 |
| Titel |
Variability of upper ocean characteristics and tropical cyclones in the South West Indian Ocean |
| VerfasserIn |
Daneeja Mawren, Chris Reason |
| Konferenz |
EGU General Assembly 2017
|
| Medientyp |
Artikel
|
| Sprache |
en
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141362
|
| Publikation (Nr.) |
 EGU/EGU2017-4866.pdf |
|
|
|
|
|
| Zusammenfassung |
| Track and intensity are key aspects of tropical cyclone behaviour. Intensity may be impacted
by the upper ocean heat content integrated over a variable mixing length (known as
Tdy) and barrier layer thickness (BLT). Here, the variability of Tdy and BLT in
the South West Indian Ocean and their relationships with tropical cyclones are
investigated. It is shown that rapid cyclone intensification is influenced by large
Tdy values, thick barrier layers and the presence of anticyclonic eddies. For TC
generation in the South West Indian Ocean, the parameter Tdy was found to be
important.
Large BLT overlay with large Tdy values during summer (r = 0.47, November-April) and
are modulated by Rossby waves propagation. Tdy and BLT are strongly correlated with
ENSO. The 1997-1998 El Niño shows a strong signal in Tdy, SST and BLT over the South
West Indian Ocean. Thereafter, an increasing trend in Tdy occurred over most of the basin
which may be associated with changes in atmospheric circulation. Increasing SST, Power
Dissipation Index and frequency of Category-5 tropical cyclones also occurred from 1980 to
2010.
To further examine the links between tropical cyclones, Tdy and BLT, an analysis of the
ocean response to Category 5 Tropical Cyclone Bansi that developed near Madagascar during
January 2015 is performed. Its unusual track was found to be linked with the strengthening of
the monsoonal north westerlies while its rapid intensification from Category-2 to Category-4
was linked to a high-Tdy region, associated with a warm core eddy and large BLT. |
|
|
|
|
|
|