Tools
ToolsPeatman, Simon C., Birch, Cathryn E., Schwendike, Juliane, Marsham, John H., Howard, Emma, Woolnough, Steven J., Mustafa, Jack M. and Matthews, Adrian J. (2025) Physical controls on the variability of offshore propagation of convection from Sumatra. Journal of Geophysical Research: Atmospheres, 130 (7). ISSN 2169-897X
Preview |
PDF (Peatman_etal_2025_JGRAtmospheres)
- Published Version
Available under License Creative Commons Attribution. Download (4MB) | Preview |
Abstract
Previous work has explained the physical mechanisms behind nocturnal offshore propagation of convection southwest of Sumatra. Low-level moisture flux convergence due to the land breeze front controls the progression of convection, typically a squall line, away from the coast overnight. However, the diurnal convection over the mountains occurs on only 57% of days in December–February (DJF) and propagates offshore on only 49% of those days. We investigate day-to-day variability in dynamical and thermodynamical conditions to explain the variability in diurnal convection and offshore propagation, using a convection-permitting simulation run for 900 DJF days. A convolutional neural network is used to identify regimes of the diurnal cycle and offshore propagation behavior. The diurnal cycle and offshore propagation are most likely to occur ahead of an active Madden-Julian oscillation, or during El Niño or positive Indian Ocean Dipole; however, any regime can occur in any phase of these large-scale drivers, because the major control arises from the local scale. When the diurnal cycle of convection occurs over land, low-level wind is generally onshore, providing convergence over the mountains, and low-level humidity over the mountains is high enough to make the air column unstable for moist convection. When this convection propagates offshore, midlevel offshore winds provide a steering flow, combined with stronger convergence offshore due to more onshore environmental winds. Low-level moisture around the coast also means that as the convection propagates, the storm-relative inflow of air into the system adds greater instability than would be the case on other days.
| Item Type: | Article |
|---|---|
| Additional Information: | Data Availability Statement: Raw and processed model data are available along with analysis code at https://doi.org/10.5281/zenodo.13747261 (Peatman et al., 2024). GPM IMERG precipitation (Huffman et al., 2019) is available from the National Aeronautics and Space Administration (NASA) Goddard Earth Sciences Data and Information Services Center (GES DISC; https://pmm.nasa.gov/data-access/downloads/gpm). RMM indices are available from the Bureau of Meteorology (BoM, 2024, www.bom.gov.au/climate/mjo/graphics/rmm.74toRealtime.txt). GLOBE orography (Hastings et al., 1999) is available from the National Oceanic and Atmospheric Administration (NOAA; https://www.ngdc.noaa.gov/mgg/topo/globe.html). Funding information: This research was funded by the National Environment Research Council (NERC) through the TerraMaris project, grants NE/R016739/1, NE/R016704/1, and NE/R016712/1. JS was funded by the Met Office Weather and Climate Science for Service Partnership (WCSSP) Southeast Asia. SJW was also supported by the National Centre for Atmospheric Science, a collaborative center. |
| Uncontrolled Keywords: | maritime continent,convection,diurnal cycle,offshore propagation,precipitation,geophysics,space and planetary science,earth and planetary sciences (miscellaneous),atmospheric science,sdg 15 - life on land ,/dk/atira/pure/subjectarea/asjc/1900/1908 |
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Groups > Fluids & Structures Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 18 Mar 2025 14:30 |
| Last Modified: | 23 Apr 2025 10:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/98783 |
| DOI: | 10.1029/2024JD042458 |
Downloads
Downloads per month over past year
Actions (login required)
 |
View Item |