Teleconnections between tropical SST modes and Indian summer monsoon in observation and CMIP5 models

Roy, Indrani; Kripalani, R. H.

doi:10.1016/b978-0-12-822402-1.00012-0

Cited by 3 publications

(1 citation statement)

References 81 publications

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“…Researchers have prioritized practical solutions to changing climate and the environment at multi‐scale systems. Recent studies have marked SST with large variations in precipitation, that is, increase (decrease) over high (low) latitudes, and clinched inconclusiveness over global precipitation changes (Boschat et al., 2012; Das et al., 2020; Lee et al., 2023; Roy & Kripalani, 2021). Moreover, patterns of large‐scale climatic indicators and teleconnection influence the variability of the spatial and temporal interaction of global precipitation and thus the availability of global water resources (Falga & Wang, 2022; Irannezhad et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Impact of Long‐Distance Interaction Indicator (Monsoon Indices) on Spatio‐Temporal Variability of Precipitation Over the Mahanadi River Basin

Sahu

Verma

Ahmad

2023

Water Resources Research

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Sea Surface Temperature (SST) is the most important physical characteristic of the ocean, that is, the temperature of water at the surface level, and it plays a significant role mainly with latitude (Ashok et al., 2001;Sahai et al., 2003;Verma, 1994). Atmospheric and oceanic behavior have been studied, but recent research has augmented the concern for an incomplete understanding of climate phenomena (Chakraborty & Singhai, 2021;Di Capua et al., 2020;Sundaram & Holland, 2022). The above concern is in connection with multi-scale system interaction, which typically exhibits unique local and non-local interrelationships (a statistical conceptualization). The SST and air temperature have a significant impact on the atmospheric moisture content, which is an

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Section: Introductionmentioning

confidence: 99%

Impact of Long‐Distance Interaction Indicator (Monsoon Indices) on Spatio‐Temporal Variability of Precipitation Over the Mahanadi River Basin

Sahu

Verma

Ahmad

2023

Water Resources Research

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Flash Drought Teleconnection With the Large‐Scale Climate Drivers in the Homogeneous Rainfall Regions of India

Pachore,

Remesan,

Kuttippurath

2024

Intl Journal of Climatology

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Flash drought events can be characterised by the quick depletion of crop root zone soil moisture (rapid intensification) and hence can be termed as agricultural flash droughts. These events can have devastating impacts, such as increasing the risk of agricultural yield loss, heatwaves and increased wildfire risk, which further have cascading impacts on the socio‐economic conditions. The regional hotspots of flash droughts are analysed for winter, pre‐monsoon, monsoon and post‐monsoon seasons over India from 1981 to 2020. We assess the impact of the El Niño‐Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on the flash drought frequency (FDF: number of flash drought events). The causal connection of the FDF with the ENSO and IOD is analysed using the PCMCI (Peter and Clark's algorithm combined with the Momentary Conditional Independence) algorithm. The monsoon season (June–September) is found to be more prone to flash droughts with higher spatial/regional average values of total per pixel FDF during the 40‐year period over the Central Northeast (~54) and West Central (~41) regions. It is observed that the fraction of the total number of flash droughts during the El Niño years (38.8%) is higher as compared with that in La Niña years (25.7%). It is also found that the co‐occurrence of positive/negative IOD with the El Niño phase can alter the seasonal fraction of FDF over India, highlighting the high complexity in the ENSO–IOD interactions. The causal analysis shows that only the Southern Peninsula and West Central regions have significant direct and lagged causal links of average per pixel FDF with IOD. Whereas, similar (direct and lagged) causal connections are observed between the ENSO and IOD. This study reveals that flash droughts and their teleconnections vary greatly among the seasons and regions in India, limiting its accurate predictions and increasing the risk to agricultural communities.

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Important drivers of East African monsoon variability and improving rainy season onset prediction

Roy,

Mliwa,

Troccoli

2023

Nat Hazards

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Monsoon rain and its year-to-year variability have a profound influence on Africa’s socio-economic structure by heavily impacting sectors such as agricultural and energy. This study focuses on major drivers of the east African monsoon during October-November-December (OND) which is the standard time window for the onset of the rainy season, be it unimodal or bimodal. Two drivers viz. Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO) both separately indicate very strong positive connections with monsoon (OND) rain not only in the OND season with zero seasonal lag, but the signal is also present even taking IOD and ENSO a season ahead. A compositing approach is applied that can additionally identify strong signals when different combinations of ENSO and IOD phases act as confounding factors. Results of precipitation anomaly suggest that when IOD and ENSO are both on the same phase in July-August-September (JAS), a significant OND rainfall anomaly occurs around the east African sector: A deficit (excess) of OND monsoon rain occurs when both drivers are in a negative (positive) phase during JAS. A location Kibaha in Tanzania, for which station data are available, is considered for a more in-depth analysis. The uncertainty range in cumulative OND rainfall is also reduced to a large degree when IOD and ENSO phases are both negative in JAS. These results can be used for prediction purposes and interestingly, that criterion of IOD and ENSO being of same phase in JAS was again matched in 2022 (both negative) and hence it was possible to deliver early warnings for a deficit in rainfall a season ahead. Techniques to compute the monsoon onset as determined by meteorological services such as the Tanzania Meteorological Authority rely on various thresholds, which may also vary by country. To overcome some of the issues with thresholds-based techniques, other definitions of ‘onset’ take into account cumulative rainfall amount and such technique has also been tested and compared. In both approaches, late (early) onsets dominate in years when ENSO and IOD are both negative (positive) during JAS. In these cases, it is therefore possible to provide an estimation of cumulative rainfall and onset for OND in terms of average, median value, range and distribution of rainfall one season in advance. Such results have implications for optimizing agricultural, water and energy management, also mitigating possible severe production losses, which would impact the livelihoods of millions of Africans.

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Teleconnections between tropical SST modes and Indian summer monsoon in observation and CMIP5 models

Cited by 3 publications

References 81 publications

Impact of Long‐Distance Interaction Indicator (Monsoon Indices) on Spatio‐Temporal Variability of Precipitation Over the Mahanadi River Basin

Impact of Long‐Distance Interaction Indicator (Monsoon Indices) on Spatio‐Temporal Variability of Precipitation Over the Mahanadi River Basin

Flash Drought Teleconnection With the Large‐Scale Climate Drivers in the Homogeneous Rainfall Regions of India

Important drivers of East African monsoon variability and improving rainy season onset prediction

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