Article
Geosciences, Multidisciplinary
Satyaban B. Ratna, Annalisa Cherchi, Timothy J. Osborn, Manoj Joshi, Umakanth Uppara
Summary: The extremely positive Indian Ocean Dipole (IOD) event in 2019 had a significant influence on the Indian Summer Monsoon (ISM) rainfall, particularly towards the end of the season. However, warm sea surface temperature anomalies in the central equatorial Pacific also played a role in affecting rainfall patterns over India.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
U. N. Athira, S. Abhilash
Summary: This study explores the interaction between the atmosphere and ocean before the onset of the Indian Ocean monsoon, revealing a complex mechanism involving radiation, sea surface temperature gradient, wind speed, evaporation, and convection processes. It demonstrates how the warming of the Arabian Sea leads to enhanced wind stress, cooling of sea surface temperature, and the development of SST gradients, ultimately contributing to the onset of the monsoon. Significant inter-annual correlations are found between wind stress, total precipitable water, and precipitation over the North Indian Ocean during this period, supporting the proposed mechanism.
Article
Geosciences, Multidisciplinary
Mengjiao Qin, Linshu Hu, Zhuoya Qin, Lin Wan, Lianjie Qin, Wenting Cao, Sensen Wu, Zhenhong Du
Summary: In this paper, a deep spatiotemporal embedding network (DSEN) is proposed to accurately predict the Pacific decadal oscillation (PDO) index. The model outperforms six benchmark methods and can skillfully predict the PDO index up to 1 year, based on 39 years of test data (1982-2020).
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Shaoyu Zhang, Yimin Liu, Buwen Dong, Chen Sheng
Summary: This study identifies the relationship between tropical southern Atlantic sea surface temperature anomaly and the El Nino-Southern Oscillation, and focuses on how the Pacific Decadal Oscillation modulates this relationship. The results show a significant but non-stationary interannual relationship, which undergoes a significant decadal shift. The study also proposes two processes to explain this decadal shift.
GEOPHYSICAL RESEARCH LETTERS
(2023)
Article
Geosciences, Multidisciplinary
Kai Cui, Yongbo Wang, Xingqi Liu, Ji Shen, Yong Wang
Summary: The sediment record from Beihai Wetland in southwestern China provides insights into the temporal variation of the Indian Summer Monsoon (ISM) during the Holocene. The study suggests that the sea-surface temperature (SST) anomalies in the tropical Indian Ocean played a significant role in modulating the strength of the ISM. Human activities were also found to have impacted the regional climate and contributed to catchment erosion in the area.
Article
Geosciences, Multidisciplinary
Mengjiao Qin, Zhenhong Du, Linshu Hu, Wenting Cao, Zhiyi Fu, Lianjie Qin, Sensen Wu, Feng Zhang
Summary: This paper presents a novel seasonal gated recurrent unit (SGRU) model based on deep learning for forecasting the Pacific decadal oscillation (PDO) at multiple time scales. The SGRU model demonstrates superior performance compared to other models in PDO forecasting and is capable of producing high-performance forecasts at multiple time scales.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Multidisciplinary Sciences
Arindam Chakraborty, Priyanshi Singhai
Summary: The relationship between tropical teleconnections and the Indian summer monsoon can be explained by net moisture convergence driven by surface pressure gradients surrounding the Indian region. The positive and negative phases of major tropical climate patterns asymmetrically modulate these pressure gradients, resulting in asymmetric impacts on ISM rainfall. Stronger El Nino droughts are attributed to greater decreased eastward moisture flux over the Arabian Sea during El Nino compared to La Nina, driven by proportionate meridional pressure gradients.
