scholarly journals The ECPC Coupled Prediction Model

2008 ◽  
Vol 136 (1) ◽  
pp. 295-316 ◽  
Author(s):  
E. Yulaeva ◽  
M. Kanamitsu ◽  
J. Roads
Keyword(s):  
Prediction Model ◽  
Internal Variability ◽  
Reanalysis Data ◽  
Ocean Model ◽  
Department Of Energy ◽  
Massachusetts Institute Of Technology ◽  
Seasonal Forecasts ◽  
Coupled Models ◽  
Global Spectral Model ◽  
Institute Of Technology

Abstract This paper presents a new Experimental Climate Prediction Center (ECPC) Coupled Prediction Model (ECPM). The ECPM includes the Jet Propulsion Laboratory (JPL) version of the Massachusetts Institute of Technology (MIT) ocean model coupled to the ECPC version of the National Centers for Environmental Prediction (NCEP) Atmospheric Global Spectral Model (GSM). The adjoint and forward versions of the MIT model forced with the NCEP atmospheric analyses are routinely used at JPL for ocean state assimilation. An earlier version of the GSM was used for the NCEP–Department of Energy reanalysis-2 project and for operational seasonal forecasts at NCEP. The ECPM climatology and internal variability derived from a 56-yr-long coupled integration are compared with the observations and reanalysis data. Though the ECPM exhibits climatological biases, these biases are relatively small and comparable to the systematic errors produced by other well-known coupled models, including the recent NCEP Climate Forecast System. The internal variability of the model resembles the observations. ECPM simulates both seasonal and interannual variability in the tropical Pacific reasonably well. The model has good skill in reproducing the mechanism of ENSO evolution as well as ENSO teleconnection patterns (including the Indian monsoon–ENSO relationship). The skill of the ECPM in predicting 1994–2006 SST anomalies over the Niño-3.4 region is shown to be comparable to other coupled models. These retrospective forecasts were used for deriving a model climatology for real-time seasonal forecasts that are currently produced and displayed at ECPC.

GEOS-MITgcm coupled atmosphere-ocean simulation for DYAMOND

2021 ◽  
Author(s):  
Ehud Strobach ◽  
Andrea Molod ◽  
Atanas Trayanov ◽  
William Putman ◽  
Dimitris Menemenlis ◽  
...  
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Atmospheric Model ◽  
Ocean Model ◽  
Second Phase ◽  
Massachusetts Institute Of Technology ◽  
Grid Spacing ◽  
Institute Of Technology ◽  
Horizontal Grid ◽  
Ocean Simulation

<p>During the past few years, the Goddard Earth Observing System (GEOS) and Massachusetts Institute of Technology general circulation model (MITgcm) groups have produced, respectively, global atmosphere-only and ocean-only simulations with km-scale grid spacing. These simulations have proved invaluable for process studies and the development of satellite and in-situ sampling strategies. Nevertheless, a key limitation of these simulations is the lack of feedback between the ocean and the atmosphere, limiting their usefulness for studying air-sea interactions and designing observing missions to study these interactions. To remove this limitation, we have coupled the km-scale GEOS atmospheric model with the km-scale MITgcm ocean model. We will present preliminary results from the GEOS-MITgcm contribution to the second phase of the DYAMOND (DYnamics of the Atmospheric general circulation Modeled On Non-hydrostatic Domains) initiative.</p><p>The coupled atmosphere-ocean simulation was integrated using a cubed-sphere-1440 (~6-7 km horizontal grid spacing) configuration of GEOS and a lat-lon-cap-2160 (2–5-km horizontal grid spacing) configuration of MITgcm. We will show results from a preliminary analysis of air-sea interactions between Sea Surface Temperature (SST) and surface winds. In particular, we will discuss non-local atmospheric overturning circulation formed above the Gulf Stream SST front with characteristic sub-mesoscale width. This formation of a secondary circulation above the front suggests that capturing such air-sea interaction phenomena requires high-resolution capabilities in both the models' oceanic and atmospheric components.</p>

State estimates and forecasts of the eddy field in the Subtropical Countercurrent in the Northern Philippine Sea

2021 ◽  
Author(s):  
Ganesh Gopalakrishnan ◽  
Bruce D. Cornuelle ◽  
Matthew R. Mazloff ◽  
Peter F. Worcester ◽  
Matthew A. Dzieciuch
Keyword(s):  
General Circulation ◽  
Circulation Model ◽  
Ocean Model ◽  
The State ◽  
Massachusetts Institute Of Technology ◽  
Philippine Sea ◽  
Subtropical Countercurrent ◽  
Continuous State ◽  
Eddy Field ◽  
Institute Of Technology

