We present a climate modeling approach to reproduce the rainfall patterns over Iran due to the cl... more We present a climate modeling approach to reproduce the rainfall patterns over Iran due to the climatic forcings during the past 6000 years. The selected periods are simulated using a spatially high-resolved atmosphere General Circulation Model (GCM). Our results show that the winter rainfall patterns over Iran have changed due to the changes in solar insolation with a wetter condition starting around 3 ka BP and reaching its maximum during the Medieval Climate Anomaly ca. 1 ka BP. The rainfall variability can be explained by the changes in atmospheric conditions as a result of changing incoming solar irradiance based on the Milankovitch theory. A shift in the Earth's energy budget leads to the modulation of the West Asian Subtropical Westerly Jet (WASWJ). The investigations support the hypothesis that during the Holocene a northward shift in the WASWJ contributes to the less cyclonic activities over Iran. This brings less moisture into the region during the winter.
International journal of biometeorology, Jan 6, 2015
In this study, a minimum distance classification and forward feature selection technique are join... more In this study, a minimum distance classification and forward feature selection technique are joined to determine the relationship between weather conditions and the increase of the risk of type A acute aortic dissection (AAD) events in Berlin. The results demonstrate that changes in the amount of cloudiness and air temperature are the most representative weather predictors among the studied parameters. A discrimination surface was developed for the prediction of AAD events 6 h ahead, and it is found that, under a specific amount of cloudiness and air temperature, the risk of AAD events in Berlin increases about 20 %.
ENVI-met is a computer program to simulate the microclimate in urban environment. It is a helpful... more ENVI-met is a computer program to simulate the microclimate in urban environment. It is a helpful program to simulate the urban climate in cities and can assist for environmental planning of new towns. One of the objective of climatological part of the project Young Cities „Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region‟ is to simulate the micro climate (with 1m resolution) in 35ha area of new town Hashtgerd, which is located 65 km far from mega city Tehran
Aim of this study is to investigate the future climate for the province Tehran till 2100. The cli... more Aim of this study is to investigate the future climate for the province Tehran till 2100. The climate model ECHAM5 and the regional climate model COSMO-CLM were used to simulate the regional climate change in this region. Using double nesting, the temperature and precipitation have been simulated with a resolution of 7km for this region. Results (2m temperature and precipitation) have been evaluated in 4 time slices (1981-2000, 2001-2020, 2031-2050, 2081-2100). For the first time slice, the observation data from the local stations have been compared with COSMO-CLM, CRU and GPCC reanalyze data. The COSMO-CLM model is warm and humid for this region. The maximum mean absolute error is for the station Abali in summer. This station is located in mountainous area. Results of comparison of first and fourth time slices show, that in winter the temperature will increase about 2 -3°C and in summer about 4°C in Tehran province. By calculation of extreme events (number of days with temperature ...
Urban heat island (UHI) is one of the most important environmental hazards in the city that impac... more Urban heat island (UHI) is one of the most important environmental hazards in the city that impact on quality of life. This might prove to be a very unsustainable factor, leading to excessive energy use for cooling and putting urban population at great morbidity and mortality risks and then to unliveable city. UHI is expected to pose increasing challenges for Tehran metropolitan area in the following decades, placing greater stress and impacts on multiple social and biophysical systems, including population health, social comfort, urban infrastructure, energy demand and water supplies. Therefore, we should take an action now to avoid possible serious environmental damage and design our cities to reduce the UHI effects significantly. The focus of this research was on the effects of two factors including vegetation cover and albedo of materials on the intensity of the UHI, through a case study on the Tehran metropolitan area. The original contributions of the research work were develo...
One of the objectives of climatological part of project Young Cities 'Developing Energy-Effic... more One of the objectives of climatological part of project Young Cities 'Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region' is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions ("energy-efficient fabric"). Climate sensitive form also means designing and planning for climate change and its related effects for Hashtgerd New Town. By configuration of buildings and open spaces according to solar radiation, wind and vegetation, climate sensitive urban form can create outdoor thermal comfort. To simulate the climate on small spatial scales, the micro climate model Envi-met has been used to simulate the micro climate in 35 ha. The E...
