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 Modeling the response 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 ◽  
Precipitation Intensity ◽  
Annual Rainfall ◽  
Climate Scenarios ◽  
Moisture Condition ◽  
Soil Moisture Condition ◽  
Temperature And Precipitation ◽  
The Mediterranean ◽  
The Impact

Abstract. Future climate scenarios for the Mediterranean region indicate a possible decrease in annual precipitation associated with an intensification of extreme rainfall 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 impact of climate change on soil moisture since it is a proxy for agricultural droughts and the antecedent soil moisture condition plays a key role on runoff generation. This study focuses on 10 sites, located in Southern France, with available soil moisture, temperature, and precipitation observations on a 10 year time period. Soil moisture is simulated at each site at the hourly time step using a model of soil water content. The sensitivity of the simulated soil moisture to different changes in precipitation and temperature is evaluated by simulating the soil moisture response to temperature and precipitation scenarios 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. Overall, increased temperature and precipitation intensity associated with more intermittent precipitation leads to decreased soil moisture and an increase in the annual number of days with dry soil moisture conditions. In particular, a temperature increase of +4 °C combined with a decrease of annual rainfall between 10 and 20 %, corresponding to the current available climate scenarios for the Mediterranean, lead to a lengthening of the drought period from June to October 15 with in average +22 days of soil moisture drought per year.

scholarly journals Modeling the response of soil moisture to climate variability in the Mediterranean region

2021 ◽  
Vol 25 (2) ◽  
pp. 653-669
Author(s):  
Louise Mimeau ◽  
Yves Tramblay ◽  
Luca Brocca ◽  
Christian Massari ◽  
Stefania Camici ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Mediterranean Region ◽  
Precipitation Intensity ◽  
Annual Rainfall ◽  
Climate Scenarios ◽  
Moisture Condition ◽  
Soil Moisture Condition ◽  
Temperature And Precipitation ◽  
The Mediterranean ◽  
The Impact

Abstract. Future climate scenarios for the Mediterranean region indicate a possible decrease in annual precipitation associated with an intensification of extreme rainfall 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 impact of climate change on soil moisture since it is a proxy for agricultural droughts, and the antecedent soil moisture condition plays a key role on runoff generation. This study focuses on 10 sites, located in southern France, with available soil moisture, temperature, and precipitation observations for a 10-year time period. Soil moisture is simulated at each site at the hourly time step using a model of soil water content. The sensitivity of the simulated soil moisture to different changes in precipitation and temperature is evaluated by simulating the soil moisture response to temperature and precipitation scenarios generated using a delta change method for temperature and a stochastic model (the 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. Overall, increased temperature and precipitation intensity associated with more intermittent precipitation leads to decreased soil moisture and an increase in the annual number of days with dry soil moisture conditions. In particular, a temperature increase of +4 ∘C combined with a decrease of annual rainfall between 10 % and 20 %, corresponding to the current available climate scenarios for the Mediterranean, lead to a lengthening of the drought period from June to October with an average of +28 d of soil moisture drought per year.

scholarly journals Temperature and precipitation seasonal forecasts over the Mediterranean region: added value compared to simple forecasting methods

2021 ◽  
Author(s):  
Filippo Calì Quaglia ◽  
Silvia Terzago ◽  
Jost von Hardenberg
Keyword(s):  
Lead Time ◽  
Mediterranean Region ◽  
Added Value ◽  
Lead Times ◽  
Model Ensemble ◽  
Seasonal Forecasts ◽  
Anomaly Correlation ◽  
Temperature And Precipitation ◽  
Precipitation Anomalies ◽  
The Mediterranean

AbstractThis study considers a set of state-of-the-art seasonal forecasting systems (ECMWF, MF, UKMO, CMCC, DWD and the corresponding multi-model ensemble) and quantifies their added value (if any) in predicting seasonal and monthly temperature and precipitation anomalies over the Mediterranean region compared to a simple forecasting method based on the ERA5 climatology (CTRL) or the persistence of the ERA5 anomaly (PERS). This analysis considers two starting dates, May 1st and November 1st and the forecasts at lead times up to 6 months for each year in the period 1993–2014. Both deterministic and probabilistic metrics are employed to derive comprehensive information on the forecast quality in terms of association, reliability/resolution, discrimination, accuracy and sharpness. We find that temperature anomalies are better reproduced than precipitation anomalies with varying spatial patterns across different forecast systems. The Multi-Model Ensemble (MME) shows the best agreement in terms of anomaly correlation with ERA5 precipitation, while PERS provides the best results in terms of anomaly correlation with ERA5 temperature. Individual forecast systems and MME outperform CTRL in terms of accuracy of tercile-based forecasts up to lead time 5 months and in terms of discrimination up to lead time 2 months. All seasonal forecast systems also outperform elementary forecasts based on persistence in terms of accuracy and sharpness.

