A new study led by Tandon lab PhD student Siddhant (Sid) Kerhalkar sheds light on the recovery of ocean thermal structures after cyclone passage, a largely unexplored area due to limited direct observations. As part of an international research effort in the Arabian Sea, Sid and his co-authors (including Dr Tandon) analyzed data from the R/V Thompson’s 2023 field campaign to study the aftermath of Cyclone Biparjoy. Their findings reveal that the cyclone’s slow movement, combined with monsoon winds, triggered small-scale oceanic processes that created asymmetrical temperature, salinity, and velocity structures in its wake—marking first such measurements in the region.

These observations were part of the “Enhancing Knowledge of the Arabian Sea Marine Environment through Science and Advanced Training (EKAMSAT)” program, an international collaboration funded by India’s Ministry of Earth Sciences and the U.S. Office of Naval Research. The initiative aims to improve monsoon prediction models by gathering critical oceanographic and atmospheric data in the Arabian Sea, a region that has been anomalously warm in recent years but remains less studied than many of the world’s oceans.

“Our research shows that these submesoscale processes, play a critical role in accelerating the recovery of the ocean’s thermal structure after a cyclone”, said Sid. “This has major implications for ocean heat transport, nutrient distribution, and weather predictability, particularly for monsoon forecasts”.

The study highlights how oceanic processes influence air-sea heat exchange and climate dynamics, providing valuable insights for improving storm behavior and monsoon predictions, which are crucial for climate forecasting and disaster preparedness affecting nearly a third of the world’s population.

“Siddhant’s research provides new observational evidence that will help refine predictive models for extreme weather events”, said Dr. Tandon.

The paper, titled “Monsoon-Frontal Interactions Drive Cyclone Biparjoy’s Wake Recovery in the Arabian Sea” is published in Geophysical Research Letters and is available at [here].

Fig: Schematic explaining the forcing conditions and the asymmetric response of the cold wake

Congratulations Sid and Dr Tandon!

A recent study led by former post-doctoral fellow Dr. Suraj Singh, in collaboration with Dr. Amit Tandon and former research professor Dr. Christian E. Buckingham, titled ‘On baroclinic instability of curved fronts’, explores how introducing slight curvature to oceanic fronts impacts baroclinic instabilities.
The research extends the classic Eady and Charney models on a cylindrical polar coordinate system by adding a slight curvature to a predominantly zonal flow. Under quasi-geostrophic scaling, the team analyzed the structure and growth rates of the pressure perturbations.
A key finding reveals that while unstable Eady modes remain largely unaffected by curvature, unstable Charney modes deepen owing to the introduction of a depth scale, enhancing vertical buoyancy flux—a phenomenon highlighted in their results (figure below).
The study also acknowledges certain limitations and suggests that understanding curved fronts could improve future parametrization of baroclinic instabilities in ocean models, and eddies which are deeper than the mixed layers. (here)

Fig: Vertical structure of the along-front averaged buoyancy flux for several values of the radius of curvature (Fig 8 of the paper)

In September 2024, Dr. Amit Tandon was felicitated with the title of Commonwealth Professor (here) at UMass Dartmouth, an achievement celebrated on November 4th, 2024, during the Faculty Recognition Ceremony.

Colleagues, students and family gathered on the university’s main campus to honor his contributions to academia.

Congratulations, Dr. Tandon, on this well-earned recognition!

Teledyne Marine, a global leader in developing deep ocean floats, recently highlighted the remarkable work of Dr. Amit Tandon and graduate student Patrick Pasteris in their recent feature.

They worked with four undergraduate engineering students for their capstone projects, with the help from the chief engineer from Teledyne Marine Bob Melvin and capstone instructor Prof. Hamed Samandari. The main objective of the project was to improve the design of the buoyancy engine and make the previous product more energy efficient. The students researched a combination of many components like pumps, motors, bladders, battery chemistries, in different ocean conditions to make the floats “Go-Anywhere”.

“…The students were motivated and talented, working well as a team to engineer and test a concept…I look forward to more capstone opportunities”, said Teledyne chief engineer Bob Melvin.

More information in the article: here and on YouTube: here

Picture of R/V Thompson in the Bay of Bengal. (Picture: San Nguyen)

In the pursuit of advancing our understanding of the monsoons and air-sea interaction, Tandon Lab members recently participated in a remarkable 45-day field campaign (following the pilot cruise in 2023) as part of the EKAMSAT (Enhancing Knowledge of the Arabian Sea Marine Environment through Science and Advanced Training) program on R/V Thomas G Thompson. This collaborative effort involved scientists from the USA and India, with the U.S. team funded by the U.S. Office of Naval Research and the Indian team supported by the Ministry of Earth Sciences (MoES). NASA-funded scientists also joined the research team to examine the ocean ecosystem. Originally planned for the Arabian Sea, the fieldwork had to pivot to the Bay of Bengal due to geopolitical tensions in the region . Around 60 scientists from various prestigious institutions, including the University of Washington, Scripps Institution of Oceanography, Woods Hole Oceanographic Institution, Columbia University, NOAA Center for Weather and Climate Prediction, University of Alaska-Fairbanks were part of this fieldwork. Indian institutions such as INCOIS, NIOT, NCMRWF, SAC-ISRO, and IITM-Pune also participated in the effort.

