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Land-atmosphere coupling can have a crucial impact on convective initiation. Yet, uncertainty remains in the analyses of the atmospheric segment of the coupling between land surface wetness and the triggering of deep moist convection, particularly over Europe. One reason for this is a lack of suitable data. To overcome this limitation, we perturb early-morning temperature and moisture profiles from a regional climate simulation covering the period 1986–2015 over Europe to create a spread in atmospheric conditions. Applying the ‘Convective Triggering Potential – low-level Humidity Index’ framework, we analyze whether and how strongly the coupling strength and the predominance of positive versus negative feedbacks are sensitive to modifications in the atmospheric conditions. The results show that the hotspot region in northeastern Europe, in which strong feedbacks are likely to occur, is insensitive to temperature and moisture changes, but the number of potential feedback days varies by up to 20 days per season in dependence of the atmospheric background conditions. Temperature modifications rather control differences in the coupling strength in the north of the domain, while moisture changes dominant the control in the south. In the north of the hotspot region, a predominance for positive feedbacks (deep convection over wet soils) remains, but a switch of the dominant feedback class between positive feedbacks and a transition zone (convection over any soil, but usually shallow convection) occurred from the Alps to around the Black Sea. This indicates a dependence of the dominant feedback class on temperature and relative humidity in this region.
Lisa Lea Jach; Thomas Schwitalla; Oliver Branch; Kirsten Warrach-Sagi; Volker Wulfmeyer. Sensitivity of land-atmosphere coupling strength to perturbations of early-morning temperature and moisture profiles in the European summer. 2021, 2021, 1 -32.
AMA StyleLisa Lea Jach, Thomas Schwitalla, Oliver Branch, Kirsten Warrach-Sagi, Volker Wulfmeyer. Sensitivity of land-atmosphere coupling strength to perturbations of early-morning temperature and moisture profiles in the European summer. . 2021; 2021 ():1-32.
Chicago/Turabian StyleLisa Lea Jach; Thomas Schwitalla; Oliver Branch; Kirsten Warrach-Sagi; Volker Wulfmeyer. 2021. "Sensitivity of land-atmosphere coupling strength to perturbations of early-morning temperature and moisture profiles in the European summer." 2021, no. : 1-32.
Effective numerical weather forecasting is vital in arid regions like the United Arab Emirates (UAE) where extreme events like heat waves, flash floods, and dust storms are severe. Hence, accurate forecasting of quantities like surface temperatures and humidity is very important. To date, there have been few seasonal-to-annual scale verification studies with WRF at high spatial and temporal resolution. This study employs a convection-permitting scale (2.7 km grid scale) simulation with WRF with Noah-MP, in daily forecast mode, from 1 January to 30 November 2015. WRF was verified using measurements of 2 m air temperature (T2 m), 2 m dew point (TD2 m), and 10 m wind speed (UV10 m) from 48 UAE WMO-compliant surface weather stations. Analysis was made of seasonal and diurnal performance within the desert, marine, and mountain regions of the UAE. Results show that WRF represents temperature (T2 m) quite adequately during the daytime with biases ≤+1 ∘C. There is, however, a nocturnal cold bias (−1 to −4 ∘C), which increases during hotter months in the desert and mountain regions. The marine region has the smallest T2 m biases (≤-0.75 ∘C). WRF performs well regarding TD2 m, with mean biases mostly ≤ 1 ∘C. TD2 m over the marine region is overestimated, though (0.75–1 ∘C), and nocturnal mountain TD2 m is underestimated (∼-2 ∘C). UV10 m performance on land still needs improvement, and biases can occasionally be large (1–2 m s−1). This performance tends to worsen during the hot months, particularly inland with peak biases reaching ∼ 3 m s−1. UV10 m is better simulated in the marine region (bias ≤ 1 m s−1). There is an apparent relationship between T2 m bias and UV10 m bias, which may indicate issues in simulation of the daytime sea breeze. TD2 m biases tend to be more independent. Studies such as these are vital for accurate assessment of WRF nowcasting performance and to identify model deficiencies. By combining sensitivity tests, process, and observational studies with seasonal verification, we can further improve forecasting systems for the UAE.
Oliver Branch; Thomas Schwitalla; Marouane Temimi; Ricardo Fonseca; Narendra Nelli; Michael Weston; Josipa Milovac; Volker Wulfmeyer. Seasonal and diurnal performance of daily forecasts with WRF V3.8.1 over the United Arab Emirates. Geoscientific Model Development 2021, 14, 1615 -1637.