AbstractA strongly nonlinear eddy field is present in and around the Subtropical Countercurrent in the Northern Philippine Sea (NPS). A regional implementation of the Massachusetts Institute of Technology general circulation model–Estimating the Circulation and Climate of the Ocean four-dimensional variational (MITgcm-ECCO 4DVAR) assimilation system is found to be able to produce a series of two-month-long dynamically-consistent optimized state estimates between April 2010 and April 2011 for the eddy-rich NPS region. The assimilation provides a stringent dynamical test of the model, showing that a free run of the model forced using adjusted controls remains consistent with the observations for two months. The 4DVAR iterative optimization reduced the total cost function for the observations and controls by 40–50% from the reference solution, initialized using the Hybrid Coordinate Ocean Model 1/12° global daily analysis, achieving residuals approximately equal to the assumed uncertainties for the assimilated observations. The state estimates are assessed by comparing with assimilated and withheld observations and also by comparing one-month model forecasts with future data. The state estimates and forecasts were more skillful than model persistence and the reference solutions. Finally, the continuous state estimates were used to detect and track the eddies, analyze their structure, and quantify their vertically-integrated meridional heat and salt transports.

Friction Reduction by Piston Ring Pack Modifications of a Lean-Burn 4-Stroke Natural Gas Engine: Experimental Results

2006 ◽  
Author(s):  
Kris Quillen ◽  
Rudolf H. Stanglmaier ◽  
Luke Moughon ◽  
Rosalind Takata ◽  
Victor Wong ◽  
...  
Keyword(s):  
Natural Gas ◽  
Piston Ring ◽  
Department Of Energy ◽  
Experimental Results ◽  
Friction Reduction ◽  
Massachusetts Institute Of Technology ◽  
Test Bed ◽  
Computational Tools ◽  
Ring Pack ◽  
Institute Of Technology

A project to reduce frictional losses from natural gas engines is currently being carried out by a collaborative team from Waukesha Engine Dresser, Massachusetts Institute of Technology (MIT) and Colorado State University (CSU). This project is part of the Advanced Reciprocating Engine System (ARES) program led by the US Department of Energy. Previous papers have discussed the computational tools used to evaluate piston-ring/cylinder friction and described the effects of changing various ring pack parameters on engine friction. These computational tools were used to optimize the ring pack of a Waukesha VGF 18-liter engine, and this paper presents the experimental results obtained on the engine test bed. Measured reductions in friction mean effective pressure (FMEP) were observed with a low tension oil control ring (LTOCR) and a skewed barrel top ring (SBTR). A negative twist second ring (NTSR) was used to counteract the oil consumption increase due to the LTOCR. The LTOCR and SBTR each resulted in a ∼ 0.50% improvement in mechanical efficiency (ηmech).

scholarly journals Numerical experiments on subaqueous melting of Greenland tidewater glaciers in response to ocean warming and enhanced subglacial discharge

2012 ◽  
Vol 53 (60) ◽  
pp. 229-234 ◽  
Author(s):  
Yun Xu ◽  
Eric Rignot ◽  
Dimitris Menemenlis ◽  
Michele Koppes
Keyword(s):  
General Circulation ◽  
Sea Water ◽  
Water Flux ◽  
Circulation Model ◽  
Melting Process ◽  
Ocean Model ◽  
Massachusetts Institute Of Technology ◽  
Thermal Forcing ◽  
Tidewater Glaciers ◽  
Institute Of Technology

AbstractThe largest dischargers of ice in Greenland are glaciers that terminate in the ocean and melt in contact with sea water. Studies of ice-sheet/ocean interactions have mostly focused on melting beneath near-horizontal floating ice shelves. For tidewater glaciers, melting instead takes place along the vertical face of the calving front. Here we modify the Massachusetts Institute of Technology general circulation model (MITgcm) to include ice melting from a calving face with the freshwater outflow at the glacier grounding line. We use the model to predict melt rates and their sensitivity to ocean thermal forcing and to subglacial discharge. We find that melt rates increase with approximately the one-third power of the subglacial water flux, and increase linearly with ocean thermal forcing. Our simulations indicate that, consistent with limited field data, melting ceases when subglacial discharge is shut off, and reaches several meters per day when subglacial discharge is high in the summer. These results are a first step toward a more realistic representation of subglacial discharge and of ocean thermal forcing on the subaqueous melting of tidewater glaciers in a numerical ocean model. Our results illustrate that the ice-front melting process is both complex and strongly time-dependent.

