scholarly journals Evaluating the effects of climate change on groundwater level in the Varamin plain

2021 ◽  
Author(s):  
Hamidreza Azizi ◽  
Hossein Ebrahimi ◽  
Hossein Mohammad Vali Samani ◽  
Vida Khaki
Keyword(s):  
Groundwater Level ◽  
General Circulation ◽  
Climate Model ◽  
Three Dimensional ◽  
General Circulation Models ◽  
Annual Rainfall ◽  
Observation Data ◽  
Base Period ◽  
The Future ◽  
Varamin Plain

Abstract In this research, a number of paired three-dimensional Atmosphere-Ocean General Circulation Models (AOGCM) from CMIP (Climate Model Inter Comparison Project) 5 group with the base period of 1989–2005 have been evaluated and the output of these models was micro-scaled and calibrated by LARS-WG software. The appropriate model was selected to simulate temperature and rainfall data under the emission scenarios of RCP (Representative Concentration Pathway) 2.6, RCP4.5 and RCP8.5 for the future period of 2020–2050, and then to model the groundwater level of the region, GMS software for both stable and transient states for one water year was calibrated and then was validated by observation data. The results in the future periods showed an increase of 1–1.5 degrees in temperature and an increase in rainfall in the early months of the year to late spring season and a decrease in rainfall in autumn season. Generally, the RCP4.5 scenario showed slightly more annual rainfall increase over the next 30 years compared to the base period than the other two scenarios. The time series investigation of the average of groundwater level shows that the implementation of RCP 2.6, RCP 4.5 and RCP 8.5 scenarios respectively leads to an average monthly increase of 4.2, 4.3 and 4.6 cm of the groundwater level.

Parameterized orographic gravity wave drag in CMIP6 models, distribution, variability, trends and intermodel spread

2021 ◽  
Author(s):  
Dominika Hájková ◽  
Petr Šácha ◽  
Petr Pišoft ◽  
Roland Eichinger
Keyword(s):  
Gravity Wave ◽  
General Circulation ◽  
Climate Model ◽  
Three Dimensional ◽  
General Circulation Models ◽  
Internal Gravity Waves ◽  
Wave Drag ◽  
Dynamical Structure ◽  
Dimensional Distribution ◽  
Climate Model Simulations

<p>Internal gravity waves (GWs) are a naturally occurring and intermittent phenomenon in the atmosphere. GWs can propagate horizontally and vertically and are important for atmospheric dynamics, influencing the atmospheric thermal and dynamical structure. Research on GWs is connected with some of the most challenging issues of Earth climate and atmospheric science. Consideration of GW-related processes is necessary for a proper description and modelling of the middle and upper atmosphere. However, as GWs exist on scales from a few to thousands of kilometers, they cannot be fully resolved by general circulation models (GCMs) and hence have to be parameterized. Although recently satellite and reanalysis datasets with improved resolution and novel analysis methods together with high-resolution atmospheric models have been tightening the constraints for GW parameterizations in GCMs, the parameterized GW effects still bear a significant margin of uncertainty.</p> <p>To quantify this uncertainty, we analyze the three-dimensional distribution and interannual variability of orographic gravity wave drag (OGWD) in chemistry-climate model simulations. For this, we use a set of AMIP simulations produced within the CMIP6 activity. In particular, we focus on the intermodel spread in the vertical and horizontal OGWD distribution. The different models generaly agree on the areas of the OGWD hotspots. However, in all these regions we find considerable intermodel differences in OGWD magnitude as well as in the altitude of the strongest GW dissipation. In this presentation, we show our findings and discuss possible explanations for the intermodel differences, like different parametrization schemes and choices of tunable parameters.</p>

scholarly journals On the Future Role of the most Parsimonious Climate Module in Integrated Assessment

2017 ◽  
Author(s):  
Mohammad M. Khabbazan ◽  
Hermann Held
Keyword(s):  
Integrated Assessment ◽  
Radiative Forcing ◽  
General Circulation ◽  
Climate Model ◽  
General Circulation Models ◽  
Box Model ◽  
Global Mean Temperature ◽  
The Future ◽  
The One ◽  
The Mind

