Showing papers in "Atmosphere-ocean in 2000"
TL;DR: In this paper, the authors analyzed trends in Canadian temperature and precipitation during the 20th century using recently updated and adjusted station data and found that from 1900 to 1998, the annual mean temperature has increased between 0.5 and 1.5°C in the south.
Abstract: Trends in Canadian temperature and precipitation during the 20th century are analyzed using recently updated and adjusted station data. Six elements, maximum, minimum and mean temperatures along with diurnal temperature range (DTR), precipitation totals and ratio of snowfall to total precipitation are investigated. Anomalies from the 1961–1990 reference period were first obtained at individual stations, and were then used to generate gridded datasets for subsequent trend analyses. Trends were computed for 1900–1998 for southern Canada (south of 60°N), and separately for 1950–1998 for the entire country, due to insufficient data in the high arctic prior to the 1950s. From 1900–1998, the annual mean temperature has increased between 0.5 and 1.5°C in the south. The warming is greater in minimum temperature than in maximum temperature in the first half of the century, resulting in a decrease of DTR. The greatest warming occurred in the west, with statistically significant increases mostly seen during...
1,046 citations
TL;DR: In this paper, a hydraulic parametrization for peatland environments in the Canadian Land Surface Scheme (CLASS) is developed for three wetland soil classes account for the typical variation in the hydraulic characteristics of the uppermost 0.5 m of organic soils.
Abstract: A hydraulic parametrization is developed for peatland environments in the Canadian Land Surface Scheme (CLASS). Three ‐wetland soil classes account for the typical variation in the hydraulic characteristics of the uppermost 0.5 m of organic soils. Review of the literature reveals that saturated hydraulic conductivity varies from a median of 1.0 × 10−7m/s in deeply humified sapric peat to 2.8 × 10−4 m/s in relatively undecomposed fibric peat. Average pore volume fraction ranges from 0.83 to 0.93. Parameters have been designed for the soil moisture characteristic curves for fibric, hemic and sapric peat using the Campbell (1974) equation employed in CLASS, and the van Genuchten (1980) formulation. There is little difference in modelled soil moisture between the two formulations within the range of conditions normally found in peatlands. Validation of modelled water table depth and peat temperature is performed for a fen in northern Quebec and a bog in north‐central Minnesota. The new parametrizatio...
295 citations
TL;DR: The Canadian Land Surface Scheme (CLASS) as discussed by the authors was developed in the late 1980s for the Canadian GCM, in response to the perceived need for a “second-generation “ land surface model which would adequately treat the effects of vegetation, snow and soil on exchanges of heat and moisture with the atmosphere.
Abstract: The Canadian Land Surface Scheme “CLASS” was developed in the late 1980s for the Canadian GCM, in response to the perceived need for a “second‐generation “ land surface model which would adequately treat the effects of vegetation, snow and soil on exchanges of heat and moisture with the atmosphere. CLASS has been tested both in coupled mode with the GCM and in various experiments that have been carried out in conjunction with PILPS, the international Project for Intercomparison of Land‐Surface Parameterization Schemes. In the context of those runs, CLASS has been shown to perform quite ‐well. However, it is recognized that a more rigorous framework of testing against field data is required before the model can be used with confidence for studies involving the scaling up of surface fluxes, or the modelling of severely heterogeneous landscapes. The series of papers which follows (to which this one provides an introductory overview) describes the testing of CLASS against a wide variety of micrometeo...
192 citations
TL;DR: In this article, a two-way interface to WATFLOOD, a distributed hydrologic model developed at the University of Waterloo, was designed to improve the representation of the soil water balance in order to simulate, more properly, exchanges with the atmosphere.
Abstract: Second generation land surface schemes are the subject of much development activity among atmospheric modellers. This work is aimed at, among other things, improving the representation of the soil water balance in order to simulate, more properly, exchanges with the atmosphere and to permit the use of model output to generate streamflow for model validation. The Canadian development program is centred on CLASS, the Canadian Land Surface Scheme, developed at Environment Canada. This paper focuses on the improvement of hydrology in CLASS. This was accomplished by designing a two‐way interface to WATFLOOD, a distributed hydrologic model developed at the University of Waterloo. The two models share many features, which facilitated the coupling procedure. The interface retains the three‐layer vertical moisture budget representation in CLASS but adds three horizontal runoff possibilities. Runoff from the surface water follows Manning's equation for overland flow. Interflow is generated from the near‐su...