AMA StyleOliver Branch, Thomas Schwitalla, Marouane Temimi, Ricardo Fonseca, Narendra Nelli, Michael Weston, Josipa Milovac, Volker Wulfmeyer. Seasonal and diurnal performance of daily forecasts with WRF V3.8.1 over the United Arab Emirates. Geoscientific Model Development. 2021; 14 (3):1615-1637.
Chicago/Turabian StyleOliver Branch; Thomas Schwitalla; Marouane Temimi; Ricardo Fonseca; Narendra Nelli; Michael Weston; Josipa Milovac; Volker Wulfmeyer. 2021. "Seasonal and diurnal performance of daily forecasts with WRF V3.8.1 over the United Arab Emirates." Geoscientific Model Development 14, no. 3: 1615-1637.
We present exciting Doppler lidar and cloud radar measurements from a high-vantage mountain observatory in the hyper-arid United Arab Emirates (UAE) - initiated as part of the UAE Research Program for Rain Enhancement Science (UAEREP). The observatory was designed to study the clear-air pre-convective environment and subsequent convective events in the arid Al Hajar Mountains, with the overarching goal of improving understanding and nowcasting of seedable orographic clouds. During summer in the Al Hajar Mountains (June to September), weather processes are often complex, with summer convection being initiated by several phenomena acting in concert, e.g., interaction between sea breeze and horizontal convective rolls. These interactions can combine to initiate sporadic convective storms and these can be intense enough to cause flash floods and erosion. Such events here are influenced by mesoscale phenomena like the low-level jet and local sea breeze, and are constrained by larger-scale synoptic conditions.
The Doppler lidar and cloud radar were employed for approximately two years at a high vantage-point to capture valley wind flows and observe convective cells. The instruments were configured to run synchronized polar (PPI) scans at 0°, 5°, and 45° elevation angles and vertical cross-section (RHI) scans at 0°, 30°, 60, 90°, 120°, and 150° azimuth angles. Using this imagery, along with local C-band radar and satellite data, we were able to identify and analyze several convective cases. To illustrate our results, we have selected two cases under unstable conditions - the 5 and 6 September 2018. In both cases, we observed areas of low-level convergence/divergence, particularly associated with wind flow around a peak 2 km to the south-west of the observatory. The extension of these deformations are visible in the atmosphere to a height of 3 km above sea level. Subsequently, we observed convective cells developing at those approximate locations – apparently initiated because of these phenomena. The cloud radar images provided detailed observations of cloud structure, evolution, and precipitation. In both convective cases, pre-convective signatures were apparent before CI, in the form of convergence, wind shear structures, and updrafts.
These results have demonstrated the value of synergetic observations for understanding orographic convection initiation, improvement of forecast models, and cloud seeding guidance. The manuscript based on these results is now the subject of a peer review (Branch et al., 2021).
Branch, O., Behrendt, Andreas Alnayef, O., Späth, F., Schwitalla, Thomas, Temimi, M., Weston, M., Farrah, S., Al Yazeedi, O., Tampi, S., Waal, K. de and Wulfmeyer, V.: The new Mountain Observatory of the Project “Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)” in the United Arab Emirates: First results on Convection Initiation, J. Geophys. Res. Atmos., 2021. In review (submitted 23.11.2020).
Oliver Branch; Andreas Behrendt; Osama Alnayef; Florian Späth; Thomas Schwitalla; Marouane Temimi; Michael Weston; Sufian Farrah; Omar Al Yazeedi; Siddharth Tampi; Karel de Waal; Volker Wulfmeyer. First Doppler lidar and cloud radar measurements of orographic convection initiation from a mountain observatory in the Al Hajar Mountains of the United Arab Emirates. 2021, 1 .
AMA StyleOliver Branch, Andreas Behrendt, Osama Alnayef, Florian Späth, Thomas Schwitalla, Marouane Temimi, Michael Weston, Sufian Farrah, Omar Al Yazeedi, Siddharth Tampi, Karel de Waal, Volker Wulfmeyer. First Doppler lidar and cloud radar measurements of orographic convection initiation from a mountain observatory in the Al Hajar Mountains of the United Arab Emirates. . 2021; ():1.
