DOCSLIB.ORG

Sensitivity of the GFDL Modular Ocean Model to Parameterization of Double-Diffusive Processes*

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Sensitivity of the GFDL Modular Ocean Model to Parameterization of Double-Diffusive Processes* APRIL 1998 ZHANG ET AL. 589 Sensitivity of the GFDL Modular Ocean Model to Parameterization of Double-Diffusive Processes* JUBAO ZHANG MIT/WHOI Joint Program, Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts RAYMOND W. S CHMITT AND RUI XIN HUANG Department of Physical Oceanography, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts (Manuscript received 24 February 1997, in ®nal form 7 July 1997) ABSTRACT The effect of double-diffusive mixing on the general circulation is explored using the GFDL MOM2 model. The motivation for this comes from the known sensitivity of the thermohaline circulation to the vertical diffusivity and the earlier work of Gargett and Holloway, who studied the effects of a simple nonunity ratio between heat and salt diffusivities in a GCM. In this work, a more realistic, yet conservative, parameterization of the double- diffusive mixing is applied, with the intensity depending on the local density ratio Rr 5 aTz/bSz. A background diffusivity is used to represent non-double-diffusive turbulent mixing in the stably strati®ed environment. The numerical model is forced by relaxation boundary conditions on both temperature and salinity at the sea surface. Three control experiments have been carried out: one with the double-diffusive parameterization (DDP) deter- mined by the local density ratio, one with constant but different diffusivities for heat and salt as previously considered by Gargett and Holloway (GHD), and the other with the same constant diapycnal eddy diffusivity for both heat and salt (CDD). The meridional overturning in run DDP is 22% less than in run CDD, and the maximum poleward heat transport is about 8% less. In comparison, the overturning rate and poleward heat transport in run GHD display reductions that are about half as large. The interior temperature and salinity in run DDP and GHD are higher than in run CDD, with the change in run DDP more than twice that in run GHD. In addition, in DDP and GHD, the density ratio distribution becomes closer to unity than in run CDD, with the change in run DDP being larger than in GHD. Interestingly, the double diffusion is stronger in the western boundary current region than the interior, implying a close relation between vertical shear and the intensity of double diffusion. These results indicate a greater sensitivity of the thermohaline circulation to double diffusion than had previously been suspected due to the tendency of the double-diffusive mixing to generate self-reinforcing ¯ows. This effect appears to be more signi®cant when the double-diffusive mixing is applied only when the strati®cation is favorable rather than uniformly applied. In addition, parameter sensitivity experiments suggest that double diffusion could have stronger effects on the meridional overturning and poleward heat transport than modeled here since the parameterizations chosen are rather conservative. 1. Introduction pycnal) eddy diffusivity (K), which is the mechanism that provides the necessary warming of the rising abys- The thermohaline circulation of the ocean plays an sal waters. F. Bryan (1987) found an approximate K 1/3 important role in the climate system of the earth, es- dependence of the MOC; however, his model runs may pecially in controlling the oceanic part of the poleward not have reached equilibrium; later work has found a heat transport. The large-scale structure of the ther- K 2/3 dependence (Marotzke 1997; Zhang et al. 1997, mohaline circulation and its variability has been studied submitted to J. Phys. Oceanogr.), when the conventional extensively in models (Weaver and Hughes 1992; Huang ``relaxation'' boundary conditions are applied for the 1995). One result of these studies is the ®nding that the surface forcing. Whatever the speci®c power law de- strength of the meridional overturning cell (MOC) is pendence, the continual production of cold deep water strongly dependent on the value of the vertical (or dia- at high latitudes requires vertical mixing to close the circulation (Munk 1966). Observational microstructure work in recent years * WHOI Contribution Number 9239. (Gregg 1989; Polzin et al. 1995) has indicated that tur- bulent mixing in the ocean interior caused by internal Corresponding author address: Mr. Jubao Zhang, Room 54-1419, wave breaking is generally much weaker than has been Massachusetts Institute of Technology, Cambridge, MA 02139. inferred from the large-scale budget approach of Munk E-mail: [email protected] (1966), Hogg et al. (1982), and others. However, evi- q 1998 American Meteorological Society Unauthenticated | Downloaded 09/23/21 07:45 PM UTC 590 JOURNAL OF PHYSICAL OCEANOGRAPHY VOLUME 28 dence is emerging that turbulence near rough topogra- plied in the climate-scale numerical model runs de- phy may be suf®ciently