Objectives and Operations

The campaign aimed to study the atmospheric and oceanic boundary layer during the formation and destruction of a mini-warm pool in the Bay of Bengal. A mini-warm pool is a localized region of warm water that promotes water vapor convection, significantly impacting large-scale weather systems, such as the propagation of the monsoon. The team sought to observe the spatial extent of the mini-warm pool, the dynamics associated within it as this can affect regional weather patterns. The destruction of mini-warm pool or mixing of the warm water by the monsoon winds was also the focus of this study, amidst cyclones.

The fieldwork was split into two distinct legs. The first leg, from April 26 to May 14, 2024, focused on surveying the Bay of Bengal basin using an underway CTD (uCTD) to capture the spatial and vertical extent of the mini-warm pool across the Bay of Bengal basin. The team sailed from Chennai, India. Prof. Amit Tandon was one of the senior scientists on the first leg of the cruise, with Dr. Craig Lee from the University of Washington serving as the chief scientist. This phase also involved deploying autonomous instruments like wave-gliders, sea-gliders, and floats to measure various oceanographic parameters across a small part of the region.

EKAMSAT Leg-1 Science team (top). Prof Amit Tandon with AB Brian (bottom).

The second leg, from May 15 to June 15, 2024, led by Dr. Leah Johnson, focused on more detailed measurements using shipboard instruments like the FastCTD, Epsi, and T-Pads—cutting-edge devices developed by the Multi-scale Ocean Dynamics group at Scripps Institution of Oceanography. These instruments collected fine-scale ocean profiles. The configuration of the remote and shipboard instruments was aimed as to close the heat budget for the ocean and to understand the small-scale variabilities within the mini-warm pool’s dynamics. Radiosondes were also launched to collect atmospheric data, providing a more comprehensive view of how atmosphere evolved during the onset of the monsoon.

EKAMSAT Leg-2 Science team (Picture: San Nguyen)

Tandon Lab’s Contributions

Debarshi and Sid braving heavy rain and rough sea conditions during their deploying/monitoring instruments (Picture: San Nguyen and Kerstin Bergentz)

Sid Kerhalkar (PhD candidate at SMAST) and Debarshi Sarkar (PhD student in EAS program) from Tandon Lab braved challenging conditions—battling monsoon rains, tropical cyclones and high waves—while participating in watches to monitor, deploy, and recover shipboard instruments. Sid led the analysis of wave parameters during this fieldwork, while Debarshi contributed to the air-sea interaction analysis. In addition to their technical contributions, both were also involved in learning to launch radiosondes to capture atmospheric conditions during key periods of the monsoon.

Sid deploying the Radiosonde (Picture: Devmi Gamage)

Life at Sea

Beyond the scientific work, which bonded the team, life aboard the R/V Thomas G. Thompson was a unique experience. Daily science meetings provided an opportunity for the team to share findings from their earlier studies, discuss the upcoming weather and discuss new, exciting data collected during the cruise. Sid and Debarshi, along with their scientific contributions, added some flavor to ship life—quite literally! They were the part of the Indian-origin members of science team who volunteered to give the ship’s chefs a break for a meal, whipping up an Indian feast for the entire science team and crew (~60 people), which turned out to be a memorable event.

Sid (top left) and Debarshi (bottom left) busy cooking the Indian meal with the Indian team. Science team (right) seems happy with the meal serving. (Picture: San Nguyen and Sid Kerhalkar)

Sid also continued his hobby of video documentation, capturing the essence of life at sea and the exciting moments of the cruise—just as he had done in the previous year’s pilot expedition .

Underwater picture of Epsi profiler (top right), fishes (top left), T-Pads with fish in the background (bottom left) and a picture of sunset during the fieldwork (Picture: Sid Kerhalkar)

Despite the change in location, the EKAMSAT mission in the Bay of Bengal provided an invaluable opportunity to deepen the scientific community’s understanding of air-sea interaction during monsoon formation. The collaboration between international institutions and the deployment of cutting-edge technology highlighted the importance of such field campaigns in addressing complex climate phenomena. The data gathered will help inform future studies on how warm pools form, interact with atmosphere with respect to monsoon evolution, which eventually leads to its destruction, thus contributing to better weather forecasting globally and a deeper understanding of regional climate systems.

Dr. Amit Tandon, along with his colleagues from National Institute of Ocean Technology (NIOT) Chennai and Woods Hole Oceanographic Institute (WHOI), collaborated on the recently published paper: “Performance of Moored Real-Time Ocean Observations During Cyclones in the Bay of Bengal”.