The importance of air pollution monitoring networks in urban areas is well known because of their... more The importance of air pollution monitoring networks in urban areas is well known because of their miscellaneous applications. At the beginning of the 1990s, Berlin had more than 40 particulate matter monitoring stations, whereas, by 2013, there were only 12 stations. In this study, a new and free-of-charge methodology for the densifying of the PM10 monitoring network of Berlin is presented. It endeavors to find the non-linear relationship between the hourly PM10 concentration of the still-operating PM10 monitoring stations and the shut-down stations by using the Artificial Neural Network (ANN), and, consequently, the results of the shut-down stations were simulated and re-constructed. However, input-variables selection is a pre-requisite for any ANN simulation, and hence a new fuzzy-heuristic input selection has been developed and joined to the ANN for the simulation. The hourly PM10 concentrations of the 20 shut-down stations were simulated and re-constructed. The mean error, bias and absolute error of the simulations were 27.7%, -0.03 (µg/m 3 ), and 7.4 (µg/m 3 ), respectively. Then, the simulated hourly PM10 concentration data were converted to a daily scale and the performance of ANN models which were developed for the simulation of the daily PM10 data were evaluated (correlation coefficient >0.94). These appropriate results imply the ability of the developed input selection technique to make the appropriate selection of the input variables, and it can be introduced as a new input variable selection for the ANN. In addition, a dense PM10 monitoring network was developed by the combination of both the re-constructed (20 stations) and the current (12 stations) stations. This dense monitoring network was applied in order to determine a reliable mean annual PM10 concentration in the different areas in Berlin in 2012.
This study tackles one of the most debated questions around the evolution of Central Asian climat... more This study tackles one of the most debated questions around the evolution of Central Asian climate: the "Puzzle" of moisture changes in Arid Central Asia (ACA) throughout the past millennium. A state-of-the-art Regional Climate Model (RCM) is subsequently employed to investigate four different 31-year time slices of extreme dry and wet spells, chosen according to changes in the driving data, in order to analyse the spatio-temporal evolution of the moisture variability in two different climatological epochs: Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). There is a clear regime behavior and bimodality in the westerly Jet phase space throughout the past millennium in ACA. The results indicate that the regime changes during LIA show a moist ACA and a dry East China. During the MCA, the Kazakhstan region shows a stronger response to the westerly jet equatorward shift than during the LIA. The out-of-phase pattern of moisture changes between India and ACA exists during both the LIA and the MCA. However, the pattern is more pronounced during the LIA.
The spatial representativity of monitoring stations plays a major role for the reasonable estimat... more The spatial representativity of monitoring stations plays a major role for the reasonable estimation of air pollutants. The ranking of air pollution monitoring stations based upon their spatial representativity identifies the level of representativeness of the stations and is very useful for developing optimum monitoring networks. In this study, a new ranking method, named RTFI (Ranking Technique based upon Fuzzy Interpolation) is introduced. This ranking method is able to rank air pollution monitoring stations in the urban areas based upon their spatial representativity. Although spatial correlation techniques are often used in the ranking techniques in order to consider spatial representativity, in this ranking technique, the spatial representativity of a station is not limited to its surroundings and is measured independently of its location. RTFI was applied to airborne Particulate Matter (PM) at seven stations in Berlin, and ranked them according to their spatial representativity. The results showed that the Neukölln-Nanenstr station (MC 42) is the most spatially representative station among the studied stations.
Maximum covariance analysis (MCA) and isometric feature mapping (Isomap) are applied to investiga... more Maximum covariance analysis (MCA) and isometric feature mapping (Isomap) are applied to investigate the spatio-temporal atmosphere-ocean interactions otherwise hidden in observational data for the period of 1979-2010. Despite an established long-term surface warming trend for the whole northern hemisphere, sea surface temperatures (SST) in the East Pacific have remained relatively constant for the period of 2001-2010. Our analysis reveals that SST anomaly probability density function of the leading two Isomap components is bimodal. We conclude that Isomap shows the existence of two distinct regimes in surface ocean temperature, resembling the break and active phases of rainfall over equatorial land areas. These regimes occurred within two separated time windows during the past three decades. Strengthening of trade winds over Pacific was coincident with the cold phase of east equatorial Pacific. This pattern was reversed during the warm phase of east equatorial Pacific. The El Niño event of 1997/1998 happened within the transition mode between these two regimes and may be a trigger for the SST changes in the Pacific. Furthermore, we suggest that Isomap, compared with MCA, provides more information about the behavior and predictability of the inter-seasonal atmosphere-ocean interactions.
