#160;km3, respectively.&#160;

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Efficient Patch-Wise Semantic Segmentation for Large-Scale Remote Sensing Images

Sensors ◽

10.3390/s18103232 ◽

2018 ◽

Vol 18 (10) ◽

pp. 3232 ◽

Cited By ~ 17

Author(s):

Yan Liu ◽

Qirui Ren ◽

Jiahui Geng ◽

Meng Ding ◽

Jiangyun Li

Keyword(s):

Remote Sensing ◽

High Resolution ◽

Large Scale ◽

Semantic Segmentation ◽

Remote Sensing Image ◽

Training Data ◽

Land Resources ◽

Remote Sensing Images ◽

Training Strategy ◽

The Impact

Efficient and accurate semantic segmentation is the key technique for automatic remote sensing image analysis. While there have been many segmentation methods based on traditional hand-craft feature extractors, it is still challenging to process high-resolution and large-scale remote sensing images. In this work, a novel patch-wise semantic segmentation method with a new training strategy based on fully convolutional networks is presented to segment common land resources. First, to handle the high-resolution image, the images are split as local patches and then a patch-wise network is built. Second, training data is preprocessed in several ways to meet the specific characteristics of remote sensing images, i.e., color imbalance, object rotation variations and lens distortion. Third, a multi-scale training strategy is developed to solve the severe scale variation problem. In addition, the impact of conditional random field (CRF) is studied to improve the precision. The proposed method was evaluated on a dataset collected from a capital city in West China with the Gaofen-2 satellite. The dataset contains ten common land resources (Grassland, Road, etc.). The experimental results show that the proposed algorithm achieves 54.96% in terms of mean intersection over union (MIoU) and outperforms other state-of-the-art methods in remote sensing image segmentation.

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An example of aerosol pattern variability over bright surface using high resolution MODIS MAIAC: The eastern and western areas of the Dead Sea and environs

Atmospheric Environment ◽

10.1016/j.atmosenv.2017.06.047 ◽

2017 ◽

Vol 165 ◽

pp. 359-369 ◽

Cited By ~ 9

Author(s):

Lee Sever ◽

Pinhas Alpert ◽

Alexei Lyapustin ◽

Yujie Wang ◽

Alexandra Chudnovsky

Keyword(s):

High Resolution ◽

Dead Sea ◽

Bright Surface ◽

The Dead ◽

Pattern Variability

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Near East Desertification: impact of Dead Sea drying on convective rainfall

10.5194/acp-2019-544 ◽

2019 ◽

Author(s):

Samiro Khodayar ◽

Johannes Hoerner

Keyword(s):

Lake Level ◽

Weather Prediction ◽

Regional Climate ◽

Atmospheric Stability ◽

Lower Boundary ◽

Heavy Precipitation ◽

Dead Sea ◽

Decadal Scale ◽

The Dead ◽

The Impact

Abstract. The Dead Sea desertification-threatened region is affected by continual lake level decline and occasional, but life-endangering flash-floods. Climate change has aggravated such issues in the past decades. In this study, the impact of the Dead Sea drying on the severe convection generating heavy precipitation in the region is investigated. Perturbation simulations with the high-resolution convection-permitting regional climate model COSMO-CLM and several numerical weather prediction (NWP) runs on an event time scale are performed over the Dead Sea area. A reference simulation covering the 2003 to 2013 period and a twin sensitivity experiment, in which the Dead Sea is dried out and set to bare soil, are compared. NWP simulations focus on heavy precipitation events exhibiting relevant differences between the reference and the sensitivity decadal realization to assess the impact on the underlying convection-related processes. On a decadal scale, the difference between the simulations points out that in future regional climate, under ongoing lake level decline, a decrease in evaporation, higher air temperatures and less precipitation is to expect. Particularly, an increase in the number of dry days and in the intensity of heavy precipitation is foreseen. The drying of the Dead Sea is seen to affect the atmospheric conditions leading to convection in two ways: (a) the local decrease in evaporation reduces moisture availability in the lower boundary layer locally and in the neighbouring, directly affecting atmospheric stability. Weaker updrafts characterize the drier and more stable atmosphere of the simulations where the Dead Sea has been dried out. (b) Thermally driven wind system circulations and resulting divergence/convergence fields are altered preventing in many occasions convection initiation because of the omission of convergence lines.

