Scripps Institution of Oceanography Explorations Article

August 1, 2014


Scripps Institution of Oceanography Explorations Article this week.

Mixing to Monsoons: Air-Sea Interactions in the Bay of Bengal

August 1, 2014

Mixing to Monsoons: Air-Sea Interactions in the Bay of Bengal

Cover story in this week’s Eos – weekly of the American Geophysical Union.

Working Waterfront Festival 2012: Visit by Congressman Frank

October 2, 2012

Last saturday September 30th 2012, Dr. Sanjiv Ramachandran and graduate student Rahul Kashyap were on hand to demonstrate rotating table experiments for the Working Waterfront Festival at New Bedford. Despite heavy rains on saturday, a large number of  attendees came by to attend the demonstrations. They answered many questions. Congressman Barney Frank and U.S. Senate Candidate Elizabeth Warren also visited the display.


Dr. Sanjiv Ramachandran explains rotating table experiment during Waterfront Festival 2012.

Jason Olejarz wins BU Physics Research Performance Award

May 6, 2012

Jason Olejarz, an alumni of our research group

Every year Boston University Physics department chooses ONE out of its roughly 100 students for a research performance award. For the academic year 2011-12, this award goes to JASON OLEJARZ, a UMass Dartmouth undergraduate alumni who worked with me on research projects as an undergraduate. Jason has published three articles on his research as a graduate student and more are in the works!

Effect of subgrid-scale mixing on the evolution of submesoscale instabilities (PREPRINT, click below to download)

April 19, 2012


We study the effect of subgrid-scale (SGS) mixing on the evolution of a zonal, frontal jet initially in thermal-wind balance with a meridional density    gradient and forced by downfront surface winds. The horizontal size of the model domain (O (100 km)) is large enough to contain mesoscale eddies while the horizontal grid resolution (\(500\)m) is fine enough  to resolve submesoscale eddies. We compare the performance of two subgrid-scale (SGS) models: (i) constant lateral SGS viscosities (1 m^2/s and 5 m^2/s) and an analytically prescribed vertical SGS viscosity; and (ii) an existing variant of the original Smagorinsky SGS model developed for anisotropic grids with large aspect ratios.  Our simulations show the subgrid model can influence adversely the dynamics at scales of motion far removed from the grid cutoff scale. In particular, we find the following are insufficiently robust     to changes in the subgrid model or the model constant for a given subgrid model: (i) the strength of the inverse and forward cascades; (ii) the efficiency of conversion of available potential energy (APE) to eddy kinetic energy (EKE); and (iii) the zonally-averaged resolved-scale EKE budgets. Among the different simulations, those using a constant lateral SGS viscosity of 5 m^2/s exhibit the weakest inverse and forward cascades, and the most inefficient conversion of APE to EKE. Differences in the zonally-averaged resolved-scale EKE budgets obtained using the two SGS models are minimal  within     a near-surface layer similar to the traditional Monin-Obukhov (MO) layer. Below this MO-like layer, however, the differences are significant as simulations with a constant lateral SGS viscosity and a background SGS vertical viscosity  fail to reproduce a realistic balance between the various terms in the     EKE budget. A lateral viscosity of 1 m^2/s predicts the production of EKE is balanced solely by pressure transport with negligible SGS destruction, whereas recent experimental studies show enhanced destruction near fronts. For a constant lateral viscosity of 5 m^2/s the magnitude of the  dominant production term is an order of magnitude smaller than  scaling estimates in the literature due to the poor conversion of APE to EKE. The EKE budgets obtained using the anisotropic Smagorinsky model (ASM) show production of EKE is balanced by a combination of  pressure transport and SGS destruction. The magnitude of the dominant production term is consistent with existing scaling estimates in the literature.






Oceanography in 2025

October 13, 2010

This collection of articles from an ONR sponsored workshop in 2009 is interesting. Read on..


September 26, 2010

“When someone tells you that ‘Oh, math is not really my thing,’ respond back, ‘and working at McDonald’s isn’t mine.’”

Danny Crichton, Stanford University Student

“We had more sports-exercise majors graduate than electrical engineering graduates last year. If you want to become the massage capital of the world, you’re well on your way.”

Jeff Immelt, CEO, General Electric Co.

“. . . of the seventy finalists in an NSA (National Security Agency)-backed computer coding contest, twenty were from China, ten from Russia and two from the USA.”

Patrick Thibodeau, Computerworld

“The 19th century belonged to England, the 20th century belonged to the United States, and the 21st century belongs to China. Invest accordingly.”

Warren Buffett

Last year, U.S. consumers spent $7.1 billion on potato chips — $2 billion more than the federal government’s total 2009 investment on energy research and development.

Research Group Picture after Eric’s MS defense

July 14, 2010

Our Research Group Summer 2010

Our Research Group Summer 2010

L to R: Sonaljit Mukherjee (PhD student), Xianquin Yao (M.S. Student), Prof. Amala Mahadevan (Boston University and UMass Dartmouth), Eric Holmes (MS student, just defended!), Prof. Amit Tandon, Prof. Takeyoshi Nagai (on sabbatical visit from Tokyo Inst. of Marine Sci. & Tech.), and Dr. Gualtiero Badin (Postdoctoral Fellow, Boston University). Missing from the Picture is Sudip Majumder (PhD student).

This picture was taken just after Eric Holmes’s successful M.S. defense. Congratulations, Eric!

Using GPUs to parallelize Process Studies Ocean Model

June 16, 2010

Our research group uses the Process Studies Ocean Model originally crafted by Prof. Amala Mahadevan at Boston University and now in use for multiple process studies at many institutions.

Graduate students Xianquin Yao and Eric Holmes at UMass Dartmouth are now beginning to investigate whether we can get a speedup of this model by harnessing the parallelizing potential of GPUs. Rakesh Ginjupalli and Prof. Gaurav Khanna have used CUDA Fortran for Astrophysical Black hole simulations, and we would be getting their advice  and help on PSOM optimizations. The computational power for this work will be enabled by our participation on the recent MRI granted to Prof. Bob Fisher and colleagues at UMass Dartmouth by the National Science Founfdation; see this link.

Sudip Majumder and Eric Holmes at OSM 2010

February 26, 2010

Graduate students Sudip Majumder and Eric Holmes presented their research work in poster format at the Ocean Sciences Meeting 2010.

It is an enjoyable experience to meet many scientists from around the World, and to share one’s research results with them.