Engineering Applications of Artificial Intelligence, 2015
Parameter and structure identifications are necessary in any modelling which aims to achieve a ge... more Parameter and structure identifications are necessary in any modelling which aims to achieve a generalised model. Although ANFIS (Adaptive Network-based Fuzzy Inference System) employs well-known parameteridentification techniques, it needs to structure identification techniques for the determination of an optimum number of fuzzy rules and the selection of significant input variables from among the candidate input variables. In this study, a new structure identification scheme is developed and introduced, which is simultaneously capable of the selection of significant input variables and the determination of an optimum number of rules. This new structure identification was joined to ANFIS, and this joined modelling framework was applied to the simulation of virtual air-pollution monitoring stations in Berlin. In this study, 18 virtual particulate matter stations were simulated using the particulate matter data of some of the current stations. In other words, the particulate matter monitoring network of Berlin has been intensified. The evaluation of simulated virtual stations shows that, although the uncertainty of daily particulate matter measurement is about 10 percent, the simulated virtual stations can estimate the mean daily particulate matter with less than 10 percent of error. Mean absolute error and root mean square error of the simulations are less than 2.4 and 3.4 mg/m 3 , respectively. The correlation coefficient of the simulation results was more than 0.94. In addition, the range of mean bias error is between À 1.0 and 0.5 mg/m 3 , and the range of factor of exceedance is between À 14.8 and 10.8 percent. It means that the simulated virtual stations have a small bias. These results demonstrated the appropriate performance of the joined new structure identification scheme and ANFIS for development of a virtual air pollution monitoring network.
Home | ePosters | GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtg... more Home | ePosters | GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtgerd new Town Search ePosters Upload Your ePoster GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtgerd new Town « Return to search results · New Search Authors: Sahar Sodoudi, Ines Langer, Ulrich Cubasch Author Institutions: Institut of meteorology, Berlin, Germany General InformationDiscussion One of the objectives of climatological part of project Young Cities ‘Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region’ is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions (“energy-efficient fabric”ù). Climate sensitive form...
Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called "u... more Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called "urban heat island" (UHI) effect. Climate change projections also indicate increase in the frequency and intensity of heat waves, which will intensify the UHI effect. As megacity Tehran is affected by severe heatwaves in summer, this study investigates its UHI characteristics and suggests some feasible mitigation strategies in order to reduce the air temperature and save energy. Temperature monitoring in Tehran shows clear evidence of the occurrence of the UHI effect, with a peak in July, where the urban area is circa 6 K warmer than the surrounding areas. The mobile measurements show a park cool island of 6-7 K in 2 central parks, which is also confirmed by satellite images. The effectiveness of three UHI mitigation strategies high albedo material (HAM), greenery on the surface and on the roofs (VEG), and a combination of them (HYBRID) has been studied using simulation with the microscale model ENVI-met. All three strategies show higher cooling effect in the daytime. The average nocturnal cooling effect of VEG and HYBRID (0.92, 1.10 K) is much higher than HAM (0.16 K), although high-density trees show a negative effect on nocturnal cooling.
In this paper, the performance of the Centre for Medium Range Weather Forecast (ECMWF) model (t+ ... more In this paper, the performance of the Centre for Medium Range Weather Forecast (ECMWF) model (t+ 27 h to t+51 h) in predicting precipitation is discussed. This model is the first, which has been verified over Iran. The spatial resolution of the model is 0.351°and the 24-h forecasts are compared with daily observations. The study concentrates on year 2001 and the precipitation measurements were collected from the data of 2,048 rain gauges in Iran. The accuracy of four different interpolation methods (nearest neighborhood, inverse distance, kriging, and upscaling) was investigated. Using cross-validation, the inverse distance method (IDM) with minimum mean error was applied. Verification results are given in terms of difference fields (mean error=0.46 mm/day), rank-order correlation coefficients (0.70), as well as accuracy scores (false alarm ratio=0.50 and probability of detection=0.60) and skill scores (true skill statistics [TSS]=0.45) in year 2001. The position of the rain band was only partly captured by the ECMWF model; however, the position of maximum precipitations agrees with the observations well. The results show that the high values of TSS are associated with the large amounts of precipitation (over 25 mm). Slight to moderate precipitation events have been underforecasted by the model (bias<1) and it leads to a small value of TSS for these thresholds (5-25 mm/day). The ECMWF model has better performance in high and mountainous regions than over flat terrain and in deserts. Comparing TSS over the Alborz and the Zagros Mountains, it is obvious that the ability of the model to predict the convective precipitation events needs some improvement. The amount of daily precipitation has been also slightly overestimated over Iran. From the beginning of January up to 21 March 2001, the ECMWF time series indicates an obvious phase shift of 1 day, although in other months, no phase shift is noticed.