SCIENTIFIC REPORTS
(2021)
Review
Environmental Sciences
Antonietta Capotondi, Shayne McGregor, Michael J. McPhaden, Sophie Cravatte, Neil J. Holbrook, Yukiko Imada, Sara C. Sanchez, Janet Sprintall, Malte F. Stuecker, Caroline C. Ummenhofer, Mathias Zeller, Riccardo Farneti, Giorgio Graffino, Shijian Hu, Kristopher B. Karnauskas, Yu Kosaka, Fred Kucharski, Michael Mayer, Bo Qiu, Agus Santoso, Andrea S. Taschetto, Fan Wang, Xuebin Zhang, Ryan M. Holmes, Jing-Jia Luo, Nicola Maher, Cristian Martinez-Villalobos, Gerald A. Meehl, Rajashree Naha, Niklas Schneider, Samantha Stevenson, Arnold Sullivan, Peter van Rensch, Tongtong Xu
Summary: In this Review, the mechanisms and characteristics of tropical Pacific decadal variability (TPDV) are synthesized, including oceanic processes and atmospheric processes. Oceanic processes involve Rossby waves, upper-ocean overturning circulation, and salinity-compensated temperature anomalies, while atmospheric processes involve internal variability and atmospheric teleconnections. The tropical adjustment mechanism is likely the dominant mechanism, but the origin and spectral characteristics of TPDV-related winds remain uncertain.
NATURE REVIEWS EARTH & ENVIRONMENT
(2023)
Article
Multidisciplinary Sciences
Sunyong Kim, Jae-Heung Park, Jong-Seong Kug
Summary: The record-breaking rainfall extremes in East Asia during summer 2020 can be explained by the teleconnections associated with the tropical origins among the Indian, Pacific, and Atlantic Oceans and their interbasin interactions.
SCIENTIFIC REPORTS
(2022)
Article
Meteorology & Atmospheric Sciences
Xiangbai Wu, Gen Li, Wenping Jiang, Shang-Min Long, Bo Lu
Summary: The relationship between ENSO and SST anomalies in the tropical Indian Ocean during the decaying summer is asymmetric, with a weaker relationship between La Nina and SST anomalies relative to El Nino. This can be explained by asymmetries in initial SST, oceanic Rossby wave response, and ENSO decaying rate. La Nina events tend to have stronger initial warming and a slower decay, impacting climate predictability for the region.
JOURNAL OF CLIMATE
(2021)
Article
Geosciences, Multidisciplinary
Jianxiang Xu, Jing-Jia Luo, Chaoxia Yuan
Summary: The Arctic is currently experiencing significant warming, which has widespread impacts on global climate. A new study suggests that Indian Ocean warming contributes to the Arctic warming through enhancing the Atlantic Meridional Overturning Circulation, leading to increased ocean heat transport from the North Atlantic to the Arctic. This results in upper ocean warming dominating the surface warming in the Arctic. Additionally, despite the net negative contribution of atmospheric heat transport, more warm air is conveyed to the Kara Seas, North Eurasia, and North America sectors, contributing to local warming.
GEOPHYSICAL RESEARCH LETTERS
(2022)
Article
Meteorology & Atmospheric Sciences
Edwin K. Schneider, Benjamin P. Kirtman, Natalie Perlin
Summary: A comparison between a multicentury climate model control and an interactive ensemble simulation reveals the significant role of atmospheric noise in simulations of decadal internal variability of SST. The results suggest that almost all decadal SST variability is forced by internal atmospheric variability. The analysis of regional heat budgets indicates that the net atmospheric surface heat flux is in equilibrium with ocean dynamics forcing in the South Pacific and midlatitude North Atlantic regions. The study also investigates the relative contributions of atmospheric heat flux noise and ocean dynamics to the decadal volume-averaged heat budget of the upper ocean.
JOURNAL OF CLIMATE
(2023)
Article
Meteorology & Atmospheric Sciences
Lei Zhang, Gang Wang, Matthew Newman, Weiqing Han
Summary: This study analyzes sea surface temperature variability in the Indian Ocean, focusing on both internal processes and external influences from the Pacific. Results show that internally generated SST variability in the Indian Ocean is comparable to that forced by ENSO, indicating that the Indian Ocean actively influences the tropical Pacific.
JOURNAL OF CLIMATE
(2021)
Article
Meteorology & Atmospheric Sciences
Xiaoxue Yin, Lian-Tong Zhou, Kui Liu, Yongqiu Han, Zhaoyang Du
Summary: This study confirms the contribution of the warm sea surface temperature anomalies in the north Indian Ocean (NIO) and the north tropical Atlantic (NTA) to the extreme flood event in the Yangtze River valley (YRV) in 2020. The NIO warming influences the flooding through an anomalous Kelvin wave and a reversed Walker circulation, while the NTA warming enhances the flood through an anomalous zonal vertical circulation. These findings highlight the importance of considering sea surface temperature anomalies in the NIO and NTA regions when predicting extreme climate events in China.