Abstract. We test the validity of a one-box climate model as an emulator for Atmosphere-Ocean General Circulation Models (AOGCMs) when the application is confined to the subset of scenarios approximately in-line with the 2° target. The one-box climate model is currently in use in the integrated assessment models FUND and MIND. For our assessment, we crucially rely on 14 recent CMIP5 AOGCM diagnostics of the total radiative forcing for various representative concentration pathways. Our findings are two-fold. Firstly, when directly prescribing AOGCMs’ respective equilibrium climate sensitivities (ECSs) and transient climate responses (TCRs) to the one-box model, global mean temperature (GMT) projections are generically too large by 0.5 K at peak temperature. Accordingly, corresponding integrated assessment studies might overestimate mitigation need and cost. Secondly, the one-box model becomes an excellent emulator of those AOGCMs once their ECS and TCR values are universally mapped onto effective one-box intrinsic counterparts. We suggest utilizing this one-box model in integrated assessment also in the future, in particular when computationally demanding decision-making under climate response uncertainty might be modelled. However, then the roles of ECS and TCR must be re-interpreted. For the MIND model as used over the past 5 years, even the transformed ECS values comply with the ranges explicated by IPCC AR5, however now at the high-end.

scholarly journals Simulation of Extreme Precipitation in Four Climate Regions in China by General Circulation Models (GCMs): Performance and Projections

Water ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1509
Author(s):  
Mengru Zhang ◽  
Xiaoli Yang ◽  
Liliang Ren ◽  
Ming Pan ◽  
Shanhu Jiang ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
General Circulation ◽  
Global Climate ◽  
Summer Precipitation ◽  
General Circulation Models ◽  
Cumulative Distribution ◽  
Extreme Precipitation Events ◽  
Increasing Trend ◽  
The Future ◽  
Semi Arid

In the context of global climate change, it is important to monitor abnormal changes in extreme precipitation events that lead to frequent floods. This research used precipitation indices to describe variations in extreme precipitation and analyzed the characteristics of extreme precipitation in four climatic (arid, semi-arid, semi-humid and humid) regions across China. The equidistant cumulative distribution function (EDCDF) method was used to downscale and bias-correct daily precipitation in eight Coupled Model Intercomparison Project Phase 5 (CMIP5) general circulation models (GCMs). From 1961 to 2005, the humid region had stronger and longer extreme precipitation compared with the other regions. In the future, the projected extreme precipitation is mainly concentrated in summer, and there will be large areas with substantial changes in maximum consecutive 5-day precipitation (Rx5) and precipitation intensity (SDII). The greatest differences between two scenarios (RCP4.5 and RCP8.5) are in semi-arid and semi-humid areas for summer precipitation anomalies. However, the area of the four regions with an increasing trend of extreme precipitation is larger under the RCP8.5 scenario than that under the RCP4.5 scenario. The increasing trend of extreme precipitation in the future is relatively pronounced, especially in humid areas, implying a potential heightened flood risk in these areas.

scholarly journals The relevance of mid-Holocene Arctic warming to the future

2019 ◽  
Vol 15 (4) ◽  
pp. 1375-1394 ◽  
Author(s):  
Masakazu Yoshimori ◽  
Marina Suzuki
Keyword(s):  
Surface Temperature ◽  
General Circulation ◽  
Temperature Response ◽  
Longwave Radiation ◽  
General Circulation Models ◽  
Cross Model ◽  
Arctic Warming ◽  
Temperature Changes ◽  
The Future ◽  
Arctic Climate Change

Abstract. There remain substantial uncertainties in future projections of Arctic climate change. There is a potential to constrain these uncertainties using a combination of paleoclimate simulations and proxy data, but such a constraint must be accompanied by physical understanding on the connection between past and future simulations. Here, we examine the relevance of an Arctic warming mechanism in the mid-Holocene (MH) to the future with emphasis on process understanding. We conducted a surface energy balance analysis on 10 atmosphere and ocean general circulation models under the MH and future Representative Concentration Pathway (RCP) 4.5 scenario forcings. It is found that many of the dominant processes that amplify Arctic warming over the ocean from late autumn to early winter are common between the two periods, despite the difference in the source of the forcing (insolation vs. greenhouse gases). The positive albedo feedback in summer results in an increase in oceanic heat release in the colder season when the atmospheric stratification is strong, and an increased greenhouse effect from clouds helps amplify the warming during the season with small insolation. The seasonal progress was elucidated by the decomposition of the factors associated with sea surface temperature, ice concentration, and ice surface temperature changes. We also quantified the contribution of individual components to the inter-model variance in the surface temperature changes. The downward clear-sky longwave radiation is one of major contributors to the model spread throughout the year. Other controlling terms for the model spread vary with the season, but they are similar between the MH and the future in each season. This result suggests that the MH Arctic change may not be analogous to the future in some seasons when the temperature response differs, but it is still useful to constrain the model spread in the future Arctic projection. The cross-model correlation suggests that the feedbacks in preceding seasons should not be overlooked when determining constraints, particularly summer sea ice cover for the constraint of autumn–winter surface temperature response.

