Subramanian Aneesh C.

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Last Name
Subramanian
First Name
Aneesh C.
ORCID
0000-0001-7805-0102

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Now showing 1 - 10 of 10
  • Article
    Towards an end-to-end analysis and prediction system for weather, climate, and marine applications in the Red Sea
    (American Meteorological Society, 2021-01-01) Hoteit, Ibrahim ; Abualnaja, Yasser ; Afzal, Shehzad ; Ait-El-Fquih, Boujemaa ; Akylas, Triantaphyllos ; Antony, Charls ; Dawson, Clint N. ; Asfahani, Khaled ; Brewin, Robert J. W. ; Cavaleri, Luigi ; Cerovecki, Ivana ; Cornuelle, Bruce D. ; Desamsetti, Srinivas ; Attada, Raju ; Dasari, Hari ; Sanchez-Garrido, Jose ; Genevier, Lily ; El Gharamti, Mohamad ; Gittings, John A. ; Gokul, Elamurugu ; Gopalakrishnan, Ganesh ; Guo, Daquan ; Hadri, Bilel ; Hadwiger, Markus ; Hammoud, Mohammed Abed ; Hendershott, Myrl ; Hittawe, Mohamad ; Karumuri, Ashok ; Knio, Omar ; Kohl, Armin ; Kortas, Samuel ; Krokos, George ; Kunchala, Ravi ; Issa, Leila ; Lakkis, Issam ; Langodan, Sabique ; Lermusiaux, Pierre F. J. ; Luong, Thang ; Ma, Jingyi ; Le Maitre, Olivier ; Mazloff, Matthew R. ; El Mohtar, Samah ; Papadopoulos, Vassilis P. ; Platt, Trevor ; Pratt, Lawrence J. ; Raboudi, Naila ; Racault, Marie-Fanny ; Raitsos, Dionysios E. ; Razak, Shanas ; Sanikommu, Sivareddy ; Sathyendranath, Shubha ; Sofianos, Sarantis S. ; Subramanian, Aneesh C. ; Sun, Rui ; Titi, Edriss ; Toye, Habib ; Triantafyllou, George ; Tsiaras, Kostas ; Vasou, Panagiotis ; Viswanadhapalli, Yesubabu ; Wang, Yixin ; Yao, Fengchao ; Zhan, Peng ; Zodiatis, George
    The Red Sea, home to the second-longest coral reef system in the world, is a vital resource for the Kingdom of Saudi Arabia. The Red Sea provides 90% of the Kingdom’s potable water by desalinization, supporting tourism, shipping, aquaculture, and fishing industries, which together contribute about 10%–20% of the country’s GDP. All these activities, and those elsewhere in the Red Sea region, critically depend on oceanic and atmospheric conditions. At a time of mega-development projects along the Red Sea coast, and global warming, authorities are working on optimizing the harnessing of environmental resources, including renewable energy and rainwater harvesting. All these require high-resolution weather and climate information. Toward this end, we have undertaken a multipronged research and development activity in which we are developing an integrated data-driven regional coupled modeling system. The telescopically nested components include 5-km- to 600-m-resolution atmospheric models to address weather and climate challenges, 4-km- to 50-m-resolution ocean models with regional and coastal configurations to simulate and predict the general and mesoscale circulation, 4-km- to 100-m-resolution ecosystem models to simulate the biogeochemistry, and 1-km- to 50-m-resolution wave models. In addition, a complementary probabilistic transport modeling system predicts dispersion of contaminant plumes, oil spill, and marine ecosystem connectivity. Advanced ensemble data assimilation capabilities have also been implemented for accurate forecasting. Resulting achievements include significant advancement in our understanding of the regional circulation and its connection to the global climate, development, and validation of long-term Red Sea regional atmospheric–oceanic–wave reanalyses and forecasting capacities. These products are being extensively used by academia, government, and industry in various weather and marine studies and operations, environmental policies, renewable energy applications, impact assessment, flood forecasting, and more.
