Impact of convection over the equatorial through on indian summer monsoon activity
By: Gopika S.
Contributor(s): Kurien E K (Guide).
Material type:
BookPublisher: Vellanikkara Academy of Climate Change Education and Research 2015Description: 72 pages.Subject(s): Climate Change AdaptationDDC classification: 551.6 Online resources: Click here to access online Dissertation note: MSc Abstract: The existence or nonexistence of break and active cycle of rainfall over the
Indian subcontinent during the mid-monsoon months of July and August decides the
success and failure of Indian monsoon rainfall. Effect of active or break cycle,
convective systems and convection over the equatorial trough (ET) on Indian summer
monsoon rainfall (ISMR) were studied. An increased number of convective systems in
the west Pacific showed high negative correlation with rainfall over equatorial trough
regions. During active monsoon years, cyclones are focused between 10° - 25° N and
110° - 140° E whereas the cyclones were widely distributed during the break monsoon
years. The co-occurrence of active or break spells and convective activity have
considerable influence on ISMR. During an active spell, enhanced convection was
observed over North Indian Ocean (NIO) while during break spell it was over ET
regions. Strong, widespread and short duration cyclonic activity over North West
Pacific (NWP) resulted in a break spell in ISMR.
The relative influence of El-Niño Southern oscillation and Indian Ocean Dipole
(IOD) events on ISMR have been further studied for the period 1950-2010. In order to
look into the role of El-Niño on the monsoon, the SST data over five regions (REG-I
to REG-IV) were studied. SSTs in the central Pacific (Niño 3.4; REG- II) and eastern
Pacific (Niño 3; REG- III) regions were more correlated with ISMR during the
observation period. Decadal analysis showed that the temperature of central Pacific
region indicated rapid cooling in the recent decades and increased the temperature
gradient between western and eastern Pacific Ocean. This cooling in the central Pacific
could create La-Niña type conditions. During El-Niño (La-Niña) years, the weakened
(strengthened) Walker circulation influence the summer monsoon rainfall over the
Indian subcontinent. The newly created Walker circulation index is a promising tool to
examine the strengthening (weakening) of the Walker circulation to predict the Indian
summer monsoon in future research.
| Item type | Current location | Collection | Call number | Status | Date due | Barcode |
|---|---|---|---|---|---|---|
Theses
|
KAU Central Library, Thrissur Theses | Reference Book | 551.6 GOP/IM (Browse shelf) | Not For Loan | 173775 |
MSc
The existence or nonexistence of break and active cycle of rainfall over the
Indian subcontinent during the mid-monsoon months of July and August decides the
success and failure of Indian monsoon rainfall. Effect of active or break cycle,
convective systems and convection over the equatorial trough (ET) on Indian summer
monsoon rainfall (ISMR) were studied. An increased number of convective systems in
the west Pacific showed high negative correlation with rainfall over equatorial trough
regions. During active monsoon years, cyclones are focused between 10° - 25° N and
110° - 140° E whereas the cyclones were widely distributed during the break monsoon
years. The co-occurrence of active or break spells and convective activity have
considerable influence on ISMR. During an active spell, enhanced convection was
observed over North Indian Ocean (NIO) while during break spell it was over ET
regions. Strong, widespread and short duration cyclonic activity over North West
Pacific (NWP) resulted in a break spell in ISMR.
The relative influence of El-Niño Southern oscillation and Indian Ocean Dipole
(IOD) events on ISMR have been further studied for the period 1950-2010. In order to
look into the role of El-Niño on the monsoon, the SST data over five regions (REG-I
to REG-IV) were studied. SSTs in the central Pacific (Niño 3.4; REG- II) and eastern
Pacific (Niño 3; REG- III) regions were more correlated with ISMR during the
observation period. Decadal analysis showed that the temperature of central Pacific
region indicated rapid cooling in the recent decades and increased the temperature
gradient between western and eastern Pacific Ocean. This cooling in the central Pacific
could create La-Niña type conditions. During El-Niño (La-Niña) years, the weakened
(strengthened) Walker circulation influence the summer monsoon rainfall over the
Indian subcontinent. The newly created Walker circulation index is a promising tool to
examine the strengthening (weakening) of the Walker circulation to predict the Indian
summer monsoon in future research.
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