Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations
Abstract We investigate a scaling relationship between global tropical cyclone (TC) frequency and the latitude of the intertropical convergence zone (ITCZ) in simulations performed with a 50‐km‐resolution aquaplanet version of the Geophysical Fluid Dynamics Laboratory Atmosphere Model 4.0. The simul...
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American Geophysical Union (AGU)
2025-07-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004868 |
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| author | Adam C. Burnett Aditi Sheshadri Thomas Robinson Pu Lin |
| author_facet | Adam C. Burnett Aditi Sheshadri Thomas Robinson Pu Lin |
| author_sort | Adam C. Burnett |
| collection | DOAJ |
| description | Abstract We investigate a scaling relationship between global tropical cyclone (TC) frequency and the latitude of the intertropical convergence zone (ITCZ) in simulations performed with a 50‐km‐resolution aquaplanet version of the Geophysical Fluid Dynamics Laboratory Atmosphere Model 4.0. The simulations use fixed, zonally symmetric sea surface temperature distributions, including some with uniform warming and cooling perturbations. We find that TC frequency per unit area is proportional to the Coriolis parameter at the ITCZ, following the same scaling introduced in a previous study. We hypothesize that TCs in these simulations originate as precursor disturbances at the ITCZ and intensify into TCs upon reaching sufficiently warm SSTs. We test this interpretation by tracking TC precursors, with different methods based on precipitation and vorticity, and comparing TC precursor frequency with TC frequency and ITCZ latitude. Both tracking methods show that precursors predominantly originate around the poleward edge of the ITCZ, consistent with our hypothesized TC genesis pathway. We also verify that most TC genesis events are immediately preceded by the occurrence of a precursor in the same area. However, precursor frequency is only weakly correlated with the Coriolis parameter at the ITCZ and precursor frequency. The correlation is stronger for vorticity‐based precursors than for precipitation‐based precursors. These mixed results provide partial, but not complete, support for our hypothesized interpretation. They also illustrate how results can depend on the choice of precursor tracking scheme, underlining a need for improved understanding of how best to define and track TC precursors. |
| format | Article |
| id | doaj-art-1467c3a67b804bde89e4e15e09e0beb6 |
| institution | DOAJ |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-1467c3a67b804bde89e4e15e09e0beb62025-08-20T03:09:19ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-07-01177n/an/a10.1029/2024MS004868Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet SimulationsAdam C. Burnett0Aditi Sheshadri1Thomas Robinson2Pu Lin3Department of Earth System Science Stanford University Stanford CA USADepartment of Earth System Science Stanford University Stanford CA USAGeophysical Fluid Dynamics Laboratory Princeton NJ USAGeophysical Fluid Dynamics Laboratory Princeton NJ USAAbstract We investigate a scaling relationship between global tropical cyclone (TC) frequency and the latitude of the intertropical convergence zone (ITCZ) in simulations performed with a 50‐km‐resolution aquaplanet version of the Geophysical Fluid Dynamics Laboratory Atmosphere Model 4.0. The simulations use fixed, zonally symmetric sea surface temperature distributions, including some with uniform warming and cooling perturbations. We find that TC frequency per unit area is proportional to the Coriolis parameter at the ITCZ, following the same scaling introduced in a previous study. We hypothesize that TCs in these simulations originate as precursor disturbances at the ITCZ and intensify into TCs upon reaching sufficiently warm SSTs. We test this interpretation by tracking TC precursors, with different methods based on precipitation and vorticity, and comparing TC precursor frequency with TC frequency and ITCZ latitude. Both tracking methods show that precursors predominantly originate around the poleward edge of the ITCZ, consistent with our hypothesized TC genesis pathway. We also verify that most TC genesis events are immediately preceded by the occurrence of a precursor in the same area. However, precursor frequency is only weakly correlated with the Coriolis parameter at the ITCZ and precursor frequency. The correlation is stronger for vorticity‐based precursors than for precipitation‐based precursors. These mixed results provide partial, but not complete, support for our hypothesized interpretation. They also illustrate how results can depend on the choice of precursor tracking scheme, underlining a need for improved understanding of how best to define and track TC precursors.https://doi.org/10.1029/2024MS004868tropical cyclonestropical cyclone precursorstropical cyclone frequencytropical meteorologyatmospheric dynamicsclimate modeling |
| spellingShingle | Adam C. Burnett Aditi Sheshadri Thomas Robinson Pu Lin Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations Journal of Advances in Modeling Earth Systems tropical cyclones tropical cyclone precursors tropical cyclone frequency tropical meteorology atmospheric dynamics climate modeling |
| title | Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations |
| title_full | Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations |
| title_fullStr | Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations |
| title_full_unstemmed | Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations |
| title_short | Connecting Tropical Cyclones, Precursor Disturbances, and the ITCZ in Aquaplanet Simulations |
| title_sort | connecting tropical cyclones precursor disturbances and the itcz in aquaplanet simulations |
| topic | tropical cyclones tropical cyclone precursors tropical cyclone frequency tropical meteorology atmospheric dynamics climate modeling |
| url | https://doi.org/10.1029/2024MS004868 |
| work_keys_str_mv | AT adamcburnett connectingtropicalcyclonesprecursordisturbancesandtheitczinaquaplanetsimulations AT aditisheshadri connectingtropicalcyclonesprecursordisturbancesandtheitczinaquaplanetsimulations AT thomasrobinson connectingtropicalcyclonesprecursordisturbancesandtheitczinaquaplanetsimulations AT pulin connectingtropicalcyclonesprecursordisturbancesandtheitczinaquaplanetsimulations |