  • Article
    The role of air-sea interactions in atmospheric rivers: Case studies using the SKRIPS regional coupled model
    (American Geophysical Union, 2021-02-12) Sun, Rui ; Subramanian, Aneesh C. ; Cornuelle, Bruce D. ; Mazloff, Matthew R. ; Miller, Arthur J. ; Ralph, F. Martin
    Atmospheric rivers (ARs) play a key role in California's water supply and are responsible for most of the extreme precipitation and major flooding along the west coast of North America. Given the high societal impact, it is critical to improve our understanding and prediction of ARs. This study uses a regional coupled ocean–atmosphere modeling system to make hindcasts of ARs up to 14 days. Two groups of coupled runs are highlighted in the comparison: (1) ARs occurring during times with strong sea surface temperature (SST) cooling and (2) ARs occurring during times with weak SST cooling. During the events with strong SST cooling, the coupled model simulates strong upward air–sea heat fluxes associated with ARs; on the other hand, when the SST cooling is weak, the coupled model simulates downward air–sea heat fluxes in the AR region. Validation data shows that the coupled model skillfully reproduces the evolving SST, as well as the surface turbulent heat transfers between the ocean and atmosphere. The roles of air–sea interactions in AR events are investigated by comparing coupled model hindcasts to hindcasts made using persistent SST. To evaluate the influence of the ocean on ARs we analyze two representative variables of AR intensity, the vertically integrated water vapor (IWV) and integrated vapor transport (IVT). During strong SST cooling AR events the simulated IWV is improved by about 12% in the coupled run at lead times greater than one week. For IVT, which is about twice more variable, the improvement in the coupled run is about 5%.
  • Article
    Observational needs supporting marine ecosystems modeling and forecasting: from the global ocean to regional and coastal systems
    (Frontiers Media, 2019-10-15) Capotondi, Antonietta ; Jacox, Michael ; Bowler, Chris ; Kavanaugh, Maria T. ; Lehodey, Patrick ; Barrie, Daniel ; Brodie, Stephanie ; Chaffron, Samuel ; Cheng, Wei ; Dias, Daniela F. ; Eveillard, Damien ; Guidi, Lionel ; Iudicone, Daniele ; Lovenduski, Nicole S. ; Nye, Janet A. ; Ortiz, Ivonne ; Pirhalla, Douglas ; Pozo Buil, Mercedes ; Saba, Vincent S. ; Sheridan, Scott ; Siedlecki, Samantha A. ; Subramanian, Aneesh C. ; de Vargas, Colomban ; Di Lorenzo, Emanuele ; Doney, Scott C. ; Hermann, Albert J. ; Joyce, Terrence M. ; Merrifield, Mark ; Miller, Arthur J. ; Not, Fabrice ; Pesant, Stephane
    Many coastal areas host rich marine ecosystems and are also centers of economic activities, including fishing, shipping and recreation. Due to the socioeconomic and ecological importance of these areas, predicting relevant indicators of the ecosystem state on sub-seasonal to interannual timescales is gaining increasing attention. Depending on the application, forecasts may be sought for variables and indicators spanning physics (e.g., sea level, temperature, currents), chemistry (e.g., nutrients, oxygen, pH), and biology (from viruses to top predators). Many components of the marine ecosystem are known to be influenced by leading modes of climate variability, which provide a physical basis for predictability. However, prediction capabilities remain limited by the lack of a clear understanding of the physical and biological processes involved, as well as by insufficient observations for forecast initialization and verification. The situation is further complicated by the influence of climate change on ocean conditions along coastal areas, including sea level rise, increased stratification, and shoaling of oxygen minimum zones. Observations are thus vital to all aspects of marine forecasting: statistical and/or dynamical model development, forecast initialization, and forecast validation, each of which has different observational requirements, which may be also specific to the study region. Here, we use examples from United States (U.S.) coastal applications to identify and describe the key requirements for an observational network that is needed to facilitate improved process understanding, as well as for sustaining operational ecosystem forecasting. We also describe new holistic observational approaches, e.g., approaches based on acoustics, inspired by Tara Oceans or by landscape ecology, which have the potential to support and expand ecosystem modeling and forecasting activities by bridging global and local observations.
  • Article
    Coupled impacts of the diurnal cycle of sea surface temperature on the Madden–Julian oscillation
    (American Meteorological Society, 2014-11-15) Seo, Hyodae ; Subramanian, Aneesh C. ; Miller, Arthur J. ; Cavanaugh, Nicholas R.