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Seasonal dynamics of internal waves governed by stratification stability and wind: Analysis of high‐resolution observations from the Dead Sea

Limnology and Oceanography ◽

10.1002/lno.11156 ◽

2019 ◽

Vol 64 (5) ◽

pp. 1864-1882 ◽

Cited By ~ 2

Author(s):

Ali Arnon ◽

Steve Brenner ◽

John S. Selker ◽

Isaac Gertman ◽

Nadav G. Lensky

Keyword(s):

High Resolution ◽

Internal Waves ◽

Seasonal Dynamics ◽

Dead Sea ◽

Wind Analysis ◽

The Dead

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Effects of high spatial and temporal resolution Earth observations on simulated hydrometeorological variables in a cropland (southwestern France)

Hydrology and Earth System Sciences ◽

10.5194/hess-21-5693-2017 ◽

2017 ◽

Vol 21 (11) ◽

pp. 5693-5708 ◽

Cited By ~ 3

Author(s):

Jordi Etchanchu ◽

Vincent Rivalland ◽

Simon Gascoin ◽

Jérôme Cros ◽

Tiphaine Tallec ◽

...

Keyword(s):

Remote Sensing ◽

High Resolution ◽

Land Surface ◽

Agricultural Landscapes ◽

Surface Model ◽

Spatial And Temporal Variability ◽

Area Index ◽

The Impact ◽

Sentinel 2

Abstract. Agricultural landscapes are often constituted by a patchwork of crop fields whose seasonal evolution is dependent on specific crop rotation patterns and phenologies. This temporal and spatial heterogeneity affects surface hydrometeorological processes and must be taken into account in simulations of land surface and distributed hydrological models. The Sentinel-2 mission allows for the monitoring of land cover and vegetation dynamics at unprecedented spatial resolutions and revisit frequencies (20 m and 5 days, respectively) that are fully compatible with such heterogeneous agricultural landscapes. Here, we evaluate the impact of Sentinel-2-like remote sensing data on the simulation of surface water and energy fluxes via the Interactions between the Surface Biosphere Atmosphere (ISBA) land surface model included in the EXternalized SURface (SURFEX) modeling platform. The study focuses on the effect of the leaf area index (LAI) spatial and temporal variability on these fluxes. We compare the use of the LAI climatology from ECOCLIMAP-II, used by default in SURFEX-ISBA, and time series of LAI derived from the high-resolution Formosat-2 satellite data (8 m). The study area is an agricultural zone in southwestern France covering 576 km2 (24 km  ×  24 km). An innovative plot-scale approach is used, in which each computational unit has a homogeneous vegetation type. Evaluation of the simulations quality is done by comparing model outputs with in situ eddy covariance measurements of latent heat flux (LE). Our results show that the use of LAI derived from high-resolution remote sensing significantly improves simulated evapotranspiration with respect to ECOCLIMAP-II, especially when the surface is covered with summer crops. The comparison with in situ measurements shows an improvement of roughly 0.3 in the correlation coefficient and a decrease of around 30 % of the root mean square error (RMSE) in the simulated evapotranspiration. This finding is attributable to a better description of LAI evolution processes with Formosat-2 data, which further modify soil water content and drainage of soil reservoirs. Effects on annual drainage patterns remain small but significant, i.e., an increase roughly equivalent to 4 % of annual precipitation levels with simulations using Formosat-2 data in comparison to the reference simulation values. This study illustrates the potential for the Sentinel-2 mission to better represent effects of crop management on water budgeting for large, anthropized river basins.

