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Samy A Anwar

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Dr. Samy Ashraf Anwar Rateb is a researcher in the research department in the Egyptian Meteorological Authority (EMA). His PhD degree is from Cairo University in collaboration with the International Center of Theoretical Physics (ICTP) through STEP program. His major research involves the role of land-surface processes in constraining the surface climate and terrestrial carbon cycle using a regional climate model (RegCM4).

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Papers by Samy A Anwar

Constraining the Potential Evapotranspiration of Egypt Using the Regional Climate Model (RegCM4) and Climate Research Unit Dataset (CRU)

Journal of biomedical research & environmental sciences, May 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

Correction to: The influence of two land-surface hydrology schemes on the regional climate of Africa using the RegCM4 model

Theoretical and Applied Climatology, Aug 20, 2018

The original version of this article unfortunately contained a mistake. Fig. 10e was missing. The... more

The influence of two land‐surface hydrology schemes on the terrestrial carbon cycle of Africa: A regional climate model study

International Journal of Climatology, Sep 1, 2020

A RCM investigation of the influence of vegetation status and runoff scheme on the summer gross primary production of Tropical Africa

Theoretical and Applied Climatology, Jul 6, 2021

Three 16-year simulations were conducted to investigate the potential influence of the vegetation... more Three 16-year simulations were conducted to investigate the potential influence of the vegetation cover changes (static versus interactive) alone and vegetation-runoff systems (CN-TOP versus CN-VIC) on the gross primary production (GPP) over tropical Africa using a regional climate model RegCM4-CLM45. CLM45 is the land surface model coupled to the RegCM4, CN is the carbon–nitrogen module, SIMTOP (TOP) is the default runoff scheme and Variable Infiltration Capacity (VIC) is the optional runoff scheme of the CLM45. The results showed that when the vegetation cover changes were considered alone, the RegCM4 model shows a low bias of GPP—relative to the static vegetation case—in comparison with the observation-based dataset (Machine Tree Ensemble (MTE)). On the other hand, when the effects of the soil moisture (as represented by the runoff scheme) and vegetation cover changes were combined together, the difference between the two vegetation-runoff systems was larger than when the vegetation cover changes were considered alone. This was evident as the CN-VIC severely underestimated the GPP with respect to the MTE; meanwhile the CN-TOP reversed this effect particularly over the Congo basin. Overall, GPP is more sensitive to vegetation-runoff systems than when the vegetation cover changes are only considered. In addition, the regional coupled RegCM4-CLM45-CN-VIC model can simulate the GPP with a reasonable bias as long as the four parameters of the VIC surface dataset are calibrated against in-situ observations of tropical Africa.

Influence of Direct-Downscaling and One-Way Nesting on Daily Mean Air Temperature of Egypt Using the RegCM4

Journal of biomedical research & environmental sciences, Mar 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

On the Role of Leaf Area Index Parameterization in Simulating the Terrestrial Carbon Fluxes of Africa Using a Regional Coupled Climate–Vegetation Model

This article is an open access article distributed under the terms and conditions of the Creative... more

On the sensitivity of the Amazon surface climate to two land‐surface hydrology schemes using a high‐resolution regional climate model ( <scp>RegCM4</scp> )

International Journal of Climatology, Sep 15, 2021

Two 11‐year simulations were conducted to investigate the influence of two runoff schemes in the ... more Two 11‐year simulations were conducted to investigate the influence of two runoff schemes in the community land model version 4.5 (CLM45) on the Amazon surface energy balance and surface climate using a high‐resolution regional climate model (RegCM4‐CLM45). The default scheme is TOPMODEL (TOP), while the alternative is Variable Infiltration Capacity (VIC). In the two simulations, the vegetation status is prescribed (satellite phenology; SP). The first simulation was designated as SP‐TOP, while the second simulation was referred to as SP‐VIC, and both of them were evaluated using reanalysis products (e.g., ERA5) and micrometeorology data measurements. Results show that the SP‐VIC severely underestimates latent heat and overestimates sensible heat fluxes, more than SP‐TOP in comparison with the ERA5. This explains the large warm bias observed in the winter season. On the other hand, the SP‐VIC shows a slightly smaller dry bias than SP‐TOP against the Climate Research Unit (CRU) data. Our results show that SP‐VIC does not improve the quality of the simulation compared to SP‐TOP, which suggests the necessity of additional calibration of the VIC surface parameters using in situ observations of the Amazon and revising the VIC runoff scheme to perform new sensitivity experiments. The same needs to be done with SP‐TOP.