This study is a part of main program RIMAX "risk management of extreme flood events", w... more This study is a part of main program RIMAX "risk management of extreme flood events", which concerns itself of "extremes floodwater and damage potential in the Bode river basin in Germany „with the variable occurrence of flood events in this area for the past 1000 years. The objective of the project is to produce the local climate time series (climate downscaling) as the input for a runoff model in the Bode basin for the last 1000 years on a grid of 5x5 km as well as the estimation of the spatial distributions and temporal variability of the precipitation, the amount of precipitation and further meteorological parameter (temperature, radiation and relative humidity) for this area. A nonlinear downscaling based on Fuzzy rules has been used to produce 1000 year climate time series. The global model ECHO from Max Planck institute for Meteorology (MPI) with T30 resolution and 1000 years data has been used as the global model (GCM). The regional model REMO, with 10 km reso...
Scale invariance property in the global geometry of Earth may lead to a coupled interactive behav... more Scale invariance property in the global geometry of Earth may lead to a coupled interactive behaviour between various components of the climate system. One of the most interesting correlations exists between spatial statistics of the global topography and the temperature on Earth. Here we show that the power-law behaviour observed in the Earth topography via different approaches, resembles a scaling law in the global spatial distribution of independent atmospheric parameters. We report on observation of scaling behaviour of such variables characterized by distinct universal exponents. More specifically, we find that the spatial power-law behaviour in the fluctuations of the near surface temperature over the lands on Earth, shares the same universal exponent as of the global Earth topography, indicative of the global persistent role of the static geometry of Earth to control the steady state of a dynamical atmospheric field. Such a universal feature can pave the way to the theoretical understanding of the chaotic nature of the atmosphere coupled to the Earth's global topography. The estimation of future climate variability is of the major concerns of the recent century. Exploring the intrinsic properties of the climate system will improve the understanding of the characteristics of dynamical processes involved within the climate system so as to the downscaling procedures (e.g., stochastic parametrization schemes). Lower boundary conditions as a large-scale forcing may lend predictability to climate system 1–4. Lower boundary conditions (e.g., topography, sea surface temperature, etc.) are usually prescribed in the General Circulation Models (GCMs). GCMs can realistically simulate the dominant modes of variations in the tropo-sphere 5. Earth-atmosphere interactions between the surface and the free troposphere are mainly influenced by the characteristics of the atmospheric boundary layer. Thus, the net exchange of heat, mass and momentum are determined by the lower boundary conditions. Outside the boundary layer, the unresolved scales of motion may not be a big deal for the forecasting of synoptic and large-scale circulations 6. However, they are crucial for the mesoscale forecasting. The Earth's surface is the main heat source and sink for the atmosphere. The inhomoge-neous distribution of land properties leads to the temperature gradient within the boundary layer 7. The complex climate system transports heat (driven by solar insolation) from tropics to the higher latitudes. The midlatitude topographies are the main driver of Rossby waves which contribute to the heat transport in the atmosphere 6,8–10. The Rossby waves control the formation of the atmospheric flows up to very remote regions and modify the wind pattern in the atmosphere 6. Previous studies revealed that, for a wide spectrum of scales, there exists a " power law " behaviour in the linear transects of the Earth's topography (i.e., S ∝ k −2 , where k is the wave number) 11–15. However, much less attention has been paid on the scale invariant analysis within the atmospheric system in connection with the scaling behaviour of the underlying topographic system. Power spectrum of temporal changes of atmospheric temperatures have been previously studied for different time scales 16–19. It has been shown that the rainfall amounts do not obey an overall scaling (power-law) form within the hydrological scales 20. The power spectrum analysis is not applied to different length scales in such studies. Here, we report, for the first time, on a novel observation that the fingerprint of the power-law relationship in the global Earth's topography also exists in the atmospheric dynamics as a result of Earth-atmosphere interaction.