enhanced to provide the re- scribed below. However, the parameterization of mixing quired downward heat ¯ux (Toole et al. 1994; Polzin et processes, both vertical and horizontal, requires careful al. 1997). One problem with near-bottom mixing is that treatment in numerical models. The oceanic circulation the strati®cation is weak in the abyss, so heat ¯uxes involves extremely broad scales in both time and space; tend to be small, even with very large eddy diffusivities. thus, we can never resolve all the temporal and spatial This reduced effectiveness of deep internal-wave-in- scales in numerical models. Consequently, for the fore- duced turbulence (the mixing of already mixed water) seeable future, subgrid-scale phenomena must be par- leads us to examine the other mixing processes occur- ameterized in ocean general circulation models. In fact, ring in the more strongly strati®ed thermocline. determining suitable parameterizations of subgrid-scale The primary processes that must be considered are phenomena is one of the most critical problems in nu- the double-diffusive instabilities of salt ®ngering, which merical modeling of the general circulation. Early ocean occurs when temperature and salinity both decrease with circulation models were mostly based on z coordinates, depth, and diffusive convection, which occurs when and subgrid-scale mixing was parameterized in terms of temperature and salinity both increase with depth. It is constant horizontal and vertical mixing. However, such well known that on the molecular level heat and salt simple horizontal/vertical mixing schemes can introduce have diffusivities that are two orders of magnitude dif- strong arti®cial cross-isopycnal mixing near fronts, such ferent. This difference drives convective motions even as the Gulf Stream, where isopycnals slope sharply. To if the overall density pro®le is stable. Substantial evi- overcome the arti®cial cross-isopycnal mixing in low- resolution z-coordinate models, a numerical technique dence is now available that these processes play a sig- of rotating the mixing tensor has been proposed by Redi ni®cant role in ocean mixing (Schmitt 1994). Their prin- (1982) and has been implemented here. cipal effect is to transport heat and salt at different rates In addition, Gent and McWilliams (1990, hereafter in the vertical and cause a net upgradient ¯ux of buoy- GM90) pointed out that there is an extra advection term ancy. A number of recent modeling studies show that in the tracer balance equation of non-eddy-resolving such differential transports have important effects on models, whose existence is due to the Lagrangian mean the stability and structure of the large-scale thermoha- transport of mesoscale eddies. They introduced a pa- line circulation. rameterization based on a downgradient diffusion of the In particular, Gargett and Holloway (1992, hereafter isopycnal layer thickness in adiabatic ¯ow. The addition GH92) ®rst investigated the effects of a simple double- of this transport term makes the tracer conservation diffusive parameterization in an ocean model. They equations in a non-eddy-resolving model self-consistent showed that the steady-state characteristics of low-res- and eliminates the unphysical background horizontal olution GCMs used in climate studies are very sensitive diffusion require in the earlier version of the isopycnal/ to the ratio of the vertical eddy diffusivities for salinity diapycnal mixing schemes. The dynamic effect and and temperature. Large differences in meridional trans- model sensitivity on the isopycnal/diapycnal mixing ports resulted due to the upgradient buoyancy ¯ux, have been discussed in several recent papers (Gent et which forced different advective±diffusive balances to al. 1995; Danabasoglu and McWilliams 1995). be realized. Ruddick and Zhang (1989) found that the In this study we will focus on the parameterization ``salt oscillator'' mechanism in a box model could be of diapycnal mixing in connection with double-diffusive completely stabilized by incorporating salt ®ngers into processes. Based on results from theory, laboratory ex- the model. Most recently, Gargett and Ferron (1996) periments, and oceanic observations, the intensity of found that multibox models with nonequal heat and salt double diffusion must depend on the local density ratio diffusivities exhibited extended ranges of multiple equi- Rr 5 aTz/bSz. There is strong evidence indicating that libria, a different mode transition near present-day val- double diffusion is important in controlling the diapyc- ues of freshwater forcing magnitude, and the possibility nal mixing process in the ocean only if Rr is suf®ciently of quasiperiodic oscillatory states
Load more

Recommended publications
  • Ocean Circulation Models and Modeling