Revisiting Cyclone Detection and Tracking Methods using ECMWF ERA5 dataset for climatological purposes in the Mediterranean Region

2020 ◽  
Author(s):  
Leonardo Aragão ◽  
Federico Porcù
Keyword(s):  
Data Model ◽  
Mediterranean Region ◽  
Cyclone Track ◽  
Time Step ◽  
Interesting Point ◽  
Detection And Tracking ◽  
Full Resolution ◽  
The Mediterranean ◽  
Tracking Point ◽  
Cyclone Frequency

<p>The main target of this study is to evaluate the Cyclone Detection and Tracking Methods (CDTM) using the ECMWF ERA5 dataset, state-of-the-art in reanalysis models, to identify the main cyclogenesis zones and cyclone tracks inside the Mediterranean region during a climatological period. Several studies based on ECMWF analysis and reanalysis (ERA40 and ERA Interim) datasets indicate a large divergence related to the average number of cyclones passing through the Mediterranean region by year. However, the majority agrees on the most important cyclogenesis areas, seasonality variation of the number of cyclones, and trends of cyclone track. In general, the differences between those methodologies concerns to the meteorological variable used to detect cyclones and the metric used to define its intensity. Nevertheless, spatial and temporal resolutions were fundamental to achieve the results, since the most advanced dataset used in the literature presented relatively low values ​​such as 1.125°x1.125° and 6h, respectively. Past studies reported that these values ​​were already high enough to produce numerical noises. Here, the geopotential height at 1000 hPa (Z1000) was used, with horizontal spatial resolution of 0.25°x0.25° and time resolution of 1h, to identify the local minima for each time step (hereafter, candidates), and filtering those with negative gradients of Z1000 within a radius of 1000 km to exclude candidates associated with thermal lows or geopotential troughs.<br>Following the literature, the domain for Mediterranean region was defined by the area within 9°W to 42°E, and 27°N to 48°N, where were considered only cyclones with at least one tracking point inside the domain. Also, the results were produced for the period 1979-2008 using two types of input data: (Model I) ERA5 data with resolutions reduced to 1.5°x1.5° and 6h, as well as the main previous studies; and (Model II) full-resolution ERA5 data. As expected, Model I results were very similar to those found in the literature in all aspects (number of cyclones, seasonal distribution, areas of cyclogenesis and tracks). On the other hand, since the use of higher resolution data provides greater spatiotemporal detailing of the climatological period, the results of Model II presented a total number of cyclones substantially higher than that of Model I (~25%), but still within the range described in the literature. The models indicated more frequent cyclones during the spring months with maximums in April (Model I) and May (Model II). An interesting point highlighted in other studies but not observed in their results, is an increase in cyclone frequency between August and October, captured in both Models I and II and more evident in Model II. An explanation is found in the greater number of short-life cyclones, which act in relatively narrow areas intangible to datasets with limited resolution.</p>

scholarly journals A high space-time resolution dataset linking meteorological forcing and hydro-sedimentary response in a mesoscale Mediterranean catchment (Auzon) of the Ardèche region, France

2016 ◽  
Author(s):  
Guillaume Nord ◽  
Brice Boudevillain ◽  
Alexis Berne ◽  
Flora Branger ◽  
Isabelle Braud ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Time Resolution ◽  
Suspended Solids ◽  
Space Time ◽  
Surface Hydrology ◽  
Time Step ◽  
Rain Gauges ◽  
The Mediterranean ◽  
High Space ◽  
Observation Period