Chicago/Turabian StyleOliver Branch; Andreas Behrendt; Osama Alnayef; Florian Späth; Thomas Schwitalla; Marouane Temimi; Michael Weston; Sufian Farrah; Omar Al Yazeedi; Siddharth Tampi; Karel de Waal; Volker Wulfmeyer. 2021. "First Doppler lidar and cloud radar measurements of orographic convection initiation from a mountain observatory in the Al Hajar Mountains of the United Arab Emirates." , no. : 1.
In this study, we discuss a new mountain peak observatory in the United Arab Emirates (UAE). Using coordinated scan patterns, a Doppler lidar and cloud radar were employed to study seedable convective clouds, and identify pre-convection initiation (CI) clear-air signatures. The instruments were employed for approximately two years in an extreme environment with a high vantage point for observing valley wind flows and convective cells. The instruments were configured to run synchronized polar (PPI) scans at 0°, 5°, and 45° elevation angles and vertical cross-section (RHI) scans at 0°, 30°, 60, 90°, 120°, and 150° azimuth angles. Using this output imagery, along with local C-band radar and satellite data, we were able to identify and analyze several convective cases. To illustrate our results, we selected two cases in unstable conditions - the 5 and 6 September 2018. In both cases, we observed areas of convergence/divergence, particularly associated with wind flow around a peak 2 km to the south-west. The extension of these deformations were visible in the atmosphere as high as 3 km above sea level. Subsequently, we observed convective cells developing in the same directions – apparently connected with these phenomena. The cloud radar images provided detailed observations of cloud structure, evolution, and precipitation. In both convective cases, pre-convective signatures were apparent before CI, in the form of convergence, wind shear structures, and updrafts. These results demonstrate the value of synergetic observations for understanding convection initiation, improvement of forecast models, and cloud seeding guidance.
Oliver BranchiD; Andreas BehrendtiD; Osama Alnayef; Florian Späthid; Thomas Schwitalla; Maouane Temimi; Michael WestoniD; Sufian Farah; Karel De Waal; Siddharth Tampi; Omar Al YazeediiD; Volker Wulfmeyer. The new Mountain Observatory of the Project "Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)" in the United Arab Emirates: First results on Convection Initiation. 2020, 1 .
AMA StyleOliver BranchiD, Andreas BehrendtiD, Osama Alnayef, Florian Späthid, Thomas Schwitalla, Maouane Temimi, Michael WestoniD, Sufian Farah, Karel De Waal, Siddharth Tampi, Omar Al YazeediiD, Volker Wulfmeyer. The new Mountain Observatory of the Project "Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)" in the United Arab Emirates: First results on Convection Initiation. . 2020; ():1.
Chicago/Turabian StyleOliver BranchiD; Andreas BehrendtiD; Osama Alnayef; Florian Späthid; Thomas Schwitalla; Maouane Temimi; Michael WestoniD; Sufian Farah; Karel De Waal; Siddharth Tampi; Omar Al YazeediiD; Volker Wulfmeyer. 2020. "The new Mountain Observatory of the Project "Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)" in the United Arab Emirates: First results on Convection Initiation." , no. : 1.
Effective numerical weather forecasting is vital in arid regions like the United Arab Emirates (UAE) where extreme events like heat waves, flash floods and dust storms are severe. Hence, accurate forecasting of quantities like surface temperatures and humidity is very important. To date, there have been few seasonal-to-annual scale verification studies with WRF at high spatial and temporal resolution. This study employs a convection-permitting scale (2.7 km grid scale) simulation with WRF-NOAHMP, in daily forecast mode, from January 01 to November 30 2015. WRF was verified using measurements of 2 m air temperature (T-2m), dew point (TD-2m), and 10 m windspeed (UV-10m) from 48 UAE surface stations. Analysis was made of seasonal and diurnal performance within the desert, marine and mountain regions of the UAE. Results show that WRF represents temperature (T-2m) quite adequately during the daytime with biases ≤ +1 ˚C. There is however a nocturnal cold bias (−1 to −4 ˚C), which increases during hotter months in the desert and mountain regions. The marine region has the lowest T-2m biases (≤−0.75 ˚C). WRF performs well regarding TD-2m, with mean biases mostly ≤ 1 ˚C. TD-2m over the marine region is overestimated though (0.75–1 ˚C), and nocturnal mountain TD-2m is underestimated (~ −2 ˚C). UV-10m performance on land still needs improvement, and biases can occasionally be large (1–2 m s−1). This performance tends to worsen during the hot months, particularly inland with peak biases reaching ~ 3 m s−1. UV-10m are better simulated in the marine region (bias ≤ 1 m s−1). There is an apparent relationship between T-2m bias and UV-10m bias, which may indicate issues in simulation of the daytime sea breeze. TD-2m biases tend to be more independent. Studies such as these are vital for accurate assessment of WRF nowcasting performance and to identify model deficiencies. By combining sensitivity tests, process and observational studies with seasonal verification, we can further improve forecasting systems for the UAE.
