ENSO teleconnections to the Indian summer monsoon in observations and models

Abstract

The teleconnections of different types of El Niño Southern Oscillation (ENSO) to the Indian summer monsoon are investigated in observations and models. We find that, not all regions in India are strongly affected by ENSO, so we focus on two regional teleconnections: (1) a negative rainfall signal around central north east (CNE) India and ‘hilly’ region during El Niño (and vice versa for La Niña) and (2) similar signal for parts of southern peninsular region. Using correlations, it is found that >50% of the fifth phase of the Coupled Model Inter‐comparison Project models capture these two regional teleconnections, with first captured by >80% of models. Furthermore, using a compositing technique that may better capture asymmetries in response to warm and cold events, the authors find that most models again agree on the sign of regional teleconnection around the CNE and hilly region, suggesting the robustness of ENSO signal in that region. The peninsular teleconnection is less well simulated in models. We find a clear connection between the Walker circulation and Indian summer monsoon rainfall around central India in models.

Evaluating ENSO teleconnections using observations and CMIP5 models

“…Modoki also indicate lesser mean observed SST value for both EN and LN phases than that from its respective counterpart in Canonical phase (as both have same x-axis range). Analysing spatial pattern, Roy et al (2017) earlier discussed that in terms of sign of SST, all CMIP5 models agree with observed SST composites. Ensemble mean SST spatial pattern of 23 models is also presented (Fig.…”

“…SAM is originated in the upper stratosphere and related to stratospheric polar vortex features. Hence, our initial task was also to examine whether E N S O M o d o k i f e a t u r e s a n d r e l a t e d o c e a n i c teleconnections are better captured for H models than L. Roy et al (2017) considered the period June-JulyAugust (JJA) and analysed ENSO-ISM teleconnection. It showed that observed regional spatial patterns in different ENSO phases are not very well captured by models.…”

“…For instance, Brown et al (2009), Cai and Cowan (2009), and Taschetto and England (2009) described the climatic impacts of each type of ENSO on Australian rainfall, while Roy et al (2017) and Roy and Tedeschi (2016) studied its impact on Indian Summer Monsoon. Similar studies were also performed by Weng et al (2007Weng et al ( , 2009 in the Pacific Rim region, Chang et al (2008) in the South China Sea, Feng et al (2010Feng et al ( , 2011 on the East Asian climate and at the global scale by Ashok et al (2007).…”

Indian Summer Monsoon and El Niño Southern Oscillation in CMIP5 Models: A Few Areas of Agreement and Disagreement

“…Figure 1. Map of the Indian subcontinent with CI and CII regions marked with appropriate boundaries (also shown in [39]). CI is the region chosen by [5], and CII is the region chosen by [8].…”

“…In those studies, they elaborately discussed the teleconnection focusing on two different types of ENSO: Eastern Pacific (EP)-type ENSO (and often known as Canonical ENSO) and Central Pacific (CP)-type ENSO (often known as Modoki ENSO). This is because various studies suggested that there are differences in global and local influences between ENSO Modoki and Canonical ENSO ( [39], among others). Focusing on ISM, it was indicated [38] that more than 80% of the CMIP5 models capture ENSO-ISM regional teleconnections around the CNE region, irrespective of EP or CP ENSO category.…”