THEORETICAL AND APPLIED CLIMATOLOGY
(2022)
Article
Geosciences, Multidisciplinary
Midhila Varna, Arvind Singh, Deepika Sahoo, Debasis Sengupta
Summary: During the winter months of 1990-2010, observations showed a decreasing trend in sea surface salinity in the southeastern Arabian Sea. This decline was primarily attributed to a 2-3 fold increase in the influx of low-salinity water due to the strengthening of the Northeast Monsoon Current and the West India Coastal Current.
GEOPHYSICAL RESEARCH LETTERS
(2021)
Article
Meteorology & Atmospheric Sciences
Subrota Halder, Anant Parekh, Jasti S. Chowdary, Chellappan Gnanaseelan, Ashwini Kulkarni
Summary: The study shows that CMIP6 models can capture the interannual and decadal variability of TIO SST reasonably well, with KACE-1-0-G model exhibiting the highest skill. Radiative and latent heat flux are found to be the primary drivers of interannual variability in TIO SST, and better representation of these fluxes in models leads to better simulation of TIO SST variability.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2021)
Article
Meteorology & Atmospheric Sciences
Nimmakanti Mahendra, Jasti Sriranga Chowdary, Patekar Darshana, Pilli Sunitha, Anant Parekh, Chellappan Gnanaseelan
Summary: The study examined the inter-decadal modulations of inter-annual ENSO-ISM rainfall regional teleconnection patterns in observations and CMIP6 models. The relationship between ENSO and all-India summer rainfall showed strong epochal changes, with varying teleconnection strengths in different epochs. Regional rainfall responses, including anomalous upward motion and low-level cyclonic circulation patterns, were found to influence the epochal changes in ENSO-ISM rainfall teleconnections over India. The CMIP6 models differed in their representations of these epochal changes, with approximately 35% of models accurately simulating the teleconnections.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2021)
Article
Meteorology & Atmospheric Sciences
J. S. Deepa, C. Gnanaseelan, Anant Parekh
Summary: This study examines the representation of interannual and decadal variability of sea level in the Indo-Pacific region using CMIP5 models. Results show that local wind forcing plays a dominant role in sea level variability, with differences in spatial patterns projected under different emission scenarios for the 21st century.
Article
Geography, Physical
J. S. Deepa, C. Gnanaseelan
Summary: The study found a close association between decadal sea level variability in the Indian Ocean and global decadal climate modes, particularly with the PDO and AMO. The sea level in regions like the west coast of India, east coast of India, and west coast of Australia shows an anti-phase evolution with the PDO index. Furthermore, the relationship between sea level variability and the AMO index is stronger in certain locations, such as Mumbai, than in others like Fremantle, suggesting spatial variations in the impact of these climate modes.
GLOBAL AND PLANETARY CHANGE
(2021)
Article
Remote Sensing
Ananya Karmakar, Anant Parekh, Jasti S. Chowdary, C. Gnanaseelan
Summary: This study demonstrates the importance of using multi satellite-based chlorophyll-a in an ocean model to accurately represent penetrative shortwave radiation, especially during the peak phase of strong El Nino events. Utilizing interannual chlorophyll-a variability can effectively improve surface temperature biases in models and enhance model realism.
INTERNATIONAL JOURNAL OF REMOTE SENSING
(2021)
Article
Meteorology & Atmospheric Sciences
K. Prasanna, Jasti S. Chowdary, Prem Singh, D. Chiranjeevi, C. V. Naidu, Anant Parekh, C. Gnanaseelan
Summary: The study evaluates the fidelity of eight climate models in representing the inter-annual variability and decadal shift in northeast monsoon rainfall over Southern Peninsular India. Most models exhibited poor skill in capturing inter-annual variability, with only one model showing good consistency with observed rainfall variations. The study also highlights the presence of clear decadal variability in rainfall patterns over the past few decades in the Southern Peninsular India region.