Oliver Branch; Thomas Schwitalla; Marouane Temimi; Ricardo Fonseca; Narendra Nelli; Michael Weston; Josipa Milovac; Volker Wulfmeyer. Seasonal and diurnal performance of daily forecasts with WRF-NOAHMP V3.8.1 over the United Arab Emirates. 2020, 2020, 1 -40.
AMA StyleOliver Branch, Thomas Schwitalla, Marouane Temimi, Ricardo Fonseca, Narendra Nelli, Michael Weston, Josipa Milovac, Volker Wulfmeyer. Seasonal and diurnal performance of daily forecasts with WRF-NOAHMP V3.8.1 over the United Arab Emirates. . 2020; 2020 ():1-40.
Chicago/Turabian StyleOliver Branch; Thomas Schwitalla; Marouane Temimi; Ricardo Fonseca; Narendra Nelli; Michael Weston; Josipa Milovac; Volker Wulfmeyer. 2020. "Seasonal and diurnal performance of daily forecasts with WRF-NOAHMP V3.8.1 over the United Arab Emirates." 2020, no. : 1-40.
The aerodynamic roughness length is a crucial parameter that controls surface variables including the horizontal wind, surface temperature, and heat fluxes. Despite its importance, in the Weather Research and Forecasting (WRF) model, this parameter is typically assigned a predefined value, mostly based on the dominant land‐use type. In this work, the roughness length is first estimated from eddy‐covariance measurements at Al Ain in the United Arab Emirates (UAE), a hyper‐arid region, and then ingested into WRF. The estimated roughness length is in the range 1.3 to 2.2 mm, one order smaller than the default value used in WRF. In line with previous studies, and from WRF model simulations during the warm and cold seasons, it is concluded that, when the roughness length is decreased by an order of magnitude, the horizontal wind speed increases by up to 1 m s‐1, the surface temperature rises by up to 2.5°C, and the sensible heat flux decreases by as much as 10 W m‐2. In comparison with in situ station and eddy covariance data, and when forced with the updated roughness length, WRF gives more accurate 2‐m air temperature and sensible heat flux predictions.For prevailing wind speeds > 6 m s‐1, the model underestimates the strength of the near‐surface wind, a tendency that can be partially corrected, typically by 1‐3 m s‐1, when the updated roughness length is considered. For low wind speeds (< 4 m s‐1), however, WRF generally overestimates the strength of the wind.
Narendra Reddy Nelli; Marouane Temimi; Ricardo Morais Fonseca; Michael John Weston; Mohana Satyanarayana Thota; Vineeth Krishnan Valappil; Oliver Branch; Volker Wulfmeyer; Youssef Wehbe; Taha Al Hosary; AbdelTawab Shalaby; Noor Al Shamsi; Hajer Al Naqbi. Impact of Roughness Length on WRF Simulated Land‐Atmosphere Interactions Over a Hyper‐Arid Region. Earth and Space Science 2020, 7, 1 .
AMA StyleNarendra Reddy Nelli, Marouane Temimi, Ricardo Morais Fonseca, Michael John Weston, Mohana Satyanarayana Thota, Vineeth Krishnan Valappil, Oliver Branch, Volker Wulfmeyer, Youssef Wehbe, Taha Al Hosary, AbdelTawab Shalaby, Noor Al Shamsi, Hajer Al Naqbi. Impact of Roughness Length on WRF Simulated Land‐Atmosphere Interactions Over a Hyper‐Arid Region. Earth and Space Science. 2020; 7 (6):1.