We present a climate modeling approach to reproduce the rainfall patterns over Iran due to the cl... more We present a climate modeling approach to reproduce the rainfall patterns over Iran due to the climatic forcings during the past 6000 years. The selected periods are simulated using a spatially high-resolved atmosphere General Circulation Model (GCM). Our results show that the winter rainfall patterns over Iran have changed due to the changes in solar insolation with a wetter condition starting around 3 ka BP and reaching its maximum during the Medieval Climate Anomaly ca. 1 ka BP. The rainfall variability can be explained by the changes in atmospheric conditions as a result of changing incoming solar irradiance based on the Milankovitch theory. A shift in the Earth's energy budget leads to the modulation of the West Asian Subtropical Westerly Jet (WASWJ). The investigations support the hypothesis that during the Holocene a northward shift in the WASWJ contributes to the less cyclonic activities over Iran. This brings less moisture into the region during the winter.
International journal of biometeorology, Jan 6, 2015
In this study, a minimum distance classification and forward feature selection technique are join... more In this study, a minimum distance classification and forward feature selection technique are joined to determine the relationship between weather conditions and the increase of the risk of type A acute aortic dissection (AAD) events in Berlin. The results demonstrate that changes in the amount of cloudiness and air temperature are the most representative weather predictors among the studied parameters. A discrimination surface was developed for the prediction of AAD events 6 h ahead, and it is found that, under a specific amount of cloudiness and air temperature, the risk of AAD events in Berlin increases about 20 %.
ENVI-met is a computer program to simulate the microclimate in urban environment. It is a helpful... more ENVI-met is a computer program to simulate the microclimate in urban environment. It is a helpful program to simulate the urban climate in cities and can assist for environmental planning of new towns. One of the objective of climatological part of the project Young Cities „Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region‟ is to simulate the micro climate (with 1m resolution) in 35ha area of new town Hashtgerd, which is located 65 km far from mega city Tehran
Aim of this study is to investigate the future climate for the province Tehran till 2100. The cli... more Aim of this study is to investigate the future climate for the province Tehran till 2100. The climate model ECHAM5 and the regional climate model COSMO-CLM were used to simulate the regional climate change in this region. Using double nesting, the temperature and precipitation have been simulated with a resolution of 7km for this region. Results (2m temperature and precipitation) have been evaluated in 4 time slices (1981-2000, 2001-2020, 2031-2050, 2081-2100). For the first time slice, the observation data from the local stations have been compared with COSMO-CLM, CRU and GPCC reanalyze data. The COSMO-CLM model is warm and humid for this region. The maximum mean absolute error is for the station Abali in summer. This station is located in mountainous area. Results of comparison of first and fourth time slices show, that in winter the temperature will increase about 2 -3°C and in summer about 4°C in Tehran province. By calculation of extreme events (number of days with temperature ...
Urban heat island (UHI) is one of the most important environmental hazards in the city that impac... more Urban heat island (UHI) is one of the most important environmental hazards in the city that impact on quality of life. This might prove to be a very unsustainable factor, leading to excessive energy use for cooling and putting urban population at great morbidity and mortality risks and then to unliveable city. UHI is expected to pose increasing challenges for Tehran metropolitan area in the following decades, placing greater stress and impacts on multiple social and biophysical systems, including population health, social comfort, urban infrastructure, energy demand and water supplies. Therefore, we should take an action now to avoid possible serious environmental damage and design our cities to reduce the UHI effects significantly. The focus of this research was on the effects of two factors including vegetation cover and albedo of materials on the intensity of the UHI, through a case study on the Tehran metropolitan area. The original contributions of the research work were develo...
One of the objectives of climatological part of project Young Cities 'Developing Energy-Effic... more One of the objectives of climatological part of project Young Cities 'Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region' is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions ("energy-efficient fabric"). Climate sensitive form also means designing and planning for climate change and its related effects for Hashtgerd New Town. By configuration of buildings and open spaces according to solar radiation, wind and vegetation, climate sensitive urban form can create outdoor thermal comfort. To simulate the climate on small spatial scales, the micro climate model Envi-met has been used to simulate the micro climate in 35 ha. The E...
