Lars Petter Røed

Lars Petter Røed
Norwegian Meteorological Institute · Research and Development Department

Dr. Philos.

About

76
Publications
7,957
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Introduction
I am a retired senior research scientist at MET Norway and emeritus professor at Univ. of Oslo, Dep. Geosciences. Current research interest is modeling of storm surges, sea ice and eddy resolving ocean circulation models including fjord models applying the ocean model ROMS. I have recently published a textbook on numerical modeling entitled "Atmospheres and Oceans on Computers" (Springer Nature, 2019)
Additional affiliations
September 1994 - present
Norwegian Meteorological Institute
Position
  • Senior Researcher
September 1994 - July 2019
Norwegian Meteorological Institute
Position
  • Professor Emeritus
September 1990 - September 1994
Nansen Environmental and Remote Sensing Center
Position
  • Head, Oslo Office & Research Director

Publications

Publications (76)
Article
Full-text available
We consider the Norwegian Meteorological Institute’s system regarding the daily forecasts of water level, and warnings of possible dangerous water level events along the Norwegian coast. The system consists of three parts, the production of water level forecasts, a decision support system, and a system for dissemination of warnings to key users and...
Chapter
This chapter investigates the effect of including more than one dimension in space. In particular, it discusses the impact on numerical stability and the stability criterion. Extension to three dimensions is then straightforward.
Chapter
So far, we have only used the Cartesian geopotential coordinate system consisting of three orthogonal spatial coordinates x, y, z. Relaxing the orthogonality between the vertical coordinate z and the two horizontal coordinates x, y can make it much easier to analyze phenomena in atmospheres and oceans, and devise compelling models of them. The deve...
Chapter
The purpose of this chapter is to present some properties inherent in the governing equations listed in Sect. 1.1. Most problems in the geophysical sciences, including atmospheres, oceans, seas, and lakes, involve solving so-called time marching problems. Typically, the state of the fluid in question is known at one specific time. As postulated by...
Chapter
In this chapter, we present a general analysis of partial differential equations (henceforth, PDEs). These are of importance here because the governing equations of the atmosphere and the ocean, including the hierarchy of simpler equations outlined in Chap. 1, belong to this class. We shall see that a PDE has a different character depending on the...
Chapter
The purpose of this chapter is to learn how to solve a simple subset of the momentum equations ( 1.1) numerically. The focus is on the shallow water equations, and in particular their depth integrated versions ( 1.33) and ( 1.34). Despite their simplicity, the shallow water equations include the essence of the momentum equations. For instance, we r...
Chapter
The purpose of this chapter is to study potentially useful schemes and discretizations of the linear advection equation. We discuss various stable and consistent schemes such as the leap-frog scheme, the upstream scheme (or upwind scheme), the Lax–Wendroff scheme, and the semi-Lagrangian scheme. The conditions under which they are stable are also d...
Chapter
The purpose of this chapter is to familiarize the reader with the equations governing the motion of atmospheres and the oceans. It introduces the well-known Boussinesq and hydrostatic approximations, and outlines the way the shallow water equations and the quasi-geostrophic equations follow from these approximations. The importance of boundary cond...
Chapter
The purpose of this chapter is to use the knowledge acquired in the previous chapters to learn about some slightly more advanced topics. For instance, we sketch ways to construct schemes of higher order accuracy, and ways to solve problems when advection and diffusion are equally important. Furthermore, we consider ways to treat nonlinearities nume...
Chapter
In this chapter, we discuss the fundamentals of how to cast a PDE into finite difference form. More specifically, the reader will learn how to discretize the diffusion equation, and learn why some discretizations work and some do not. This will be the opportunity to introduce concepts such as numerical stability, convergence, and consistency. It wi...
Chapter
The aim here is to summarize a set of sound procedures for establishing what is referred to below as a “good” model. The text is based on earlier reports by the author on the subject, in particular McClimans et al. (1992) and Røed (1993). For more extensive reading on the subject, the reader is referred to the in-depth analysis documented in the GE...
