Application of remote sensing and Geographic Information System (GIS) is a detailed and elegant p... more Application of remote sensing and Geographic Information System (GIS) is a detailed and elegant procedure for land cover classification and detecting changes in the classified land use. We utilized Landsat images to classify land cover / land use of Shiraz city for the 1987-2016 period. Dynamic of this classification was then assessed by detecting land use-land cover change (LULCC) in the obtained maps. Some appropriate statistical tests were performed to ensure that the results are significant. The city of Shiraz with the area of 50160 ha (501.6 km2), was firstly classified into three land cover types including, barren lands, built up area and vegetation. For the year 1987, 77.5%, 11.8% and 10.7% of the city were associated to these three land covers, respectively. These three statistics have changed to 55.4%, 36.8% and 7.8% in 2016 inferring about 210% increase in the built up area as compared to the base year of 1987. The vegetation and barren areas have reduced by about 26% and ...
Present study focuses on assessing application of OIF index on Landsat images, TM, ETM and OLI se... more Present study focuses on assessing application of OIF index on Landsat images, TM, ETM and OLI sensor for monitoring shoreline fluctuations in Dayyer city, and its relation between El Niño and La Niño with estimative sediment and erosion volume during the coast of this city in 1991, 2001 and 2014. Results of coastline oscillation investigation showed shifting coastline to sea side (Sedimentation) and inland (Erosion). Rate of sedimentation and erosion in Dayyer coastal from 1991 to 2001 are about 545964/9 and 248307/42 km and from 2001 to 2014 about 981661/67, and 566883/7 km, respectively.
Background: Malaria is one of the most widespread communicable diseases in the southeast of Iran ... more Background: Malaria is one of the most widespread communicable diseases in the southeast of Iran particularly in Chahbahar County. Comprehensive understanding of the influence of climate on this disease is a key element for success in the environmental-based malaria elimination programs. After analyzing the spatio-temporal distribution of the disease, the relationships between the infection statistics and some important climate indices particularly the El Niño-Southern Oscillation (ENSO) and rainfall were investigated.Methods: The malaria statistics collected from various health centers were composited with the corresponding data of Southern Oscillation Index (SOI), ground-based meteorological records and satellite-based rainfall data. Non-parametric Mann-whitely test was applied to detect the significant difference between patient number between El Niño and La Niña and between the adopted wet and dry episodes.Findings: Patient number from highest to lowest was associated to summer,...
ABSTRACT In arid areas, the variation of air temperature can be considerable, so instantaneous ai... more ABSTRACT In arid areas, the variation of air temperature can be considerable, so instantaneous air temperature (Tai) estimation is needed in different environmental researches. In this research, two different remote sensing data are used for estimating Tai for clear sky days in 2009 in Fars Province, Iran, including atmospheric temperature profile and land surface temperature (LST) data from Moderate Resolution Imaging Spectroradiometer. The Tai from a number of surface weather sites is used to judge the best Tai estimation. Stations’ elevation, latitude, and land cover type are considered to show their effect on Tai estimation. The estimated Tai evaluation focuses on daily and seasonal timescales in the daytime and night time separately. Both LST and vertical temperature profile data produced relatively high coefficient of determination values and small root mean square error value for Tai estimation, especially during the night time. Land cover and elevation vary the error values in Tai estimation more, when LST data is used. In comparison atmospheric temperature profile indicates a smaller error in Tai estimation in spring and summer and in urban land cover type, while using LST data presents a better result in fall and winter especially at night time.
By utilizing summertime (June-September) gridded data of air temperature (AT), relative humidity ... more By utilizing summertime (June-September) gridded data of air temperature (AT), relative humidity (RH) and vector wind (VW), climate change was investigated over the whole of the Middle East (ME) and its ten sub-regions for the period of 1961-2020. Although changes were detected according to each individual variable, their interrelationships are discussed to justify the physical causes of the changes. For assessing the dynamic of climate change, stability in the changes was analyzed when significant results are compared between three choices comprising A) 1961 1990 and 1991-2020, B) 1961-1970 and 2011-2020 and C) 1961-1965 and 2016-2020. We proved that AT (westerly wind and RH) has (have) been predominantly increasing (decreasing) over the study area. The greatest (smallest) frequency of significant results was associated with choice C (A) suggesting changes are on the rise. After proving that the Mediterranean Sea-based northwesterly winds are the main climate controller of the ME, ...