Friction Reduction by Piston Ring Pack Modifications of a Lean-Burn Four-Stroke Natural Gas Engine: Experimental Results

2007 ◽  
Vol 129 (4) ◽  
pp. 1088-1094
Author(s):  
Kris Quillen ◽  
Rudolf H. Stanglmaier ◽  
Luke Moughon ◽  
Rosalind Takata ◽  
Victor Wong ◽  
...  
Keyword(s):  
Natural Gas ◽  
Piston Ring ◽  
Department Of Energy ◽  
Experimental Results ◽  
Friction Reduction ◽  
Massachusetts Institute Of Technology ◽  
Test Bed ◽  
Computational Tools ◽  
Ring Pack ◽  
Institute Of Technology

A project to reduce frictional losses from natural gas engines is currently being carried out by a collaborative team from Waukesha Engine Dresser, Massachusetts Institute of Technology (MIT), and Colorado State University (CSU). This project is part of the Advanced Reciprocating Engine System (ARES) program led by the U.S. Department of Energy. Previous papers have discussed the computational tools used to evaluate piston-ring/cylinder friction and described the effects of changing various ring pack parameters on engine friction. These computational tools were used to optimize the ring pack of a Waukesha VGF 18-liter engine, and this paper presents the experimental results obtained on the engine test bed. Measured reductions in friction mean effective pressure (FMEP) were observed with a low tension oil control ring (LTOCR) and a skewed barrel top ring (SBTR). A negative twist second ring (NTSR) was used to counteract the oil consumption increase due to the LTOCR. The LTOCR and SBTR each resulted in a ∼0.50% improvement in mechanical efficiency (ηmech).

scholarly journals Features of fluid flows in strongly nonlinear internal solitary waves

2014 ◽  
Vol 1 (2) ◽  
pp. 1919-1946 ◽  
Author(s):  
S. Semin ◽  
O. Kurkina ◽  
A. Kurkin ◽  
T. Talipova ◽  
E. Pelinovsky ◽  
...  
Keyword(s):  
Reverse Flow ◽  
Fluid Flows ◽  
Bottom Layer ◽  
Ocean Model ◽  
Massachusetts Institute Of Technology ◽  
Fully Nonlinear ◽  
Weakly Nonlinear ◽  
Weakly Nonlinear Theory ◽  
Highly Nonlinear ◽  
Institute Of Technology

Abstract. The characteristics of highly nonlinear solitary internal waves (solitons) are calculated within the fully nonlinear numerical model of the Massachusetts Institute of Technology. The verification and adaptation of the model is based on the data from laboratory experiments. The present paper also compares the results of our calculations with the calculations performed in the framework of the fully nonlinear Bergen Ocean Model. The comparison of the computed soliton parameters with the predictions of the weakly nonlinear theory based on the Gardner equation is given. The occurrence of reverse flow in the bottom layer directly behind the soliton is confirmed in the numerical simulations. The trajectories of Lagrangian particles in the internal soliton on the surface, on the pycnocline and near the bottom are computed.

scholarly journals A regional coupled ocean–atmosphere modeling framework (MITgcm–WRF) using ESMF/NUOPC: description and preliminary results for the Red Sea

2018 ◽  
Author(s):  
Rui Sun ◽  
Aneesh Subramanian ◽  
Art Miller ◽  
Matt Mazloff ◽  
Ibrahim Hoteit ◽  
...  
Keyword(s):  
Red Sea ◽  
System Modeling ◽  
Coupled Model ◽  
Reanalysis Data ◽  
Ocean Model ◽  
Modeling Framework ◽  
Coupled Models ◽  
Ocean Atmosphere ◽  
Atmosphere Model ◽  
Regional Coupled Model

Abstract. A new regional coupled ocean–atmosphere model is developed to study air–sea feedbacks. The coupled model is based on two open-source community model components: (1) MITgcm ocean model; (2) Weather Research and Forecasting (WRF) atmosphere model. The coupling between these components is performed using ESMF (Earth System Modeling Framework) and implemented according to National United Operational Prediction Capability (NUOPC) consortium. The regional coupled model allows affordable simulation where oceanic mixed layer heat and momentum interact with atmospheric boundary layer dynamics at mesoscale and higher resolution. This can capture the feedbacks which are otherwise not well-resolved in coarse resolution global coupled models and are absent in regional uncoupled models. To test the regional coupled model, we focus on a series of heat wave events that occurred on the eastern shore of the Red Sea region in June 2012 using a 30-day simulation. The results obtained using the coupled model, along with those in forced uncoupled ocean or atmosphere model simulations, are compared with observational and reanalysis data. All configurations of coupled and uncoupled models have good skill in modeling variables of interest in the region. The coupled model shows improved skill in temperature and circulation evaluation metrics. In addition, a scalability test is performed to investigate the parallelization of the coupled model. The results indicate that the coupled model scales linearly for up to 128 CPUs and sublinearly for more processors. In the coupled simulation, the ESMF/NUOPC interface also scales well and accounts for less than 10 % of the total computational resources compared with uncoupled models. Hence this newly developed regional model scales efficiently for a large number of processors and can be applied for high-resolution coupled regional modeling studies.