    This study quantifies, from a systematic set of regional ocean–atmosphere coupled model simulations employing various coupling intervals, the effect of subdaily sea surface temperature (SST) variability on the onset and intensity of Madden–Julian oscillation (MJO) convection in the Indian Ocean. The primary effect of diurnal SST variation (dSST) is to raise time-mean SST and latent heat flux (LH) prior to deep convection. Diurnal SST variation also strengthens the diurnal moistening of the troposphere by collocating the diurnal peak in LH with those of SST. Both effects enhance the convection such that the total precipitation amount scales quasi-linearly with preconvection dSST and time-mean SST. A column-integrated moist static energy (MSE) budget analysis confirms the critical role of diurnal SST variability in the buildup of column MSE and the strength of MJO convection via stronger time-mean LH and diurnal moistening. Two complementary atmosphere-only simulations further elucidate the role of SST conditions in the predictive skill of MJO. The atmospheric model forced with the persistent initial SST, lacking enhanced preconvection warming and moistening, produces a weaker and delayed convection than the diurnally coupled run. The atmospheric model with prescribed daily-mean SST from the coupled run, while eliminating the delayed peak, continues to exhibit weaker convection due to the lack of strong moistening on a diurnal basis. The fact that time-evolving SST with a diurnal cycle strongly influences the onset and intensity of MJO convection is consistent with previous studies that identified an improved representation of diurnal SST as a potential source of MJO predictability.
  • Article
    Ocean observations to improve our understanding, modeling, and forecasting of subseasonal-to-seasonal variability
    (Frontiers Media, 2019-08-08) Subramanian, Aneesh C. ; Balmaseda, Magdalena A. ; Centurioni, Luca R. ; Chattopadhyay, Rajib ; Cornuelle, Bruce D. ; DeMott, Charlotte ; Flatau, Maria ; Fujii, Yosuke ; Giglio, Donata ; Gille, Sarah T. ; Hamill, Thomas M. ; Hendon, Harry ; Hoteit, Ibrahim ; Kumar, Arun ; Lee, Jae-Hak ; Lucas, Andrew J. ; Mahadevan, Amala ; Matsueda, Mio ; Nam, SungHyun ; Paturi, Shastri ; Penny, Stephen G. ; Rydbeck, Adam ; Sun, Rui ; Takaya, Yuhei ; Tandon, Amit ; Todd, Robert E. ; Vitart, Frederic ; Yuan, Dongliang ; Zhang, Chidong
    Subseasonal-to-seasonal (S2S) forecasts have the potential to provide advance information about weather and climate events. The high heat capacity of water means that the subsurface ocean stores and re-releases heat (and other properties) and is an important source of information for S2S forecasts. However, the subsurface ocean is challenging to observe, because it cannot be measured by satellite. Subsurface ocean observing systems relevant for understanding, modeling, and forecasting on S2S timescales will continue to evolve with the improvement in technological capabilities. The community must focus on designing and implementing low-cost, high-value surface and subsurface ocean observations, and developing forecasting system capable of extracting their observation potential in forecast applications. S2S forecasts will benefit significantly from higher spatio-temporal resolution data in regions that are sources of predictability on these timescales (coastal, tropical, and polar regions). While ENSO has been a driving force for the design of the current observing system, the subseasonal time scales present new observational requirements. Advanced observation technologies such as autonomous surface and subsurface profiling devices as well as satellites that observe the ocean-atmosphere interface simultaneously can lead to breakthroughs in coupled data assimilation (CDA) and coupled initialization for S2S forecasts. These observational platforms should also be tested and evaluated in ocean observation sensitivity experiments with current and future generation CDA and S2S prediction systems. Investments in the new ocean observations as well as model and DA system developments can lead to substantial returns on cost savings from disaster mitigation as well as socio–economic decisions that use S2S forecast information.