136 citations
TL;DR: In this article, the authors examined variations in daily precipitation intensity over Canada and compared the observed variations with those in total accumulation and two dominant modes of atmospheric variability, namely the North Atlantic Oscillation (NAO) and the Pacific/North America teleconnection pattern (PNA).
Abstract: Past research has unveiled important variations in total precipitation, often related to large‐scale shifts in atmospheric circulation, and consistent with projected responses to enhanced greenhouse warming. More recently, however, it has been realized that important and influential changes in the variability of daily precipitation events have also occurred in the past, often unrelated to changes in total accumulation. This study aims to uncover variations in daily precipitation intensity over Canada and to compare the observed variations with those in total accumulation and two dominant modes of atmospheric variability, namely the North Atlantic Oscillation (NAO) and the Pacific/North America teleconnection pattern (PNA). Results are examined on both annual and seasonal bases, and with regions defined by similarities in monthly variability. Seasonally increasing trends in total precipitation that result from increases in all levels of event intensity during the 20th century are found in southern...
104 citations
TL;DR: In this article, the action of tides on density-driven circulation, internal gravity waves, and mixing was investigated in the St. Lawrence Estuary between Rimouski and Quebec City.
Abstract: The action of tides on density‐driven circulation, internal gravity waves, and mixing was investigated in the St. Lawrence Estuary between Rimouski and Quebec City. Time‐varying fields of water level, currents and density were computed under typical summer conditions using a three‐dimensional hydrostatic coastal ocean model that incorporates a second order turbulence closure submodel. These results are compared with current meter records and other observations. The model and the observations reveal buoyancy effects produced by tidal forcing. The semi‐diurnal tide raises the isopycnals over the sills at the head of the Laurentian Trough and English Bank, producing internal tides radiating seaward. Relatively dense intermediate waters rise from below 75‐m depth to the near surface over the sills, setting up gravity currents on the inner slopes. Internal hydraulic controls develop over the outer sills; during flood, surface flow separation occurs at the entrances of the Saguenay Fjord and the upper ...
88 citations
TL;DR: In this paper, an interactive mixed layer/thermodynamic ice lake model coupled with the Canadian Regional Climate Model (CRCM) is presented, which uses a grid mesh of 45 km on a polar stereographic projection, 10 vertical levels and a timestep of 15 min.
Abstract: This study reports on the implementation of an interactive mixed‐layer/thermodynamic‐ice lake model coupled with the Canadian Regional Climate Model (CRCM). For this application the CRCM, which uses a grid mesh of 45 km on a polar stereographic projection, 10 vertical levels, and a timestep of 15 min, is nested with the second generation Canadian General Circulation Model (GCM) simulated output. A numerical simulation of the climate of eastern North America, including the Laurentian Great Lakes, is then performed in order to evaluate the coupled model. The lakes are represented by a “mixed layer” model to simulate the evolution of the surface water temperature, and a thermodynamic ice model to simulate evolution of the ice cover. The mixed‐layer depth is allowed to vary spatially. Lake‐ice leads are parametrized as a function of ice thickness based on observations. Results from a 5‐year integration show that the coupled CRCM/lake model is capable of simulating the seasonal evolution of surface te...
82 citations
TL;DR: In this article, the validation of the Canadian Land Surface Scheme (CLASS) for several wetland types: fen, marsh and bog was undertaken, and a significant improvement in turbulent flux estimates for the vascular dominated fen and marsh wetlands, yet non-vascular bog type wetlands are relatively poorly modelled.
Abstract: The validation of the Canadian Land Surface Scheme (CLASS) for several wetland types: fen, marsh and bog was undertaken. Incorporating organic soil parameters resulted in a significant improvement in turbulent flux estimates for the vascular dominated fen and marsh wetlands, yet non‐vascular bog‐type wetlands are relatively poorly modelled. Bog surfaces were treated as bare soil surfaces in this testing procedure since the non‐vascular nature is not readily incorporated within the current CLASS model vegetation categories. CLASS does not contain a method for moisture transfer from vegetation other than transpiration by the vascular pathway of root, stem and leaf while evaporation of water from moss and lichen dominated surfaces found in bogs is presently not included. With improved parametrization of the water table already introduced, and an additional non‐vascular vegetation category, it should be possible to model accurately the range of wetland types with CLASS.