Chicago/Turabian StyleNarendra Reddy Nelli; Marouane Temimi; Ricardo Morais Fonseca; Michael John Weston; Mohana Satyanarayana Thota; Vineeth Krishnan Valappil; Oliver Branch; Volker Wulfmeyer; Youssef Wehbe; Taha Al Hosary; AbdelTawab Shalaby; Noor Al Shamsi; Hajer Al Naqbi. 2020. "Impact of Roughness Length on WRF Simulated Land‐Atmosphere Interactions Over a Hyper‐Arid Region." Earth and Space Science 7, no. 6: 1.
Oliver Branch; Volker Wulfmeyer. Reply to Wang and D’Odorico: On the sustainability of large-scale desert plantations as a partial solution for climate change. Proceedings of the National Academy of Sciences 2019, 116, 24927 -24928.
AMA StyleOliver Branch, Volker Wulfmeyer. Reply to Wang and D’Odorico: On the sustainability of large-scale desert plantations as a partial solution for climate change. Proceedings of the National Academy of Sciences. 2019; 116 (50):24927-24928.
Chicago/Turabian StyleOliver Branch; Volker Wulfmeyer. 2019. "Reply to Wang and D’Odorico: On the sustainability of large-scale desert plantations as a partial solution for climate change." Proceedings of the National Academy of Sciences 116, no. 50: 24927-24928.
Large-scale afforestation is increasingly being considered as a negative emissions method for sequestering large quantities of atmospheric CO2. At the same time, regional weather modification methods, like cloud seeding, are being used to counteract increasing water scarcity in arid regions. Large-scale sustainable desert agroforestry plantations can contribute to climate change mitigation and can also be used to modify regional climate, particularly rainfall. Climate impacts from plantations need to be well understood before considering implementation. Typically, impact studies are attempted at continental or global scales and use coarse-resolution models, which suffer from severe systematic errors. This is highly problematic because decision makers should only countenance geoengineering schemes like global afforestation if impacts are understood on the regional scale. We posit the necessity of using high-resolution regional models with sophisticated representations of land–atmosphere feedback and vegetation. This approach allows for studying desert plantations and the process chain leading to climate modification. We demonstrate that large-scale plantations enhance regional clouds and rainfall and derive an index for predicting plantation impacts. Thus, desert plantations represent a unique environmental solution via predictable regional weather modification and carbon storage.
Oliver Branch; Volker Wulfmeyer. Deliberate enhancement of rainfall using desert plantations. Proceedings of the National Academy of Sciences 2019, 116, 18841 -18847.
AMA StyleOliver Branch, Volker Wulfmeyer. Deliberate enhancement of rainfall using desert plantations. Proceedings of the National Academy of Sciences. 2019; 116 (38):18841-18847.
Chicago/Turabian StyleOliver Branch; Volker Wulfmeyer. 2019. "Deliberate enhancement of rainfall using desert plantations." Proceedings of the National Academy of Sciences 116, no. 38: 18841-18847.
This study investigates an extreme weather event that impacted the United Arab Emirates (UAE) in March 2016, using the Weather Research and Forecasting (WRF) model version 3.7.1 coupled with its hydrological modeling extension package (WRF-Hydro). Six-hourly forecasted forcing records at 0.5∘ spatial resolution, obtained from the National Center for Environmental Prediction (NCEP) Global Forecast System (GFS), are used to drive the three nested downscaling domains of both standalone WRF and coupled WRF–WRF-Hydro configurations for the recent flood-triggering storm. Ground and satellite observations over the UAE are employed to validate the model results. The model performance was assessed using precipitation from the Global Precipitation Measurement (GPM) mission (30 min, 0.1∘ product), soil moisture from the Advanced Microwave Scanning Radiometer 2 (AMSR2; daily, 0.1∘ product) and the NOAA Soil Moisture Operational Products System (SMOPS; 6-hourly, 0.25∘ product), and cloud fraction retrievals from the Moderate Resolution Imaging Spectroradiometer Atmosphere product (MODATM; daily, 5 km product). The Pearson correlation coefficient (PCC), relative bias (rBIAS), and root-mean-square error (RMSE) are used as performance measures. Results show reductions of 24 % and 13 % in RMSE and rBIAS measures, respectively, in precipitation forecasts from the coupled WRF–WRF-Hydro model configuration, when compared to standalone WRF. The coupled system also shows improvements in global radiation forecasts, with reductions of 45 % and 12 % for RMSE and rBIAS, respectively. Moreover, WRF-Hydro was able to simulate the spatial distribution of soil moisture reasonably well across the study domain when compared to AMSR2-derived soil moisture estimates, despite a noticeable dry and wet bias in areas where soil moisture is high and low. Temporal and spatial variabilities of simulated soil moisture compare well to estimates from the NOAA SMOPS product, which indicates the model's capability to simulate surface drainage. Finally, the coupled model showed a shallower planetary boundary layer (PBL) compared to the standalone WRF simulation, which is attributed to the effect of soil moisture feedback. The demonstrated improvement, at the local scale, implies that WRF-Hydro coupling may enhance hydrological and meteorological forecasts in hyper-arid environments.