On the role of a coupled vegetation-runoff system in simulating the tropical African climate: a regional climate model sensitivity study

Theoretical and Applied Climatology, May 3, 2021

The role of vegetation-runoff system—in simulating the tropical African climate—was examined by a... more The role of vegetation-runoff system—in simulating the tropical African climate—was examined by analysing two 13-year simulations with two runoff schemes of the community land model version 4.5 (CLM45): the default one is TOPMODEL (TOP) and the other one is the Variable Infiltration Capacity (VIC) using a regional climate model (RegCM4-CLM45). In both simulations, the carbon-nitrogen (CN) module was activated. The first simulation was referred to as CN-TOP, while the second one was designated as CN-VIC. Overall, the results showed that the CN-VIC severely decreases the leaf area index (LAI), vegetation transpiration and soil evaporation relative to the CN-TOP. Eventually, it severely underestimates the total evapotranspiration but overestimates the sensible heat flux in comparison with the reanalysis product; meanwhile the CN-TOP opposes this effect. As a result, the CN-TOP shows a strong cold bias, and the CN-VIC shows a slightly warm bias in comparison with the observation. Moreover, enabling the interactive vegetation module leads to intensifying the dry bias of the total surface precipitation in both simulations with respect to the static vegetation case against the reanalysis product; however the CN-VIC still outperforms the CN-TOP in comparison with the observations. In conclusion, the coupled vegetation-runoff system has a strong influence on the tropical African climate relative to the static case, and calibrating the four parameters of the VIC surface dataset ensures a better and more reliable performance of the coupled RegCM4-CLM45-CN-VIC model for simulating the tropical African climate.

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

Earth systems and environment, Sep 15, 2021

The community land model version 4.5 provides two ways for treating the vegetation cover changes ... more The community land model version 4.5 provides two ways for treating the vegetation cover changes (a static versus an interactive) and two runoff schemes for tracking the soil moisture changes. In this study, we examined the sensitivity of the simulated boreal summer potential evapotranspiration (PET) to the aforementioned options using a regional climate model. Three different experiments with each one covering 16 years have been performed. The two runoff schemes were designated as SIMTOP (TOP) and variable infiltration capacity (VIC). Both runoff schemes were coupled to the carbon-nitrogen (CN) module, thus the vegetation status can be influenced by soil moisture changes. Results show that vegetation cover changes alone affect considerably the simulated 2-m mean air temperature (T2M). However, they do not affect the global incident solar radiation (RSDS) and PET. Conversely to the vegetation cover changes alone, the vegetation-runoff systems affect both the T2M and RSDS. Therefore, they considerably affect the simulated PET. Also, the CN-VIC overestimates the PET more than the CN-TOP compared to the Climatic Research Unit observational dataset. In comparison with the static vegetation case and CN-VIC, the CN-TOP shows the least bias of the simulated PET. Overall, our results show that the vegetationrunoff system is relevant in constraining the PET, though the CN-TOP can be recommended for future studies concerning the PET of tropical Africa.

On the Sensitivity of the Daily Mean Air Temperature of Egypt to Boundary Layer Schemes Using a High-Resolution Regional Climate Model (RegCM4)

Journal of biomedical research & environmental sciences, Mar 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

Simulating the Surface Solar Irradiance of Africa Using a Regional Climate Model: Influence of Vegetation-Runoff Coupled System

This article is an open access article distributed under the terms and conditions of the Creative... more

Modelling the Tropical African Climate using a state-of-the-art coupled regional climate-vegetation model