67 citations
Abstract: We analyzed the relationship between an index of Great Lakes winter severity (winters 1950–1998) and atmospheric circulation characteristics. Classification and Regression Tree analysis methods allowed us to develop a simple characterization of warm, normal and cold winters in terms of teleconnection indices and their combinations. Results are presented in the form of decision trees. The single most important classifier for warm winters was the Polar/Eurasian index (POL). A majority of warm winters (12 out of 15) occurred when this index was substantially positive (POL > 0.23). There were no cold winters when this condition was in place. Warm winters are associated with a positive phase of the Western Pacific pattern and El Nino events in the equatorial Pacific. The association between cold winters and La Nina events was much weaker. Thus, the effect of the El Nino/Southern Oscillation (ENSO) on severity of winters in the Great Lakes basin is not symmetric. The structure of the relationship betwe...
50 citations
TL;DR: In this article, the authors examined the validity of this approach through the 6000-year integration of a coupled atmosphere-ocean-sea-ice model and compared the results from two additional simulations, in which the model is spun up with perpetual 1850 (preindustrial) and 1998 (present day) atmospheric CO2 concentrations and orbital parameters.
Abstract: The most common method used to evaluate climate models involves spinning them up under perpetual present‐day forcing and comparing the model results with present‐day observations. This approach clearly ignores any potential long‐term memory of the model ocean to past climatic conditions. Here we examine the validity of this approach through the 6000‐year integration of a coupled atmosphere–ocean–sea‐ice model. The coupled model is initially spun‐up with atmospheric CO2 concentrations and orbital parameters applicable for 6KBP. The model is then integrated forward in time to 2100. Results from this transient coupled model simulation are compared with the results from two additional simulations, in which the model is spun up with perpetual 1850 (preindustrial) and 1998 (present‐day) atmospheric CO2 concentrations and orbital parameters. This comparison leads to substantial differences between the equilibrium climatologies and the transient simulation, even at 1850 (in weakly ventilated regions), pr...
24 citations
TL;DR: Canopy conductance of an old boreal aspen forest and a west coast Douglas-fir forest was calculated from the inversion of the Penman-Monteith (PM) equation with above-canopy water vapour flux measurements as discussed by the authors.
Abstract: Canopy conductance (gc) of an old boreal aspen forest and a west coast Douglas‐fir forest was calculated from the inversion of the Penman‐Monteith (PM) equation with above‐canopy water vapour flux measurements. Values of aspen gc agreed reasonably well with those obtained by scaling up from leafstomatal conductance measurements. Comparison of values of gc obtained from the CLASS (Canadian LAnd Surface Scheme) parametrization with values of Douglas‐fir gc in 1983 and 1984 calculated from the PM equation showed that the CLASS parametrization (based on the Jarvis‐Stewart (JS) model) worked well at high soil water potential (ψ), but underestimated gc at low ψ. In the case of the aspen forest during a wet growing season in 1994, the CLASS parametrization underestimated gc for high values of incident photosynthetic photon flux density. The effectiveness of three parametrizations of gc, developed using linear or non‐linear least squares analysis, was evaluated for the two forests. The first (based on th...
TL;DR: In this article, the authors measured the error introduced by the mismatch of effective resolutions of low-resolution GCM or NWP analysis winds to deduce very fine structure in the distribution of chemical species and of potential vorticity.
Abstract: In a number of applications several numerical modellers have recently used low‐resolution GCM or NWP analysis winds to deduce very fine structure in the distribution of chemical species and of potential vorticity. This study aims to measure the error introduced by this mismatch of effective resolutions. By appealing to earlier theoretical work by Batchelor (1959), the approach has been organized around the steepness of the kinetic energy spectrum, E(k). It is found that when the spectrum is steeper than E(k) ∼ k–3 the root mean square error is proportional to the square of the wind truncation scale. By contrast, when E(k) approaches k–5/3 rms error is approximately proportional to the square root of the wind truncation scale. As a result coarse wind resolution produces remarkably accurate global scalar fields after a few advective timescales in the large spatial scales of the troposphere and in the stratosphere, but this result is not expected to hold at smaller scales or in the mesosphere where ...
TL;DR: The Canadian Land Surface Scheme (CLASS) was evaluated using off-line tests, with data collected at temperate aspen-birch and mixed forests located near Chalk River, Ontario, and at a young jack pine forest located near Thompson, Manitoba.