This Article is brought to you for free and open access by the Drought-- National Drought Mitigat... more This Article is brought to you for free and open access by the Drought-- National Drought Mitigation Center at DigitalCommons@University of
In this paper, annual precipitation data sets from five old rain gauge stations (Bushehr, Isfahan... more In this paper, annual precipitation data sets from five old rain gauge stations (Bushehr, Isfahan, Meshed, Tehran, and Jask) in Iran were fitted to nonparametric kernel function by using rectangular, triangular, and Gaussian or normal as kernel functions. The smoothing parameter was calculated by four methods including rule of thumb, Adamowski criterion, least squares cross-validation, and Sheater and Jones plug-in. The Adamowski criterion showed a better performance compared to other methods due to goodness of fit tests. The results of these proposed nonparametric methods will be then compared to the results of the parametric density functions including normal, two and three parameter log-normal, two parameter gamma, Pearson and log-Pearson type 3, Gumbel or extreme value type 1 and also Fourier series method which were applied by a previous study for the same stations. It was concluded that the annual precipitation data were fitted to nonparametric methods better than parametric methods.
International Journal of Environmental Science and Technology, 2021
Land use Land cover changes have a momentous influence on land surface temperature. Therefore, in... more Land use Land cover changes have a momentous influence on land surface temperature. Therefore, investigating spatial distribution of heat islands is a remarkable issue in environmental studies. The purpose of this study was to assess the interaction between land surface temperature variations with land cover change by using Landsat time-series and utilizing Normalized Vegetation Difference Index in Arsanjan County, Fars, Iran from 1987 to 2018. After estimating Normalized Vegetation Difference Index and land surface temperature time-series value in the experimental areas, index differencing technique was applied to identify their changes. Based on the findings, the reducing or rising trends of land surface temperature in vegetation stratums was related to the increasing or decreasing trend of Normalized Vegetation Difference Index from 1987 to 2003 and 2003 to 2018, respectively. Compared to the period 1987–2003, it is noteworthy that the noticeable increase in changed land surface temperature in the rangeland, farmland and Bakhtegan Lake by 18.2 °C, 21.2 °C and 18.3 °C, respectively, were attributed to the significant shift of Normalized Vegetation Difference Index by − 0.04, − 0.33 and + 0.6 in the mentioned area during the period 2003–2018. The correlations between land cover and land surface temperature were considerably positive in the water area by 0.95 and 0.83 from 1987 to 2003 and 2003 to 2018, respectively, while some negative coefficients were estimated by − 0.95 and − 0.94 in farmland in the mentioned period. These results are applicable with regard to managing heat islands by improving the cultivated area, afforestation and artificial Bakhtegan Lake recharge.
... The Hurst effect is not observed in all long streamflow data series and it does not seem to b... more ... The Hurst effect is not observed in all long streamflow data series and it does not seem to be present in rainfall data series. ... 107 Hydrological models in a non stationary environment ... Temporal variation of relations between New South Wales rainfall and the Southern Oscillation. ...
Although gridded precipitation products (GPPs) are essential when evaluating weather and climate ... more Although gridded precipitation products (GPPs) are essential when evaluating weather and climate systems, their reliability must be known before application for scientific works. This study assessed the correspondence of observed daily precipitation data over southwestern Iran and the corresponding precipitation values from two well-known GPPs, CHIRPS and CPC-Unified (CPC), from 1998 through 2018. The datasets were for the Jan-Mar period, which contributes to 30 to 80% of annual precipitation in northwestern Iran and Persian Gulf coastal areas. Principal component analysis was used to divide 218 rain-gauge stations in the study area into three main zones, the western and northwestern (Zone 1), south-central (zone 2), and coastal areas (zone 3). The area-averaged time series of zonal precipitation data were then compared with the corresponding zonal GPPs values. All precipitation data that was equal to or greater than 1 mm (wet day) and equaled or exceeded the 95th or 99th percentiles (very wet or extremely wet days, respectively) were compared for each zone. The comparison was repeated for 3-day cumulative precipitation data. The statistical tests demonstrated significant relationships between the observational-based and model-based GPPs. The results were more robust for the CPC and 3-day cumulative datasets than for CHIRPS and the daily records. The strongest results were for estimation of extremely wet days and were significant for CPC estimations of the three-day cumulative precipitation in zone 3.