Climate Dynamics, Aug 4, 2021

In this study, three sixteen-year simulations were conducted to examine the influence of a new le... more In this study, three sixteen-year simulations were conducted to examine the influence of a new leaf area index (LAI) formula (derived from a modified version of the BIOME-BGC model) on the surface energy balance and surface climate of Tropical Africa using the Regional Climate Model version 4 (RegCM4) coupled with the Community Land Model version 4.5 (CLM45) including a module of carbon–nitrogen cycling (CN) (hereafter RegCM4-CLM45-CN). The first simulation considers the Satellite Phenology (SP) mode, the second one uses the old LAI formula and the third one uses the new LAI formula. The three simulations were designated as CLM45-SP, CLM45-CNold, and CLM45-CNnew respectively. The results showed that the simulated surface energy balance and surface climate are substantially affected by the new LAI formula. The CLM45-CNnew succeeds in reducing the high positive difference of LAI with respect to the CLM45-SP relative to the CLM45-CNold in some regions, although in other regions new differences appear. Also, the CLM45-CNnew is able to simulate the total evapotranspiration better than the CLM45-CNold in comparison with the reanalysis product and it shows a similar response relative to the CLM45-SP. Moreover, the CLM45-CNnew succeeds in reducing the cold bias relative to the CLM45-SP and CLM45-CNold against the observational dataset. For the total surface precipitation, the CLM45-CNnew shows a similar response to the CLM45-SP relative to the CLM45-CNold in comparison with the observational dataset. Overall, this study provides useful insights related to the advantage of the regional coupled RegCM4-CLM45-CNnew model and recommends its utilization for future studies on the potential roles/impacts of biosphere–atmosphere in modulating the climate of Tropical Africa.

On the contribution of dynamic leaf area index in simulating the African climate using a regional climate model (RegCM4)

Theoretical and Applied Climatology, Oct 8, 2020

To understand the contribution of dynamic leaf area index (LAI) in simulating the surface African... more To understand the contribution of dynamic leaf area index (LAI) in simulating the surface African climate, two 12-year simulations were analysed. The first simulation operates in the satellite phenology (SP) mode; meanwhile the second simulation relies on activating the carbon-nitrogen (CN) module. Both simulations used the variable infiltration capacity (VIC) as a land-surface hydrology scheme. The first simulation was referred to as SP-VIC, and the second one was designated as CN-VIC. The results showed that CN-VIC severely decrease LAI more than the SP-VIC particularly over the Congo basin. This leads to a severe decrease in vegetative evaporation and transpiration and a pronounced increase of soil evaporation in comparison with the SP-VIC. As a result, a remarkable decrease of total evapotranspiration was observed leading to a high warm bias relative to an observational dataset. The rate of total precipitation was less than when it is simulated by the SP-VIC, due to a decrease in the amount of water vapour transferred to the atmosphere. To ensure a superior performance of the coupled CN-VIC system, the four surface parameters of the VIC all need to be recalibrated over Africa particularly over the Congo basin, so the vegetation status and surface climate of Africa can be properly simulated.

The Influence of Different Initial Conditions on the Soil Temperature Profile of Egypt Using a Regional Climate Model

This article is an open access article distributed under the terms and conditions of the Creative... more

Understanding the contribution of the vegetation-runoff system for simulating the African climate using the RegCM4 model

Theoretical and Applied Climatology, May 18, 2019

Experiments are conducted with a regional climate model (RegCM4) to understand the role of the ve... more Experiments are conducted with a regional climate model (RegCM4) to understand the role of the vegetation-runoff system in simulating African climate. In some tests, the original leaf area index (LAI) formula is replaced with a new one derived from the BIOME-BGC model and then three simulations were conducted: SP-TOP (SP, satellite phenology with TOP as the default runoff scheme in the community land model, CLM), CN-TOP (CN, carbon-nitrogen module), and finally CN-VIC, the CN module with the variable infiltration capacity (VIC) runoff scheme turned on. Results show that the different vegetation-runoff configurations have a significant effect on the energy balance and regional climate. For example, the CN-VIC configuration leads to decreased evapotranspiration and increased sensible heat flux. Consequent changes to the surface energy balance also affect the regional climate. The CN-TOP configuration shows a cold bias over evergreen forest, while the CN-VIC configuration replaces this with a large warm bias. Regarding total precipitation, both CN-TOP and CN-VIC configurations do not affect the overall magnitude relative to the SP-TOP configuration; however, they simulate the timing of onset and offset in comparison with the observational dataset. Despite the substantial biases in the CN-VIC configuration, it can be recommended for future climate studies over Africa, as long as the four VIC parameters are calibrated over the African domain to obtain good results for the surface climate.

