scholarly journals Hot European Summers and the Role of Soil Moisture in the Propagation of Mediterranean Drought

2009 ◽  
Vol 22 (18) ◽  
pp. 4747-4758 ◽  
Author(s):  
Matteo Zampieri ◽  
Fabio D’Andrea ◽  
Robert Vautard ◽  
Philippe Ciais ◽  
Nathalie de Noblet-Ducoudré ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Mediterranean Region ◽  
Large Scale ◽  
Mesoscale Model ◽  
Early Summer ◽  
Atmospheric Conditions ◽  
Evaporative Demand ◽  
European Continent ◽  
Mediterranean Regions ◽  
The Mediterranean

Abstract Drought in spring and early summer has been shown to precede anomalous hot summer temperature. In particular, drought in the Mediterranean region has been recently shown to precede and to contribute to the development of extreme heat in continental Europe. In this paper, this mechanism is investigated by performing integrations of a regional mesoscale model at the scale of the European continent in order to reproduce hot summer inception, starting with different initial values of soil moisture south of 46°N. The mesoscale model is driven by the large-scale atmospheric conditions corresponding to the 10 hottest summers on record from the European Climate Assessment dataset. A northward progression of heat and drought from late spring to summer is observed from the Mediterranean regions, which leads to a further increase of temperature during summer in temperate continental Europe. Dry air formed over dry soils in the Mediterranean region induces less convection and diminished cloudiness, which gets transported northward by occasional southerly wind, increasing northward temperature and vegetation evaporative demand. Later in the season, drier soils have been established in western and central Europe where they further amplify the warming through two main feedback mechanisms: 1) higher sensible heat emissions and 2) favored upper-air anticyclonic circulation. Drier soils in southern Europe accelerate the northward propagation of heat and drying, increasing the probability of strong heat wave episodes in the middle or the end of the summer.

Investigation of the Climate Change Effects on the Mediterranean Region with the Hypothetical inclusion of the Istanbul Isthmus

2020 ◽  
Author(s):  
Elcin Tan
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Mediterranean Region ◽  
Climate Model ◽  
Wrf Model ◽  
Ocean Model ◽  
Atmospheric Conditions ◽  
Sea Level Changes ◽  
The Mediterranean ◽  
The Impact

<p>A debate on the probable Istanbul Isthmus Project that may have catastrophic impacts on our ecosystem has been recently accelerated in public, due to the fact that the approved environmental impact assessment (EIA) report of the hypothetical Istanbul Isthmus (HII) Project has recently been announced. The EIA report indicates that the assessment covers only the current conditions and the conditions that may arise during the construction of the HII. Unfortunately, The EIA report did not evaluate the climate change impact on either the Istanbul Area or Mediterranean Region after the inclusion of the HII, only the current conditions were evaluated. Therefore, the aim of this study is to investigate the impact of HII on the climate of the Mediterranean Region. The climate version of the WRF Model is utilized with 9 km resolution for the Region 12: Mediterranean (CORDEX) for the historical conditions and RCP8.5 scenarios of available climate model results from CMIP5 and CMIP6 projects. Land surface and land use maps are prepared by following the EIA report if the necessary information is included, otherwise, the current conditions are applied. The atmospheric conditions were not coupled to an Ocean Model, only the Sea Surface Temperature (SST) values of the Ocean Models are coupled to the WRF model during both historical and future simulations. The model results are evaluated in terms of temperature, precipitation, and sea-level changes. Consequently, the results indicate that the HII may decrease the resilience of the Mediterranean Region to Climate Change.</p>

Seasonal and diurnal trends of heat pulse velocity in Douglas-fir and ponderosa pine

1986 ◽  
Vol 16 (4) ◽  
pp. 814-821 ◽  
Author(s):  
W. Lopushinsky
Keyword(s):  
Soil Moisture ◽  
Ponderosa Pine ◽  
Heat Pulse ◽  
Pulse Velocity ◽  
Early Summer ◽  
Douglas Fir ◽  
Evaporative Demand ◽  
Maximum Heat ◽  
Weather Patterns ◽  
Summer Maximum

