Climatology
Yagob Dinpashoh; Saeid Jahanbakhsh-Asl; Asma Azadeh Garebagh
Abstract
In this study the values of potential reference crop evapotranspiration were calculated using the FAO-56 Penman Monteith method in six stations located in southern shores of Caspian Sea. Trends in annual ET0 values of the stations were analyzed using the Mann-Kendall test. Then to determine the relative ...
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In this study the values of potential reference crop evapotranspiration were calculated using the FAO-56 Penman Monteith method in six stations located in southern shores of Caspian Sea. Trends in annual ET0 values of the stations were analyzed using the Mann-Kendall test. Then to determine the relative importance of climatic variables on ET0 in a certain station factor analysis conducted. To do this, correlation matrix (R) of seven variables also called similarity matrix was constructed. The significance of correlation coefficients were tested. Results of trends in ET0 showed that in all the stations (except Noshahr) trends of annual ET0 were upward and significant. The slopes of trend lines were positive in all the stations. Factor analysis showed that the first two factors accounted the total variance in the range of 56.5 per cent in the Rasht to 79.6 per cent in the Sari. The largest loading of the first factor is attributed to sunshine hours in the station Rasht, however, it was maximum air temperature in all other sites. In the case of the second factor, the largest loading belonged to wind speed (in Rasht, Gorgan, Sari and Noshahr) and precipitation (in Ramsar and Astara). The findings of this study can be helpful in optimum management of regional water resources.
Climatology
Hashem Rostamzadeh; Saied Jahanbakhsh asl; Mir kamel Hosseini; Mohammad Omidfar
Abstract
AbstractChanges in the incidental behaviors are among the most important aspects of global climate change with significant consequences on human society and the environment. Monitoring and measuring heavy rainfall events are important for understanding the nature of severe weather fundamentals and future ...
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AbstractChanges in the incidental behaviors are among the most important aspects of global climate change with significant consequences on human society and the environment. Monitoring and measuring heavy rainfall events are important for understanding the nature of severe weather fundamentals and future assessment. In this study, Global Precipitation Measurement (GPM) experiments with ground station data were performed at 20 synoptic stations for intense daily detection (25 mm and above) of precipitation over an 8-year period (2021-2014). Statistics such as coefficient of determination (R2), correlation coefficient (R) and root mean square error (RMSE) were used to compare and evaluate the observational and satellite data. Comparison of the maps obtained from GPM satellites and ground stations showed that the spatial distribution of precipitation from two similar bases is the same and the low and high rainfall areas correspond to the region. GPM satellite detected precipitation zones well so that the spatial correlation coefficient between GPM satellite and observed was 0.81. The results of the ANOVA test between the observational data and the GPM satellites showed that due to the low significance level of p-value of 0.000, the assumption that the average precipitation is the same between the two databases is rejected. There is a significant relationship between the average precipitation at ground and satellite stations. Also, the results of Kolmogorov-Smirnov test showed that since the obtained p-value (0.819) is a number higher than the error value of the test (0.05), so the null hypothesis based on the equality of precipitation values recorded at ground stations and modeled are the same and the null hypothesis is confirmed.