The importance of air pollution monitoring networks in urban areas is well known because of their... more The importance of air pollution monitoring networks in urban areas is well known because of their miscellaneous applications. At the beginning of the 1990s, Berlin had more than 40 particulate matter monitoring stations, whereas, by 2013, there were only 12 stations. In this study, a new and free-of-charge methodology for the densifying of the PM10 monitoring network of Berlin is presented. It endeavors to find the non-linear relationship between the hourly PM10 concentration of the still-operating PM10 monitoring stations and the shut-down stations by using the Artificial Neural Network (ANN), and, consequently, the results of the shut-down stations were simulated and re-constructed. However, input-variables selection is a pre-requisite for any ANN simulation, and hence a new fuzzy-heuristic input selection has been developed and joined to the ANN for the simulation. The hourly PM10 concentrations of the 20 shut-down stations were simulated and re-constructed. The mean error, bias and absolute error of the simulations were 27.7%, -0.03 (µg/m 3 ), and 7.4 (µg/m 3 ), respectively. Then, the simulated hourly PM10 concentration data were converted to a daily scale and the performance of ANN models which were developed for the simulation of the daily PM10 data were evaluated (correlation coefficient >0.94). These appropriate results imply the ability of the developed input selection technique to make the appropriate selection of the input variables, and it can be introduced as a new input variable selection for the ANN. In addition, a dense PM10 monitoring network was developed by the combination of both the re-constructed (20 stations) and the current (12 stations) stations. This dense monitoring network was applied in order to determine a reliable mean annual PM10 concentration in the different areas in Berlin in 2012.
This study tackles one of the most debated questions around the evolution of Central Asian climat... more This study tackles one of the most debated questions around the evolution of Central Asian climate: the "Puzzle" of moisture changes in Arid Central Asia (ACA) throughout the past millennium. A state-of-the-art Regional Climate Model (RCM) is subsequently employed to investigate four different 31-year time slices of extreme dry and wet spells, chosen according to changes in the driving data, in order to analyse the spatio-temporal evolution of the moisture variability in two different climatological epochs: Medieval Climate Anomaly (MCA) and Little Ice Age (LIA). There is a clear regime behavior and bimodality in the westerly Jet phase space throughout the past millennium in ACA. The results indicate that the regime changes during LIA show a moist ACA and a dry East China. During the MCA, the Kazakhstan region shows a stronger response to the westerly jet equatorward shift than during the LIA. The out-of-phase pattern of moisture changes between India and ACA exists during both the LIA and the MCA. However, the pattern is more pronounced during the LIA.
The spatial representativity of monitoring stations plays a major role for the reasonable estimat... more The spatial representativity of monitoring stations plays a major role for the reasonable estimation of air pollutants. The ranking of air pollution monitoring stations based upon their spatial representativity identifies the level of representativeness of the stations and is very useful for developing optimum monitoring networks. In this study, a new ranking method, named RTFI (Ranking Technique based upon Fuzzy Interpolation) is introduced. This ranking method is able to rank air pollution monitoring stations in the urban areas based upon their spatial representativity. Although spatial correlation techniques are often used in the ranking techniques in order to consider spatial representativity, in this ranking technique, the spatial representativity of a station is not limited to its surroundings and is measured independently of its location. RTFI was applied to airborne Particulate Matter (PM) at seven stations in Berlin, and ranked them according to their spatial representativity. The results showed that the Neukölln-Nanenstr station (MC 42) is the most spatially representative station among the studied stations.
Maximum covariance analysis (MCA) and isometric feature mapping (Isomap) are applied to investiga... more Maximum covariance analysis (MCA) and isometric feature mapping (Isomap) are applied to investigate the spatio-temporal atmosphere-ocean interactions otherwise hidden in observational data for the period of 1979-2010. Despite an established long-term surface warming trend for the whole northern hemisphere, sea surface temperatures (SST) in the East Pacific have remained relatively constant for the period of 2001-2010. Our analysis reveals that SST anomaly probability density function of the leading two Isomap components is bimodal. We conclude that Isomap shows the existence of two distinct regimes in surface ocean temperature, resembling the break and active phases of rainfall over equatorial land areas. These regimes occurred within two separated time windows during the past three decades. Strengthening of trade winds over Pacific was coincident with the cold phase of east equatorial Pacific. This pattern was reversed during the warm phase of east equatorial Pacific. The El Niño event of 1997/1998 happened within the transition mode between these two regimes and may be a trigger for the SST changes in the Pacific. Furthermore, we suggest that Isomap, compared with MCA, provides more information about the behavior and predictability of the inter-seasonal atmosphere-ocean interactions.