Abstract: The Canadian Land Surface Scheme (CLASS) was evaluated using off‐line tests, with data collected at temperate aspen‐birch and mixed forests located near Chalk River, Ontario, and at a young jack pine forest located near Thompson, Manitoba. Measurements of stomatal conductance and leaf area index were used to develop canopy conductance parametrizations for the aspen‐birch and the jack pine stands, and these were incorporated into CLASS in a modified run. The behaviour of the residuals from the unmodified run with respect to environmental variables at the mixed stand were used as a guide to producing a modified ad‐hoc canopy conductance parametrization for use at that site. It was found that CLASS exaggerates the diurnal range in soil heat flux. This leads to an underestimation of the diurnal range in available energy, and it is argued that this has implications for its partitioning into the turbulent fluxes of sensible and latent heat. Over time, systematic errors will accumulate which, in the cas...
TL;DR: In this paper, the Canadian Land Surface Scheme (CLASS) is tested for two major terrain types found in the northern Hudson Bay Lowland, including sedge fen wetland and dwarf willow-birch forest near Churchill, Manitoba.
Abstract: The Canadian Land Surface Scheme (CLASS) is tested for two major terrain types found in the northern Hudson Bay Lowland. Soil temperature and energy balance measurements for sedge fen wetland and dwarf willow‐birch forest near Churchill, Manitoba, are compared with simulations both with and without the new organic soil parametrization that has been developed for CLASS (Letts et al., 2000), for eight datasets spanning six years (1990 through 1995). With the exception of the sensible heat flux at the sedge site, the new version of CLASS with the organic soil parametrization improves the energy budget simulation at each of the research sites. Both the latent (QE) and ground (QG) heat flux were modelled well; however, some modifications were required to simulate the continued evaporation from these sites once the water table receded below the first soil layer. The sensible heat flux (QH) was the least well simulated component of the energy balance in both versions. Temperatures for the top two soil l...
TL;DR: In this paper, a historical episode of extreme cold in the shelf waters off southeast Canada and the northeastern United States between April and August of 1882 was hypothesized to be the consequence of enhanced equatorward transport of cold water in the Labrador Current (LC), coincident with strongly negative North Atlantic Oscillation (NAO) indices in preceding winters (notably 1878/79 and 1880/81), and driven by associated anomalies in large-scale wind forcing.
Abstract: Proxy evidence suggests a historical episode of extreme cold in the shelf waters off southeast Canada and the northeastern United States between April and August of 1882. This event is hypothesized to be the consequence of enhanced equatorward transport of cold water in the Labrador Current (LC), coincident with strongly negative North Atlantic Oscillation (NAO) indices in preceding winters (notably 1878/79 and 1880/81), and driven by associated anomalies in large‐scale wind forcing. In a model sensitivity experiment, the reconstructed wind forcing of 1877–82 is applied to a General Circulation Model (GCM) of the North Atlantic. Under this wind forcing, the model subpolar gyre strengthens and expands to the south. The offshore, wind‐driven component of the LC accordingly strengthens and extends around the Tail of the Grand Banks. During periods of relatively strong transport around the Tail, sub‐surface temperatures fall by up to 6°C in a region inshore of the Gulf Stream and to the south and wes...
TL;DR: In this article, the performance of the organic soil version of the Canadian Land Surface Scheme (CLASS) in modelling the hydrology and energy balance of the Beverly Swamp, Southern Ontario is presented.
Abstract: This paper documents the performance of the organic soil version of the Canadian Land Surface Scheme (CLASS) in modelling the hydrology and energy balance of the Beverly Swamp, Southern Ontario. The hydrometeorological dataset used to assess model performance begins in the autumn of 1983 and spans 33 months, presenting the first multi‐year characterization of the area. The Beverly Swamp receives approximately 900 mm of precipitation per year, of which one third is lost to net runoff, and the remainder to evaporation. Vertical drainage at this site is impeded, due to the presence of a marl layer below the highly decomposed peat soil, at approximately 1‐m depth. This mixed‐forest wetland is unique among surfaces used for CLASS testing to date. Within CLASS, vertical drainage at the bottom of the soil profile is set to zero to represent the marl subsurface boundary. Preliminary runs have shown that after each melt period this produced ponded water on site which persisted from year to year. The inclu...
TL;DR: In contrast to most forest environments, the floor of the open forest plays a large role in total ecosystem energy exchange, which presents a significant challenge for land surface models like CLASS and their simplified treatment of vegetation canopies as mentioned in this paper.
