The Diurnal Path to Persistent Convective Self-Aggregation
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The Diurnal Path to Persistent Convective Self-Aggregation. / Jensen, Gorm G.; Fievet, Romain; Haerter, Jan O.
In: Journal of Advances in Modeling Earth Systems, Vol. 14, No. 5, e2021MS002923, 05.05.2022.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The Diurnal Path to Persistent Convective Self-Aggregation
AU - Jensen, Gorm G.
AU - Fievet, Romain
AU - Haerter, Jan O.
PY - 2022/5/5
Y1 - 2022/5/5
N2 - Clustering of tropical thunderstorms constitutes an important climate feedback because it influences the radiative balance. Convective self-aggregation (CSA) is a profound modeling paradigm for explaining the clustering of tropical oceanic thunderstorms. However, CSA is hampered in the realistic limit of fine model resolution when cold pools-dense air masses beneath thunderstorm clouds-are well-resolved. Studies on CSA usually assume the surface temperature to be constant, despite realistic surface temperatures varying significantly between night and day. Here we mimic the diurnal cycle in cloud-resolving numerical experiments by prescribing a surface temperature oscillation. Our simulations show that the diurnal cycle enables CSA at fine resolutions, and that the process is even accelerated by finer resolutions. We attribute these findings to vigorous combined cold pools emerging in symbiosis with mesoscale convective systems. Such cold pools suppress buoyancy in extended regions (similar to 100 km) and enable the formation of persistent dry patches. Our findings help clarify how the tropical cloud field forms sustained clusters under the diurnal forcing and may have implications for the origin of extreme thunderstorm rainfall and tropical cyclones.
AB - Clustering of tropical thunderstorms constitutes an important climate feedback because it influences the radiative balance. Convective self-aggregation (CSA) is a profound modeling paradigm for explaining the clustering of tropical oceanic thunderstorms. However, CSA is hampered in the realistic limit of fine model resolution when cold pools-dense air masses beneath thunderstorm clouds-are well-resolved. Studies on CSA usually assume the surface temperature to be constant, despite realistic surface temperatures varying significantly between night and day. Here we mimic the diurnal cycle in cloud-resolving numerical experiments by prescribing a surface temperature oscillation. Our simulations show that the diurnal cycle enables CSA at fine resolutions, and that the process is even accelerated by finer resolutions. We attribute these findings to vigorous combined cold pools emerging in symbiosis with mesoscale convective systems. Such cold pools suppress buoyancy in extended regions (similar to 100 km) and enable the formation of persistent dry patches. Our findings help clarify how the tropical cloud field forms sustained clusters under the diurnal forcing and may have implications for the origin of extreme thunderstorm rainfall and tropical cyclones.
KW - convection
KW - self-aggregation
KW - diurnal
KW - mesoscale
KW - clouds
KW - CLOUD
KW - PRECIPITATION
KW - EQUILIBRIUM
KW - OCEAN
KW - CYCLE
KW - CIRCULATION
KW - SIMULATIONS
KW - ATMOSPHERE
KW - FREQUENCY
KW - EXPLICIT
U2 - 10.1029/2021MS002923
DO - 10.1029/2021MS002923
M3 - Journal article
C2 - 35865232
VL - 14
JO - Journal of Advances in Modeling Earth Systems
JF - Journal of Advances in Modeling Earth Systems
SN - 1942-2466
IS - 5
M1 - e2021MS002923
ER -
ID: 315767598