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The new Mountain Observatory of the Project “Optimizing Cloud Seeding by Advanced Remote Sensing and Land Cover Modification (OCAL)” in the United Arab Emirates: First results on Convection Initiation
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  • Oliver Branch,
  • Andreas Behrendt,
  • Osama Alnayef,
  • Florian Späth,
  • Thomas Schwitalla,
  • Maouane Temimi,
  • Michael Weston,
  • Sufian Farah,
  • Karel de Waal,
  • Siddharth Tampi,
  • Omar Al Yazeedi,
  • Volker Wulfmeyer
Oliver Branch
University of Hohenheim, Germany

Corresponding Author:[email protected]

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Andreas Behrendt
University of Hohenheim
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Osama Alnayef
University of Hohenheim
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Florian Späth
University of Hohenheim
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Thomas Schwitalla
University of Hohenheim
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Maouane Temimi
Stevens Institute of Technology
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Michael Weston
Masdar Institute, Khalifa University
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Sufian Farah
National Center of Meteorology, UAE
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Karel de Waal
National Center of Meteorology, UAE
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Siddharth Tampi
National Center of Meteorology, UAE
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Omar Al Yazeedi
National Center of Meteorology, UAE
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Volker Wulfmeyer
University of Hohenheim
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Abstract

In this study, we discuss a new mountain peak observatory in the United Arab Emirates (UAE). Using coordinated scan patterns, a Doppler lidar and cloud radar were employed to study seedable convective clouds, and identify pre-convection initiation (CI) clear-air signatures. The instruments were employed for approximately two years in an extreme environment with a high vantage point for observing valley wind flows and convective cells. The instruments were configured to run synchronized polar (PPI) scans at 0°, 5°, and 45° elevation angles and vertical cross-section (RHI) scans at 0°, 30°, 60, 90°, 120°, and 150° azimuth angles. Using this output imagery, along with local C-band radar and satellite data, we were able to identify and analyze several convective cases. To illustrate our results, we selected two cases in unstable conditions - the 5 and 6 September 2018. In both cases, we observed areas of convergence/divergence, particularly associated with wind flow around a peak 2 km to the south-west. The extension of these deformations were visible in the atmosphere as high as 3 km above sea level. Subsequently, we observed convective cells developing in the same directions – apparently connected with these phenomena. The cloud radar images provided detailed observations of cloud structure, evolution, and precipitation. In both convective cases, pre-convective signatures were apparent before CI, in the form of convergence, wind shear structures, and updrafts. These results demonstrate the value of synergetic observations for understanding convection initiation, improvement of forecast models, and cloud seeding guidance.