Engineering Applications of Artificial Intelligence, 2015
Parameter and structure identifications are necessary in any modelling which aims to achieve a ge... more Parameter and structure identifications are necessary in any modelling which aims to achieve a generalised model. Although ANFIS (Adaptive Network-based Fuzzy Inference System) employs well-known parameteridentification techniques, it needs to structure identification techniques for the determination of an optimum number of fuzzy rules and the selection of significant input variables from among the candidate input variables. In this study, a new structure identification scheme is developed and introduced, which is simultaneously capable of the selection of significant input variables and the determination of an optimum number of rules. This new structure identification was joined to ANFIS, and this joined modelling framework was applied to the simulation of virtual air-pollution monitoring stations in Berlin. In this study, 18 virtual particulate matter stations were simulated using the particulate matter data of some of the current stations. In other words, the particulate matter monitoring network of Berlin has been intensified. The evaluation of simulated virtual stations shows that, although the uncertainty of daily particulate matter measurement is about 10 percent, the simulated virtual stations can estimate the mean daily particulate matter with less than 10 percent of error. Mean absolute error and root mean square error of the simulations are less than 2.4 and 3.4 mg/m 3 , respectively. The correlation coefficient of the simulation results was more than 0.94. In addition, the range of mean bias error is between À 1.0 and 0.5 mg/m 3 , and the range of factor of exceedance is between À 14.8 and 10.8 percent. It means that the simulated virtual stations have a small bias. These results demonstrated the appropriate performance of the joined new structure identification scheme and ANFIS for development of a virtual air pollution monitoring network.
Home | ePosters | GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtg... more Home | ePosters | GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtgerd new Town Search ePosters Upload Your ePoster GC11B-0993: Impacts of Vegetation and Urban planning on micro climate in Hashtgerd new Town « Return to search results · New Search Authors: Sahar Sodoudi, Ines Langer, Ulrich Cubasch Author Institutions: Institut of meteorology, Berlin, Germany General InformationDiscussion One of the objectives of climatological part of project Young Cities ‘Developing Energy-Efficient Urban Fabric in the Tehran-Karaj Region’ is to simulate the micro climate (with 1m resolution) in 35ha of new town Hashtgerd, which is located 65 km far from mega city Tehran. The Project aims are developing, implementing and evaluating building and planning schemes and technologies which allow to plan and build sustainable, energy-efficient and climate sensible form mass housing settlements in arid and semi-arid regions (“energy-efficient fabric”ù). Climate sensitive form...
Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called "u... more Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called "urban heat island" (UHI) effect. Climate change projections also indicate increase in the frequency and intensity of heat waves, which will intensify the UHI effect. As megacity Tehran is affected by severe heatwaves in summer, this study investigates its UHI characteristics and suggests some feasible mitigation strategies in order to reduce the air temperature and save energy. Temperature monitoring in Tehran shows clear evidence of the occurrence of the UHI effect, with a peak in July, where the urban area is circa 6 K warmer than the surrounding areas. The mobile measurements show a park cool island of 6-7 K in 2 central parks, which is also confirmed by satellite images. The effectiveness of three UHI mitigation strategies high albedo material (HAM), greenery on the surface and on the roofs (VEG), and a combination of them (HYBRID) has been studied using simulation with the microscale model ENVI-met. All three strategies show higher cooling effect in the daytime. The average nocturnal cooling effect of VEG and HYBRID (0.92, 1.10 K) is much higher than HAM (0.16 K), although high-density trees show a negative effect on nocturnal cooling.
In this paper, the performance of the Centre for Medium Range Weather Forecast (ECMWF) model (t+ ... more In this paper, the performance of the Centre for Medium Range Weather Forecast (ECMWF) model (t+ 27 h to t+51 h) in predicting precipitation is discussed. This model is the first, which has been verified over Iran. The spatial resolution of the model is 0.351°and the 24-h forecasts are compared with daily observations. The study concentrates on year 2001 and the precipitation measurements were collected from the data of 2,048 rain gauges in Iran. The accuracy of four different interpolation methods (nearest neighborhood, inverse distance, kriging, and upscaling) was investigated. Using cross-validation, the inverse distance method (IDM) with minimum mean error was applied. Verification results are given in terms of difference fields (mean error=0.46 mm/day), rank-order correlation coefficients (0.70), as well as accuracy scores (false alarm ratio=0.50 and probability of detection=0.60) and skill scores (true skill statistics [TSS]=0.45) in year 2001. The position of the rain band was only partly captured by the ECMWF model; however, the position of maximum precipitations agrees with the observations well. The results show that the high values of TSS are associated with the large amounts of precipitation (over 25 mm). Slight to moderate precipitation events have been underforecasted by the model (bias<1) and it leads to a small value of TSS for these thresholds (5-25 mm/day). The ECMWF model has better performance in high and mountainous regions than over flat terrain and in deserts. Comparing TSS over the Alborz and the Zagros Mountains, it is obvious that the ability of the model to predict the convective precipitation events needs some improvement. The amount of daily precipitation has been also slightly overestimated over Iran. From the beginning of January up to 21 March 2001, the ECMWF time series indicates an obvious phase shift of 1 day, although in other months, no phase shift is noticed.