    2512-5 Fundamentals of Ocean Climate Modelling at Global and Regional Scales (Hyderabad - India) 5 - 14 August 2013 Ocean Circulation Models and Modeling GRIFFIES Stephen Princeton University U.S. Department of Commerce N.O.A.A., Geophysical Fluid Dynamics Laboratory, 201 Forrestal Road, Forrestal Campus P.O. Box 308, 08542-6649 Princeton NJ U.S.A. 5.1: Ocean Circulation Models and Modeling Stephen.Griffi[email protected] NOAA/Geophysical Fluid Dynamics Laboratory Princeton, USA [email protected] Laboratoire de Physique des Oceans,´ LPO Brest, France Draft from May 24, 2013 1 5.1.1. Scope of this chapter 2 We focus in this chapter on numerical models used to understand and predict large- 3 scale ocean circulation, such as the circulation comprising basin and global scales. It 4 is organized according to two themes, which we consider the “pillars” of numerical 5 oceanography. The first addresses physical and numerical topics forming a foundation 6 for ocean models. We focus here on the science of ocean models, in which we ask 7 questions about fundamental processes and develop the mathematical equations for 8 ocean thermo-hydrodynamics. We also touch upon various methods used to represent 9 the continuum ocean fluid with a discrete computer model, raising such topics as the 10 finite volume formulation of the ocean equations; the choice for vertical coordinate; 11 the complementary issues related to horizontal gridding; and the pervasive questions 12 of subgrid scale parameterizations. The second theme of this chapter concerns the 13 applications of ocean models, in particular how to design an experiment and how to 14 analyze results.
    [Show full text]
  • Assimila Blank
    NERC NERC Strategy for Earth System Modelling: Technical Support Audit Report Version 1.1 December 2009 Contact Details Dr Zofia Stott Assimila Ltd 1 Earley Gate The University of Reading Reading, RG6 6AT Tel: +44 (0)118 966 0554 Mobile: +44 (0)7932 565822 email: [email protected] NERC STRATEGY FOR ESM – AUDIT REPORT VERSION1.1, DECEMBER 2009 Contents 1. BACKGROUND ....................................................................................................................... 4 1.1 Introduction .............................................................................................................. 4 1.2 Context .................................................................................................................... 4 1.3 Scope of the ESM audit ............................................................................................ 4 1.4 Methodology ............................................................................................................ 5 2. Scene setting ........................................................................................................................... 7 2.1 NERC Strategy......................................................................................................... 7 2.2 Definition of Earth system modelling ........................................................................ 8 2.3 Broad categories of activities supported by NERC ................................................. 10 2.4 Structure of the report ...........................................................................................
    [Show full text]
  • Executive Summary Workshop on Improving ALE Ocean Modeling NOAA Center for Weather and Climate Prediction College Park, MD October 3-4, 2016
    Executive Summary Workshop on Improving ALE Ocean Modeling NOAA Center for Weather and Climate Prediction College Park, MD October 3-4, 2016 A one-and-a-half-day workshop on ocean models that employ the ALE (Arbitrary Lagrangian-Eulerian) method to permit general vertical coordinates was held at NCWCP on October 3-4, 2016. Four different ALE models (GO2, HYCOM, MOM6, and MPAS-Ocean) were discussed. Workshop participants included users and developers of these models, from academia and from seven different national modeling centers (ESRL, GFDL, GISS, LANL, NCAR, NCEP, NRL). A more detailed report on the workshop follows this executive summary, and a workshop agenda with a list of workshop speakers is attached as an appendix. A number of recommendations for future action were developed during the meeting. The recommendations fall into four broad categories: Code Sharing, Community Building, Code Merger and Performance and Future Development. The recommendations are listed below. 1. Code Sharing Sharing of common codes for the equation of state, grid generation and remapping, and column physics such as mixing parameterizations, is recommended. The group suggested making vertical remapping/grid generator routines an open source package that can be shared in the manner of CVMix. a. The development of prognostic equations for the grid generator based upon physical mixing should be considered. b. We recommend open-source GIT repositories (hosted on code-sharing sites such as Github) for submodules such as CVMix. c. We recommend the development of common tests for self-consistency, conservation, and known solutions. 2. Community Building d. The ALE modeling group should consider whether semi-regular meetings similar to this workshop should be undertaken; perhaps via merger/inclusion with the Layered Ocean Model workshop.
