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Title: Topographic Effects on the Luzon Diurnal Cycle during the BSISO

Abstract

Cloud-resolving simulations are used to evaluate the importance of topography to the diurnal cycle (DC) of precipitation (DCP) over Luzon, Philippines, and surrounding ocean during the July–August 2016 boreal summer intraseasonal oscillation (BSISO) event. Composites of surface precipitation for each 30-min time increment during the day are made to determine the mean DCP. The mean DCP is computed separately for suppressed and active BSISO conditions and compared across three simulations with varying topography—flat, true, and doubled topographic height. The magnitude of the topographic height helps to dictate the timing, intensity, and location of diurnal precipitation over and near Luzon. For example, the mean DCP in the true topography run peaks 1.5 h later, is broader by 1 h, and has a 9% larger amplitude during active conditions relative to suppressed conditions. By contrast, the flat run mean DCP is earlier and narrower by 0.5 h with a 5% smaller amplitude during active conditions versus suppressed conditions. Within the suppressed or active BSISO conditions, the mean DCP peak and amplitude increase as the topographic height increases. The presence of elevated topography focuses precipitation over the coastal mountains during suppressed conditions, while dictating which side of the domain (i.e., east Luzon andmore » the Philippine Sea vs west Luzon and the South China Sea) more precipitation occurs in during active conditions. These topographic-induced changes are discussed in terms of mechanical and thermodynamic forcing differences between the two large-scale BSISO regimes for the three runs.« less

Authors:
 [1];  [1];  [1];  [1];  [1]
  1. Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1577218
Grant/Contract Number:  
FG02-97ER25308
Resource Type:
Published Article
Journal Name:
Journal of the Atmospheric Sciences
Additional Journal Information:
Journal Name: Journal of the Atmospheric Sciences Journal Volume: 77 Journal Issue: 1; Journal ID: ISSN 0022-4928
Publisher:
American Meteorological Society
Country of Publication:
United States
Language:
English

Citation Formats

Riley Dellaripa, Emily M., Maloney, Eric D., Toms, Benjamin A., Saleeby, Stephen M., and van den Heever, Susan C. Topographic Effects on the Luzon Diurnal Cycle during the BSISO. United States: N. p., 2020. Web. doi:10.1175/JAS-D-19-0046.1.
Riley Dellaripa, Emily M., Maloney, Eric D., Toms, Benjamin A., Saleeby, Stephen M., & van den Heever, Susan C. Topographic Effects on the Luzon Diurnal Cycle during the BSISO. United States. doi:10.1175/JAS-D-19-0046.1.
Riley Dellaripa, Emily M., Maloney, Eric D., Toms, Benjamin A., Saleeby, Stephen M., and van den Heever, Susan C. Wed . "Topographic Effects on the Luzon Diurnal Cycle during the BSISO". United States. doi:10.1175/JAS-D-19-0046.1.
@article{osti_1577218,
title = {Topographic Effects on the Luzon Diurnal Cycle during the BSISO},
author = {Riley Dellaripa, Emily M. and Maloney, Eric D. and Toms, Benjamin A. and Saleeby, Stephen M. and van den Heever, Susan C.},
abstractNote = {Cloud-resolving simulations are used to evaluate the importance of topography to the diurnal cycle (DC) of precipitation (DCP) over Luzon, Philippines, and surrounding ocean during the July–August 2016 boreal summer intraseasonal oscillation (BSISO) event. Composites of surface precipitation for each 30-min time increment during the day are made to determine the mean DCP. The mean DCP is computed separately for suppressed and active BSISO conditions and compared across three simulations with varying topography—flat, true, and doubled topographic height. The magnitude of the topographic height helps to dictate the timing, intensity, and location of diurnal precipitation over and near Luzon. For example, the mean DCP in the true topography run peaks 1.5 h later, is broader by 1 h, and has a 9% larger amplitude during active conditions relative to suppressed conditions. By contrast, the flat run mean DCP is earlier and narrower by 0.5 h with a 5% smaller amplitude during active conditions versus suppressed conditions. Within the suppressed or active BSISO conditions, the mean DCP peak and amplitude increase as the topographic height increases. The presence of elevated topography focuses precipitation over the coastal mountains during suppressed conditions, while dictating which side of the domain (i.e., east Luzon and the Philippine Sea vs west Luzon and the South China Sea) more precipitation occurs in during active conditions. These topographic-induced changes are discussed in terms of mechanical and thermodynamic forcing differences between the two large-scale BSISO regimes for the three runs.},
doi = {10.1175/JAS-D-19-0046.1},
journal = {Journal of the Atmospheric Sciences},
number = 1,
volume = 77,
place = {United States},
year = {2020},
month = {1}
}

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This content will become publicly available on December 4, 2020
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