  • Article
    A road map to IndOOS-2 better observations of the rapidly warming Indian Ocean
    (American Meteorological Society, 2020-11-01) Beal, Lisa M. ; Vialard, Jérôme ; Roxy, Mathew Koll ; Li, Jing ; Andres, Magdalena ; Annamalai, Hariharasubramanian ; Feng, Ming ; Han, Weiqing ; Hood, Raleigh R. ; Lee, Tong ; Lengaigne, Matthieu ; Lumpkin, Rick ; Masumoto, Yukio ; McPhaden, Michael J. ; Ravichandran, M. ; Shinoda, Toshiaki ; Sloyan, Bernadette M. ; Strutton, Peter G. ; Subramanian, Aneesh C. ; Tozuka, Tomoki ; Ummenhofer, Caroline C. ; Unnikrishnan, Shankaran Alakkat ; Wiggert, Jerry D. ; Yu, Lisan ; Cheng, Lijing ; Desbruyères, Damien G. ; Parvathi, V.
    The Indian Ocean Observing System (IndOOS), established in 2006, is a multinational network of sustained oceanic measurements that underpin understanding and forecasting of weather and climate for the Indian Ocean region and beyond. Almost one-third of humanity lives around the Indian Ocean, many in countries dependent on fisheries and rain-fed agriculture that are vulnerable to climate variability and extremes. The Indian Ocean alone has absorbed a quarter of the global oceanic heat uptake over the last two decades and the fate of this heat and its impact on future change is unknown. Climate models project accelerating sea level rise, more frequent extremes in monsoon rainfall, and decreasing oceanic productivity. In view of these new scientific challenges, a 3-yr international review of the IndOOS by more than 60 scientific experts now highlights the need for an enhanced observing network that can better meet societal challenges, and provide more reliable forecasts. Here we present core findings from this review, including the need for 1) chemical, biological, and ecosystem measurements alongside physical parameters; 2) expansion into the western tropics to improve understanding of the monsoon circulation; 3) better-resolved upper ocean processes to improve understanding of air–sea coupling and yield better subseasonal to seasonal predictions; and 4) expansion into key coastal regions and the deep ocean to better constrain the basinwide energy budget. These goals will require new agreements and partnerships with and among Indian Ocean rim countries, creating opportunities for them to enhance their monitoring and forecasting capacity as part of IndOOS-2.
  • Article
    Seasonal-to-interannual prediction of North American coastal marine ecosystems: forecast methods, mechanisms of predictability, and priority developments
    (Elsevier, 2020-02-20) Jacox, Michael ; Alexander, Michael A. ; Siedlecki, Samantha A. ; Chen, Ke ; Kwon, Young-Oh ; Brodie, Stephanie ; Ortiz, Ivonne ; Tommasi, Desiree ; Widlansky, Matthew J. ; Barrie, Daniel ; Capotondi, Antonietta ; Cheng, Wei ; Di Lorenzo, Emanuele ; Edwards, Christopher ; Fiechter, Jerome ; Fratantoni, Paula S. ; Hazen, Elliott L. ; Hermann, Albert J. ; Kumar, Arun ; Miller, Arthur J. ; Pirhalla, Douglas ; Pozo Buil, Mercedes ; Ray, Sulagna ; Sheridan, Scott ; Subramanian, Aneesh C. ; Thompson, Philip ; Thorne, Lesley ; Annamalai, Hariharasubramanian ; Aydin, Kerim ; Bograd, Steven ; Griffis, Roger B. ; Kearney, Kelly ; Kim, Hyemi ; Mariotti, Annarita ; Merrifield, Mark ; Rykaczewski, Ryan R.
    Marine ecosystem forecasting is an area of active research and rapid development. Promise has been shown for skillful prediction of physical, biogeochemical, and ecological variables on a range of timescales, suggesting potential for forecasts to aid in the management of living marine resources and coastal communities. However, the mechanisms underlying forecast skill in marine ecosystems are often poorly understood, and many forecasts, especially for biological variables, rely on empirical statistical relationships developed from historical observations. Here, we review statistical and dynamical marine ecosystem forecasting methods and highlight examples of their application along U.S. coastlines for seasonal-to-interannual (1–24 month) prediction of properties ranging from coastal sea level to marine top predator distributions. We then describe known mechanisms governing marine ecosystem predictability and how they have been used in forecasts to date. These mechanisms include physical atmospheric and oceanic processes, biogeochemical and ecological responses to physical forcing, and intrinsic characteristics of species themselves. In reviewing the state of the knowledge on forecasting techniques and mechanisms underlying marine ecosystem predictability, we aim to facilitate forecast development and uptake by (i) identifying methods and processes that can be exploited for development of skillful regional forecasts, (ii) informing priorities for forecast development and verification, and (iii) improving understanding of conditional forecast skill (i.e., a priori knowledge of whether a forecast is likely to be skillful). While we focus primarily on coastal marine ecosystems surrounding North America (and the U.S. in particular), we detail forecast methods, physical and biological mechanisms, and priority developments that are globally relevant.