– An investigation was conducted to detect the change-point years in the Southern Oscillation Ind... more – An investigation was conducted to detect the change-point years in the Southern Oscillation Index (SOI) and precipitation time series in Iran for the period 1951-1999 (49 years). Due to the unavailability of data, the record length of the precipitation time series was not consistent for all stations, varying from 34 to 49 years. The Pettitt-Mann-Whitney and Mann-Whitney-Wilcoxon tests were applied to determine the significance of the detected changes. The difference in SOI and precipitation amounts for the period before and after the change years was investigated. The coincidence of change-point years in the SOI time series and precipitation data was explored to evaluate the possible forcing effects of the El Niño-Southern Oscillation (ENSO) phenomenon on the suppression or enhancement of Iran’s hydrological cycle. The results indicated that the mid 1970s are the most probable change-point years in the time series of Southern Oscillation Index (SOI) data. The frequency and intensi...
Asia-Pacific Journal of Atmospheric Sciences, 2020
In addition to the tropical data , the OLR/U850/U200 data on a restricted region in southwestern ... more In addition to the tropical data , the OLR/U850/U200 data on a restricted region in southwestern Asia (17.5 ° N-35 ° N, 30°E-60°E) has been incorporated into the calculation of the Real-time Multivariate MJO (RMM) index. Introducing this data modifies the leading EOFs of the RMM index slightly and rotates them 14 ° eastward as a consequence of the change in the column variances of the RMM anomaly matrix at 30°E-60°E longitudes. However, the leading principal components of the new index, which is called Regionally Modified RMM (hereafter, RM-RMM), remain approximately unchanged. Owing to this close relationship between the two indices, the 14 ° phase-shift is considered as a basis for comparing the influences of the intraseasonal tropics-southwestern Asia variabilities on the precipitation over Iran with those of the MJO. Accordingly, by generating the spatial patterns of the precipitation anomaly, precipitation occurrence probability and other fields based on every active phase of the RM-RMM and RMM indices, the significant differences are revealed between the corresponding phases of the two indices for the phases 1, 3, 5, 7, and 8, separately. These results ameliorate the estimation of the impacts of the MJO on the precipitation and indicate that the RM-RMM index could be used as a companion to the RMM to forecast the precipitation in Iran. Remarkably, the precipitation forecast skill of the lag-regression model based on the RM-RMM index exceeds that of the model based on the RMM for certain time lags during the phases 1, 3, 5, 7 and 8 of the two indices.
Application of remote sensing and Geographic Information System (GIS) is a detailed and elegant p... more Application of remote sensing and Geographic Information System (GIS) is a detailed and elegant procedure for land cover classification and detecting changes in the classified land use. We utilized Landsat images to classify land cover / land use of Shiraz city for the 1987-2016 period. Dynamic of this classification was then assessed by detecting land use-land cover change (LULCC) in the obtained maps. Some appropriate statistical tests were performed to ensure that the results are significant. The city of Shiraz with the area of 50160 ha (501.6 km2), was firstly classified into three land cover types including, barren lands, built up area and vegetation. For the year 1987, 77.5%, 11.8% and 10.7% of the city were associated to these three land covers, respectively. These three statistics have changed to 55.4%, 36.8% and 7.8% in 2016 inferring about 210% increase in the built up area as compared to the base year of 1987. The vegetation and barren areas have reduced by about 26% and ...
Present study focuses on assessing application of OIF index on Landsat images, TM, ETM and OLI se... more Present study focuses on assessing application of OIF index on Landsat images, TM, ETM and OLI sensor for monitoring shoreline fluctuations in Dayyer city, and its relation between El Niño and La Niño with estimative sediment and erosion volume during the coast of this city in 1991, 2001 and 2014. Results of coastline oscillation investigation showed shifting coastline to sea side (Sedimentation) and inland (Erosion). Rate of sedimentation and erosion in Dayyer coastal from 1991 to 2001 are about 545964/9 and 248307/42 km and from 2001 to 2014 about 981661/67, and 566883/7 km, respectively.
Background: Malaria is one of the most widespread communicable diseases in the southeast of Iran ... more Background: Malaria is one of the most widespread communicable diseases in the southeast of Iran particularly in Chahbahar County. Comprehensive understanding of the influence of climate on this disease is a key element for success in the environmental-based malaria elimination programs. After analyzing the spatio-temporal distribution of the disease, the relationships between the infection statistics and some important climate indices particularly the El Niño-Southern Oscillation (ENSO) and rainfall were investigated.Methods: The malaria statistics collected from various health centers were composited with the corresponding data of Southern Oscillation Index (SOI), ground-based meteorological records and satellite-based rainfall data. Non-parametric Mann-whitely test was applied to detect the significant difference between patient number between El Niño and La Niña and between the adopted wet and dry episodes.Findings: Patient number from highest to lowest was associated to summer,...