THEORETICAL AND APPLIED CLIMATOLOGY
(2021)
Article
Meteorology & Atmospheric Sciences
Jasti S. Chowdary, Amol S. Vibhute, Patekar Darshana, Anant Parekh, C. Gnanaseelan, Raju Attada
Summary: This study examines the impact of the meridional displacement of the Asian jet on Indian summer monsoon rainfall. The findings suggest that the southward displacement of the Asian jet leads to reduced precipitation over central and northern India regions. The study also reveals the physical mechanisms linking the southward displacement of the Asian jet and monsoon rainfall reduction.
Article
Meteorology & Atmospheric Sciences
Jayshri Patel, Chellappan Gnanaseelan, Jasti S. Chowdary, Anant Parekh
Summary: This study evaluated the decadal hindcast simulations of SAT over India from seven different ocean-atmosphere coupled models in CMIP5, finding that using the QM approach for bias corrections significantly improved forecasting skill, reducing absolute mean difference and uncertainty.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2022)
Article
Meteorology & Atmospheric Sciences
Subrota Halder, Anant Parekh, Jasti S. Chowdary, C. Gnanaseelan
Summary: This study found that there is significant decadal variability in summer monsoon rainfall in the Western Ghats, with increasing magnitude in recent years. The Indian and Pacific Oceans play a crucial role in influencing the rainfall patterns in this region. These findings are valuable for developing decadal prediction systems and understanding the evolution of the Western Ghats ecosystem.
NPJ CLIMATE AND ATMOSPHERIC SCIENCE
(2022)
Article
Meteorology & Atmospheric Sciences
T. S. Fousiya, Chellappan Gnanaseelan, Subrota Halder, Rashmi Kakatkar, Jasti S. Chowdary, Patekar Darshana, Anant Parekh
Summary: Predicting Indian Summer Monsoon (ISM) is challenging due to its complexity and nonlinear interactions. Three sets of hindcast experiments were conducted using NCEP-CFSv2, with different initializations. The experiments showed that Exp, which used a specific initialization strategy, improved the skill of ISM rainfall prediction and reduced initial shocks, resulting in better representation of mean tropical Indo-Pacific SST and atmospheric conditions. Exp also reduced the known biases and overdependence on El Nino Southern Oscillation in MayIC.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2023)
Article
Meteorology & Atmospheric Sciences
Amol S. Vibhute, Jasti S. Chowdary, Patekar Darshana, Hyo-Seok Park, K. Koteswara Rao, Anant Parekh, C. Gnanaseelan
Summary: The Indian subcontinent experienced abnormal subseasonal rainfall variations during the summer monsoon season in 2021. The study identifies the southward displacement of the Asian jet and the westward and northwestward extension of the Western north Pacific anticyclone as the main factors causing deficit rainfall in August, and the northward displacement of the Asian jet and the mid-latitude wave train from the northeast Atlantic as the factors contributing to enhanced rainfall in September. The Climate Forecast System version 2 and the North American Multi Model Ensemble models had limited prediction skill in capturing these changes.
ATMOSPHERIC RESEARCH
(2023)
Article
Meteorology & Atmospheric Sciences
Rahul U. Pai, Anant Parekh, Subrota Halder, Jasti S. Chowdary, C. Gnanaseelan
Summary: This study examines the impact of intra-decadal variability of Meridional Heat Transport (MHT) associated with Indian Ocean Shallow Meridional Overturning Circulation (SMOC) on rainfall variability over Southern Africa. It finds that the strength of MHT is closely related to sea surface temperature, sea level pressure, low level circulation, and moist static energy, which in turn affect the rainfall patterns in the region.
INTERNATIONAL JOURNAL OF CLIMATOLOGY
(2023)
Article
Geosciences, Multidisciplinary
S. Swetha, Jasti S. Chowdary, Anant Parekh, C. Gnanaseelan
Summary: The study evaluates the decadal prediction skill of Surface Air Temperature (SAT) over India in spring and summer, and its relationship with Sea Surface Temperature (SST) using the NCEP CFSv2 coupled model. Results show significant prediction skills in certain regions of India, but an underestimation of the relationship between SAT and SST in tropical and sub-tropical regions compared to observations and CNRM model.
JOURNAL OF EARTH SYSTEM SCIENCE
(2021)