Chapter
The aim of this chapter is to discuss open boundaries and some of the techniques used to deal with them. An open boundary is defined as a computational boundary at which disturbances originating in the interior of the computational domain are allowed to leave without disturbing or deteriorating the interior solution (Røed and Cooper, Advanced physi...
Technical Report
Full-text available
Provided is an evaluation on the performance of the FjordOs model, a new circulation model covering the Oslofjord, Norway. The model is developed to improve the ocean input (e.g., currents) to emergency models used to predict pathways of oil and/or other effluents. The FjordOs model is a regional adaption of the Regional Ocean Modeling System (ROMS...
Article
To model currents in a fjord accurate tidal forcing is of extreme importance. Due to complex topography with narrow and shallow straits, the tides in the innermost parts of a fjord are both shifted in phase and altered in amplitude compared to the tides in the open water outside the fjord. Commonly, coastal tide information extracted from global or...
Article
Full-text available
We consider the distribution and level of local vertical mixing inside of the Drøbak Sill in the Oslofjord, Norway. The work is motivated by observations of long periods (~ years) of hypoxic or even anoxic conditions in the innermost basin, episodes attributed to weak vertical mixing. In line with earlier work on the subject we assume that the loca...
Book
Full-text available
Lecture notes (compendium) to the Master Course at the University of Oslo of the same name. Presented are fundamental numerical methods behind numerical weather prediction and numerical ocean weather prediction models (advection, diffusion, shallow water equations). Also treated are open boundary condtions, and general vertical coordinate systems.
Technical Report
Full-text available
We report on the progress of work with regard to the project LOfoten and VEsterålen CURents Phase II (henceforth LOVECUR II) under Contract No. 4502227631 (henceforth Contract) performed by the Norwegian Meteorological Institute (met.no) in collaboration with the Institute of Marine Research (IMR). LOVECUR II was initiated at met.no on June 1, 2011...
Article
We consider results from two 27-year-long simulation pairs derived using two different ocean models. We focus on the Skagerrak/North Sea area. Each pair consists of the two terrain-following coordinate models ROMS and MIPOM. The first pair utilizes an eddy-permitting grid, that is, a grid in which the Rossby radius is barely resolved. The second pa...
Conference Paper
Full-text available
A first step to enable eddy-resolving ocean predictions is to investigate the forecast model's ability to produce realistic mesoscale patterns in the application area. We explore whether the numerical ocean weather prediction system at the Norwegian Meteorological Institute provides reasonable mesoscale patterns in an area covering the Barents Sea...
Article
We consider possible changes in the future climate of wind speed (WS), significant wave height (SWH) and storm surge residual (SSR) for a region covering the Northern Seas. Our results are based on an analysis of changes in the response derived with regional atmosphere, wave, and storm surge models run for two time periods 1961–1990 and 2071–2100....
Article
Full-text available
We consider possible changes in the future climate of wind speed (WS), significant wave height (SWH) and storm surge residual (SSR) for a region covering the Northern Seas. Our results are based on an analysis of changes in the response derived with regional atmosphere, wave, and storm surge models run for two time periods 1961–1990 and 2071–2100....
Article
We assess the performance of an eddy-recognizing numerical ocean model in simulating the pattern and variability of the hydrography in the Skagerrak/northern North Sea area. The model we use is a version of the widely used Princeton ocean model employing a terrain-following vertical coordinate. Results from a series of five multi-year simulations o...
Article
Full-text available
The Lofoten-Barents Sea area, which contains some of the most valuable fish stocks of the Atlantic Ocean, is being considered for offshore oil production. We review the effects of a hypothetical oil spill on fishes in this area, with a focus on effects on the egg and larval stage of the 3 dominating fish stocks: NE Arctic cod Gadus morhua, Barents...
Technical Report
Full-text available
We compare the results from a three year simulation with the three eddy-permitting numerical ocean models MIPOM, ROMS and HYCOM, for a limited area of the northeastern Atlantic Ocean. The forcing, boundary conditions and model set ups were chosen to be as similar as possible. We validate the model velocities by comparing them to those derived from...