    [Show full text]
  • Challenges and Prospects in Ocean Circulation Models
    Challenges and Prospects in Ocean Circulation Models The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Fox-Kemper, Baylor, et al. “Challenges and Prospects in Ocean Circulation Models.” Frontiers in Marine Science 6 (February 2019): 65. © The Authors As Published http://dx.doi.org/10.3389/fmars.2019.00065 Publisher Frontiers Media SA Version Final published version Citable link https://hdl.handle.net/1721.1/125142 Terms of Use Creative Commons Attribution 4.0 International license Detailed Terms https://creativecommons.org/licenses/by/4.0/ REVIEW published: 26 February 2019 doi: 10.3389/fmars.2019.00065 Challenges and Prospects in Ocean Circulation Models Baylor Fox-Kemper 1*, Alistair Adcroft 2,3, Claus W. Böning 4, Eric P. Chassignet 5, Enrique Curchitser 6, Gokhan Danabasoglu 7, Carsten Eden 8, Matthew H. England 9, Rüdiger Gerdes 10,11, Richard J. Greatbatch 4, Stephen M. Griffies 2,3, Robert W. Hallberg 2,3, Emmanuel Hanert 12, Patrick Heimbach 13, Helene T. Hewitt 14, Christopher N. Hill 15, Yoshiki Komuro 16, Sonya Legg 2,3, Julien Le Sommer 17, Simona Masina 18, Simon J. Marsland 9,19,20, Stephen G. Penny 21,22,23, Fangli Qiao 24, Todd D. Ringler 25, Anne Marie Treguier 26, Hiroyuki Tsujino 27, Petteri Uotila 28 and Stephen G. Yeager 7 1 Department of Earth, Environmental, and Planetary Sciences, Brown University, Providence, RI, United States, 2 Atmospheric and Oceanic Sciences Program, Princeton University, Princeton, NJ, United States, 3 NOAA Geophysical
    [Show full text]
  • North Atlantic Simulations in Coordinated Ocean-Ice Reference
    Ocean Modelling Archimer January 204, Volume 73, Pages 76–107 http://dx.doi.org/10.1016/j.ocemod.2013.10.005 http://archimer.ifremer.fr © 2013 Elsevier Ltd. All rights reserved. North Atlantic simulations in Coordinated Ocean-ice Reference is available on the publisher Web site Web publisher the on available is Experiments phase II (CORE-II). Part I: Mean states Gokhan Danabasoglua, *, Steve G. Yeagera, David Baileya, Erik Behrensb, Mats Bentsenc, Daohua Bid, Arne Biastochb, Claus Böningb, Alexandra Bozece, Vittorio M. Canutof, Christophe Cassoug, Eric Chassignete, Andrew C. Cowardh, Sergey Danilovi, Nikolay Dianskyj, Helge Drangek, Riccardo Farnetil, Elodie Fernandezg, Pier Giuseppe Foglim, Gael Forgetn, Yosuke Fujiio, authenticated version authenticated - Stephen M. Griffiesp, Anatoly Gusevj, Patrick Heimbachn, Armando Howardf, q, Thomas Jungi, Maxwell Kelleyf, William G. Largea, Anthony Leboissetierf, Jianhua Lue, Gurvan Madecr, Simon J. Marslandd, Simona Masinam, s, Antonio Navarram, s, A.J. George Nurserh, Anna Piranit, David Salas y Méliau, Bonita L. Samuelsp, Markus Scheinertb, Dmitry Sidorenkoi, Anne-Marie Treguierv, Hiroyuki Tsujinoo, Petteri Uotilad, Sophie Valckeg, Aurore Voldoireu, Qiang Wangi a National Center for Atmospheric Research (NCAR), Boulder, CO, USA b Helmholtz Center for Ocean Research, GEOMAR, Kiel, Germany c Uni Climate, Uni Research Ltd., Bergen, Norway d Centre for Australian Weather and Climate Research, a partnership between CSIRO and the Bureau of Meteorology, Commonwealth Scientific and Industrial Research
    [Show full text]
  • Volume and Heat Transports in the World Oceans from an Ocean General Circulation Model