Abstract. A comprehensive hydrometeorological dataset is presented spanning the period 1 January 2011–31 December 2014 to improve the understanding of the hydrological processes leading to flash floods and the relation between rainfall, runoff, erosion and sediment transport in a mesoscale catchment (Auzon, 116 km2) of the Mediterranean region. Badlands are present in the Auzon catchment and well connected to high gradient channels of bedrock rivers which promotes the transfer of suspended solids downstream. The specificity of the dataset is its high space-time resolution, especially concerning rainfall and the hydrological response which is particularly adapted to the highly spatially variable rainfall events that may occur in this region. This type of dataset is rare in scientific literature because of the quantity and type of sensors for meteorology and surface hydrology. Rainfall data include continuous precipitation measured by rain gauges (5 min time step for the research network of 21 rain gauges and 5 min or 1 h time step for the operational network of 10 rain gauges), S-band Doppler dual-polarization radars (1 km2, 5 min resolution), disdrometers (16 sensors working at 30 s or 1 min time step) and Micro Rain Radars (5 sensors, 100 m height resolution). Additionally, during the special observation period (SOP-1) and enhanced observation period (Sep–Dec 2012, Sep–Dec 2013) of the HyMeX (Hydrological Cycle in the Mediterranean Experiment) project, two X-band radars provided precipitation measurements at very fine spatial and temporal scales (1 ha, 5 min). Meteorological data are taken from the operational surface weather observation stations of Météo-France (including 2-m air temperature, atmospheric pressure, 2-m relative humidity, 10-m wind speed and direction, global radiation) at the hourly time resolution (6 stations in the region of interest). The monitoring of surface hydrology and suspended sediment is multi-scale and based on nested catchments. Three hydrometric stations measure water discharge at a 2 to 10 min time resolution. Two of these stations also measure additional physico-chemical variables (turbidity, temperature, conductivity) and water samples are collected automatically during floods allowing further geochemical characterization of water and suspended solids. Two experimental plots monitor overland flow and erosion at 1 min time resolution on a hillslope with vineyard. A network of 11 sensors installed in the intermittent hydrographic network continuously measures water level and water temperature in headwater subcatchments (from 0.17 km2 to 116 km2) at a time resolution of 2–5 min. A network of soil moisture sensors enable the continuous measurement of soil volumetric water content at 20 min time resolution at 9 sites. Additionally, opportunistic observations (soil moisture measurements and stream gauging) were performed during floods between 2012 and 2014. The data are appropriate for understanding the rainfall variability in time and space at fine scales, improving areal rainfall estimations and progressing in distributed hydrological and erosion modelling. DOI of the referenced dataset: dx.doi.org/10.6096/MISTRALS-HyMeX.1438

scholarly journals Investigating Decadal Changes of Multiple Hydrological Products and Land-Cover Changes in the Mediterranean Region for 2009–2018

2021 ◽  
Author(s):  
Wenzhao Li ◽  
Sachi Perera ◽  
Erik Linstead ◽  
Rejoice Thomas ◽  
Hesham El-Askary ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Land Cover ◽  
Mediterranean Region ◽  
Vegetation Index ◽  
Surface Soil ◽  
The North ◽  
Land Data Assimilation ◽  
The Mediterranean ◽  
Land Data Assimilation System ◽  
Data Assimilation System

AbstractLand-cover change is a critical concern due to its climatic, ecological, and socioeconomic consequences. In this study, we used multiple variables including precipitation, vegetation index, surface soil moisture, and evapotranspiration obtained from different satellite sources to study their association with land-cover changes in the Mediterranean region. Both observational and modeling data were used for climatology and correlation analysis. Famine Early Warning Systems Network (FEWS NET) Land Data Assimilation System (FLDAS) and Global Land Data Assimilation System (GLDAS) were used to extract surface soil moisture and evapotranspiration data. Intercomparing the results of FLDAS and GLDAS suggested that FLDAS data had better accuracy compared to GLDAS for its better coherence with observational data. Climate Hazards Group Infra-Red Precipitation with Station Data (version 2.0 final) (CHIRPS Pentad) were used to extract precipitation data while Moderate Resolution Imaging Spectroradiometer (MODIS) products were used to extract the vegetation indices used in this study. The land-cover change detection was demonstrated during the 2009–2018 period using MODIS Land-Cover data. Some of the barren and crop lands in Euphrates-Tigris and Algeria have converted to low-vegetated shrublands over the time, while shrublands and barren areas in Egypt’s southwestern Delta region became grasslands. These observations were well explained by changing trends of hydrological variables which showed that precipitation and soil moisture had higher values in the countries located to the east of the Mediterranean region compared to the ones on the west. For evapotranspiration, the countries in the north had lower values except for countries in Europe such as Bosnia, Romania, Slovenia, and countries in Africa such as Egypt and Libya. The enhanced vegetation index appeared to be decreasing from north to south, with countries in the north such as Germany, Romania, and Czechia having higher values, while countries in the south such as Libya, Egypt, and Iraq having lower trends. Time series analysis for selected countries was also done to understand the change in hydrological parameters, including Enhanced Vegetation Index, evapotranspiration, and soil moisture, which showed alternating drop and rise as well as stagnant values for different parameters in each country.

scholarly journals A high space–time resolution dataset linking meteorological forcing and hydro-sedimentary response in a mesoscale Mediterranean catchment (Auzon) of the Ardèche region, France

2017 ◽  
Vol 9 (1) ◽  
pp. 221-249 ◽  
Author(s):  
Guillaume Nord ◽  
Brice Boudevillain ◽  
Alexis Berne ◽  
Flora Branger ◽  
Isabelle Braud ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Time Resolution ◽  
Suspended Solids ◽  
Space Time ◽  
Research Network ◽  
Observation System ◽  
Surface Hydrology ◽  
Time Step ◽  
Rain Gauges ◽  
The Mediterranean