  • Article
    Integrated observations of global surface winds, currents, and waves: Requirements and challenges for the next decade
    (Frontiers Media, 2019-07-24) Villas Bôas, Ana B. ; Ardhuin, Fabrice ; Ayet, Alex ; Bourassa, Mark A. ; Brandt, Peter ; Chapron, Bertrand ; Cornuelle, Bruce D. ; Farrar, J. Thomas ; Fewings, Melanie R. ; Fox-Kemper, Baylor ; Gille, Sarah T. ; Gommenginger, Christine ; Heimbach, Patrick ; Hell, Momme C. ; Li, Qing ; Mazloff, Matthew R. ; Merrifield, Sophia T. ; Mouche, Alexis ; Rio, Marie H. ; Rodriguez, Ernesto ; Shutler, Jamie D. ; Subramanian, Aneesh C. ; Terrill, Eric ; Tsamados, Michel ; Ubelmann, Clement ; van Sebille, Erik
    Ocean surface winds, currents, and waves play a crucial role in exchanges of momentum, energy, heat, freshwater, gases, and other tracers between the ocean, atmosphere, and ice. Despite surface waves being strongly coupled to the upper ocean circulation and the overlying atmosphere, efforts to improve ocean, atmospheric, and wave observations and models have evolved somewhat independently. From an observational point of view, community efforts to bridge this gap have led to proposals for satellite Doppler oceanography mission concepts, which could provide unprecedented measurements of absolute surface velocity and directional wave spectrum at global scales. This paper reviews the present state of observations of surface winds, currents, and waves, and it outlines observational gaps that limit our current understanding of coupled processes that happen at the air-sea-ice interface. A significant challenge for the coming decade of wind, current, and wave observations will come in combining and interpreting measurements from (a) wave-buoys and high-frequency radars in coastal regions, (b) surface drifters and wave-enabled drifters in the open-ocean, marginal ice zones, and wave-current interaction “hot-spots,” and (c) simultaneous measurements of absolute surface currents, ocean surface wind vector, and directional wave spectrum from Doppler satellite sensors.
  • Article
    A sustained ocean observing system in the Indian Ocean for climate related scientific knowledge and societal needs
    (Frontiers Media, 2019-06-28) Hermes, Juliet ; Masumoto, Yukio ; Beal, Lisa M. ; Roxy, Mathew Koll ; Vialard, Jérôme ; Andres, Magdalena ; Annamalai, Hariharasubramanian ; Behera, Swadhin ; D’Adamo, Nick ; Doi, Takeshi ; Feng, Ming ; Han, Weiqing ; Hardman-Mountford, Nick ; Hendon, Harry ; Hood, Raleigh R. ; Kido, Shoichiro ; Lee, Craig M. ; Lee, Tong ; Lengaigne, Matthieu ; Li, Jing ; Lumpkin, Rick ; Navaneeth, K. N. ; Milligan, Ben ; McPhaden, Michael J. ; Ravichandran, M. ; Shinoda, Toshiaki ; Singh, Arvind ; Sloyan, Bernadette M. ; Strutton, Peter G. ; Subramanian, Aneesh C. ; Thurston, Sidney ; Tozuka, Tomoki ; Ummenhofer, Caroline C. ; Unnikrishnan, Shankaran Alakkat ; Venkatesan, Ramasamy ; Wang, Dongxiao ; Wiggert, Jerry D. ; Yu, Lisan ; Yu, Weidong
    The Indian Ocean is warming faster than any of the global oceans and its climate is uniquely driven by the presence of a landmass at low latitudes, which causes monsoonal winds and reversing currents. The food, water, and energy security in the Indian Ocean rim countries and islands are intrinsically tied to its climate, with marine environmental goods and services, as well as trade within the basin, underpinning their economies. Hence, there are a range of societal needs for Indian Ocean observation arising from the influence of regional phenomena and climate change on, for instance, marine ecosystems, monsoon rains, and sea-level. The Indian Ocean Observing System (IndOOS), is a sustained observing system that monitors basin-scale ocean-atmosphere conditions, while providing flexibility in terms of emerging technologies and scientificand societal needs, and a framework for more regional and coastal monitoring. This paper reviews the societal and scientific motivations, current status, and future directions of IndOOS, while also discussing the need for enhanced coastal, shelf, and regional observations. The challenges of sustainability and implementation are also addressed, including capacity building, best practices, and integration of resources. The utility of IndOOS ultimately depends on the identification of, and engagement with, end-users and decision-makers and on the practical accessibility and transparency of data for a range of products and for decision-making processes. Therefore we highlight current progress, issues and challenges related to end user engagement with IndOOS, as well as the needs of the data assimilation and modeling communities. Knowledge of the status of the Indian Ocean climate and ecosystems and predictability of its future, depends on a wide range of socio-economic and environmental data, a significant part of which is provided by IndOOS.