Youssef Wehbe; Marouane Temimi; Michael Weston; Naira Chaouch; Oliver Branch; Thomas Schwitalla; Volker Wulfmeyer; Xiwu Zhan; Jicheng Liu; Abdulla Al Mandous. Analysis of an extreme weather event in a hyper-arid region using WRF-Hydro coupling, station, and satellite data. Natural Hazards and Earth System Sciences 2019, 19, 1129 -1149.
AMA StyleYoussef Wehbe, Marouane Temimi, Michael Weston, Naira Chaouch, Oliver Branch, Thomas Schwitalla, Volker Wulfmeyer, Xiwu Zhan, Jicheng Liu, Abdulla Al Mandous. Analysis of an extreme weather event in a hyper-arid region using WRF-Hydro coupling, station, and satellite data. Natural Hazards and Earth System Sciences. 2019; 19 (6):1129-1149.
Chicago/Turabian StyleYoussef Wehbe; Marouane Temimi; Michael Weston; Naira Chaouch; Oliver Branch; Thomas Schwitalla; Volker Wulfmeyer; Xiwu Zhan; Jicheng Liu; Abdulla Al Mandous. 2019. "Analysis of an extreme weather event in a hyper-arid region using WRF-Hydro coupling, station, and satellite data." Natural Hazards and Earth System Sciences 19, no. 6: 1129-1149.
This study investigates an extreme weather event that impacted the United Arab Emirates (UAE) in March 2016 using the Weather Research and Forecasting (WRF) model version 3.7.1 coupled with its hydrological modeling extension package (Hydro). Six-hourly forecasted forcing records at 0.5o spatial resolution, obtained from the NCEP Global Forecast System (GFS), are used to drive the three nested downscaling domains of both standalone WRF and coupled WRF/WRF-Hydro configurations for the recent flood-triggering storm. Ground and satellite observations over the UAE are employed to validate the model results. Precipitation, soil moisture, and cloud fraction retrievals from GPM (30-minute, 0.1o product), AMSR2 (daily, 0.1o product), and MODIS (daily, 5 km product), respectively, are used to assess the model output. The Pearson correlation coefficient (PCC), relative bias (rBIAS) and root-mean-square error (RMSE) are used as performance measures. Results show reductions of 24 % and 13 % in RMSE and rBIAS measures, respectively, in precipitation forecasts from the coupled WRF/WRF-Hydro model configuration, when compared to standalone WRF. The coupled system also shows improvements in global radiation forecasts, with reductions of 45 % and 12 % for RMSE and rBIAS, respectively. Moreover, WRF-Hydro was able to simulate the spatial distribution of soil moisture reasonably well across the study domain when compared to AMSR2 satellite soil moisture estimates, despite a noticeable dry/wet bias in areas where soil moisture is high/low. The demonstrated improvement, at the local scale, implies that WRF-Hydro coupling may enhance hydrologic forecasts and flash flood guidance systems in the region.
Youssef Wehbe; Marouane Temimi; Michael Weston; Naira Chaouch; Oliver Branch; Thomas Schwitalla; Volker Wulfmeyer; Abdulla Al Mandous. Analysis of an Extreme Weather Event in a Hyper Arid Region Using WRF-Hydro Coupling, Station, and Satellite data. 2018, 2018, 1 -34.
AMA StyleYoussef Wehbe, Marouane Temimi, Michael Weston, Naira Chaouch, Oliver Branch, Thomas Schwitalla, Volker Wulfmeyer, Abdulla Al Mandous. Analysis of an Extreme Weather Event in a Hyper Arid Region Using WRF-Hydro Coupling, Station, and Satellite data. . 2018; 2018 ():1-34.
