Multidecadal Weakening of Indian Summer Monsoon Circulation Induces an Increasing Northern Indian Ocean Sea Level

Swapna, P.; Jyoti, J.; Krishnan, R.; Sandeep, N.; Griffies, Stephen M.

doi:10.1002/2017gl074706

Cited by 76 publications

(41 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The results here support this and further document nutrient declines. There is also evidence of sea level rise and associated weakening of the summer monsoon in the Equatorial Indian Ocean in recent decades (Swapna et al 2017). Such weakening could reduce the upwelling of nutrients and suppress ocean PP as we find here.…”

Section: Resultssupporting

confidence: 67%

Global ocean primary production trends in the modern ocean color satellite record (1998–2015)

Gregg

Rousseaux

2019

Environ. Res. Lett.

View full text Add to dashboard Cite

Ocean primary production (PP), representing the uptake of inorganic carbon through photosynthesis, supports marine life and affects carbon exchange with the atmosphere. It is difficult to ascertain its magnitude, variability, and trends due to our inability to measure it directly at large scales. Yet it is paramount for understanding changes in marine health, fisheries, and the global carbon cycle. Using assimilation of ocean color satellite data into an ocean biogeochemical model, we estimate that global net ocean PP has experienced a small but significant decline −0.8 PgC y −1 (−2.1%) decade −1 (P<0.05) in the 18-year satellite record from 1998 to 2015. This decline is associated with shallowing surface mixed layer depth (−2.4% decade −1 ) and decreasing nitrate concentrations (−3.2% decade −1 ). Relative contributions to PP by various types of ocean phytoplankton have changed, with decreases in production by intermediate-sized phytoplankton represented by chlorophytes (−14.3% decade −1 ). This is partially compensated by increases from the unique, more nutrient-efficient, coccolithophores (8.4% decade −1 ). Geographically, the North and Equatorial Indian Oceans are responsible for much of the decline in PP, falling 0.16 and 0.69 PgC y −1 decade −1 , respectively. Reduced production by large, fast-growing diatoms along with chlorophytes characterizes the decline here. In contrast, increases in PP are found in the North and North Central Pacific. The increases here are led by chlorophytes in the North Pacific and the small cyanobacteria in the North Central Pacific. These results suggest that the multi-decadal satellite observational record, coupled with an underlying representation of marine biodiversity in a model, can monitor the uptake of carbon by phytoplankton and that changes, although small, are occurring in the global oceans.

show abstract

Section: Resultssupporting

confidence: 67%

Global ocean primary production trends in the modern ocean color satellite record (1998–2015)

Gregg

Rousseaux

2019

Environ. Res. Lett.

View full text Add to dashboard Cite

show abstract

“…While some IOD events co-occur with ENSO, others are ENSO-independent (e.g., Meyers et al 2007; Sun et al 2015; Yang et al 2015). Additionally, variations of monsoon winds, which are often correlated with ENSO and IOD but sometimes act independently, also induce variability in sea level over the Indian Ocean (Han et al 2017b; Swapna et al 2017). In the south Indian Ocean, the subtropical Indian Ocean dipole (SIOD) was identified as a coupled ocean–atmosphere mode (Behera and Yamagata 2001; Suzuki et al 2004).…”

Section: The Indian Oceanmentioning

confidence: 99%

Impacts of Basin-Scale Climate Modes on Coastal Sea Level: a Review

et al. 2019

View full text Add to dashboard Cite

Global sea level rise (SLR) associated with a warming climate exerts significant stress on coastal societies and low-lying island regions. The rates of coastal SLR observed in the past few decades, however, have large spatial and temporal differences from the global mean, which to a large part have been attributed to basin-scale climate modes. In this paper, we review our current state of knowledge about climate modes’ impacts on coastal sea level variability from interannual-to-multidecadal timescales. Relevant climate modes, their impacts and associated driving mechanisms through both remote and local processes are elaborated separately for the Pacific, Indian and Atlantic Oceans. This paper also identifies major issues and challenges for future research on climate modes’ impacts on coastal sea level. Understanding the effects of climate modes is essential for skillful near-term predictions and reliable uncertainty quantifications for future projections of coastal SLR.

show abstract

“…preindustrial-control simulation are shaded and zonal and meridional surface wind fields are shown as vectors in the figure. The AllForc experiment (Figure 14c) shows a weakening of monsoon circulation with reversal in monsoon cross-equatorial flow over the Arabian Sea, Bay of Bengal as well as over the Indian land mass similar to the observed trend in summer monsoon circulation (Krishnan et al, 2016;Swapna et al, 2017;Bollasina et al, 2011). The precipitation response from the AllForc Exp shows decrease in precipitation over the Indian region associated with the weakening of summer monsoon circulation.…”

Section: Climate Change Modeling Capabilitiesmentioning

confidence: 53%

Long‐Term Climate Simulations Using the IITM Earth System Model (IITM‐ESMv2) With Focus on the South Asian Monsoon

Swapna

Krishnan

Sandeep

et al. 2018

J Adv Model Earth Syst

Self Cite

View full text Add to dashboard Cite

Long-term climate simulations are performed using the IITM Earth System Model version 2 (IITM-ESMv2), a sequel to the earlier version (IITM-ESMv1), to assess climate variability and change with a special focus on the South Asian monsoon. Substantial improvements are incorporated in IITM-ESMv2 to obtain a radiatively balanced global climate modeling framework. The IITM-ESMv2 includes time-varying aerosol forcing and land-use land-cover changes. Multicentury simulations corresponding to preindustrial and present-day conditions show major improvements in capturing key aspects of time-mean atmosphere and ocean large-scale circulation. Representations of the Atlantic Meridional Overturning Circulation and poleward ocean heat transport, and major global climate drivers are superior to ESMv1. Teleconnections of the South Asian monsoon with climate drivers such as the El-Niño-Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) are found to be more robust in IITM-ESMv2, thus leading to improved simulation of South Asian monsoon and its variability. The IITM-ESMv2 takes a novel pursuit from India to contribute in the Intergovernmental Panel for Climate Change (IPCC) sixth assessment report (AR6).Plain Language Summary This study details the capabilities of the IITM Earth System Model version 2 (IITM-ESMv2), developed at the Indian Institute of Tropical Meteorology, Pune, India, for investigating long-term climate variability and change with special focus on the South Asian monsoon.

show abstract

Multidecadal Weakening of Indian Summer Monsoon Circulation Induces an Increasing Northern Indian Ocean Sea Level

Cited by 76 publications

References 56 publications

Global ocean primary production trends in the modern ocean color satellite record (1998–2015)

Global ocean primary production trends in the modern ocean color satellite record (1998–2015)

Impacts of Basin-Scale Climate Modes on Coastal Sea Level: a Review

Long‐Term Climate Simulations Using the IITM Earth System Model (IITM‐ESMv2) With Focus on the South Asian Monsoon

Contact Info

Product

Resources

About