Using a Synoptic-Scale Mixing Diagnostic to Explain Global Precipitation Variability from Weekly to Interannual Time ScalesSource: Journal of Climate:;2022:;volume( 035 ):;issue: 024::page 4625DOI: 10.1175/JCLI-D-22-0110.1Publisher: American Meteorological Society
Abstract: Precipitation often happens along organized filaments or bands of moisture such as convergence zones. Recent regional studies have shown that these moisture filaments arise from synoptic-scale mixing features known as attracting Lagrangian coherent structures (LCSs). In this study, we present a climatology of synoptic-scale mixing and investigate its covariability with precipitation on temporal scales ranging from weekly to interannual. We characterize mixing with the finite-time Lyapunov exponent (FTLE), a measure of parcel deformation, in ERA5 data between 1980 and 2009. Attracting LCSs are identified as ridges of the FTLE. At the interannual time scale, we compare El Niño and La Niña events and find that composites of precipitation and mixing anomalies share similar spatial patterns. We also compare summer and winter seasons and find that composites of seasonal-mean precipitation and mixing anomalies present similar characteristics, with precipitation being particularly intense (weak) where mixing is strong (weak). In particular, these patterns closely match the typical signatures of the intertropical convergence zone (ITCZ) and monsoon systems and the migrations of extratropical cyclone tracks. At the subseasonal scale, we employ daily composites to investigate the influence of the Madden–Julian oscillation and the North Atlantic Oscillation on the mixing regimes of the Atlantic and east Pacific; our results indicate that these oscillations control the synoptic-scale horizontal mixing and the occurrence of LCSs as to suppress or enhance precipitating systems like the ITCZ and the South Atlantic convergence zone. The results presented in this first climatology of synoptic-scale mixing and LCSs indicate that these are powerful diagnostics to identify circulation mechanisms underlying precipitation variability.
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contributor author | Gabriel M. P. Perez | |
contributor author | Pier Luigi Vidale | |
contributor author | Helen Dacre | |
contributor author | Jorge L. García-Franco | |
date accessioned | 2023-04-12T18:44:41Z | |
date available | 2023-04-12T18:44:41Z | |
date copyright | 2022/12/02 | |
date issued | 2022 | |
identifier other | JCLI-D-22-0110.1.pdf | |
identifier uri | http://yetl.yabesh.ir/yetl1/handle/yetl/4290167 | |
description abstract | Precipitation often happens along organized filaments or bands of moisture such as convergence zones. Recent regional studies have shown that these moisture filaments arise from synoptic-scale mixing features known as attracting Lagrangian coherent structures (LCSs). In this study, we present a climatology of synoptic-scale mixing and investigate its covariability with precipitation on temporal scales ranging from weekly to interannual. We characterize mixing with the finite-time Lyapunov exponent (FTLE), a measure of parcel deformation, in ERA5 data between 1980 and 2009. Attracting LCSs are identified as ridges of the FTLE. At the interannual time scale, we compare El Niño and La Niña events and find that composites of precipitation and mixing anomalies share similar spatial patterns. We also compare summer and winter seasons and find that composites of seasonal-mean precipitation and mixing anomalies present similar characteristics, with precipitation being particularly intense (weak) where mixing is strong (weak). In particular, these patterns closely match the typical signatures of the intertropical convergence zone (ITCZ) and monsoon systems and the migrations of extratropical cyclone tracks. At the subseasonal scale, we employ daily composites to investigate the influence of the Madden–Julian oscillation and the North Atlantic Oscillation on the mixing regimes of the Atlantic and east Pacific; our results indicate that these oscillations control the synoptic-scale horizontal mixing and the occurrence of LCSs as to suppress or enhance precipitating systems like the ITCZ and the South Atlantic convergence zone. The results presented in this first climatology of synoptic-scale mixing and LCSs indicate that these are powerful diagnostics to identify circulation mechanisms underlying precipitation variability. | |
publisher | American Meteorological Society | |
title | Using a Synoptic-Scale Mixing Diagnostic to Explain Global Precipitation Variability from Weekly to Interannual Time Scales | |
type | Journal Paper | |
journal volume | 35 | |
journal issue | 24 | |
journal title | Journal of Climate | |
identifier doi | 10.1175/JCLI-D-22-0110.1 | |
journal fristpage | 4625 | |
journal lastpage | 4643 | |
page | 4625–4643 | |
tree | Journal of Climate:;2022:;volume( 035 ):;issue: 024 | |
contenttype | Fulltext |