Chicago/Turabian StyleYoussef Wehbe; Marouane Temimi; Michael Weston; Naira Chaouch; Oliver Branch; Thomas Schwitalla; Volker Wulfmeyer; Abdulla Al Mandous. 2018. "Analysis of an Extreme Weather Event in a Hyper Arid Region Using WRF-Hydro Coupling, Station, and Satellite data." 2018, no. : 1-34.
This research aims at assessing land suitability for large-scale agriculture using multiple spatial datasets which include climate conditions, water potential, soil capabilities, topography and land management. The study case is in the Emirate of Abu Dhabi, in the UAE. The aridity of climate in the region requires accounting for non-renewable sources like desalination and treated sewage effluent (TSE) for an accurate and realistic assessment of irrigated agriculture suitability. All datasets were systematically aggregated using an analytical hierarchical process (AHP) in a GIS model. A hierarchal structure is built and pairwise comparisons matrices are used to calculate weights of the criteria. All spatial processes were integrated to model land suitability and different types of crops are considered in the analysis. Results show that jojoba and sorghum show the best capabilities to survive under the current conditions, followed by date palm, fruits and forage. Vegetables and cereals proved to be the least preferable options. Introducing desalinated water and TSE enhanced land suitability for irrigated agriculture. These findings have positive implications for national planning, the decision-making process of land alteration for agricultural use and addressing sustainable land management and food security issues.
Amal Aldababseh; Marouane Temimi; Praveen Maghelal; Oliver Branch; Volker Wulfmeyer. Multi-Criteria Evaluation of Irrigated Agriculture Suitability to Achieve Food Security in an Arid Environment. Sustainability 2018, 10, 803 .
AMA StyleAmal Aldababseh, Marouane Temimi, Praveen Maghelal, Oliver Branch, Volker Wulfmeyer. Multi-Criteria Evaluation of Irrigated Agriculture Suitability to Achieve Food Security in an Arid Environment. Sustainability. 2018; 10 (3):803.
Chicago/Turabian StyleAmal Aldababseh; Marouane Temimi; Praveen Maghelal; Oliver Branch; Volker Wulfmeyer. 2018. "Multi-Criteria Evaluation of Irrigated Agriculture Suitability to Achieve Food Security in an Arid Environment." Sustainability 10, no. 3: 803.
A 10 × 10 km irrigated biomass plantation was simulated in an arid region of Israel to simulate diurnal energy balances during the summer of 2012 (JJA). The goal is to examine daytime horizontal flux gradients between plantation and desert. Simulations were carried out within the coupled WRF-NOAH atmosphere/land surface model. MODIS land surface data was adjusted by prescribing tailored land surface and soil/plant parameters, and by adding a controllable sub-surface irrigation scheme to NOAH. Two model cases studies were compared – Impact and Control. Impact simulates the irrigated plantation. Control simulates the existing land surface, where the predominant land surface is bare desert soil. Central to the study is parameter validation against land surface observations from a desert site and from a 400 ha Simmondsia chinensis (jojoba) plantation. Control was validated with desert observations, and Impact with Jojoba observations. Model evapotranspiration was validated with two Penman–Monteith estimates based on the observations. Control simulates daytime desert conditions with a maximum deviation for surface 2 m air temperatures (T2) of 0.2 °C, vapour pressure deficit (VPD) of 0.25 hPa, wind speed (U) of 0.5 m s−1, surface radiation (Rn) of 25 W m−2, soil heat flux (G) of 30 W m−2 and 5 cm soil temperatures (ST5) of 1.5 °C. Impact simulates irrigated vegetation conditions with a maximum deviation for T2 of 1–1.5 °C, VPD of 0.5 hPa, U of 0.5 m s−1, Rn of 50 W m−5, G of 40 W m−2 and ST5 of 2 °C. Latent heat curves in Impact correspond closely with Penman–Monteith estimates, and magnitudes of 160 W m−2 over the plantation are usual. Sensible heat fluxes, are around 450 W m−2 and are at least 100–110 W m−2 higher than the surrounding desert. This surplus is driven by reduced albedo and high surface resistance, and demonstrates that high evaporation rates may not occur over Jojoba if irrigation is optimized. Furthermore, increased daytime T2 over plantations highlight the need for hourly as well as daily mean statistics. Daily mean statistics alone may imply an overall cooling effect due to surplus nocturnal cooling, when in fact a daytime warming effect is observed.