Abstract. A comprehensive hydrometeorological dataset is presented spanning the period 1 January 2011–31 December 2014 to improve the understanding of the hydrological processes leading to flash floods and the relation between rainfall, runoff, erosion and sediment transport in a mesoscale catchment (Auzon, 116 km2) of the Mediterranean region. Badlands are present in the Auzon catchment and well connected to high-gradient channels of bedrock rivers which promotes the transfer of suspended solids downstream. The number of observed variables, the various sensors involved (both in situ and remote) and the space–time resolution ( ∼  km2,  ∼  min) of this comprehensive dataset make it a unique contribution to research communities focused on hydrometeorology, surface hydrology and erosion. Given that rainfall is highly variable in space and time in this region, the observation system enables assessment of the hydrological response to rainfall fields. Indeed, (i) rainfall data are provided by rain gauges (both a research network of 21 rain gauges with a 5 min time step and an operational network of 10 rain gauges with a 5 min or 1 h time step), S-band Doppler dual-polarization radars (1 km2, 5 min resolution), disdrometers (16 sensors working at 30 s or 1 min time step) and Micro Rain Radars (5 sensors, 100 m height resolution). Additionally, during the special observation period (SOP-1) of the HyMeX (Hydrological Cycle in the Mediterranean Experiment) project, two X-band radars provided precipitation measurements at very fine spatial and temporal scales (1 ha, 5 min). (ii) Other meteorological data are taken from the operational surface weather observation stations of Météo-France (including 2 m air temperature, atmospheric pressure, 2 m relative humidity, 10 m wind speed and direction, global radiation) at the hourly time resolution (six stations in the region of interest). (iii) The monitoring of surface hydrology and suspended sediment is multi-scale and based on nested catchments. Three hydrometric stations estimate water discharge at a 2–10 min time resolution. Two of these stations also measure additional physico-chemical variables (turbidity, temperature, conductivity) and water samples are collected automatically during floods, allowing further geochemical characterization of water and suspended solids. Two experimental plots monitor overland flow and erosion at 1 min time resolution on a hillslope with vineyard. A network of 11 sensors installed in the intermittent hydrographic network continuously measures water level and water temperature in headwater subcatchments (from 0.17 to 116 km2) at a time resolution of 2–5 min. A network of soil moisture sensors enables the continuous measurement of soil volumetric water content at 20 min time resolution at 9 sites. Additionally, concomitant observations (soil moisture measurements and stream gauging) were performed during floods between 2012 and 2014. Finally, this dataset is considered appropriate for understanding the rainfall variability in time and space at fine scales, improving areal rainfall estimations and progressing in distributed hydrological and erosion modelling. DOI of the referenced dataset: doi:10.6096/MISTRALS-HyMeX.1438.

scholarly journals A multi-model, multi-scenario, and multi-domain analysis of regional climate projections for the Mediterranean

2019 ◽  
Vol 19 (8) ◽  
pp. 2621-2635 ◽  
Author(s):  
George Zittis ◽  
Panos Hadjinicolaou ◽  
Marina Klangidou ◽  
Yiannis Proestos ◽  
Jos Lelieveld
Keyword(s):  
Climate Change ◽  
Regional Climate Model ◽  
Mediterranean Region ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Change Signal ◽  
Climate Projections ◽  
Temperature And Precipitation ◽  
The Mediterranean ◽  
Projected Changes

AbstractObservation and model-based studies have identified the Mediterranean region as one of the most prominent climate change “hot-spots.” Parts of this distinctive region are included in several Coordinated Regional Downscaling Experiment (CORDEX) domains such as those for Europe, Africa, the Mediterranean, and the Middle East/North Africa. In this study, we compile and analyze monthly temperature and precipitation fields derived from regional climate model simulations performed over different CORDEX domains at a spatial resolution of 50 km. This unique multi-model, multi-scenario, and multi-domain “super-ensemble” is used to update projected changes for the Mediterranean region. The statistical robustness and significance of the climate change signal is assessed. By considering information from more than one CORDEX domains, our analysis addresses an additional type of uncertainty that is often neglected and is related to the positioning of the regional climate model domain. CORDEX simulations suggest a general warming by the end of the century (between 1 and 5 °C with respect to the 1986–2005 reference period), which is expected to be strongest during summer (up to 7 °C). A general drying (between 10 and 40%) is also inferred for the Mediterranean. However, the projected precipitation change signal is less significant and less robust. The CORDEX ensemble corroborates the fact that the Mediterranean is already entering the 1.5 °C climate warming era. It is expected to reach 2 °C warming well within two decades, unless strong greenhouse gas concentration reductions are implemented. The southern part of the Mediterranean is expected to be impacted most strongly since the CORDEX ensemble suggests substantial combined warming and drying, particularly for pathways RCP4.5 and RCP8.5.

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.

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