Abstract
Observations of the diurnal cycle in tropical cyclones (TCs) systematically indicate a ∼12-hr offset between peak rainfall rate and the maximum height of anvil clouds in the TC cloud canopy. This phasing conflicts with archetypal models of organized deep convection, which suggest a tight coupling between rainfall, vertical cloud growth, and anvil clouds. We show that this phasing owes to the bimodal diurnal evolution of the transverse circulation, which peaks nocturnally from low–midlevels, and during daytime in the upper troposphere. The bottom-heavy nocturnal circulation state is driven by latent heating from nocturnally invigorated deep convection, while the top-heavy daytime state is the thermally direct circulation response to strong shortwave-cloud warming in the optically thick TC cloud canopy. This daytime upper-level circulation response manifests in a lifting of the maximum height of the TC outflow and, in turn, a lifting and invigoration of the upper-level anvil clouds of the TC cloud canopy.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 502-511 |
| Number of pages | 10 |
| Journal | Geophysical Research Letters |
| Volume | 46 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 16 2019 |
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All Science Journal Classification (ASJC) codes
- Geophysics
- Earth and Planetary Sciences(all)
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Diurnal Cloud and Circulation Changes in Simulated Tropical Cyclones. / Ruppert, James, Jr.,; O'Neill, Morgan E.
In: Geophysical Research Letters, Vol. 46, No. 1, 16.01.2019, p. 502-511.Research output: Contribution to journal › Article
TY - JOUR
T1 - Diurnal Cloud and Circulation Changes in Simulated Tropical Cyclones
AU - Ruppert, James, Jr.,
AU - O'Neill, Morgan E.
PY - 2019/1/16
Y1 - 2019/1/16
N2 - Observations of the diurnal cycle in tropical cyclones (TCs) systematically indicate a ∼12-hr offset between peak rainfall rate and the maximum height of anvil clouds in the TC cloud canopy. This phasing conflicts with archetypal models of organized deep convection, which suggest a tight coupling between rainfall, vertical cloud growth, and anvil clouds. We show that this phasing owes to the bimodal diurnal evolution of the transverse circulation, which peaks nocturnally from low–midlevels, and during daytime in the upper troposphere. The bottom-heavy nocturnal circulation state is driven by latent heating from nocturnally invigorated deep convection, while the top-heavy daytime state is the thermally direct circulation response to strong shortwave-cloud warming in the optically thick TC cloud canopy. This daytime upper-level circulation response manifests in a lifting of the maximum height of the TC outflow and, in turn, a lifting and invigoration of the upper-level anvil clouds of the TC cloud canopy.
AB - Observations of the diurnal cycle in tropical cyclones (TCs) systematically indicate a ∼12-hr offset between peak rainfall rate and the maximum height of anvil clouds in the TC cloud canopy. This phasing conflicts with archetypal models of organized deep convection, which suggest a tight coupling between rainfall, vertical cloud growth, and anvil clouds. We show that this phasing owes to the bimodal diurnal evolution of the transverse circulation, which peaks nocturnally from low–midlevels, and during daytime in the upper troposphere. The bottom-heavy nocturnal circulation state is driven by latent heating from nocturnally invigorated deep convection, while the top-heavy daytime state is the thermally direct circulation response to strong shortwave-cloud warming in the optically thick TC cloud canopy. This daytime upper-level circulation response manifests in a lifting of the maximum height of the TC outflow and, in turn, a lifting and invigoration of the upper-level anvil clouds of the TC cloud canopy.
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U2 - 10.1029/2018GL081302
DO - 10.1029/2018GL081302
M3 - Article
VL - 46
SP - 502
EP - 511
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 0094-8276
IS - 1
ER -