About

Anantha Aiyyer is a professor at NC State University within the Department of Marine, Earth, and Atmospheric Sciences. The provided page text does not include specific details about his research focus, background, or key contributions.

Research topics

• Geology
• Climatology
• Environmental science
• Physics
• Mechanics
• Geophysics
• Atmospheric sciences
• Meteorology
• Geography
• Statistical physics

Selected publications

• Thank You to Our 2025 Peer Reviewers

  Repository for Publications and Research Data (ETH Zurich) · 2026-03-18

  otherOpen access

  On behalf of the journal, AGU, and the scientific community, the editors of Geophysical Research Letters would like to sincerely thank those who reviewed manuscripts in 2025.

  PublisherDOI

• Thank You to Our 2025 Peer Reviewers

  Geophysical Research Letters · 2026-03-13

  articleOpen access

  Key Points The editors thank the 2025 peer reviewers

  PublisherDOI

• Case Studies of the Monsoon Onset Vortex and Early Season Monsoon Features Using the UFS Coupled Model

  Weather and Forecasting · 2026-03-18

  article

  Abstract The monsoon onset vortex (MOV) forms in the Arabian Sea during the onset phase of the Indian summer monsoon. The track and intensity of the MOV affect the monsoon rainfall during its onset phase, mainly over the west coast of India. This paper evaluates the reforecasts of MOV cases in the years 2011, 2014, and 2015 and their impacts on the monsoon rainfall in the Unified Forecast System (UFS) subseasonal to seasonal (S2S) prototypes (P5, P6, and P8). Out of the three MOV cases, the 2015 MOV is forecasted better across the UFS S2S prototypes. The possible factors influencing MOV forecasts in the UFS are analyzed through feature-based diagnostics. Our findings show that predicting the low-level Somali jet as well as the mesoscale-to-synoptic-scale evolution of deep convection is likely to result in more accurate MOV forecasts. The implications of MOV forecasts on the monsoon rainfall during the onset phase are discussed through these MOV cases. The UFS also captures the relationship between the Somali jet index and monsoon rainfall over India for the early–midpart of the monsoon (mid-June–mid-July). However, it underestimates the anomalous increase in rainfall corresponding to a stronger Somali jet. Overall, the UFS S2S prototypes P6 and P8 better forecast the MOV cases compared to P5.

  PublisherDOI

• African Easterly Waves

  Elsevier eBooks · 2025-01-01

  book-chapter1st authorCorresponding
  PublisherDOI

• Thank You to Our 2024 Reviewers

  Geophysical Research Letters · 2025-02-22

  articleOpen access

  Abstract On behalf of the journal, AGU, and the scientific community, the editors of Geophysical Research Letters would like to sincerely thank those who reviewed manuscripts in 2024. The hours reading and commenting on manuscripts not only improve the manuscripts but also increase the scientific rigor of future research in the field. With the advent of AGU's data policy, many reviewers have also helped immensely to evaluate the accessibility and availability of data, and many have provided insightful comments that helped to improve the data presentation and quality. We greatly appreciate the assistance of the reviewers in advancing open science, which is a key objective of AGU's data policy. We particularly appreciate the timely reviews in light of the demands imposed by the rapid review process at Geophysical Research Letters. We received 5,225 submissions in 2024, and 5,597 reviewers contributed to their evaluation by providing 9,697 reviews in total. We deeply appreciate their contributions. We would also like to acknowledge the passing of our beloved colleague, Harihar Rajaram. An AGU Fellow and longtime affiliate of AGU's Hydrology Section, Hari was the Editor‐in‐Chief of Geophysical Research Letters since 2019, a former editor on Water Resources Research, and served on the AGU Publications Committee.