    “main” — 2009/11/10 — 21:05 — page 181 — #1 Revista Brasileira de Geof´ısica (2009) 27(2): 181-194 © 2009 Sociedade Brasileira de Geof´ısica ISSN 0102-261X www.scielo.br/rbg VOLUME AND HEAT TRANSPORTS IN THE WORLD OCEANS FROM AN OCEAN GENERAL CIRCULATION MODEL Luiz Paulo de Freitas Assad1, Audalio Rebelo Torres Junior2, Wilton Zumpichiatti Arruda3, Affonso da Silveira Mascarenhas Junior4 and Luiz Landau5 Recebido em 29 setembro, 2008 / Aceito em 9 junho, 2009 Received on September 29, 2008 / Accepted on June 9, 2009 ABSTRACT. Monitoring the volume and heat transports around the world oceans is of fundamental importance in the study of the climate system, its variability, and possible changes. The application of an Oceanic General Circulation Model for climatic studies needs that its dynamic and thermodynamic fields are in equilibrium. The time spent by the model to reach this equilibrium is called spin-up time. This work presents some results obtained from the application of the Modular Ocean Model version 4.0 initialized with temperature, salinity, velocity and sea surface height data already in equilibrium from an ocean data assimilation experiment conducted by Geophysical Fluid Dynamics Laboratory (GFDL). The use of this dataset as initial condition aimed to diminish the spin-up time of the oceanic model. The model was integrated for seven years. Volume and heat transports in different sections around the world oceans showed to be in good agreement with the literature. The results showed a well defined seasonal cycle starting at the second integration year, also some important dynamic and thermodynamic aspects of the Global Ocean Circulation, as the great conveyor belt, are well reproduced.
    [Show full text]
  • A New Approach to the Spin-Up Problem in Ocean–Climate Models ISBN 978-90-39354414 Copyright C 2010 Erik Bernsen, the Netherlands
    A New Approach to the Spin-up Problem in Ocean–Climate Models ISBN 978-90-39354414 Copyright c 2010 Erik Bernsen, The Netherlands Institute for Marine and Atmospheric research Utrecht (IMAU) Faculty of Science, Department of Physics and Astronomy Utrecht University, The Netherlands Cover: The pattern in the background is inspired by the sparsity pattern of the Jacobian matrix of the Modular Ocean Model Version 4, as used in Chapter 5 of this thesis. A New Approach to the Spin-up Problem in Ocean–Climate Models Een Nieuwe Aanpak van het Spin-up Probleem in Oceaan–Klimaat Modellen (met een samenvatting in het Nederlands) PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. J.C. Stoof, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op woensdag 8 december 2010 des middags te 2.30 uur door Erik Bernsen geboren op 6 januari 1976 te Almelo Promotor: Prof.dr.ir. H.A. Dijkstra Contents 1 Introduction 1 1.1 TheSpin-upProblem .............................. 2 1.2 ReducingtheSpin-upTime. 6 1.3 ThisThesis ................................... 8 2 JFNKMethodforaPlanetaryGeostrophicOceanModel 11 2.1 Introduction................................... 11 2.2 TheJFNKMethod ............................... 12 2.3 TestCase .................................... 13 2.3.1 PlanetaryGeostrophicModel . 14 2.3.2 Preconditioner ............................. 16 2.4 Results...................................... 17 2.5 Summary,DiscussionandConclusion . .... 22 3 Bifurcation Analysis of wind-driven Flows with the Version 4 of the Modular Ocean Model 25 3.1 Introduction................................... 25 3.2 TheModularOceanModelVersion4 . 27 3.3 MethodandImplementation . 29 3.3.1 ResidualofMOM4........................... 29 3.3.2 Preconditioner ............................. 32 3.4 Results.....................................
