wind erosion is a significant problem on 20 million ha of iran, especially in central plains and coastal areas. winderosion samplers, meteorological equipments and measurement procedure have been developed over the last twocenturies to measure the particles moving across the field in modes of creep, saltation and suspension. in recentresearch as the first technical measurement in iran, wind ero...

This study compared dispersion calculations using a street network model (SIRANE) with results from wind tunnel experiments in order to examine model performance in simulating short-range pollutant dispersion in urban areas. The comparison was performed using a range of methodologies, from simple graphical comparisons (e.g. scatter plots) to more advanced statistical analyses. A preliminary ana...

the variety of sprinkler devices available for the center pivot and linear irrigation systems has been increased dramatically in recent years. in the current study, via conducting some indoor experiments, one type of fixed pad spray sprinkler (d3000) and two types of moving pad spray sprinklers (r3000 and s3000) with various configurations (working pressure, nozzle size and type of deflector pa...

A cellular automata fire model represents ‘elements’ of fire by autonomous agents. A few simple algebraic expressions substituted for complex physical and meteorological processes and solved iteratively yield simulations for ‘super-diffusive’ fire spread and coupled surface-layer (2-m) fire–atmosphere processes. Pressure anomalies, which are integrals of the thermal properties of the overlying ...

A small-slope approximation (SSA) is used for numerical calculations of a radar backscattering cross section of the ocean surface for both Kuand C-bands for various wind speeds and incident angles. Both the lowest order of the SSA and the one that includes the next-order correction to it are considered. The calculations were made by assuming the surface-height spectrum of Elfouhaily et al for f...

We study periodic wind-tree models, unbounded planar billiards with periodically located rectangular obstacles. For a class of rational parameters we show the existence of completely periodic directions, and recurrence; for another class of rational parameters, there are directions in which all trajectories escape, and we prove a rate of escape for almost all directions. These results extend to...

The NASA Scatterometer (NSCAT) estimates the wind speed and direction of near-surface ocean wind. Several possible wind vectors are estimated for each resolution element known as a wind vector cell (wvc). Typically, the speeds of the possible wind vectors are nearly the same, but the directions are very di erent. The correct wind must be distinguished in a step called ambiguity removal. Unfortu...

a r t i c l e i n f o Global winds provided by satellite scatterometry are an important aspect of the ocean observing system. Many applications require well-calibrated time series of winds over time periods spanned by multiple missions. But sensors on individual satellites differ, introducing differences in wind estimates. This study focuses on global winds from two scatterometers, ERS-2 (1996–...

Asymptotically exact and nonlocal third order nonlinear evolution equations are derivedfor two counterpropagating surface capillary gravity wave packets in deep water in thepresence of wind flowing over water.From these evolution equations stability analysis ismade for a uniform standing surface capillary gravity wave trains for longitudinal perturbation. Instability condition is obtained and g...

Given its biological significance, determining the dispersal kernel (i.e., the distribution of dispersal distances) of spore-producing pathogens is essential. Here, we report two field experiments designed to measure disease gradients caused by sexually- and asexually-produced spores of the wind-dispersed banana plant fungus Mycosphaerella fijiensis. Gradients were measured during a single gene...