The influence of two land-surface hydrology schemes on the regional climate of Africa using the RegCM4 model

Theoretical and Applied Climatology, Jul 17, 2018

Two 12-year simulations were conducted with the RegCM4 model to study how different hydrology sch... more Two 12-year simulations were conducted with the RegCM4 model to study how different hydrology schemes can affect the terrestrial hydrology cycle, the surface energy balance, and the regional climate of Africa and in particular tropical Africa. One simulation used the default TOP hydrology scheme in the CLM4.5 land surface model; the other used the variable infiltration capacity (VIC) hydrology model coupled to CLM4.5. The results show that the VIC scheme has a lower soil infiltration rate and hence lower surface soil moisture (10 cm in this study) relative to the default TOP scheme. This leads to a different partitioning of terms in the surface energy balance, with low evapotranspiration and high sensible heat flux, resulting in a net warming effect. The VIC simulation also has low relative humidity due to the low evapotranspiration rate. The low infiltration rate of the VIC hydrology also results in accumulation of moisture on the soil surface. In addition, the VIC scheme generates more precipitation, especially in the summer (JJA) season. Thus, the hydrology parameterization can affect not just the terrestrial hydrology cycle but also energy balance partitioning and hence the surface climate. Moreover, the VIC simulation has smaller biases in the surface energy flux and other surface climate variables in comparison with the default CLM4.5 run. We conclude that the VIC land surface hydrology scheme succeeds in controlling the infiltration rate, the surface soil moisture, and hence total evapotranspiration, which improves the surface energy balance and hence produces a better surface climate. Thus, we recommend the VIC hydrology scheme for future climate studies over Africa.

Estimating the Potential Evapotranspiration of Egypt Using a Regional Climate Model and a High-Resolution Reanalysis Dataset

Identification and dosimetry of irradiated pistachio (<i>Pistacia vera</i> L.) using EPR

Radiation Effects and Defects in Solids, Nov 23, 2022

Effects of cumulus parameterization and land-surface hydrology schemes on Tibetan Plateau climate simulation during the wet season: insights from the RegCM4 model

Climate Dynamics, May 5, 2021

Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to the region's ... more Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to the region's complex topography and several aspects of model physics, especially convection and land surface processes. This study investigated the effects of the cumulus parameterization scheme (CPS) and land-surface hydrology scheme (LSHS) on TP climate simulation during the wet season using the RegCM4 regional climate model. To address these issues and seek an optimal simulation, we conducted four experiments at a 20 km resolution using various combinations of two CPSs (Grell and MIT-Emanuel), two LSHSs (the default TOPMODEL [TOP], and Variable Infiltration Capacity [VIC]). The simulations in terms of 2-m air temperature, precipitation (including large-scale precipitation [LSP] and convective precipitation [CP]), surface energy-water balance, as well as atmospheric moisture flux transport and vertical motion were compared with surface and satellite-based observations as well as the ERA5 reanalysis dataset for the period 2006-2016. The results revealed that the model using the Grell and TOP schemes better reproduced air temperature but with a warm bias, part of which could be significantly decreased by the MIT scheme. All schemes simulated a reasonable spatial distribution of precipitation, with the best performance in the experiment using the MIT and VIC schemes. Excessive precipitation was produced by the Grell scheme, mainly due to overestimated LSP, while the MIT scheme largely reduced the overestimation, and the simulated contribution of CP to total precipitation was in close agreement with the ERA5 data. The RegCM4 model satisfactorily captured diurnal cycles of precipitation amount and frequency, although there remained some differences in phase and magnitude, which were mainly caused by the CPSs. Relative to the Grell scheme, the MIT scheme yielded a weaker surface heating by reducing net radiation fluxes and the Bowen ratio. Consequently, anomalous moisture flux transport was substantially reduced over the southeastern TP, leading to a decrease in precipitation. The VIC scheme could also help decrease the wet bias by reducing surface heating. Further analysis indicated that the high CP in the MIT simulations could be attributed to destabilization in the low and mid-troposphere, while the VIC scheme tended to inhibit shallow convection, thereby decreasing CP. This study's results also suggest that CPS interacts with LSHS to affect the simulated climate over the TP.