ABSTRACT In arid areas, the variation of air temperature can be considerable, so instantaneous ai... more ABSTRACT In arid areas, the variation of air temperature can be considerable, so instantaneous air temperature (Tai) estimation is needed in different environmental researches. In this research, two different remote sensing data are used for estimating Tai for clear sky days in 2009 in Fars Province, Iran, including atmospheric temperature profile and land surface temperature (LST) data from Moderate Resolution Imaging Spectroradiometer. The Tai from a number of surface weather sites is used to judge the best Tai estimation. Stations’ elevation, latitude, and land cover type are considered to show their effect on Tai estimation. The estimated Tai evaluation focuses on daily and seasonal timescales in the daytime and night time separately. Both LST and vertical temperature profile data produced relatively high coefficient of determination values and small root mean square error value for Tai estimation, especially during the night time. Land cover and elevation vary the error values in Tai estimation more, when LST data is used. In comparison atmospheric temperature profile indicates a smaller error in Tai estimation in spring and summer and in urban land cover type, while using LST data presents a better result in fall and winter especially at night time.
By utilizing summertime (June-September) gridded data of air temperature (AT), relative humidity ... more By utilizing summertime (June-September) gridded data of air temperature (AT), relative humidity (RH) and vector wind (VW), climate change was investigated over the whole of the Middle East (ME) and its ten sub-regions for the period of 1961-2020. Although changes were detected according to each individual variable, their interrelationships are discussed to justify the physical causes of the changes. For assessing the dynamic of climate change, stability in the changes was analyzed when significant results are compared between three choices comprising A) 1961 1990 and 1991-2020, B) 1961-1970 and 2011-2020 and C) 1961-1965 and 2016-2020. We proved that AT (westerly wind and RH) has (have) been predominantly increasing (decreasing) over the study area. The greatest (smallest) frequency of significant results was associated with choice C (A) suggesting changes are on the rise. After proving that the Mediterranean Sea-based northwesterly winds are the main climate controller of the ME, ...
This Article is brought to you for free and open access by the Drought-- National Drought Mitigat... more This Article is brought to you for free and open access by the Drought-- National Drought Mitigation Center at DigitalCommons@University of
In this paper, annual precipitation data sets from five old rain gauge stations (Bushehr, Isfahan... more In this paper, annual precipitation data sets from five old rain gauge stations (Bushehr, Isfahan, Meshed, Tehran, and Jask) in Iran were fitted to nonparametric kernel function by using rectangular, triangular, and Gaussian or normal as kernel functions. The smoothing parameter was calculated by four methods including rule of thumb, Adamowski criterion, least squares cross-validation, and Sheater and Jones plug-in. The Adamowski criterion showed a better performance compared to other methods due to goodness of fit tests. The results of these proposed nonparametric methods will be then compared to the results of the parametric density functions including normal, two and three parameter log-normal, two parameter gamma, Pearson and log-Pearson type 3, Gumbel or extreme value type 1 and also Fourier series method which were applied by a previous study for the same stations. It was concluded that the annual precipitation data were fitted to nonparametric methods better than parametric methods.
International Journal of Environmental Science and Technology, 2021
Land use Land cover changes have a momentous influence on land surface temperature. Therefore, in... more Land use Land cover changes have a momentous influence on land surface temperature. Therefore, investigating spatial distribution of heat islands is a remarkable issue in environmental studies. The purpose of this study was to assess the interaction between land surface temperature variations with land cover change by using Landsat time-series and utilizing Normalized Vegetation Difference Index in Arsanjan County, Fars, Iran from 1987 to 2018. After estimating Normalized Vegetation Difference Index and land surface temperature time-series value in the experimental areas, index differencing technique was applied to identify their changes. Based on the findings, the reducing or rising trends of land surface temperature in vegetation stratums was related to the increasing or decreasing trend of Normalized Vegetation Difference Index from 1987 to 2003 and 2003 to 2018, respectively. Compared to the period 1987–2003, it is noteworthy that the noticeable increase in changed land surface temperature in the rangeland, farmland and Bakhtegan Lake by 18.2 °C, 21.2 °C and 18.3 °C, respectively, were attributed to the significant shift of Normalized Vegetation Difference Index by − 0.04, − 0.33 and + 0.6 in the mentioned area during the period 2003–2018. The correlations between land cover and land surface temperature were considerably positive in the water area by 0.95 and 0.83 from 1987 to 2003 and 2003 to 2018, respectively, while some negative coefficients were estimated by − 0.95 and − 0.94 in farmland in the mentioned period. These results are applicable with regard to managing heat islands by improving the cultivated area, afforestation and artificial Bakhtegan Lake recharge.