  PublisherOA PDFDOI

• The Structure of a Developing Arabian Sea Monsoon Onset Vortex: Role of Moist Convection

  Journal of the Atmospheric Sciences · 2025-10-02

  articleSenior author

  Abstract The monsoon onset vortex (MOV) forms in the Arabian Sea around the beginning of the Indian summer monsoon. Many MOVs intensify into tropical cyclones and can potentially impact the onset and advance of the monsoon. The prevailing theory for the genesis of the MOV invokes the adiabatic hydrodynamic instability of the lower-tropospheric Somali jet. However, the role of precipitating moist convection in MOV formation remains unexplored. This study examines the structure of a canonical MOV, defined as a composite of 23 past cases, using reanalysis data. The MOV structure indicates lower-tropospheric maxima (from ∼700 to 850 hPa) and midtropospheric maxima (∼550 hPa) in the potential vorticity. A potential vorticity budget shows that this observed structure of the MOV likely results from adjustment to diabatic heating and vertical advection to a leading order. Both the low- and midlevel vortices in the developing MOV are primarily attributed to moist convection. Similarities and differences between the composite structures of the MOV and Bay of Bengal monsoon depressions are discussed. Additional work is needed to clarify the role of the traditional hydrodynamic instability in MOV formation. Significance Statement The monsoon onset vortex (MOV) is an important weather system that forms in about 60% of the years in the Arabian Sea during the onset of the Indian summer monsoon. The MOV can affect the northward advance of the monsoon and be a coastal and maritime hazard. Compared to monsoon depressions, much less is known about the role of moist convection in MOV formation and growth. In this paper, we examine a composite MOV based on 23 past cases. The MOV structure shows two potential vorticity maxima—one around 700–850 hPa and the other around 550 hPa. Through a potential vorticity budget, we show that the genesis of both these vortices is predominantly attributed to moist convection. Diabatic heating and vertical advection are the main contributors to the MOV growth in its early stages.

  PublisherDOI

• Understanding the organizing scales of winter flood hydroclimatology and the associated drivers over the coterminous United States

  Journal of Hydrology X · 2025-03-04 · 3 citations

  articleOpen access

  • Winter flood hydroclimatology of the CONUS is explored at different spatial scales. • Winter flood is influenced by hydroclimate modulators at a subregional scale. • Antecedent wetness dominates winter flood variability in inland regions. • Oceanic/atmospheric conditions affect the subregional variability of winter floods. Floods occur everywhere and in every season. Yet, most studies have focused only on annual maximum floods (AMFs), their climatology, and the associated impacts. Given that monthly/seasonal floods also cause significant damage and disruptions to daily life, this study may be the first to explore winter flood hydroclimatology, a predominantly a non-AMF season, and its associated large-scale climate drivers over the Coterminous US (CONUS). Using a mixed-effects model, we find that the influence of various hydroclimate predictors on winter floods is largely consistent within subregions. Antecedent land-surface conditions are crucial for winter floods in inland areas, while the Pacific sea surface temperatures (SSTs) significantly affects coastal watersheds. The Atlantic SSTs impact winter floods in the south and northeast, while atmospheric conditions influence the Midwest and California. Additional analysis reveals that damage from winter floods is more widespread compared to AMFs across the nation, affecting the entire eastern seaboard, Southwest US, and over the Great Lakes region. Thus, a comprehensive understanding of floods across all seasons (non-AMFs) is critical for developing effective mitigation measures, as it provides information on impacts and required compensation for smaller return period floods.

  PublisherDOI

• Hemisphere-Dependent Impacts of ENSO and Atmospheric Eddies on Hadley Circulation