scholarly journals Interhemispheric differences of mesosphere/lower thermosphere winds and tides investigated from three whole atmosphere models and meteor radar observations

2021 ◽  
Author(s):  
Gunter Stober ◽  
Ales Kuchar ◽  
Dimitry Pokhotelov ◽  
Huixin Liu ◽  
Han-Li Liu ◽  
...  
Keyword(s):  
General Circulation ◽  
Climate Models ◽  
Climate Model ◽  
Lower Thermosphere ◽  
Winter Season ◽  
General Circulation Models ◽  
Meteor Radar ◽  
Radar Observations ◽  
Seasonal Characteristics

Abstract. Long-term and continuous observations of mesospheric/lower thermospheric winds are rare, but they are important to investigate climatological changes at these altitudes on time scales of several years, covering a solar cycle and longer. Such long time series are a natural heritage of the mesosphere/lower thermosphere climate, and they are valuable to compare climate models or long term runs of general circulation models (GCMs). Here we present a climatological comparison of wind observations from six meteor radars at two conjugate latitudes to validate the corresponding mean winds and atmospheric diurnal and semidiurnal tides from three GCMs, namely Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA), Whole Atmosphere Community Climate Model Extension (Specified Dynamics) (WACCM-X(SD)) and Upper Atmosphere ICOsahedral Non-hydrostatic (UA-ICON) model. Our results indicate that there are interhemispheric differences in the seasonal characteristics of the diurnal and semidiurnal tide. There also are some differences in the mean wind climatologies of the models and the observations. Our results indicate that GAIA shows a reasonable agreement with the meteor radar observations during the winter season, whereas WACCM-X(SD) shows a better agreement with the radars for the hemispheric zonal summer wind reversal, which is more consistent with the meteor radar observations. The free running UA-ICON tends to show similar winds and tides compared to WACCM-X(SD).

scholarly journals Tracking Scheme Dependence of Simulated Tropical Cyclone Response to Idealized Climate Simulations

2014 ◽  
Vol 27 (24) ◽  
pp. 9197-9213 ◽  
Author(s):  
Michael Horn ◽  
Kevin Walsh ◽  
Ming Zhao ◽  
Suzana J. Camargo ◽  
Enrico Scoccimarro ◽  
...  
Keyword(s):  
Tropical Cyclone ◽  
Tropical Cyclones ◽  
General Circulation ◽  
Climate Model ◽  
Circulation Model ◽  
General Circulation Models ◽  
Tropical Cyclone Activity ◽  
Model Data ◽  
Cyclone Activity ◽  
Sensitivity Testing

Abstract Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. The influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments is examined herein. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea surface temperature and other increased CO2 effects on tropical cyclone activity. Two tracking schemes are applied to these data and the tracks provided by each modeling group are analyzed. The results herein indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, it is found that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenization in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. The results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.

scholarly journals An Investigation into the Future Changes in Onset and Cessation of Rain and Their Variability over the Aswa Catchment, Uganda

Climate ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 67
Author(s):  
Michael Iwadra ◽  
P. T. Odirile ◽  
B. P. Parida ◽  
D. B. Moalafhi
Keyword(s):  
General Circulation ◽  
Rainfall Variability ◽  
Standardized Precipitation Index ◽  
Tropical Rainfall Measuring Mission ◽  
Kendall Test ◽  
Close Correlation ◽  
General Circulation Models ◽  
Extreme Precipitation Events ◽  
Future Global Warming ◽  
The Future

Future global warming may result in extreme precipitation events leading to crop, environment and infrastructure damage. Rainfall is a major input for the livelihood of peasant farmers in the Aswa catchment where the future rainfall variability, onset and cessation are also likely to be affected. The Aswa catchment has limited rainfall data; therefore, use of secondary datasets from Tropical Rainfall Measuring Mission (TRMM) is considered in this study, based on the close correlation of the recorded and TRMM rainfall. The latter was used to calibrate the statistical downscaling model for downscaling of two general circulation models to simulate future changes in rainfall. These data were analyzed for trends, wet and dry conditions/variability; onset and cessations of rain using the Mann–Kendall test, Standardized Precipitation Index (SPI) and the cumulative percentage mean rainfall method, respectively. Results show future rainfall is likely to increase, accompanied by increasing variability reaching as high as 118.5%. The frequency of SPI values above 2 (extreme wetness) is to increase above current level during mid and end of the century. The highest rainfall variability is expected especially during the onset and cessation months, which are generally expected to come earlier and later, by up to four and five weeks, respectively. The reliability worsens from the midterm (2036–2065) to long term (2066–2099). These likely changes in rainfall quantities, variability, onset and cessation months are some of the key rainfall dynamics that have implications for future arable agriculture, environment and water resource availability and planning over the Aswa catchment, as is increasingly the case elsewhere.

