New approaches and algorithms for the analysis of vertical refractivity profile below 1 KM in a subtropical region

YesIn this paper, 17 years of high resolution surface and radiosonde meteorological data from 1997-2013 for the subtropical Gulf region are analysed. Relationships between the upper air refractivity, Nh, and vertical refractivity gradient, ΔN, in the low troposphere and the commonly available data of surface refractivity, Ns are investigated. A new approach is discussed to estimate Nh and ΔN from the analysis of the dry and wet components of Ns, which gives better results for certain cases. Results are compared with those obtained from existing linear and exponential models in the literature. The investigation focusses on three layer heights at 65 m, 100 m and 1 km above ground level. Correlation between the components of Ns with both Nh and ΔN are studied for each atmospheric layer. Where high correlations were found, empirical models are derived from best-fitting curves

New methodology for predicting vertical atmospheric profile and propagation parameters in sub-tropical Arabian Gulf region

YesA new simplified approach is proposed to evaluate the vertical refractivity profile within the lowest 1 km of atmosphere from the analysis of surface refractivity, Ns, in areas where upper air data are not available. Upper-air measurements from the nearest available radiosonde location with similar surface profile to these sites are utilized. The profiles of Ns and refractivity extrapolated to sea level, No, obtained from surface meteorological data using both fixed stations and radiosonde are investigated and compared. Vertical refractivity gradient, ΔN, is evaluated at three atmospheric layer heights within the first kilometer above the ground in addition to propagation parameters relevant to each atmospheric layer. At six sites, different approaches are compared for the analysis of three important parameters; namely effective earth radius factor, k, anomalous propagation probability parameter, β0, and point refractivity gradient at 65 m not exceeded for 1% of time, dN1. The k-factor parameter is investigated using a new weighted average approach of ΔN at 65 m, 100 m and 1 km layers above the ground. The results are compared with the latest ITU maps and tables for the same area

Seasonal statistics of anomalous propagation in United Arab Emirates

NoIn this paper, the seasonal variations of vertical refractivity gradients and statistics of anomalous Refractive Conditions in the United Arab Emirates (UAE) have been analyzed. Nine years of local radiosonde meteorological data, from 1997 to 2005, for the lowest atmospheric layer above the ground surface have been used. Monthly variations and cumulative distributions of refractivity gradients in the first 100 meters of the atmosphere are presented

Initial analysis of k-factor in the Gulf region

NoThis paper investigates the seasonal variations of effective earth radius factor, k, in the Arabian Gulf region where non-standard propagation phenomena are commonly experienced. The k-factor is derived from the vertical profile of refractivity in the area under study. The vertical refractivity gradient, δN, in the first kilometre of the atmosphere above the ground surface is analysed using long term meteorological data. Long-term radiosonde data gathered in the United Arab Emirates (UAE), are used to calculate the variations of refractivity gradient and k-factor parameter

Comparison of three vertical refractivity profiles in the Gulf region

In this paper, a set of local radiosonde meteorological data, from 1990 to 2005, have been used to statistically analyze the refractivity gradient, DeltaN, at the lowest 65 m, 100 m and 1 km of the atmosphere above the surface of the Earth in the Gulf region. These three levels are the reference atmospheric layers in which the refractivity gradients have been evaluated by the ITU-R Recommendations P.453-10 and P.452-12The vertical variations of the refractivity profile aredisplayed through the cumulative distributions of the refractivity gradients at the targeted levels. The obtained results are compared for the three layers and also compared with the estimated values in the ITU maps and tables when available. Index Terms – Atmospheric refraction, Refractivity gradient

Statistical analysis of refractivity gradient and β₀ parameter in the Gulf Region.

In this communication, nine years of local radiosonde meteorological data, from 1997 to 2005, have been used to calculate the vertical refractivity gradient, ΔΝ, in the lowest atmospheric layer above the ground surface. The values obtained are used to estimate the parameter β₀, which represents the probability of non-standard propagation. Hourly,monthly and yearly distributions of ΔΝ in the first 100 meters above the ground are given. Monthly and yearly variations of the mean of ΔΝ and β₀ are provided and the β₀ values are compared with the ITU maps