This article provides a detailed explanation of the meteorological conditions, the air-sea flux conditions (measured and derived from COARE), the temperature and salinity depth profiles (and hence the mixed layer conditions) and the ocean current velocity profiles, as measured by the NIOT BD moorings, during Tropical Cyclone (TC) Amphan, which traversed through the Bay of Bengal at May 2020.

The authors highlight the benefits and necessity of maintaining such array of moored buoys in the Northern Indian Ocean, especially with the rise in the number and strength of TCs. They also discuss the challenges faced in data telemetry, mooring design, sensor exposure, etc. during cyclones and briefly outline NIOT’s plans for improving accuracy in generating and providing real-time data.

For more information: here

Prof Tandon presenting at MUST Day

The MUST project is a prestigious multi-departmental initiative within UMass Dartmouth, funded by the Office of Naval Research. Its primary objective is to advance cutting-edge research while cultivating a highly skilled workforce to support the needs of the U.S. Navy. UMass Dartmouth hosted the MUST Day event from 24th to 25 July 2024, providing an opportunity for professors and graduate students supported by the project to showcase their research and technical advancements through a series of 10-minute presentations and poster sessions.

The Tandon Lab made a strong impact at the event. Professor Tandon led the talk, ‘MITS: Sub-mesoscale and Mesoscale Interactions Study (SubMIST),’ and contributed to the presentations ‘Regional Ocean Turbulence from Long-Duration, Autonomous Observations’ and ‘Acoustic Rainfall Measurement on Global Drifters’.

Former master’s student Patrick Pasteris on behalf of the Aurelia team presented the on-going work, ‘Optimizing the Design of a Novel Upper Ocean Variable Buoyancy Vehicle.’ This began as a senior design project a few years ago and was also a topic of Patrick’s MS thesis. Current master’s student Ersen’S Joseph showcased his ongoing research on flow-structure interactions of grooved mooring lines through a poster presentation, while current PhD student Debarshi Sarkar discussed the errors and causes of the errors in atmospheric Reanalysis Products during the southwest monsoon season, in his poster session.

Patrick, Profs Tandon and Zhou presenting at MUST day

Many scientists, including Dr. Amit Tandon, collaborated on the paper: “Ocean surface radiation measurement best practices [Riihimaki et al. 2024]”. This article explores techniques and best practices for measuring downwelling shortwave (SWR) and longwave (LWR) broadband radiation, focusing on minimizing errors in these measurements.

Challenges in measuring upwelling SWR and LWR on oceans and land are also discussed, with suggestions for mounting sensors on towers in specific orientations to reduce shadows and enhance accuracy. The article highlights the importance of accurate surface albedo representation, particularly on sea and land ice, and compares the effectiveness of using UAVs versus land station towers for these measurements. It also reviews strategies for surface temperature measurements as an indirect tool for upwelling LWR assessments.
It recommends using instruments like pyrheliometer and a shaded pyranometer for SWR to avoid errors. For LWR measurements, the article advises using shaded devices to reduce solar leakage and recommends ventilated instruments to prevent dust contamination.
The article emphasizes best practices for installing and maintaining measurement systems and advises consistent sampling rates, careful maintenance to prevent errors from natural conditions. Despite following these practices, some errors may persist, which can be corrected through post-processing, calibration, and quality control schemes (emphasizing on using redundant measurements).
The article concludes by stressing the importance of adhering to global calibration standards and suggests field intercomparison between land and sea platforms to build a unified system for measuring climate variables. For the ease of the readers, the authors summarize each of the best practices in measuring ocean radiative heat fluxes in Table 5.
More information about the article can be found here.

Congratulations Dr. Tandon

Debarshi with his poster

Tandon lab PhD student Debarshi Sarkar presented his poster “Inaccuracies in Reanalysis Products: A Case Study in Arabian Sea from 2017 to 2018”, at the Sigma Xi poster exhibit, UMass Dartmouth on April 17^th and 18^th, 2024.

(L-R) Dr. Amit Tandon, Dr. Ruolin Zhou, Dr. Lauren Freeman, Dr. Oliver Sun and Patrick Pasteris with Aurelia

After a successful proposal to the University of Massachusetts Dartmouth Marine and Undersea Technology Program V (MUST V), Tandon Labs kicked off its first meeting for the continued development  of the Aurelia Upper Ocean Profilers. In attendance were two NUWC partners Lauren Freeman and Oliver Sun, the co-principal investigators Dr. Amit Tandon and Dr. Ruolin Zhou, as well as Research Technician and Aurelia inventor Patrick Pasteris.

The kickoff meeting signifies the beginning of 3 years of funding towards the continue development of the Aurelia UOP, which is a low-cost ultra-lightweight buoyancy vehicle being developed at University of Massachusetts Dartmouth. The profiler is focused on the upper 200m of the ocean and is meant to be an inexpensive alternative to the high-cost deep ocean profilers currently being deployed.