Interdecadal variability of early summer monsoon rainfall over South China in association with the Pacific Decadal Oscillation

ABSTRACT. El Ninos which occurred during 1871-1990 are divided into two categories of events. The first category, EW, consists of the El Ninos in which the equatorial southeast (ESE) Pacific region (0-10° S; 80°W-180°W) experienced a Warn1ing phase as defined by suitable objective criteria, and the second category, E, consists of El Ninos in which the ESE Pacific region did not experience the warming phase. Sea surface temperature rise as well as anomaly over the Pacific region, summer monsoon rainfall over India and over its meteorological sub-divisions, in the categories EW and E are compared. Area-averaged rainfall of India for the summer monsoon season and for each of the months July and September are significantly (at 0.1 percent level) lower in EW events in comparison to those in E events. The summer monsoon rainfall of each of the 12 sub-divisions, from northwest and central India constituting about 50 per cent of the Indian plains, is significantly lower in EW events than that in E events, the highest rainfall deficiency in EW events being in the westernmost sub-divisions, i.e., West Rajasthan and Saurashtra-Kutch. Possible causes for the same have also been discussed.

Download Full-text

Design of a Regional Climate Model for the Simulation of South China Summer Monsoon Rainfall

Journal of the Meteorological Society of Japan Ser II ◽

10.2151/jmsj.82.1645 ◽

2004 ◽

Vol 82 (6) ◽

pp. 1645-1665 ◽

Cited By ~ 20

Author(s):

Johnny C.L. CHAN ◽

Yiming LIU ◽

K.C. CHOW ◽

Yihui DING ◽

William K.M. LAU ◽

...

Keyword(s):

Regional Climate Model ◽

Summer Monsoon ◽

South China ◽

Climate Model ◽

Monsoon Rainfall ◽

Regional Climate ◽

Summer Monsoon Rainfall

Download Full-text

Interdecadal Variability in Myanmar Rainfall in the Monsoon Season (May–October) Using Eigen Methods

Water ◽

10.3390/w13050729 ◽

2021 ◽

Vol 13 (5) ◽

pp. 729

Author(s):

Zin Mie Mie Sein ◽

Irfan Ullah ◽

Farhan Saleem ◽

Xiefei Zhi ◽

Sidra Syed ◽

...

Keyword(s):

Summer Monsoon ◽

North Atlantic ◽

Monsoon Rainfall ◽

North Atlantic Ocean ◽

Summer Monsoon Rainfall ◽

Interdecadal Variability ◽

The North ◽

Eastern Equatorial Pacific ◽

Rainfall Anomalies ◽

The North Atlantic

In this study, we investigated the interdecadal variability in monsoon rainfall in the Myanmar region. The gauge-based gridded rainfall dataset of the Global Precipitation Climatology Centre (GPCC) and Climatic Research Unit version TS4.0 (CRU TS4.0) were used (1950–2019) to investigate the interdecadal variability in summer monsoon rainfall using empirical orthogonal function (EOF), singular value decomposition (SVD), and correlation approaches. The results reveal relatively negative rainfall anomalies during the 1980s, 1990s, and 2000s, whereas strong positive rainfall anomalies were identified for the 1970s and 2010s. The dominant spatial variability mode showed a dipole pattern with a total variance of 47%. The power spectra of the principal component (PC) from EOF revealed a significant peak during decadal timescales (20–30 years). The Myanmar summer monsoon rainfall positively correlated with Atlantic multidecadal oscillation (AMO) and negatively correlated with Pacific decadal oscillation (PDO). The results reveal that extreme monsoon rainfall (flood) events occurred during the negative phase of the PDO and below-average rainfall (drought) occurred during the positive phase of the PDO. The cold phase (warm phase) of AMO was generally associated with negative (positive) decadal monsoon rainfall. The first SVD mode indicated the Myanmar rainfall pattern associated with the cold and warm phase of the PDO and AMO, suggesting that enhanced rainfall for about 53% of the square covariance fraction was related to heavy rain over the study region except for the central and eastern parts. The second SVD mode demonstrated warm sea surface temperature (SST) in the eastern equatorial Pacific (El Niño pattern) and cold SST in the North Atlantic Ocean, implying a rainfall deficit of about 33% of the square covariance fraction, which could be associated with dry El Niño conditions (drought). The third SVD revealed that cold SSTs in the central and eastern equatorial Pacific (La Niña pattern) caused enhance rainfall with a 6.7% square covariance fraction related to flood conditions. Thus, the extra-subtropical phenomena may affect the average summer monsoon trends over Myanmar by enhancing the cross-equatorial moisture trajectories into the North Atlantic Ocean.

Download Full-text