Abolfazl Neyestani

Razi University | razi · Department of Physics

It is believed that in the lower ionosphere, particularly in the ionospheric sporadic E (Es) layers (90–130 km), the planetary and tidal wave-type oscillations in the ionized component indicate the planetary and tidal waves in the neutral atmosphere. In the present work, the presence of wave-type oscillations, including planetary and tidal waves in...

Iran is located in world's dry belt, so studying the precipitation characteristics and its periodicity of different harmonics has significant role on water resources management. In this study the spatial and temporal analysis of monthly precipitation frequency over Iran are investigated using harmonic analysis techniques. To do so, long monthly pre...

Spectral decomposition is an appropriate tool for analysis frequency contents of climatologically data. Spectral analysis provide frequency contents of climatic signal in base stationary supposition of time series, but it is not indicate the exact time of frequency contents, while Wavelet transform is a useful technique for analyzing localized vari...

Iran has a complex topography and it consists of rugged, mountainous rims surrounding high interior basins. Because of this condition, in some cases the NWP output has a significant error from mesoscale variations induced by the diverse topography. Iran, covering an area of about 1,648,000 km2, is located in the southwest of Asia approximately betw...

In this research, the possible interrelationship between several global climatic indices has been investigated by employing four statistical methods. In the first step, the spectral content of the data and their intensities were obtained at different harmonics using spectral analysis. Then the correlation analysis was used to calculate the correlat...

The current study aims at improving our common knowledge of precipitation and surface temperature variabilities in Iran across different time scales (from intra-annual to decadal) by using two methods (the cumulative spectral power and wavelet coherence analyses) and linking the variabilities to several teleconnection indices, namely Mediterranean...

Separation of different frequency bands in the complex and combined signals related to meteorological variables and also climatic indices requires the use of digital filtering methods. In this way, the information on different frequency bands can be organized and used. Given that these signals generally exhibit complex and nonlinear behavior, the u...

The impact of applying three-dimensional variational data assimilation (3D-Var DA) on convective-scale forecasts is investigated by using two mesoscale models, the Weather Research and Forecasting model (WRF-ARW) and the Hirlam and Aladin Research Model On Non-hydrostatic-forecast Inside Europe (HARMONIE-AROME). One month (1 to 30 December 2013) of...

Ever increasing attention is being paid to the use of Numerical Weather Prediction (NWP) models in the convection-permitting mode for providing high-resolution forecasts. In such applications, the use of NWP models and comparison among the simulations of models help us to understand the problems associated with these scales and to unravel the syste...

Extreme weather phenomenon such as flood, thunderstorm, hurricane and etc. causes enormous casualties and property damage in different countries around the world. To provide precaution notice and reduce losses, the design of early warning system is an effective procedure to identify high risk area and disaster scenarios and scales. In management of...

Geography and Environmental Planning Journal

Complexity of climatic variables on time– spatial scales shows necessity of using efficient methods such as spectral analysis and digital filtering as a useful tool to study climate patterns. In this paper, spectral analysis has been employed to validate a GCM with observations over Iran. Precipitation values obtained from the 20C3M (run1) experime...