contributes 2.5–5.5% of annual rainfall (Vinaya Kumar et al. 2017). Research shows
that decrease in southwest monsoon rainfall and increase of post-monsoon rainfall
were observed (Krishnakumar et al. 2009; Soman et al. 1988). Climate change is a
primary element in manipulating the fishery and agricultural productivity of coastal
Karnataka (Vinaya Kumar et al. 2017). The Uttara Kannada district shows an
increasing trend for monsoon rainfall, and the Udupi district (À1.9 mm year
À1 )
and Dakshina Kannada (À7.1 mm year
À1
) show a decreasing trend in monsoon
rainfall over the period of 1980–2013 (Vinaya Kumar et al. 2017). The relationship
between El Nino and summer monsoon rainfall has been studied for the years
1875–1979 (Rasmusson and Carpenter 1983). The Southern Oscillation Index
(SOI) was established by Wright (1977). Increase in sea surface temperature (SST)
along the eastern Pacific Ocean is shown to be related to the deficits of southwest
monsoon rainfall over India (Rasmusson and Carpenter 1983; Kiladis and Diaz
1989; Mooley and Paolino 1989). Correlation between El Nino, Southern Oscillation, and summer monsoon rainfall over India has been meticulously observed
(Sikka 1980; Rasmusson and Carpenter 1983; Parthasarathy and Pant 1985; Mooley
1997).The El Nino Southern Oscillation has a strong impact on the frequency of
winter monsoon rainfall (Revadekar and Kulkarni 2008). Daily rainfall data have
been used to monitor the substantial increase in frequency and magnitude of intense
rainfall events, and a major decreasing trend in the frequency of rainy days of the
monsoon season has been observed from 1951 to 2000 (Goswami et al. 2006). For
the past two decades, the relationship between ENSO and summer monsoon rainfall
has been diminishing (Kripalani and Kulkarni 1997; Krishna Kumar et al. 1999).
Methodology
The rainfall data from 1901 to 2019 have been utilized (https://www.indiastat.com)
to correlate with the El Nino years, obtained from the Golden Gate Weather Services
to determine the impact of ENSO along coastal Karnataka. The El Nino Southern
Oscillation (ENSO) is a seasonal variability in sea surface temperature and atmospheric air pressure overlying the tropical Pacific Ocean. ENSO consist of three
phases: El Nino (warm ocean current), the La Nina (cold ocean current), and the
neutral phase. Centuries ago, fishermen along the South American coast first discovered coastal water to be warming more than normal around Christmas time, so
they termed it El Nino, which means ‘boy child’ in Spanish. Later, in the 1980s, the
opposite phase of El Niño was identified, the cooler than normal ocean temperatures,
which scientists named La Niña, which means ‘girl child’ in Spanish. El Nino and La
Nina phases last as long as 9–12 months, developing during the months of March to
June (spring), intensifying during the months of November to February (late autumn
or winter), and weakening during March to June (spring or early summer). In rare
conditions El Nino and La Nina might last more than a year. The longest El Nino
phase was 18 months, and for La Nina 33 months. The increase in sea surface
10 Impact of Climate Extremes of El Nina and La Nina in Patterns of Seasonal. . .
229
that decrease in southwest monsoon rainfall and increase of post-monsoon rainfall
were observed (Krishnakumar et al. 2009; Soman et al. 1988). Climate change is a
primary element in manipulating the fishery and agricultural productivity of coastal
Karnataka (Vinaya Kumar et al. 2017). The Uttara Kannada district shows an
increasing trend for monsoon rainfall, and the Udupi district (À1.9 mm year
À1 )
and Dakshina Kannada (À7.1 mm year
À1
) show a decreasing trend in monsoon
rainfall over the period of 1980–2013 (Vinaya Kumar et al. 2017). The relationship
between El Nino and summer monsoon rainfall has been studied for the years
1875–1979 (Rasmusson and Carpenter 1983). The Southern Oscillation Index
(SOI) was established by Wright (1977). Increase in sea surface temperature (SST)
along the eastern Pacific Ocean is shown to be related to the deficits of southwest
monsoon rainfall over India (Rasmusson and Carpenter 1983; Kiladis and Diaz
1989; Mooley and Paolino 1989). Correlation between El Nino, Southern Oscillation, and summer monsoon rainfall over India has been meticulously observed
(Sikka 1980; Rasmusson and Carpenter 1983; Parthasarathy and Pant 1985; Mooley
1997).The El Nino Southern Oscillation has a strong impact on the frequency of
winter monsoon rainfall (Revadekar and Kulkarni 2008). Daily rainfall data have
been used to monitor the substantial increase in frequency and magnitude of intense
rainfall events, and a major decreasing trend in the frequency of rainy days of the
monsoon season has been observed from 1951 to 2000 (Goswami et al. 2006). For
the past two decades, the relationship between ENSO and summer monsoon rainfall
has been diminishing (Kripalani and Kulkarni 1997; Krishna Kumar et al. 1999).
Methodology
The rainfall data from 1901 to 2019 have been utilized (https://www.indiastat.com)
to correlate with the El Nino years, obtained from the Golden Gate Weather Services
to determine the impact of ENSO along coastal Karnataka. The El Nino Southern
Oscillation (ENSO) is a seasonal variability in sea surface temperature and atmospheric air pressure overlying the tropical Pacific Ocean. ENSO consist of three
phases: El Nino (warm ocean current), the La Nina (cold ocean current), and the
neutral phase. Centuries ago, fishermen along the South American coast first discovered coastal water to be warming more than normal around Christmas time, so
they termed it El Nino, which means ‘boy child’ in Spanish. Later, in the 1980s, the
opposite phase of El Niño was identified, the cooler than normal ocean temperatures,
which scientists named La Niña, which means ‘girl child’ in Spanish. El Nino and La
Nina phases last as long as 9–12 months, developing during the months of March to
June (spring), intensifying during the months of November to February (late autumn
or winter), and weakening during March to June (spring or early summer). In rare
conditions El Nino and La Nina might last more than a year. The longest El Nino
phase was 18 months, and for La Nina 33 months. The increase in sea surface
10 Impact of Climate Extremes of El Nina and La Nina in Patterns of Seasonal. . .
229