    [Show full text]
  • Retrospective ENSO Forecasts: Sensitivity to Atmospheric Model and Ocean Resolution
    3038 MONTHLY WEATHER REVIEW VOLUME 131 Retrospective ENSO Forecasts: Sensitivity to Atmospheric Model and Ocean Resolution EDWIN K. SCHNEIDER,* DAVID G. DEWITT,1 ANTHONY ROSATI,# BEN P. K IRTMAN,* LINK JI,@ AND JOSEPH J. TRIBBIA& *George Mason University, Fairfax, Virginia, and Center for Ocean±Land±Atmosphere Studies, Calverton, Maryland 1International Research Institute for Climate Prediction, Palisades, New York #NOAA, Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey @Department of Oceanography, Texas A&M University, College Station, Texas &National Center for Atmospheric Research, Boulder, Colorado (Manuscript received 19 September 2002, in ®nal form 16 June 2003) ABSTRACT Results are described from a series of 40 retrospective forecasts of tropical Paci®c SST, starting 1 January and 1 July 1980±99, performed with several coupled ocean±atmosphere general circulation models sharing the same ocean modelÐthe Modular Ocean Model version 3 (MOM3) OGCMÐand the same initial conditions. The atmospheric components of the coupled models were the Center for Ocean±Land±Atmosphere Studies (COLA), ECHAM, and Community Climate Model version 3 (CCM3) models at T42 horizontal resolution, and no empirical corrections were applied to the coupling. Additionally, the retrospective forecasts using the COLA and ECHAM atmospheric models were carried out with two resolutions of the OGCM. The high-resolution version of the OGCM had 18 horizontal resolution (1/38 meridional resolution near the equator) and 40 levels in the vertical, while the lower-resolution version had 1.58 horizontal resolution (1/28 meridional resolution near the equator) and 25 levels. The initial states were taken from an ocean data assimilation performed by the Geophysical Fluid Dynamics Laboratory (GFDL) using the high-resolution OGCM.
    [Show full text]
  • Coastal Ocean Model Coupling Applications at the NOAA National Ocean Service: Future Plans and Recentadvances
    Coastal Ocean Model Coupling Applications at the NOAA National Ocean Service: Future Plans and RecentAdvances Saeed Moghimi , NOAA/UCAR, Saeed Moghimi1, Edward Myers1, Sergey Vinogradov1, Andre Van der Westhuysen2, Beheen Trimble2, Ali Abdolali2, Jaime Calzada1, Yuji Funakoshi1, Panagiotis Velissariou1, Joannes Westerink3, Damrongsak Wirasaet3, Maria Teresa Contreras-Vargas3, William Pringle3, Joseph Zhang4, Fei Ye4, Wei Huang4, Kendra Dresback5, Christine Szpilka5, Changsheng Chen6, Jianhua Qi6, Ayumi Fujisaki7,8, Rocky Dunlap8, Patrick Burke1, Derrick Snowden1, Shachak Pe’eri1 1 NOAA/NOS;2 NOAA/NWS; 3 University of Notre Dame; 4 Virginia Institute of Marine Science; 5 University of Oklahoma; 6 University of Massachusetts– Dartmouth; 7 Great Lakes Environmental Research Laboratory; 8 Cooperative Institute for Great Lakes Research at University of Michigan; 9 ESMF/ NUOPC Development Team; NOAA: National Oceanic and Atmospheric Administration; NOS: National Ocean Service; NWS: National Weather Service; ESMF: Earth System Modeling Framework; NUOPC: National Unified Operational Prediction Capability NOAA/NOS’ Office of Coast Survey 1 Coastal ocean models coupling framework Wave Model • Disaster mitigation Numerical Weather Coastal Ocean • Navigation Product Model Model • Water Quality EndUser • Sediment Transport Example Products • Maps and Visualizations Inland Hydrology • Ensembles, Probabilities Model • Product Uncertainties • Wave Conditions NOAA/NOS’ Office of Coast Survey NOS’ next generation high fidelity coastal ocean model (5~10
    [Show full text]
  • An Application to Ocean Modelling
    * Manuscript Click here to download Manuscript: paper_rev_final.tex Web-enabled Configuration and Control of Legacy Codes: an Application to Ocean Modelling ∗ C. Evangelinos a, , P.F.J. Lermusiaux b,S.K.Geigera, R.C. Chang a,N.M.Patrikalakisa aDepartment of Mechanical Engineering, MIT, Cambridge, MA 02139, USA bDivision of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02139, USA Abstract For modern interdisciplinary ocean prediction and assimilation systems, a sig- nificant part of the complexity facing users is the very large number of possible setups and parameters, both at build-time and at run-time, especially for the core physical, biological and acoustical ocean predictive models. The configuration of these modeling systems for both local as well as remote execution can be a daunt- ing and error-prone task in the absence of a Graphical User Interface (GUI) and of software that automatically controls the adequacy and compatibility of options and parameters. We propose to encapsulate the configurability and requirements of ocean prediction codes using an eXtensible Markup Language (XML) based descrip- tion, thereby creating new computer-readable manuals for the executable binaries. These manuals allow us to generate a GUI, check for correctness of compilation and input parameters, and finally drive execution of the prediction system components, all in an automated and transparent manner. This web-enabled configuration and automated control software has been developed (it is currently in “beta” form) and exemplified for components of the interdisciplinary Harvard Ocean Prediction Sys- tem (HOPS) and for the uncertainty prediction components of the Error Subspace Statistical Estimation (ESSE) system.
