Automatic Identification of Clear-Air Echoes Based on Millimeter-wave Cloud Radar Measurements

Yang, Ling; Wang, Yun; Wang, Zhongke; Yang, Qian; Fan, Xiaohui; Fa, Tao; Zhen, Xiaoqiong; Yang, Zhipeng

doi:10.1007/s00376-020-9270-z

Cited by 4 publications

(2 citation statements)

References 23 publications

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“…Indeed, the presence of subside dry air (except summer) moving in these Saharan areas combines with the intense heat to make the region virtually free of super-refraction. For instance, during spring at 1800 UTC, over the top of sandy lands and the rocky mountains as shown in Figure 1, super-refractive conditions are often less likely to exist than in valleys and plains (Yang et al, 2020). Over the Sahara, for example, this effect appears very clear.…”

Section: Seasonal and Diurnal Variation Of Super-refractionmentioning

confidence: 99%

Climatology of super‐refraction and trapping layers conditions over Central and West Africa

Kaïssassou

Djiotang

Komkoua

et al. 2021

Meteorological Applications

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The propagation of radio electric waves emitted from ground-based meteorological instruments is determined through stratification of the atmosphere. In super-refractive cases characterized by strong temperature inversions or strong vertical moisture gradients, the radar beam can be deflected towards the ground (trapping). This phenomenon often results in spurious returned echoes and misinterpretation of radar images such as erroneous precipitation, wind, and temperature detection. In this study, a 5-year Central and West Africa (CWA) climatology of the frequency of super-refractive and trapping-layer base height has been produced using refractivity computations from European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at a 40-km horizontal resolution and 60 levels in the vertical direction. The aim of this climatology is to improve the understanding on how frequent such anomalous propagations conditions are, which is a prerequisite for fully benefiting from radar data information for the multiple purposes of model validation, precipitation analysis, and data assimilation. First, the main climatological features are summarized for the whole CWA: Sahara and inlands seldom experience super-refraction, whereas coastal areas are strongly affected, especially in regions where the temperature inversion and the trade winds are intense lying near the surface. Over land, seasonal averages of super-refraction frequencies reach 80% (40%) over moist areas year-round but remain below 40% (15%) in most other regions. Seasonal statistics exhibit a pronounced diurnal cycle of super-refraction occurrences, with averaged frequencies peaking at 60% in summer late afternoon over the areas located on the Atlantic Ocean border but inlands region are less affected with super-refractive cases by midday.

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Section: Seasonal and Diurnal Variation Of Super-refractionmentioning

confidence: 99%

Climatology of super‐refraction and trapping layers conditions over Central and West Africa

Kaïssassou

Djiotang

Komkoua

et al. 2021

Meteorological Applications

View full text Add to dashboard Cite

show abstract

“…Atmospheric temperature and humidity profiles are one of the most important meteorological parameters characterizing the state and properties of the atmosphere, and are essential for providing real-time information on the weather situation and rainfall characteristics for weather forecasting, artificial weather impact, natural disaster prevention, and climate science research [1]. The current conventional means of obtaining atmospheric temperature and humidity profiles include the release of sounding balloons, meteorological radar, and satellite remote sensing, which suffer from low spatial and temporal resolution, high cost, and lack of flexibility [2]. Ground-based microwave radiometer obtains atmospheric temperature and humidity profiles with high spatial and temporal resolution through inversion technology, which has the advantages of all-weather, high resolution, and operability, and effectively makes up for the shortcomings of other detection means, and has unique advantages that cannot be replaced by other atmospheric detection means [3].…”

Section: Introductionmentioning

confidence: 99%