Bias-Correcting the Maximum and Minimum Air Temperatures of Egypt Using a High-Resolution Regional Climate Model (RegCM4)

This article is an open access article distributed under the terms and conditions of the Creative... more

Constraining the Potential Evapotranspiration of Egypt Using the Regional Climate Model (RegCM4) and Climate Research Unit Dataset (CRU)

Journal of biomedical research & environmental sciences, May 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

Correction to: The influence of two land-surface hydrology schemes on the regional climate of Africa using the RegCM4 model

Theoretical and Applied Climatology, Aug 20, 2018

The original version of this article unfortunately contained a mistake. Fig. 10e was missing. The... more

The influence of two land‐surface hydrology schemes on the terrestrial carbon cycle of Africa: A regional climate model study

International Journal of Climatology, Sep 1, 2020

A RCM investigation of the influence of vegetation status and runoff scheme on the summer gross primary production of Tropical Africa

Theoretical and Applied Climatology, Jul 6, 2021

Three 16-year simulations were conducted to investigate the potential influence of the vegetation... more Three 16-year simulations were conducted to investigate the potential influence of the vegetation cover changes (static versus interactive) alone and vegetation-runoff systems (CN-TOP versus CN-VIC) on the gross primary production (GPP) over tropical Africa using a regional climate model RegCM4-CLM45. CLM45 is the land surface model coupled to the RegCM4, CN is the carbon–nitrogen module, SIMTOP (TOP) is the default runoff scheme and Variable Infiltration Capacity (VIC) is the optional runoff scheme of the CLM45. The results showed that when the vegetation cover changes were considered alone, the RegCM4 model shows a low bias of GPP—relative to the static vegetation case—in comparison with the observation-based dataset (Machine Tree Ensemble (MTE)). On the other hand, when the effects of the soil moisture (as represented by the runoff scheme) and vegetation cover changes were combined together, the difference between the two vegetation-runoff systems was larger than when the vegetation cover changes were considered alone. This was evident as the CN-VIC severely underestimated the GPP with respect to the MTE; meanwhile the CN-TOP reversed this effect particularly over the Congo basin. Overall, GPP is more sensitive to vegetation-runoff systems than when the vegetation cover changes are only considered. In addition, the regional coupled RegCM4-CLM45-CN-VIC model can simulate the GPP with a reasonable bias as long as the four parameters of the VIC surface dataset are calibrated against in-situ observations of tropical Africa.

Influence of Direct-Downscaling and One-Way Nesting on Daily Mean Air Temperature of Egypt Using the RegCM4

Journal of biomedical research & environmental sciences, Mar 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

On the Role of Leaf Area Index Parameterization in Simulating the Terrestrial Carbon Fluxes of Africa Using a Regional Coupled Climate–Vegetation Model

This article is an open access article distributed under the terms and conditions of the Creative... more

On the sensitivity of the Amazon surface climate to two land‐surface hydrology schemes using a high‐resolution regional climate model ( <scp>RegCM4</scp> )

International Journal of Climatology, Sep 15, 2021

Two 11‐year simulations were conducted to investigate the influence of two runoff schemes in the ... more Two 11‐year simulations were conducted to investigate the influence of two runoff schemes in the community land model version 4.5 (CLM45) on the Amazon surface energy balance and surface climate using a high‐resolution regional climate model (RegCM4‐CLM45). The default scheme is TOPMODEL (TOP), while the alternative is Variable Infiltration Capacity (VIC). In the two simulations, the vegetation status is prescribed (satellite phenology; SP). The first simulation was designated as SP‐TOP, while the second simulation was referred to as SP‐VIC, and both of them were evaluated using reanalysis products (e.g., ERA5) and micrometeorology data measurements. Results show that the SP‐VIC severely underestimates latent heat and overestimates sensible heat fluxes, more than SP‐TOP in comparison with the ERA5. This explains the large warm bias observed in the winter season. On the other hand, the SP‐VIC shows a slightly smaller dry bias than SP‐TOP against the Climate Research Unit (CRU) data. Our results show that SP‐VIC does not improve the quality of the simulation compared to SP‐TOP, which suggests the necessity of additional calibration of the VIC surface parameters using in situ observations of the Amazon and revising the VIC runoff scheme to perform new sensitivity experiments. The same needs to be done with SP‐TOP.