Oliver Branch; Kirsten Warrach-Sagi; Volker Wulfmeyer; Shabtai Cohen. Simulation of semi-arid biomass plantations and irrigation using the WRF-NOAH model – a comparison with observations from Israel. Hydrology and Earth System Sciences 2014, 18, 1761 -1783.
AMA StyleOliver Branch, Kirsten Warrach-Sagi, Volker Wulfmeyer, Shabtai Cohen. Simulation of semi-arid biomass plantations and irrigation using the WRF-NOAH model – a comparison with observations from Israel. Hydrology and Earth System Sciences. 2014; 18 (5):1761-1783.
Chicago/Turabian StyleOliver Branch; Kirsten Warrach-Sagi; Volker Wulfmeyer; Shabtai Cohen. 2014. "Simulation of semi-arid biomass plantations and irrigation using the WRF-NOAH model – a comparison with observations from Israel." Hydrology and Earth System Sciences 18, no. 5: 1761-1783.
A large irrigated biomass plantation was simulated in an arid region of Israel within the WRF-NOAH coupled atmospheric/land surface model in order to assess land surface atmosphere feedbacks. Simulations were carried out for the 2012 summer season (JJA). The irrigated plantations were simulated by prescribing tailored land surface and soil/plant parameters, and by implementing a newly devised, controllable sub-surface irrigation scheme within NOAH. Two model cases studies were considered and compared – Impact and Control. Impact simulates a hypothetical 10 km × 10 km irrigated plantation. Control represents a baseline and uses the existing land surface data, where the predominant land surface type in the area is bare desert soil. Central to the study is model validation against observations collected for the study over the same period. Surface meteorological and soil observations were made at a desert site and from a 400 ha Simmondsia chinensis (Jojoba) plantation. Control was validated with data from the desert, and Impact from the Jojoba. Finally, estimations were made of the energy balance, applying two Penman–Monteith based methods along with observed meteorological data. These estimations were compared with simulated energy fluxes. Control simulates the daytime desert surface 2 m air temperatures (T2) with less than 0.2 °C deviation and the vapour pressure deficit (VPD) to within 0.25 hPa. Desert wind speed (U) is simulated to within 0.5 m s−1 and the net surface radiation (Rn) to 25 W m−2. Soil heat flux (G) is not so accurately simulated by Control (up to 30 W m−2 deviation) and 5 cm soil temperatures (ST5) are simulated to within 1.5 °C. Impact simulates daytime T2 over irrigated vegetation to within 1–1.5 °C, the VPD to 0.5 hPa, Rn to 50 W m−2 and ST5 to within 2 °C. Simulated Impact G deviates up to 40 W m−2, highlighting a need for re-parameterisation or better soil classification, but the overall contribution to the energy balance is small (5–6%). During the night, significant T2 and ST5 cold biases of 2–4 °C are present. Diurnal latent heat values from WRF Impact correspond closely with Penman–Monteith estimation curves, and latent heat magnitudes of 160 W m−2 over the plantation are usual. Simulated plantation sensible heat fluxes are high (450 W m−2) – around 100–110 W m−2 higher than over the surrounding desert. The high relative HFX over the vegetation, driven by high Rn and high surface resistances, indicate that low Bowen ratios should not necessarily be assumed when irrigated plantations are implemented in, and optimized for arid regions. Furthermore, the high plantation T2 magnitudes highlight the importance of considering diurnal dynamics, which drive the evolution of boundary layers, rather than only on daily mean statistics which often indicate an irrigation cooling effect.
O. Branch; K. Warrach-Sagi; V. Wulfmeyer; S. Cohen. Irrigated plantations and their effect on energy fluxes in a semi-arid region of Israel – a validated 3-D model simulation. Hydrology and Earth System Sciences Discussions 2013, 18, 1761 -1783.
AMA StyleO. Branch, K. Warrach-Sagi, V. Wulfmeyer, S. Cohen. Irrigated plantations and their effect on energy fluxes in a semi-arid region of Israel – a validated 3-D model simulation. Hydrology and Earth System Sciences Discussions. 2013; 18 (5):1761-1783.
Chicago/Turabian StyleO. Branch; K. Warrach-Sagi; V. Wulfmeyer; S. Cohen. 2013. "Irrigated plantations and their effect on energy fluxes in a semi-arid region of Israel – a validated 3-D model simulation." Hydrology and Earth System Sciences Discussions 18, no. 5: 1761-1783.