scholarly journals Evaluation of Seven Different Atmospheric Reanalysis Products in the Arctic*

2014 ◽  
Vol 27 (7) ◽  
pp. 2588-2606 ◽  
Author(s):  
R. Lindsay ◽  
M. Wensnahan ◽  
A. Schweiger ◽  
J. Zhang
Keyword(s):  
Arctic Region ◽  
Reanalysis Data ◽  
Ocean Model ◽  
Surface Fluxes ◽  
Department Of Energy ◽  
The Arctic ◽  
Ice Thickness ◽  
Ice Volume ◽  
Independent Observations ◽  
Environmental Prediction

Abstract Atmospheric reanalyses depend on a mix of observations and model forecasts. In data-sparse regions such as the Arctic, the reanalysis solution is more dependent on the model structure, assumptions, and data assimilation methods than in data-rich regions. Applications such as the forcing of ice–ocean models are sensitive to the errors in reanalyses. Seven reanalysis datasets for the Arctic region are compared over the 30-yr period 1981–2010: National Centers for Environmental Prediction (NCEP)–National Center for Atmospheric Research Reanalysis 1 (NCEP-R1) and NCEP–U.S. Department of Energy Reanalysis 2 (NCEP-R2), Climate Forecast System Reanalysis (CFSR), Twentieth-Century Reanalysis (20CR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), ECMWF Interim Re-Analysis (ERA-Interim), and Japanese 25-year Reanalysis Project (JRA-25). Emphasis is placed on variables not observed directly including surface fluxes and precipitation and their trends. The monthly averaged surface temperatures, radiative fluxes, precipitation, and wind speed are compared to observed values to assess how well the reanalysis data solutions capture the seasonal cycles. Three models stand out as being more consistent with independent observations: CFSR, MERRA, and ERA-Interim. A coupled ice–ocean model is forced with four of the datasets to determine how estimates of the ice thickness compare to observed values for each forcing and how the total ice volume differs among the simulations. Significant differences in the correlation of the simulated ice thickness with submarine measurements were found, with the MERRA products giving the best correlation (R = 0.82). The trend in the total ice volume in September is greatest with MERRA (−4.1 × 103 km3 decade−1) and least with CFSR (−2.7 × 103 km3 decade−1).

Applying the Anderson-Darling Test to Suicide Clusters

Crisis ◽  
2013 ◽  
Vol 34 (6) ◽  
pp. 434-437 ◽  
Author(s):  
Donald W. MacKenzie
Keyword(s):  
Poisson Process ◽  
Goodness Of Fit ◽  
Small Samples ◽  
Massachusetts Institute Of Technology ◽  
Homogeneous Poisson Process ◽  
Cornell University ◽  
The Difference ◽  
Suicide Clusters ◽  
Institute Of Technology ◽  
Anderson Darling

Background: Suicide clusters at Cornell University and the Massachusetts Institute of Technology (MIT) prompted popular and expert speculation of suicide contagion. However, some clustering is to be expected in any random process. Aim: This work tested whether suicide clusters at these two universities differed significantly from those expected under a homogeneous Poisson process, in which suicides occur randomly and independently of one another. Method: Suicide dates were collected for MIT and Cornell for 1990–2012. The Anderson-Darling statistic was used to test the goodness-of-fit of the intervals between suicides to distribution expected under the Poisson process. Results: Suicides at MIT were consistent with the homogeneous Poisson process, while those at Cornell showed clustering inconsistent with such a process (p = .05). Conclusions: The Anderson-Darling test provides a statistically powerful means to identify suicide clustering in small samples. Practitioners can use this method to test for clustering in relevant communities. The difference in clustering behavior between the two institutions suggests that more institutions should be studied to determine the prevalence of suicide clustering in universities and its causes.

Sign in / Sign up

Export Citation Format

Share Document