On the role of a coupled vegetation-runoff system in simulating the tropical African climate: a regional climate model sensitivity study

Theoretical and Applied Climatology, May 3, 2021

The role of vegetation-runoff system—in simulating the tropical African climate—was examined by a... more The role of vegetation-runoff system—in simulating the tropical African climate—was examined by analysing two 13-year simulations with two runoff schemes of the community land model version 4.5 (CLM45): the default one is TOPMODEL (TOP) and the other one is the Variable Infiltration Capacity (VIC) using a regional climate model (RegCM4-CLM45). In both simulations, the carbon-nitrogen (CN) module was activated. The first simulation was referred to as CN-TOP, while the second one was designated as CN-VIC. Overall, the results showed that the CN-VIC severely decreases the leaf area index (LAI), vegetation transpiration and soil evaporation relative to the CN-TOP. Eventually, it severely underestimates the total evapotranspiration but overestimates the sensible heat flux in comparison with the reanalysis product; meanwhile the CN-TOP opposes this effect. As a result, the CN-TOP shows a strong cold bias, and the CN-VIC shows a slightly warm bias in comparison with the observation. Moreover, enabling the interactive vegetation module leads to intensifying the dry bias of the total surface precipitation in both simulations with respect to the static vegetation case against the reanalysis product; however the CN-VIC still outperforms the CN-TOP in comparison with the observations. In conclusion, the coupled vegetation-runoff system has a strong influence on the tropical African climate relative to the static case, and calibrating the four parameters of the VIC surface dataset ensures a better and more reliable performance of the coupled RegCM4-CLM45-CN-VIC model for simulating the tropical African climate.

On the Influence of Vegetation Cover Changes and Vegetation-Runoff Systems on the Simulated Summer Potential Evapotranspiration of Tropical Africa Using RegCM4

Earth systems and environment, Sep 15, 2021

The community land model version 4.5 provides two ways for treating the vegetation cover changes ... more The community land model version 4.5 provides two ways for treating the vegetation cover changes (a static versus an interactive) and two runoff schemes for tracking the soil moisture changes. In this study, we examined the sensitivity of the simulated boreal summer potential evapotranspiration (PET) to the aforementioned options using a regional climate model. Three different experiments with each one covering 16 years have been performed. The two runoff schemes were designated as SIMTOP (TOP) and variable infiltration capacity (VIC). Both runoff schemes were coupled to the carbon-nitrogen (CN) module, thus the vegetation status can be influenced by soil moisture changes. Results show that vegetation cover changes alone affect considerably the simulated 2-m mean air temperature (T2M). However, they do not affect the global incident solar radiation (RSDS) and PET. Conversely to the vegetation cover changes alone, the vegetation-runoff systems affect both the T2M and RSDS. Therefore, they considerably affect the simulated PET. Also, the CN-VIC overestimates the PET more than the CN-TOP compared to the Climatic Research Unit observational dataset. In comparison with the static vegetation case and CN-VIC, the CN-TOP shows the least bias of the simulated PET. Overall, our results show that the vegetationrunoff system is relevant in constraining the PET, though the CN-TOP can be recommended for future studies concerning the PET of tropical Africa.

On the Sensitivity of the Daily Mean Air Temperature of Egypt to Boundary Layer Schemes Using a High-Resolution Regional Climate Model (RegCM4)

Journal of biomedical research & environmental sciences, Mar 1, 2023

Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of ... more Journal of Biomedical Research & Environmental Sciences main aim is to enhance the importance of science and technology to the scientifi c community and also to provide an equal opportunity to seek and share ideas to all our researchers and scientists without any barriers to develop their career and helping in their development of discovering the world.

Simulating the Surface Solar Irradiance of Africa Using a Regional Climate Model: Influence of Vegetation-Runoff Coupled System

This article is an open access article distributed under the terms and conditions of the Creative... more

Modelling the Tropical African Climate using a state-of-the-art coupled regional climate-vegetation model