  • Article
    Bay of Bengal intraseasonal oscillations and the 2018 monsoon onset
    (American Meteorological Society, 2021-10-01) Shroyer, Emily L. ; Tandon, Amit ; Sengupta, Debasis ; Fernando, Harindra J. S. ; Lucas, Andrew J. ; Farrar, J. Thomas ; Chattopadhyay, Rajib ; de Szoeke, Simon P. ; Flatau, Maria ; Rydbeck, Adam ; Wijesekera, Hemantha W. ; McPhaden, Michael J. ; Seo, Hyodae ; Subramanian, Aneesh C. ; Venkatesan, Ramasamy ; Joseph, Jossia K. ; Ramsundaram, S. ; Gordon, Arnold L. ; Bohman, Shannon M. ; Pérez, Jaynise ; Simoes-Sousa, Iury T. ; Jayne, Steven R. ; Todd, Robert E. ; Bhat, G. S. ; Lankhorst, Matthias ; Schlosser, Tamara L. ; Adams, Katherine ; Jinadasa, S. U. P. ; Mathur, Manikandan ; Mohapatra, Mrutyunjay ; Rama Rao, E. Pattabhi ; Sahai, Atul Kumar ; Sharma, Rashmi ; Lee, Craig ; Rainville, Luc ; Cherian, Deepak A. ; Cullen, Kerstin ; Centurioni, Luca R. ; Hormann, Verena ; MacKinnon, Jennifer A. ; Send, Uwe ; Anutaliya, Arachaporn ; Waterhouse, Amy F. ; Black, Garrett S. ; Dehart, Jeremy A. ; Woods, Kaitlyn M. ; Creegan, Edward ; Levy, Gad ; Kantha, Lakshmi ; Subrahmanyam, Bulusu
    In the Bay of Bengal, the warm, dry boreal spring concludes with the onset of the summer monsoon and accompanying southwesterly winds, heavy rains, and variable air–sea fluxes. Here, we summarize the 2018 monsoon onset using observations collected through the multinational Monsoon Intraseasonal Oscillations in the Bay of Bengal (MISO-BoB) program between the United States, India, and Sri Lanka. MISO-BoB aims to improve understanding of monsoon intraseasonal variability, and the 2018 field effort captured the coupled air–sea response during a transition from active-to-break conditions in the central BoB. The active phase of the ∼20-day research cruise was characterized by warm sea surface temperature (SST > 30°C), cold atmospheric outflows with intermittent heavy rainfall, and increasing winds (from 2 to 15 m s−1). Accumulated rainfall exceeded 200 mm with 90% of precipitation occurring during the first week. The following break period was both dry and clear, with persistent 10–12 m s−1 wind and evaporation of 0.2 mm h−1. The evolving environmental state included a deepening ocean mixed layer (from ∼20 to 50 m), cooling SST (by ∼1°C), and warming/drying of the lower to midtroposphere. Local atmospheric development was consistent with phasing of the large-scale intraseasonal oscillation. The upper ocean stores significant heat in the BoB, enough to maintain SST above 29°C despite cooling by surface fluxes and ocean mixing. Comparison with reanalysis indicates biases in air–sea fluxes, which may be related to overly cool prescribed SST. Resolution of such biases offers a path toward improved forecasting of transition periods in the monsoon.