- Title
- North Indian Ocean Basin [in "State of the Climate in 2019"]
- Creator
- Magee, A. D.; Schreck, C. J.
- Relation
- Bulletin of the American Meteorological Society Vol. 101, Issue 8, p. s219-s221
- Publisher Link
- http://dx.doi.org/10.1175/BAMS-D-20-0077.1
- Publisher
- American Meteorological Society
- Resource Type
- journal article
- Date
- 2020
- Description
- The North Indian Ocean (NIO) TC season typically occurs between April and December, with two peaks of activity: May–June and October–December, due to the presence of the monsoon trough over tropical waters of the NIO during these periods. Tropical cyclone genesis typically occurs in the Arabian Sea and Bay of Bengal between 8°–15°N. The Bay of Bengal, on average, experiences four times more TCs than the Arabian Sea (Dube et al. 1997). The 2019 NIO TC season was a particularly active and record-breaking TC season with eight named storms, six cyclones, and three major cyclones (tied 1999), compared to the IBTrACS–JTWC 1981–2010 climatology of 4.9, 1.5, and 0.7, respectively (Fig 4.30a). One event, Cyclone Kyarr, was the second-most intense cyclone ever observed in the Arabian Sea. The 2019 NIO TC season was also the second-costliest on record with losses exceeding $11 billion (U.S. dollars). Record-breaking ACE index values and a strongly positive Indian Ocean dipole (IOD) event characterized the 2019 NIO TC season (refer to the legend of Fig. 4.38 for the definition of IOD and its polarity). The 2019 seasonal ACE index was 85 × 104 kt2. It nearly doubled the previous record holders (2007 and 2013 each had about 45 × 104 kt2) and was over four times the 1981–2010 ACE climatology (19 × 104 kt2; Fig 4.30b). The strong positive IOD event that marked the latter half of the 2019 season is clearly seen in Fig 4.31a, where anomalously warm SSTs occurred in the western tropical Indian Ocean (10°N–10°S, 50°–70°E). In addition, enhanced convection (Fig 4.31b) and negative vertical wind shear anomalies (Fig 4.31c) provided favorable conditions in the Arabian Sea, contributing to the high number of events there. Although positive IOD events historically result in fewer TCs in the NIO (Yuan and Cao 2012), this was not the case for the 2019 TC season.
- Subject
- tropical cyclone; tc season; north indian ocean; climatology
- Identifier
- http://hdl.handle.net/1959.13/1442835
- Identifier
- uon:41808
- Identifier
- ISSN:0003-0007
- Language
- eng
- Reviewed
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