Climate Dynamics, Aug 4, 2021

In this study, three sixteen-year simulations were conducted to examine the influence of a new le... more In this study, three sixteen-year simulations were conducted to examine the influence of a new leaf area index (LAI) formula (derived from a modified version of the BIOME-BGC model) on the surface energy balance and surface climate of Tropical Africa using the Regional Climate Model version 4 (RegCM4) coupled with the Community Land Model version 4.5 (CLM45) including a module of carbon–nitrogen cycling (CN) (hereafter RegCM4-CLM45-CN). The first simulation considers the Satellite Phenology (SP) mode, the second one uses the old LAI formula and the third one uses the new LAI formula. The three simulations were designated as CLM45-SP, CLM45-CNold, and CLM45-CNnew respectively. The results showed that the simulated surface energy balance and surface climate are substantially affected by the new LAI formula. The CLM45-CNnew succeeds in reducing the high positive difference of LAI with respect to the CLM45-SP relative to the CLM45-CNold in some regions, although in other regions new differences appear. Also, the CLM45-CNnew is able to simulate the total evapotranspiration better than the CLM45-CNold in comparison with the reanalysis product and it shows a similar response relative to the CLM45-SP. Moreover, the CLM45-CNnew succeeds in reducing the cold bias relative to the CLM45-SP and CLM45-CNold against the observational dataset. For the total surface precipitation, the CLM45-CNnew shows a similar response to the CLM45-SP relative to the CLM45-CNold in comparison with the observational dataset. Overall, this study provides useful insights related to the advantage of the regional coupled RegCM4-CLM45-CNnew model and recommends its utilization for future studies on the potential roles/impacts of biosphere–atmosphere in modulating the climate of Tropical Africa.

On the contribution of dynamic leaf area index in simulating the African climate using a regional climate model (RegCM4)

Theoretical and Applied Climatology, Oct 8, 2020

To understand the contribution of dynamic leaf area index (LAI) in simulating the surface African... more To understand the contribution of dynamic leaf area index (LAI) in simulating the surface African climate, two 12-year simulations were analysed. The first simulation operates in the satellite phenology (SP) mode; meanwhile the second simulation relies on activating the carbon-nitrogen (CN) module. Both simulations used the variable infiltration capacity (VIC) as a land-surface hydrology scheme. The first simulation was referred to as SP-VIC, and the second one was designated as CN-VIC. The results showed that CN-VIC severely decrease LAI more than the SP-VIC particularly over the Congo basin. This leads to a severe decrease in vegetative evaporation and transpiration and a pronounced increase of soil evaporation in comparison with the SP-VIC. As a result, a remarkable decrease of total evapotranspiration was observed leading to a high warm bias relative to an observational dataset. The rate of total precipitation was less than when it is simulated by the SP-VIC, due to a decrease in the amount of water vapour transferred to the atmosphere. To ensure a superior performance of the coupled CN-VIC system, the four surface parameters of the VIC all need to be recalibrated over Africa particularly over the Congo basin, so the vegetation status and surface climate of Africa can be properly simulated.

The Influence of Different Initial Conditions on the Soil Temperature Profile of Egypt Using a Regional Climate Model

This article is an open access article distributed under the terms and conditions of the Creative... more

Understanding the contribution of the vegetation-runoff system for simulating the African climate using the RegCM4 model

Theoretical and Applied Climatology, May 18, 2019

Experiments are conducted with a regional climate model (RegCM4) to understand the role of the ve... more Experiments are conducted with a regional climate model (RegCM4) to understand the role of the vegetation-runoff system in simulating African climate. In some tests, the original leaf area index (LAI) formula is replaced with a new one derived from the BIOME-BGC model and then three simulations were conducted: SP-TOP (SP, satellite phenology with TOP as the default runoff scheme in the community land model, CLM), CN-TOP (CN, carbon-nitrogen module), and finally CN-VIC, the CN module with the variable infiltration capacity (VIC) runoff scheme turned on. Results show that the different vegetation-runoff configurations have a significant effect on the energy balance and regional climate. For example, the CN-VIC configuration leads to decreased evapotranspiration and increased sensible heat flux. Consequent changes to the surface energy balance also affect the regional climate. The CN-TOP configuration shows a cold bias over evergreen forest, while the CN-VIC configuration replaces this with a large warm bias. Regarding total precipitation, both CN-TOP and CN-VIC configurations do not affect the overall magnitude relative to the SP-TOP configuration; however, they simulate the timing of onset and offset in comparison with the observational dataset. Despite the substantial biases in the CN-VIC configuration, it can be recommended for future climate studies over Africa, as long as the four VIC parameters are calibrated over the African domain to obtain good results for the surface climate.