Abstract: This study reports on testing of the peatland version of the Canadian Land Surface Scheme (CLASS) for simulating the energy balance of subarctic open woodland terrain. Model results are compared against several years of measured data from a site near Churchill, Manitoba. In contrast to most forest environments, the floor of the open forest plays a large role in total ecosystem energy exchange. This behaviour presents a significant challenge for land surface models like CLASS and their simplified treatment of vegetation canopies. Simulations of summer energy balance for seven years encompassing a wide range of meteorological conditions produced consistent results. Root mean square errors for sensible and latent heat fluxes fell between 11 and 28 W m−2. CLASS consistently underestimated slightly the daily latent heat flux and overestimated the sensible heat flux, average mean bias errors being ‐7.6 and 9.1 W m−2, respectively. The soil heat flux was less well represented. In general, CLASS was able...
TL;DR: In this paper, the Bowen ratio/energy balance measurements of evaporation from a bare loam/silt-loam soil at two adjacent sites, one of which was culti-packed while the other was disc-harrowed, were examined using Bowen ratio and energy balance measurements.
Abstract: Surface soil wetness determines whether evaporation occurs at the potential rate or is limited by soil water supply. Many land surface models calculate evaporation by parametrizing the relative humidity at the soil surface (α method) or the soil water diffusion resistance (β method). The relationships of α and β to the average moisture content of soil surface layer thicknesses ranging from 0.5 to 10 cm were examined using Bowen ratio/energy balance measurements of evaporation from a bare loam/silt‐loam soil at two adjacent sites, one of which was culti‐packed while the other was disc‐harrowed. It was found that the relationships were sensitive to the surface layer thickness and tillage treatment and became better defined with larger thicknesses. Simulations of evaporation by CLASS (Canadian Land Surface Scheme) using Philip's relationship (currently used in CLASS to determine α with a 10‐cm thick surface soil layer) and our proposed relationships of α and β were compared with measurements made du...
TL;DR: The ability of the Canadian Land Surface Scheme (CLASS) to simulate energy and moisture fluxes over tundra surfaces is tested using three dataseis collected at alpine sites in southern Alberta and British Columbia, Canada.
Abstract: The ability of the Canadian Land Surface Scheme (CLASS) to simulate energy and moisture fluxes over tundra surfaces is tested using three dataseis collected at alpine sites in southern Alberta and British Columbia, Canada. Initial runs of the model indicate that the ground heat flux tends to be overestimated and the latent heat flux underestimated on average. With the incorporation of minor modifications to the surface thermal conductivity, the vegetation rooting depth and the calculation of the surface soil moisture, the mean bias errors in the latent and ground heat fluxes are reduced to more acceptable levels. Despite the fact that the current version of CLASS does not explicitly take into account the effects of spatial heterogeneity at the sites, the model is found to perform reasonably well with these modifications. It is recommended that the next version of CLASS incorporate a mosaic approach which will allow further subdivision of the modelling area, and that a set of algorithms specific t...
TL;DR: In this article, both shortwave and long-wave radiative fluxes were measured during a cruise from Australia to Antarctica during austral summer 1995/96, and the results showed that the incoming solar radiation had a mean value of 217 W m−2; this was a relatively weak value due to the large amount of fractional cloud cover observed.
Abstract: Radiative measurements were carried out continuously during a cruise from Australia to Antarctica during austral summer 1995/96. Both shortwave and longwave radiative fluxes were measured. Some of the results are: The incoming solar radiation had a mean value of 217 W m–2; this was a relatively weak value due to the large amount of fractional cloud cover observed. The sun was, for a large part of the trip, above the horizon for 24 hours a day. The reflectivity varied widely, not only as a function of sea‐ice concentration, but also as a function of ice type. Snow covered pack ice gave the highest albedo values (<70%), while flooded sea ice and thin ice reflected much less (<30%). For each sea‐ice type, short term observations showed a good relationship between albedo and ice concentration. The albedo increased with decreasing solar elevation. The net longwave radiation was negative (mean –27 W m–2); this small absolute value is due to a high amount of fractional cloud cover. There was a weak diur...
TL;DR: The Canadian Land Surface Scheme (CLASS) as mentioned in this paper is a land surface parametrization scheme for use in large scale climate models, which was assessed using the observed surface climate data from a full canopy crop in southern Ontario during a 10-day drying cycle period.