scholarly journals Impact of future climate change on water supply and irrigation demand in a small mediterranean catchment. Case study: Nebhana dam system, Tunisia

2019 ◽  
Vol 11 (4) ◽  
pp. 1724-1747 ◽  
Author(s):  
M. Allani ◽  
R. Mezzi ◽  
A. Zouabi ◽  
R. Béji ◽  
F. Joumade-Mansouri ◽  
...  
Keyword(s):  
Climate Change ◽  
Water Supply ◽  
General Circulation ◽  
General Circulation Models ◽  
Future Climate ◽  
Annual Rainfall ◽  
Future Climate Change ◽  
Cycle Duration ◽  
Climate Change Scenarios ◽  
Time Periods

Abstract This study evaluates the impacts of climate change on water supply and demand of the Nebhana dam system. Future climate change scenarios were obtained from five general circulation models (GCMs) of CMIP5 under RCP 4.5 and 8.5 emission scenarios for the time periods, 2021–2040, 2041–2060 and 2061–2080. Statistical downscaling was applied using LARS-WG. The GR2M hydrological model was calibrated, validated and used as input to the WEAP model to assess future water availability. Expected crop growth cycle lengths were estimated using a growing degree days model. By means of the WEAP-MABIA method, projected crop and irrigation water requirements were estimated. Results show an average increase in annual ETo of 6.1% and a decrease in annual rainfall of 11.4%, leading to a 24% decrease in inflow. Also, crops' growing cycles will decrease from 5.4% for wheat to 31% for citrus trees. The same tendency is observed for ETc. Concerning irrigation requirement, variations are more moderated depending on RCPs and time periods, and is explained by rainfall and crop cycle duration variations. As for demand and supply, results currently show that supply does not meet the system demand. Climate change could worsen the situation unless better planning of water surface use is done.

scholarly journals High-Resolution Solar Climate Atlas for Greece under Climate Change Using the Weather Research and Forecasting (WRF) Model

Atmosphere ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 761 ◽  
Author(s):  
Theodoros Katopodis ◽  
Iason Markantonis ◽  
Nadia Politi ◽  
Diamando Vlachogiannis ◽  
Athanasios Sfetsos
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Energy Demand ◽  
General Circulation ◽  
Wrf Model ◽  
General Circulation Models ◽  
Weather Research And Forecasting ◽  
Clear Sky ◽  
The Future ◽  
Weather Research

In the context of climate change and growing energy demand, solar technologies are considered promising solutions to mitigate Greenhouse Gas (GHG) emissions and support sustainable adaptation. In Greece, solar power is the second major renewable energy, constituting an increasingly important component of the future low-carbon energy portfolio. In this work, we propose the use of a high-resolution regional climate model (Weather Research and Forecasting model, WRF) to generate a solar climate atlas for the near-term climatological future under the Representative Concentration Pathway (RCPs) 4.5 and 8.5 scenarios. The model is set up with a 5 × 5 km2 spatial resolution, forced by the ERA-INTERIM for the historic (1980–2004) period and by the EC-EARTH General Circulation Models (GCM) for the future (2020–2044). Results reaffirm the high quality of solar energy potential in Greece and highlight the ability of the WRF model to produce a highly reliable future climate solar atlas. Projected changes between the annual historic and future RCPs scenarios indicate changes of the annual Global Horizontal Irradiance (GHI) in the range of ±5.0%. Seasonal analysis of the GHI values indicates percentage changes in the range of ±12% for both scenarios, with winter exhibiting the highest seasonal increases in the order of 10%, and autumn the largest decreases. Clear-sky fraction fclear projects increases in the range of ±4.0% in eastern and north continental Greece in the future, while most of the Greek marine areas might expect above 220 clear-sky days per year.

Sign in / Sign up

Export Citation Format

Share Document