The influence of two land-surface hydrology schemes on the regional climate of Africa using the RegCM4 model

Theoretical and Applied Climatology, Jul 17, 2018

Two 12-year simulations were conducted with the RegCM4 model to study how different hydrology sch... more Two 12-year simulations were conducted with the RegCM4 model to study how different hydrology schemes can affect the terrestrial hydrology cycle, the surface energy balance, and the regional climate of Africa and in particular tropical Africa. One simulation used the default TOP hydrology scheme in the CLM4.5 land surface model; the other used the variable infiltration capacity (VIC) hydrology model coupled to CLM4.5. The results show that the VIC scheme has a lower soil infiltration rate and hence lower surface soil moisture (10 cm in this study) relative to the default TOP scheme. This leads to a different partitioning of terms in the surface energy balance, with low evapotranspiration and high sensible heat flux, resulting in a net warming effect. The VIC simulation also has low relative humidity due to the low evapotranspiration rate. The low infiltration rate of the VIC hydrology also results in accumulation of moisture on the soil surface. In addition, the VIC scheme generates more precipitation, especially in the summer (JJA) season. Thus, the hydrology parameterization can affect not just the terrestrial hydrology cycle but also energy balance partitioning and hence the surface climate. Moreover, the VIC simulation has smaller biases in the surface energy flux and other surface climate variables in comparison with the default CLM4.5 run. We conclude that the VIC land surface hydrology scheme succeeds in controlling the infiltration rate, the surface soil moisture, and hence total evapotranspiration, which improves the surface energy balance and hence produces a better surface climate. Thus, we recommend the VIC hydrology scheme for future climate studies over Africa.

Estimating the Potential Evapotranspiration of Egypt Using a Regional Climate Model and a High-Resolution Reanalysis Dataset

Identification and dosimetry of irradiated pistachio (<i>Pistacia vera</i> L.) using EPR

Radiation Effects and Defects in Solids, Nov 23, 2022

Effects of cumulus parameterization and land-surface hydrology schemes on Tibetan Plateau climate simulation during the wet season: insights from the RegCM4 model

Climate Dynamics, May 5, 2021

Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to the region's ... more Dynamical downscaling generally performs poorly on the Tibetan Plateau (TP), due to the region's complex topography and several aspects of model physics, especially convection and land surface processes. This study investigated the effects of the cumulus parameterization scheme (CPS) and land-surface hydrology scheme (LSHS) on TP climate simulation during the wet season using the RegCM4 regional climate model. To address these issues and seek an optimal simulation, we conducted four experiments at a 20 km resolution using various combinations of two CPSs (Grell and MIT-Emanuel), two LSHSs (the default TOPMODEL [TOP], and Variable Infiltration Capacity [VIC]). The simulations in terms of 2-m air temperature, precipitation (including large-scale precipitation [LSP] and convective precipitation [CP]), surface energy-water balance, as well as atmospheric moisture flux transport and vertical motion were compared with surface and satellite-based observations as well as the ERA5 reanalysis dataset for the period 2006-2016. The results revealed that the model using the Grell and TOP schemes better reproduced air temperature but with a warm bias, part of which could be significantly decreased by the MIT scheme. All schemes simulated a reasonable spatial distribution of precipitation, with the best performance in the experiment using the MIT and VIC schemes. Excessive precipitation was produced by the Grell scheme, mainly due to overestimated LSP, while the MIT scheme largely reduced the overestimation, and the simulated contribution of CP to total precipitation was in close agreement with the ERA5 data. The RegCM4 model satisfactorily captured diurnal cycles of precipitation amount and frequency, although there remained some differences in phase and magnitude, which were mainly caused by the CPSs. Relative to the Grell scheme, the MIT scheme yielded a weaker surface heating by reducing net radiation fluxes and the Bowen ratio. Consequently, anomalous moisture flux transport was substantially reduced over the southeastern TP, leading to a decrease in precipitation. The VIC scheme could also help decrease the wet bias by reducing surface heating. Further analysis indicated that the high CP in the MIT simulations could be attributed to destabilization in the low and mid-troposphere, while the VIC scheme tended to inhibit shallow convection, thereby decreasing CP. This study's results also suggest that CPS interacts with LSHS to affect the simulated climate over the TP.

Bias-Correcting the Maximum and Minimum Air Temperatures of Egypt Using a High-Resolution Regional Climate Model (RegCM4)

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