This study is a part of main program RIMAX "risk management of extreme flood events", w... more This study is a part of main program RIMAX "risk management of extreme flood events", which concerns itself of "extremes floodwater and damage potential in the Bode river basin in Germany „with the variable occurrence of flood events in this area for the past 1000 years. The objective of the project is to produce the local climate time series (climate downscaling) as the input for a runoff model in the Bode basin for the last 1000 years on a grid of 5x5 km as well as the estimation of the spatial distributions and temporal variability of the precipitation, the amount of precipitation and further meteorological parameter (temperature, radiation and relative humidity) for this area. A nonlinear downscaling based on Fuzzy rules has been used to produce 1000 year climate time series. The global model ECHO from Max Planck institute for Meteorology (MPI) with T30 resolution and 1000 years data has been used as the global model (GCM). The regional model REMO, with 10 km reso...
Scale invariance property in the global geometry of Earth may lead to a coupled interactive behav... more Scale invariance property in the global geometry of Earth may lead to a coupled interactive behaviour between various components of the climate system. One of the most interesting correlations exists between spatial statistics of the global topography and the temperature on Earth. Here we show that the power-law behaviour observed in the Earth topography via different approaches, resembles a scaling law in the global spatial distribution of independent atmospheric parameters. We report on observation of scaling behaviour of such variables characterized by distinct universal exponents. More specifically, we find that the spatial power-law behaviour in the fluctuations of the near surface temperature over the lands on Earth, shares the same universal exponent as of the global Earth topography, indicative of the global persistent role of the static geometry of Earth to control the steady state of a dynamical atmospheric field. Such a universal feature can pave the way to the theoretical understanding of the chaotic nature of the atmosphere coupled to the Earth's global topography. The estimation of future climate variability is of the major concerns of the recent century. Exploring the intrinsic properties of the climate system will improve the understanding of the characteristics of dynamical processes involved within the climate system so as to the downscaling procedures (e.g., stochastic parametrization schemes). Lower boundary conditions as a large-scale forcing may lend predictability to climate system 1–4. Lower boundary conditions (e.g., topography, sea surface temperature, etc.) are usually prescribed in the General Circulation Models (GCMs). GCMs can realistically simulate the dominant modes of variations in the tropo-sphere 5. Earth-atmosphere interactions between the surface and the free troposphere are mainly influenced by the characteristics of the atmospheric boundary layer. Thus, the net exchange of heat, mass and momentum are determined by the lower boundary conditions. Outside the boundary layer, the unresolved scales of motion may not be a big deal for the forecasting of synoptic and large-scale circulations 6. However, they are crucial for the mesoscale forecasting. The Earth's surface is the main heat source and sink for the atmosphere. The inhomoge-neous distribution of land properties leads to the temperature gradient within the boundary layer 7. The complex climate system transports heat (driven by solar insolation) from tropics to the higher latitudes. The midlatitude topographies are the main driver of Rossby waves which contribute to the heat transport in the atmosphere 6,8–10. The Rossby waves control the formation of the atmospheric flows up to very remote regions and modify the wind pattern in the atmosphere 6. Previous studies revealed that, for a wide spectrum of scales, there exists a " power law " behaviour in the linear transects of the Earth's topography (i.e., S ∝ k −2 , where k is the wave number) 11–15. However, much less attention has been paid on the scale invariant analysis within the atmospheric system in connection with the scaling behaviour of the underlying topographic system. Power spectrum of temporal changes of atmospheric temperatures have been previously studied for different time scales 16–19. It has been shown that the rainfall amounts do not obey an overall scaling (power-law) form within the hydrological scales 20. The power spectrum analysis is not applied to different length scales in such studies. Here, we report, for the first time, on a novel observation that the fingerprint of the power-law relationship in the global Earth's topography also exists in the atmospheric dynamics as a result of Earth-atmosphere interaction.
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