... The Hurst effect is not observed in all long streamflow data series and it does not seem to b... more ... The Hurst effect is not observed in all long streamflow data series and it does not seem to be present in rainfall data series. ... 107 Hydrological models in a non stationary environment ... Temporal variation of relations between New South Wales rainfall and the Southern Oscillation. ...
Although gridded precipitation products (GPPs) are essential when evaluating weather and climate ... more Although gridded precipitation products (GPPs) are essential when evaluating weather and climate systems, their reliability must be known before application for scientific works. This study assessed the correspondence of observed daily precipitation data over southwestern Iran and the corresponding precipitation values from two well-known GPPs, CHIRPS and CPC-Unified (CPC), from 1998 through 2018. The datasets were for the Jan-Mar period, which contributes to 30 to 80% of annual precipitation in northwestern Iran and Persian Gulf coastal areas. Principal component analysis was used to divide 218 rain-gauge stations in the study area into three main zones, the western and northwestern (Zone 1), south-central (zone 2), and coastal areas (zone 3). The area-averaged time series of zonal precipitation data were then compared with the corresponding zonal GPPs values. All precipitation data that was equal to or greater than 1 mm (wet day) and equaled or exceeded the 95th or 99th percentiles (very wet or extremely wet days, respectively) were compared for each zone. The comparison was repeated for 3-day cumulative precipitation data. The statistical tests demonstrated significant relationships between the observational-based and model-based GPPs. The results were more robust for the CPC and 3-day cumulative datasets than for CHIRPS and the daily records. The strongest results were for estimation of extremely wet days and were significant for CPC estimations of the three-day cumulative precipitation in zone 3.
– An investigation was conducted to detect the change-point years in the Southern Oscillation Ind... more – An investigation was conducted to detect the change-point years in the Southern Oscillation Index (SOI) and precipitation time series in Iran for the period 1951-1999 (49 years). Due to the unavailability of data, the record length of the precipitation time series was not consistent for all stations, varying from 34 to 49 years. The Pettitt-Mann-Whitney and Mann-Whitney-Wilcoxon tests were applied to determine the significance of the detected changes. The difference in SOI and precipitation amounts for the period before and after the change years was investigated. The coincidence of change-point years in the SOI time series and precipitation data was explored to evaluate the possible forcing effects of the El Niño-Southern Oscillation (ENSO) phenomenon on the suppression or enhancement of Iran’s hydrological cycle. The results indicated that the mid 1970s are the most probable change-point years in the time series of Southern Oscillation Index (SOI) data. The frequency and intensi...
Asia-Pacific Journal of Atmospheric Sciences, 2020
In addition to the tropical data , the OLR/U850/U200 data on a restricted region in southwestern ... more In addition to the tropical data , the OLR/U850/U200 data on a restricted region in southwestern Asia (17.5 ° N-35 ° N, 30°E-60°E) has been incorporated into the calculation of the Real-time Multivariate MJO (RMM) index. Introducing this data modifies the leading EOFs of the RMM index slightly and rotates them 14 ° eastward as a consequence of the change in the column variances of the RMM anomaly matrix at 30°E-60°E longitudes. However, the leading principal components of the new index, which is called Regionally Modified RMM (hereafter, RM-RMM), remain approximately unchanged. Owing to this close relationship between the two indices, the 14 ° phase-shift is considered as a basis for comparing the influences of the intraseasonal tropics-southwestern Asia variabilities on the precipitation over Iran with those of the MJO. Accordingly, by generating the spatial patterns of the precipitation anomaly, precipitation occurrence probability and other fields based on every active phase of the RM-RMM and RMM indices, the significant differences are revealed between the corresponding phases of the two indices for the phases 1, 3, 5, 7, and 8, separately. These results ameliorate the estimation of the impacts of the MJO on the precipitation and indicate that the RM-RMM index could be used as a companion to the RMM to forecast the precipitation in Iran. Remarkably, the precipitation forecast skill of the lag-regression model based on the RM-RMM index exceeds that of the model based on the RMM for certain time lags during the phases 1, 3, 5, 7 and 8 of the two indices.
Uploads
Papers by M. Nazemosadat