    [Show full text]
  • The Fidelity of NCEP CFS Seasonal Hindcasts Over Nordeste
    618 MONTHLY WEATHER REVIEW VOLUME 135 The Fidelity of NCEP CFS Seasonal Hindcasts over Nordeste VASUBANDHU MISRA Center for Ocean–Land–Atmosphere Studies, Institute of Global Environment and Society, Inc., Calverton, Maryland YUNING ZHANG Montgomery Blair High School, Silver Spring, Maryland (Manuscript received 19 December 2005, in final form 8 May 2006) ABSTRACT The fidelity of the interannual variability of precipitation over Nordeste is examined using the suite of the NCEP Climate Forecast System (CFS) seasonal hindcasts. These are coupled ocean–land–atmosphere multiseasonal integrations. It is shown that the Nordeste rainfall variability in the season of February–April has relatively low skill in the CFS seasonal hindcasts. Although Nordeste is a comparatively small region in the northeast of Brazil, the analysis indicates that the model has a large-scale error in the tropical Atlantic Ocean. The CFS exhibits a widespread El Niño–Southern Oscillation (ENSO) forcing over the tropical Atlantic Ocean. As a consequence of this remote ENSO forcing, the CFS builds an erroneous meridional SST gradient in the tropical Atlantic that is known from observations to be a critical forcing for the rainfall variability over Nordeste. 1. Introduction tenrath and Heller 1977) have shown that tropical sea surface temperature anomaly (SSTA) over the Atlantic Nordeste or Northeast Brazil (Fig. 1) has been noted and the eastern Pacific Ocean modulates the Nordeste by many authors to be a region of high seasonal climate seasonal rainfall variability. More recently, with inno- predictability (Misra 2006, 2004; Sun et al. 2005; Moura vative modeling experiments, Giannini et al. (2001), Sa- and Hastenrath 2004; Folland et al.
    [Show full text]
  • Forecast Skill Score Assessment of a Relocatable Ocean Prediction System, Using a Simplified Objective Analysis Method
    Ocean Sci., 13, 925–945, 2017 https://doi.org/10.5194/os-13-925-2017 © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. Forecast skill score assessment of a relocatable ocean prediction system, using a simplified objective analysis method Reiner Onken Helmholtz-Zentrum Geesthacht (HZG), Max-Planck-Straße 1, 21502 Geesthacht, Germany Correspondence to: Reiner Onken ([email protected]) Received: 5 May 2017 – Discussion started: 23 May 2017 Revised: 26 September 2017 – Accepted: 9 October 2017 – Published: 20 November 2017 Abstract. A relocatable ocean prediction system (ROPS) 1 Introduction was employed to an observational data set which was col- lected in June 2014 in the waters to the west of Sardinia A relocatable ocean prediction system (ROPS) is presented (western Mediterranean) in the framework of the REP14- which enables rapid nowcasts and forecasts of ocean envi- MED experiment. The observational data, comprising more ronmental parameters in limited regions. In this study, ROPS than 6000 temperature and salinity profiles from a fleet of was implemented for the waters west of Sardinia (western underwater gliders and shipborne probes, were assimilated Mediterranean Sea) within the framework of the REP14- in the Regional Ocean Modeling System (ROMS), which is MED experiment (Onken et al., 2014, 2018). the heart of ROPS, and verified against independent observa- The major components of ocean operational systems are tions from ScanFish tows by means of the forecast skill score observations and ocean circulation models coupled with data as defined by Murphy(1993). A simplified objective analy- assimilation systems, to combine the observations with dy- sis (OA) method was utilised for assimilation, taking account namics and issue nowcasts and forecasts which are deliv- of only those profiles which were located within a predeter- ered to the customers.
    [Show full text]