Seasonal trends of heat pulse velocity in the trunks of 55-year-old ponderosa pine (Pinusponderosa Dougl. ex Laws.) and Douglas-fir (Pseudotsugamenziesii var. glauca (Beissn.) Franco) trees showed large yearly variations related to weather patterns. Onset of sap movement in the spring, seasonal variations, and summer declines in response to decreasing moisture were similar for Douglas-fir and ponderosa pine. When soil moisture was not limiting, rates of heat pulse velocity in both species were significantly related to air temperature, solar radiation, and vapor pressure deficit. As soil moisture decreased during the summer, rates of heat pulse velocity no longer followed evaporative demand. In both species, sap movement also occurred at night. Diurnal trends of heat pulse velocity also were similar in both species. During early summer, maximum heat pulse velocity occurred at midday; in the fall, maximum rates occurred earlier. The similarity of seasonal and diurnal trends of heat pulse velocity and responses to variation in site conditions suggest that on the site studied, transpiration behavior in ponderosa pine and Douglas-fir trees generally is similar.

scholarly journals Comparison between the Large-Scale Environments of Moderate and Intense Precipitating Systems in the Mediterranean Region

2009 ◽  
Vol 137 (11) ◽  
pp. 3933-3959 ◽  
Author(s):  
Beatriz M. Funatsu ◽  
Chantal Claud ◽  
Jean-Pierre Chaboureau
Keyword(s):  
Mediterranean Region ◽  
Large Scale ◽  
Deep Convection ◽  
Extreme Rainfall ◽  
Convective Precipitation ◽  
Target Area ◽  
Weather Forecasts ◽  
Microwave Sounding ◽  
The Mediterranean ◽  
Upper Level

Abstract A characterization of the large-scale environment associated with precipitating systems in the Mediterranean region, based mainly on NOAA-16 Advanced Microwave Sounding Unit (AMSU) observations from 2001 to 2007, is presented. Channels 5, 7, and 8 of AMSU-A are used to identify upper-level features, while a simple and tractable method, based on combinations of channels 3–5 of AMSU-B and insensitive to land–sea contrast, was used to identify precipitation. Rain occurrence is widespread over the Mediterranean in wintertime while reduced or short lived in the eastern part of the basin in summer. The location of convective precipitation shifts from mostly over land from April to August, to mostly over the sea from September to December. A composite analysis depicting large-scale conditions, for cases of either rain alone or extensive areas of deep convection, is performed for selected locations where the occurrence of intense rainfall was found to be important. In both cases, an upper-level trough is seen to the west of the target area, but for extreme rainfall the trough is narrower and has larger amplitude in all seasons. In general, these troughs are also deeper for extreme rainfall. Based on the European Centre for Medium-Range Weather Forecasts operational analyses, it was found that sea surface temperature anomalies composites for extreme rainfall are often about 1 K warmer, compared to nonconvective precipitation conditions, in the vicinity of the affected area, and the wind speed at 850 hPa is also stronger and usually coming from the sea.

scholarly journals Precipitation climatology over Mediterranean Basin from ten years of TRMM measurements

2008 ◽  
Vol 17 ◽  
pp. 87-91 ◽  
Author(s):  
A. V. Mehta ◽  
S. Yang
Keyword(s):  
Mediterranean Sea ◽  
Rainy Season ◽  
Mediterranean Region ◽  
Large Scale ◽  
Eastern Mediterranean ◽  
Tropical Rainfall Measuring Mission ◽  
Western Mediterranean ◽  
Sea Temperature ◽  
Maximum Rainfall ◽  
The Mediterranean

Abstract. Climatological features of mesoscale rain activities over the Mediterranean region between 5° W–40° E and 28° N–48° N are examined using the Tropical Rainfall Measuring Mission (TRMM) 3B42 and 2A25 rain products. The 3B42 rainrates at 3-hourly, 0.25°×0.25° spatial resolution for the last 10 years (January 1998 to July 2007) are used to form and analyze the 5-day mean and monthly mean climatology of rainfall. Results show considerable regional and seasonal differences of rainfall over the Mediterranean Region. The maximum rainfall (3–5 mm day−1) occurs over the mountain regions of Europe, while the minimum rainfall is observed over North Africa (~0.5 mm day−1). The main rainy season over the Mediterranean Sea extends from October to March, with maximum rainfall occurring during November–December. Over the Mediterranean Sea, an average rainrate of ~1–2 mm day−1 is observed, but during the rainy season there is 20% larger rainfall over the western Mediterranean Sea than that over the eastern Mediterranean Sea. During the rainy season, mesoscale rain systems generally propagate from west to east and from north to south over the Mediterranean region, likely to be associated with Mediterranean cyclonic disturbances resulting from interactions among large-scale circulation, orography, and land-sea temperature contrast.