Article
We perform a combined potential vorticity analysis and energy analysis to analyze instabilities and mesoscale motion in a continuously stratified, terrain-following coordinate ocean model. Care is exercised to ensure that the potential vorticity is conserved along isopycnals in the absence of sources and sinks. We also derive expressions for the en...
Article
Full-text available
By means of simulations with a global coupled AOGCM it is shown that changes in the polar energy sink region can exert a strong influence on the mid- and high-latitude climate by modulating the strength of the mid-latitude westerlies and storm tracks. It is found, that a more realistic sea-ice and snow albedo treatment changes the ice-albedo feedba...
Technical Report
Full-text available
Considered are the steps necessary to objectively establish confidence in any model aiming to answer specific management questions relating to problems involving hydrodynamic and bio-geochemical processes. In essence these guidelines may be referred to as quality assur-ance procedures, a task that is rarely undertaken to its full extent, mostly due...
Technical Report
We present a somewhat detailed documentation of the three CONMAN models MIPOM, ROMS and HYCOM and their set-up in the CONMAN project. We also present examples of the model products, examples of daily produced forecast products, and some preliminary skill comparisons.
Article
Full-text available
The mean motion in the Skagerrak/nothern North sea was studied as a measure of the large scale flow and eddy motion. The mechanism by which recurrent eddies off the southern tip of Norway are spanwed was discussed. These questions are answered by analyzing the the results of the circulation and hydrography of the Skagerrak/northen sea area. The res...
Technical Report
Full-text available
The overall objective of the project is to develop, test and demonstrate a pilot system for monitoring and prediction of the Norwegian marine coastal environment. Particular focus is on dominant physical and coupled physicalbiogeochemical interactive processes within the Norwegian Coastal Current and along its open boundaries. The tools to understa...
Technical Report
Full-text available
Considered is the most recent version of the dynamic-thermodynamic sea ice model MI-IM developed at the Norwegian Meteorological Institute. Its development is with a view to coupling to an atmosphere and an ocean model. In this the paramount principle is that fluxes exchanged between the ocean and the atmosphere are conserved. Since the heat flux p...
Article
Full-text available
Considered is a possible change in the future wind, wave, and surge climate for a regional area roughly covering the northern North-Atlantic with adjacent seas. Conclusions are drawn based on a statistical analysis of changes in the results derived with state of the art wave and storm surge models run for two 20-year time-slice periods, one fo...
Article
Mesoscale variability in the Denmark Strait overflow is investigated using a version of the Miami Isopycnic Coordinate Ocean Model that includes a recently developed intermittent and vigorous, turbulent and diffusive diapycnal mixing scheme. Earlier idealized modeling work on the subject is further extended in that a realistic replica of the shelf-...
Article
Mesoscale variability in the Denmark Strait overflow is investigated using a version of the Miami Isopycnic Coordinate Ocean Model that includes a recently developed intermittent and vigorous, turbulent and diffusive diapycnal mixing scheme. Earlier idealized modeling work on the subject is further extended in that a realistic replica of the shelf-...
Article
Considered are possible links between mesoscale features and the presence of topographic and/or coastline irregularities off the Atlantic coast of the Iberian Peninsula, and what physical processes sustain the persistent filaments. The former is investigated by contrasting the results from two suites of three model runs differing only in the specif...
Article
Considered is a pointwise energy diagnostic scheme for a multilayer, primitive equation, nonisopycnic ocean model. Both conservative as well as nonconservative energy exchange terms are considered. Moreover, the scheme is worked out for both the finite depth as well as the reduced gravity versions of the model. The work is motivated by the need to...
Article
Full-text available
A linear stability analysis combined with an energy analysis is performed to discriminate between the various instabilities that may develop at upwelling fronts. In the present study, a two-active-layer model of finite depth is considered. Thus, the model includes a variable across-front bottom topography, a sloping interface, a surface elevation,...
Article
A one active layer, eddy resolving (grid size ∼14 of the baroclinic Rossby radius) reduced gravity numerical model, forced by winds and by imposed boundary flows, is applied to the ocean area northwest of the British Isles in order to study the continental slope current and its variability during winter. It is found that local wind forcing alone is...
