Bosong Zhang

Journal of Climate (2021)

The Role of Radiative Interactions in Tropical Cyclone Development under Realistic Boundary Conditions

TC-permitting mechanism-denial experiments show that synoptic radiative interactions are required for realistic pre-TC development and global TC frequency under observed-like forcing.

TC-Permitting GCM Mechanism-Denial Experiments Moist Static Energy Budget

Lower TC Count

Suppressing synoptic-scale radiative interactions reduces global TC frequency.

Coastal Shift

Genesis locations shift and storm lifetimes shorten in ClimRad-style experiments.

Warming Dependence

Radiative-control sensitivity weakens as latent-heating influence grows in warmer climates.

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Paper Citation

Zhang, B., B. J. Soden, G. A. Vecchi, and W. Yang, 2021: The Role of Radiative Interactions in Tropical Cyclone Development under Realistic Boundary Conditions. Journal of Climate, 34, 2079-2091. https://doi.org/10.1175/JCLI-D-20-0574.1

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Scientific Logic

  • Question: Are synoptic-scale radiative interactions necessary for realistic tropical cyclone development with observed-like boundary forcing?
  • Method: Global TC-permitting GCM experiments that suppress synoptic radiative-cooling anomalies via climatological overwriting.
  • Mechanism: Radiative feedbacks amplify pre-TC moist-static-energy variance and support transition from precursor disturbances to developing storms.
  • Main Findings: Removing synoptic radiative interactions significantly reduces global TC frequency primarily by decreasing successful pre-TC development events.

Scientific Question

How strongly do synoptic-scale radiative interactions contribute to tropical cyclone development and frequency under realistic boundary conditions, and how does that role change with warming?

Experimental Design

  • Global TC-permitting model simulations with and without radiative interactions.
  • Mechanism-denial experiments to isolate boundary-layer and free-tropospheric radiative effects.
  • Diagnostics based on storm statistics, track density, and moist static energy variance budgets.

Key Findings

  • Suppressing synoptic radiative anomalies significantly reduces global TC counts.
  • The dominant pathway is fewer precursor disturbances successfully transitioning into TCs.
  • Radiative feedbacks amplify moist-static-energy variance that supports genesis and early intensification.

Figures from the Study

Extracted from Zhang et al. (2021, Journal of Climate, https://doi.org/10.1175/JCLI-D-20-0574.1).

Figure 3 (Extracted)

Extracted Figure 3 showing tropical cyclone track density maps and differences
Global track-density diagnostics comparing Control and ClimRad, including their spatial differences.

Figure 8 (Extracted)

Extracted Figure 8 showing fractional changes binned by interval for Cat 0-5 and Cat 1-5
Binned fractional changes for Cat 0-5 and Cat 1-5 storms (Control minus ClimRad diagnostics).

Additional Extracted Figure

Extracted figure showing annual tropical cyclone counts across datasets and experiments
Year-to-year TC counts in observations and model experiments, highlighting the reduced storm counts in the no-radiative-interaction run.

Additional Extracted Figure

Extracted figure showing wind-speed-dependent radiative and surface-flux contributions
Wind-speed-dependent decomposition of thermodynamic contributions and their changing fractional roles across experiments.
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