Abstract: The Canadian Land Surface Scheme (CLASS), a land surface parametrization scheme for use in large scale climate models, was assessed using the observed surface climate data from a full canopy crop in southern Ontario during a 10 day drying cycle period. Half‐hourly and daily modelled radiation and energy balance components and other surface climate parameters were compared to field observations. Different simulations using CLASS were employed and each contained different degrees of realism in model initialization. In general, CLASS simulations of radiation and energy balance components and surface climate parameters were good. Further, only modest improvements in model performance were achieved using more stringent initializations when compared to CLASS default specifications. It was also demonstrated that routine meteorological observations from an Atmospheric Environment Service network station could be used as meteorological input to CLASS without a loss in model output quality. From the resear...
TL;DR: In this paper, the authors document and explain the lifecycle of the warm Sea Surface Temperature (SST) anomaly that intensified and weakened off the west coast of the United States to peak anomalies of 4°C during April-June 1997.
Abstract: We seek to document and explain the lifecycle of the warm Sea Surface Temperature (SST) anomaly that intensified and weakened off the west coast of the United States to peak anomalies of 4°C during April‐June 1997. We use remotely sensed observational data and model analyses to compute an energy budget for the warm anomaly. The bulk of the anomalous warming was confined to the top 50 m of ocean and occurred during May. The immediate cause for the warming was twofold: latent heat fluxes decreased in magnitude as a result of both lower wind speeds and positive moisture anomalies, while the net radiative flux into the ocean increased as a result of lower than normal fractional cloud coverage. During June, the wind speed strengthened and became northerly, resulting in larger than normal latent and sensible heat fluxes that weakened the SST anomaly. Examination of the National Centers for Environmental Prediction (NCEP) 1000‐mb geopotential height for May shows that the Aleutian low extended far south...
TL;DR: In this article, the performance of the forward radiative transfer model (RTM) for satellite radiance assimilation is compared in terms of analyzed increments using the ensemble of 19 infrared channels (HIRS) of the NOAA-14 satellite.
Abstract: The direct assimilation of satellite radiances is now operational in a few forecast centres, providing global temperature (T) and moisture (Q) information. The critical parameters which influence the quality of the resulting analysis are mainly the selection of channels, the respective errors of the background field and radiance observations, and the quality of the radiative transfer model. These various aspects are studied from sensitivity experiments based on 1‐D variational assimilations using the ensemble of 19 infrared channels (HIRS) of the NOAA‐14 satellite. It is shown that significant improvements in the retrievals would be obtained if the radiance observation error (measurement plus radiative transfer), currently estimated to be about equal to that of the background (in radiance units), were decreased. This could in principle be achieved by improving the forward radiative transfer model (RTM). Two RTMs suitable for radiance assimilation are compared in terms of analyzed increments, Jaco...
TL;DR: In this article, a mesoscale model, the Regional Atmospheric Modelling System (RAMS), was used to model the vertical structure of wind and temperature at a site close to the C...
Abstract: An extensive field study (called PACIFIC ‘93), designed to obtain a comprehensive dataset for use in understanding photochemical episodes, was carried out in the Lower Fraser Valley (LFV), B.C., Canada in the summer of 1993. Although many observational studies on local chemistry and meteorology have been reported, there is no complete description of three‐dimensional, time‐varying meteorological conditions over the whole LFV. This study attempts to fill this gap by employing a mesoscale model, the Regional Atmospheric Modelling System (RAMS). In general, the model results agree well with observations, with the index of agreement for surface temperature and wind reaching as high as 0.8 during the daytime, but dropping to 0.4 at night. A good performance is achieved by the model in this long integration for less than three days. Occurrence of local weather systems such as thunderstorms deteriorates overall performance. The modelled vertical structure of wind and temperature at a site close to the C...
TL;DR: In this paper, a coupled ice, ocean model for forecasting ice conditions on the Newfoundland shelf region is assessed by comparing hindcasts with satellite-tracked ice beacon displacements and with changes in offshore ice edge location, ice thickness and southern ice extent derived from ice charts.
Abstract: A coupled ice, ocean model for forecasting ice conditions on the Newfoundland shelf region is assessed by comparing hindcasts with satellite‐tracked ice beacon displacements and with changes in offshore ice edge location, ice thickness and southern ice extent derived from ice charts. The beacon velocity fields contain short timescale fluctuations which are not resolved by the model. The ratio of rms displacement error divided by the rms beacon displacement is 0.48 after 1 day and 0.23 after 8 days. The decrease in the scaled displacement error with increasing time is related to the short timescale motions. The skill in modelling displacement of the offshore ice edge is lower than in modelling ice displacement. Between mid‐February and mid‐April 1997, the effect of ice melt on the ice edge was a mean onshore displacement of 35 km overcoming an offshore advection of 24 km in 5 days.