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High Spatiotemporal Resolution Planetary Boundary Layer Dynamics Across the Israeli Coast-Mountain-Valley Terrain Unraveled by WRF Simulations
  • David Avisar,
  • Sigalit Berkovic
David Avisar
IIBR

Corresponding Author:[email protected]

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Sigalit Berkovic
IIBR
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Abstract

The west-east terrain cross-section along ~150km of the northern part of Israel is characterized by a coastal-plain—mountain—valley structure; hereafter denodet iCMV. However, the boundary layer height (BLH) evolution mechanism across the iCMV has not yet been fully unraveled. We use Weather Research and Forecasting (WRF) simulations and ceilometer measurements to decipher the iCMV BLH evolution mechanism during a late summertime period, where the daily maximal BLH at the mountainous city of Jerusalem (JrM; 800m above sea-level) varies by ~1000m. We first verify the BLH simulated by 5 model configurations (with 4 different BL schemes). The RMSE for the 3 best configurations are around 160 and 200m for the coastal and JrM areas, respectively. An analysis of the modeled daily BL evolution reveals a general mechanism. At the early morning, the up-slope flows and synoptic forcing conspire to induce a surface flow convergence (SurFCon) zone. For pronounced westerly (easterly) general flow, the SurFCon is induced east (west) of JrM. Assisted by the inland propagating sea-breeze front, the SurFCon is advected eastwards during the afternoon. The SurFCon zone is accompanied by a substantial vertical wind column and a locally-elevated BLH. The more western the morning-time SurFCon is, the more likely the elevated BLH will pass during midday through JrM, with a higher daily maximum BLH. At the late afternoon, the SurFCon zone arrives at the valley bottom and collapses. The dependence of the mechanism upon the synoptic regime, and the corresponding temperature and humidity dynamics, require further study.