Article
The Norwegian Meteorological Institute (DNMI) runs an operational marine forecast system, which consists of 4 coupled marine numerical models: a numerical weather prediction model (HIRLAM), a wave model (WINCH), a primitive equation baroclinic ocean model (ECOM3D) which is run both in barotropic and baroclinic modes, and an oil drift model (NOROIL)...
Article
The development of a pointwise (in the horizontal) energy diagnostic scheme applicable to a 11/2-layer, nonisopycnic, primitive equation model is presented. The scheme utilizes the concept of available gravitational energy to replace the conventional potential energy. This gives a total energy (kinetic plus potential) that is zero and a minimum wit...
Chapter
Full-text available
Considered is the development of multilayer, non-isopycnic ocean models for studies of the mesoscale oceanic response. In particular a 11/2 layer model is described and results from some initial experiments, in which the observed mesoscale features off the Iberian Peninsula are realistically reproduced, are presented. The mesoscale features observe...
Chapter
Considered are the results of a model comparison study performed as part of the Metocean Modeling Project (MOMOP). The study involves the design of five test cases, relevant to the Norwegian Shelf, by which three-dimensional, baroclinic numerical ocean models can be verified. The first two of these are two-dimensional, in which processes connected...
Chapter
Two fully three-dimensional, primitive equation, baroclinic level models are applied to the mid-Norwegian shelf, and their simulations for a period in March 1988, are validated against observations from the NORCSEX'88 field experiment. The main concern is currents, but salinity and temperature fields are also compared. This validation study has ele...
Article
Two three-dimensional numerical ocean models, arbitrarily named the POM model and the SINMOD model, have been used to simulate the current, salinity and temperature structure in the Halten Bank area for March 1988 and then validated against the Norwegian Continental Shelf Experiment 1988 (NORCSEX'88) data set. Although the motion in the two models...
Article
The first ERS-1 C-band SAR image of the western coast of Norway was received at Troms∅ Satellite Station, Norway, on 21 August 1991. It depicts clearly an eddy-like structure located in the coastal water. The eddy has a cyclonic spiral structure with a diameter of about 5 km. The expressions of the dark lines outlining the spiral are probably cause...
Conference Paper
Full-text available
the need for better monitoring and Inodelingofthemarine environment has increased ch"amatiC<l.l.ly in recent years, in particular along the coastal boundaries and shelf regions where human activities are extensive and pollution has asignificaIlt impact This has been documented ina number·.of unpredicted events for example along the CQast of Norway,...
Article
Full-text available
The need :';: better monitoring and modeling of the marine en\"ironm!:'::: has increased dramatically in recent years. in particular. ;1:ang coastal boundaries and she~f regions u:hef(~ human acli"ities are extensil'e and pollution has a signifi-cant impact. This has been documented in a number of un-predicted events along the coast of Norway, such...
Technical Report
Full-text available
Executive summary The research vessel Håkon Mosby of the University of Bergen will conduct a multidisciplinary oceanographic field investigation along the Iberian coast off Portugal and Spain from about 15 November to 2 December 1993 as part of the MORENA program. MORENA is financially supported under the Commission of the European Communities (CEC...
Article
Full-text available
Considered are the capabilities of a recently developed pulse-to-pulse coherent sonar called the High Resolution Current Profiler (HRCP). Special emphasis is placed on methods whereby reliable and accurate vertical profiles of turbulence parameters, such as turbulent kinetic energy and Reynolds stresses, may be extracted from such sonars. The proto...
Article
This study focuses on the sensitivity of the interior wind-forced response of a numerical barotropic ocean model to changes in the open boundary conditions (OBCs) where the term “open” implies a sea boundary where the solution is unknown and must be assumed or extrapolated from the interior solution. Seven different OBCs are applied along the two L...
Conference Paper
The performance of a High Resolution Current Profiler (HRCP) using pulse-to-pulse coherent Doppler technique rather than conventional incoherent Doppler (ADCP) technique is discussed. The HRCP (300 KHz) was deployed on the bottom of the North Sea (at about 100 m depth) looking upwards. The sensor head was deployed separately form the electronics an...