  Journal of Climate · 2024-09-25 · 3 citations

  articleSenior author

  Abstract The variability of the Hadley circulation strength (HCS), crucial to tropical climate variability, is attributed to both oceanic and atmospheric forcings. El Niño–Southern Oscillation (ENSO) and variations in the extratropical upper-tropospheric eddies are the known drivers of the interannual HCS variability. However, the relative contributions of these oceanic and atmospheric forcings to the hemispheric HCS variability are not well understood. In particular, how much anomalous wind stress–driven ocean dynamics, including ENSO, impact HCS variability remains an open question. To address these gaps, we investigate the drivers of the interannual HCS variability using global coupled model experiments that include or exclude anomalous wind stress–driven ocean circulation variability. We find that the anomalous wind stress–driven ocean circulation variability significantly amplifies HCS variability in the Southern Hemisphere (SH). ENSO is the leading modulator of the SH HCS variability, which offers the potential to improve the predictability of Hadley circulation (HC)–related hydrological consequences. On the other hand, the Northern Hemisphere (NH) HCS variability is predominantly influenced by the eddy-driven internal atmospheric variability with little role in ocean dynamics. We hypothesize that the large eddy variability in the NH and concentrated ENSO-associated heating and precipitation in the SH lead to the hemisphere-dependent differences in the interannual HCS variability.

  PublisherDOI

• Thank You to Our 2023 Peer Reviewers

  Geophysical Research Letters · 2024-05-05 · 1 citations

  articleOpen access

  Abstract On behalf of the journal, AGU, and the scientific community, the editors of Geophysical Research Letters would like to sincerely thank those who reviewed manuscripts for us in 2023. The hours reading and commenting on manuscripts not only improve the manuscripts, but also increase the scientific rigor of future research in the field. With the advent of AGU's data policy, many reviewers have also helped immensely to evaluate the accessibility and availability of data, and many have provided insightful comments that helped to improve the data presentation and quality. We greatly appreciate the assistance of the reviewers in advancing open science, which is a key objective of AGU's data policy. We particularly appreciate the timely reviews in light of the demands imposed by the rapid review process at Geophysical Research Letters. We received 4,512 submissions in 2023 and 5,112 reviewers contributed to their evaluation by providing 8,587 reviews in total. We deeply appreciate their contributions.

  PublisherOA PDFDOI

• Surface Wind Speeds and Enthalpy Fluxes During Tropical Cyclone Formation From Easterly Waves: A CYGNSS View

  Geophysical Research Letters · 2023 · 6 citations

  1st authorCorresponding
  • Climatology
  • Atmospheric sciences
  • Environmental science

  Abstract We examined the Cyclone Global Navigation Satellite System (CYGNSS) retrievals of surface wind speeds and enthalpy fluxes in African easterly waves that led to the formation of 30 Atlantic tropical cyclones during 2018–2021. Lag composites show a cyclonic proto‐vortex as early as 3 days prior to tropical cyclogenesis. The enthalpy flux distribution does not vary substantially before cyclogenesis, but subsequently, there is a marked increase in the extreme upper values. In the composites, a negative radial gradient of enthalpy fluxes becomes apparent 2–3 days before cyclogenesis. These results—based on novel data blending satellite retrievals and global reanalysis—support the findings from recent studies that the spin‐up of tropical cyclones is associated with a shift of peak convection toward the vortex core and an inward increase of enthalpy fluxes.

  PublisherOA PDFDOI

Recent grants

• Origin, Storm Track Dynamics and Convective Feedback of African Easterly Waves

  NSF · $482k · 2014–2019

• CAREER: Dynamics of African Easterly Waves: Integrating Phenomenological Studies and Mathematical Instruction in Atmospheric Science

  NSF · $557k · 2009–2014

Frequent coauthors

• Carl J. Schreck

  Cooperative Institute for Climate and Satellites

  26 shared

• Chris D. Thorncroft

  University at Albany, State University of New York

  16 shared

• Lance F. Bosart

  Albany State University

  16 shared

• John Molinari

  12 shared

• Ademe Mekonnen

  North Carolina Agricultural and Technical State University

  10 shared

• Thomas J. Galarneau

  NOAA National Severe Storms Laboratory

  8 shared

• Joshua D. White

  Hanover College

  6 shared

• James O. H. Russell

  University of Utah

  5 shared

Education

• PhD, Atmospheric Science

  University at Albany, State University of New York

  2003

• MSc. , Physics

  Indian Institute of Technology Kharagpur

  1994