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Projected climate change over Kuwait simulated using a WRF high resolution regional climate model

10.5194/egusphere-egu2020-1867 ◽

2020 ◽

Author(s):

Hussain Alsarraf

Keyword(s):

Climate Change ◽

High Resolution ◽

Regional Climate Model ◽

Arabian Peninsula ◽

Climate Model ◽

Regional Climate ◽

Dynamic Downscaling ◽

Model Simulations ◽

Average Maximum ◽

The Impact

The purpose of this study is to examine the impact of climate change on the changes on summer surface temperatures between present (2000-2010) and future (2050-2060) over the Arabian Peninsula and Kuwait. In this study, the influence of climate change in the Arabian Peninsula and especially in Kuwait was investigated by high resolution (36, 12, and 4 km grid spacing) dynamic downscaling from the Community Climate System Model CCSM4 using the WRF Weather Research and Forecasting model. The downscaling results were first validated by comparing National Centers for Environmental Prediction NCEP model outputs with the observational data. The global climate change dynamic downscaling model was run using WRF regional climate model simulations (2000-2010) and future projections (2050-2060). The influence of climate change in the Arabian Peninsula can be projected from the differences between the two period&#8217;s model simulations. The regional model simulations of the average maximum surface temperature in summertime predicted an increase from 1&#9702;C to 3 &#9702;C over the summertime in Kuwait by midcentury.&#160;

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Lake level changes in the Dead Sea during the late Pleistocene recorded by fossil lake shorelines

10.5194/egusphere-egu2020-5669 ◽

2020 ◽

Author(s):

Julius Jara-Muñoz ◽

Amotz Agnon ◽

Jens Fohlmeister ◽

Jürgen Mey ◽

Norbert Frank ◽

...

Keyword(s):

Carbon Isotopes ◽

Lake Level ◽

Late Quaternary ◽

Dead Sea ◽

Climatic Changes ◽

Balance Model ◽

Oxygen And Carbon Isotopes ◽

Lake Level Changes ◽

The Dead ◽

The Impact

High-resolution records of lake-level changes are crucial to elucidate the impact of local and global climatic changes in lacustrine basins. The Late Quaternary evolution of the Dead Sea has been characterized by substantial variability apparently linked with global climatic changes, beign subject of many research efforts since decades. Previous studies have defined two main lake phases, the Lake Lisan and the Dead Sea, the earlier was a highstand period that lasted between ~70 and ~15 ka, the&#160; latter was the lowstand period that persisted until the present. Here we focus on the switch between Lake Lisan and Dead Sea studying fossil lake shorelines, a sequence that comprises dozens of levels exposed along the rims of the Dead Sea, containing abundant fossil stromatolites that we dated by mean of radiocarbon and U-decay series. We determined 90 radiocarbon and 35 U-Th ages from stromatolites from almost every shoreline level. We compared U-Th and radiocarbon ages to estimating a radiocarbon reservoir between 0.2 and 0.8 ka, used to correct the remaining radiocarbon ages before calibration. The resulting ages range between ~45 &#160;and ~20 ka. Dating was complemented with analysis of stable oxygen and carbon isotopes. Furthermore, we applied a distributed hydrological balance model to constrain past precipitation and temperature conditions. Our results suggest that the duration of the last Lake Lisan highstand was shorter than previously estimated. Taking this at face value, the switch between Lake Lisan and Dead Sea occurred at ~28 ka, ~10 ka earlier than previously suggested. Oxygen and carbon isotopes show a consistent pattern, displaying a switch between wet and dry conditions at ~28 ka. Preliminary results from the hydrological model indicate a much stronger sensitivity of the lake level to precipitation amounts than to air temperature. From our results we can&#8217;t observe a clear link between global temperature variations and lake-level changes in the Lisan/Dead Sea lakes. Similar non-linear response to northern hemisphere climatic changes have been also documented in Holocene Dead Sea paleoclimatic records, suggesting that global climatic variations may led to variable lake-level responses. The results of this study adds further complexity to the understanding of factors controlling climate variability in the Dead Sea.

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