Sensitivity of soil moisture to climate variability in the Mediterranean region

2020 ◽  
Author(s):  
Louise Mimeau ◽  
Yves Tramblay ◽  
Luca Brocca ◽  
Christian Massari ◽  
Stefania Camici ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Mediterranean Region ◽  
Rectangular Pulse ◽  
Precipitation Intensity ◽  
Runoff Generation ◽  
Time Step ◽  
Temperature And Precipitation ◽  
The Mediterranean ◽  
Good Proxy ◽  
Response To Temperature

<p>Studies on future precipitation trends in the Mediterranean region show a possible decrease in annual precipitation amounts with an intensification of extreme events in the coming years. A major challenge in this region is to evaluate the impacts of changing precipitation patterns on extreme hydrological events such as droughts and floods. For this, it is important to understand the effects of changing temperature and precipitation on soil moisture since it is a good proxy for drought monitoring and it plays a key role on flood runoff generation. This study focuses on 11 sites located in the South of France, with soil moisture, temperature, and precipitation observations over a 10 year time period. Soil moisture is simulated at the hourly time step for each site using a soil moisture model based on the Green-Ampt infiltration scheme. The elasticity of the simulated soil moisture to different changes in precipitation and temperature is analyzed by simulating the soil moisture response to temperature and precipitation changes, generated using a delta change method for temperature and a stochastic model (Neyman-Scott rectangular pulse model) for precipitation. Results show that soil moisture is more impacted by changes in precipitation intermittence than precipitation intensity and temperature. Although there is variability in the soil moisture response to the considered forcing scenarios, increased temperature combined to increased precipitation intensity and intermittency leads to decreased median soil moisture and an increased number of dry days.</p>

scholarly journals An Analytical Model of Evaporation Efficiency for Unsaturated Soil Surfaces with an Arbitrary Thickness

2011 ◽  
Vol 50 (2) ◽  
pp. 457-471 ◽  
Author(s):  
Olivier Merlin ◽  
Ahmad Al Bitar ◽  
Vincent Rivalland ◽  
Pierre Béziat ◽  
Eric Ceschia ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Analytical Model ◽  
Land Surface ◽  
Soil Layer ◽  
Soil Evaporation ◽  
Atmospheric Conditions ◽  
Potential Evaporation ◽  
Evaporative Demand ◽  
Soil Layers ◽  
Arbitrary Thickness

Abstract Analytical expressions of evaporative efficiency over bare soil (defined as the ratio of actual to potential soil evaporation) have been limited to soil layers with a fixed depth and/or to specific atmospheric conditions. To fill the gap, a new analytical model is developed for arbitrary soil thicknesses and varying boundary layer conditions. The soil evaporative efficiency is written [0.5 − 0.5 cos(πθL/θmax)]P with θL being the water content in the soil layer of thickness L, θmax being the soil moisture at saturation, and P being a function of L and potential soil evaporation. This formulation predicts soil evaporative efficiency in both energy-driven and moisture-driven conditions, which correspond to P < 0.5 and P > 0.5, respectively. For P = 0.5, an equilibrium state is identified when retention forces in the soil compensate the evaporative demand above the soil surface. The approach is applied to in situ measurements of actual evaporation, potential evaporation, and soil moisture at five different depths (5, 10, 30, 60, and 100 cm) collected in summer at two sites in southwestern France. It is found that (i) soil evaporative efficiency cannot be considered as a function of soil moisture only because it also depends on potential evaporation, (ii) retention forces in the soil increase in reaction to an increase of potential evaporation, and (iii) the model is able to accurately predict the soil evaporation process for soil layers with an arbitrary thickness up to 100 cm. This new model representation is expected to facilitate the coupling of land surface models with multisensor (multisensing depth) remote sensing data.

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