Chapter
Full-text available
Conditions imposed on a class of computational boundaries sometimes referred to as "open" boundaries are reviewed. A possible definition of the term "open boundary" is suggested in order to limit the discussion. Some popular and recently suggested conditions are reviewed and discussed. Emphasis is on conditions based on the Sommerfeld radiation con...
Article
A coupled ice-ocean numerical model for the marginal ice zone is considered. The model consists of a nonlinear sea ice model and a two-layer (reduced gravity) ocean model. The dependence of the upwelling response on wind stress direction is discussed. The results confirm earlier analytical work. It is shown that there exist directions for which the...
Article
Full-text available
A coupled ice-ocean model for thermodynamic growth of sea ice suitable for coupling with a similar dynamic model is considered. The model is balanced locally in that no horizontal (or vertical) advection or diffusion of properties are considered. Furthermore, the emphasis is on short time scales and focusing on applicability to the marginal ice zon...
Article
Previous studies on open boundary conditions in unbounded rotating fluid flows have concentrated on how to accurately simulate the outflow of free waves through an open boundary. In most limited area integrations of rotating fluids, however, the generated waves are forced rather than free, in which case the Sommerfeld radiation condition, applied i...
Article
An analytical coupled ice-ocean model is considered which is forced by a specified wind stress acting on the open ocean as well as the ice. The analysis supports the conjecture that the upwelling dynamics at ice edges can be understood by means of a simple analytical model. In similarity with coastal problems it is shown that the ice edge upwelling...
Article
A dynamical coupled ice-ocean numerical model for the marginal ice zone (MIZ) is suggested and used to study upwelling dynamics in the MIZ. The nonlinear sea ice model has a variable ice concentration and includes internal ice stress. The model is forced by stresses on the air/ocean and air/ice surfaces. The main coupling between the ice and the oc...
Article
It is shown in general that a geostrophic equilibrium exists in which the leading edge is displaced a finite distance from its initial position. The theory is applied to the Marginal Ice Zone (MIZ) of the Arctic ice pack. Depicted spatial scales are in reasonable agreement with existing observational data. The theory predicts the existence of an al...
Article
The idea behind the general theory of ‘hydraulic’-type problems as described by Gill (1977) is applied to an inertial boundary current. The flow considered is a single-layer inviscid fluid flowing under gravity along a rotating, irregular wall. It is shown that owing to variations in the curvature of the wall the boundary current may be controlled...
Article
Full-text available
A finite-difference scheme is used in order to study the generation and propagation of long barotropic waves and storm surges along the western coast of Norway. The performance of the numerical scheme is investigated by comparing with analytical solutions for a model with a straight coastline and a continental shelf of uniform depth and width. Simu...
Article
The theory of storm surges along a straight coast in case of a continuously stratified sea of constant depth is considered.The stratification is shown to have no appreciable effect on the surge at the coast, which therefore is mainly a barotropic response. The internal response at the coast which depends strongly on stratification is found to be ex...
Article
Full-text available
Observations taken on an expedition into the Arctic Ocean north of Spitsbergen indicated the existence of a region of wind-driven upwelling along the edge of the ice pack. Models underestimate the 12-kilometer width of the upwelling region.
Article
Storm surge situations along the western coast of Norway between 62° N and 68° N are examined. The observations show that large storm surges are caused by strong south westerly winds acting along a large section of the coast. This situation occurs when an intense low pressure center moves relatively close to the coast and in a direction nearly para...
Article
In order to estimate the climatic impact of anthropogenic aerosols, a set of 50-year simulations have been carried out using an extended version of the NCAR CCM3 global climate model, coupled to a slab ocean. The extensions consist of prognostic cloud water (Rasch-Kristjansson scheme) and a new treatment of aerosols. The direct and indirect effect...
Article
Full-text available
11.1 Introduction Operational oceanography ìs defined by the development and implementation of scientific activities, analysis tools and information systems that routinely produce and deliver observation data and model-based information for near-real-ime monitoring, for state assessment and re-analyses, for ocean forecasts and for scientific resear...

Projects

Projects (4)
Archived project
Archived project