scholarly journals An Investigation of Large Cross-Track Errors in North Atlantic Tropical Cyclones in the GEFS and ECMWF Ensembles

2020 ◽  
Author(s):  
Nicholas M. Leonardo ◽  
Brian A. Colle
Keyword(s):  
Initial Conditions ◽  
Outer Core ◽  
Common Source ◽  
Convective Parameterization ◽  
Core Convection ◽  
Lateral Boundary Conditions ◽  
Northern Atlantic ◽  
Upper Level ◽  
Cross Track ◽  
Northern Atlantic Ocean

AbstractThe largest medium-range (72-120 h) cross-track errors (CTE) of tropical cyclone (TC) forecasts from the Global Ensemble Forecast System (GEFS) over the northern Atlantic Ocean are examined for the 2008-2016 seasons. The 38 unique forecasts within the upper-quartile most negative CTEs (i.e., left-of-track bias larger than 250 km by 72 h) do not have a clear common source of steering error, though 12 of the forecasts involve the underprediction of a weak upper-level trough to the west of the TC by 36 h. Meanwhile, at least 18 of the 36 most positive CTEs (right-of-track bias) are associated with TCs embedded in the southwest extent of a subtropical ridge, the strength of which is increasingly underpredicted during the first 24 h of the forecast. Excessive height falls north of the TC are driven by overpredicted divergence aloft, which corresponds to overpredicted TC outer-core convection. The convection is triggered by a 5-to-20% overprediction of near-TC moisture and instability in the initial conditions. Weather Research Forecast (WRF) simulations are run at 36-, 12-, and 4-km grid spacing for select right-of-track cases, using the GEFS for initial and lateral boundary conditions. The 36-km WRF reproduces the same growth of errors as the GEFS due to in part sharing the same stability and moisture errors in the initial conditions. Changes in the convective parameterization affect how quickly these errors grow by affecting how much convection spins-up. The addition of a 4-km nest with no convective parameterization causes the errors to grow ~20% faster, resulting in an even larger right-of-track error.

The first Tertiary (Paleocene) marine mollusks from the Eureka Sound Group, Ellesmere Island, Canada

1991 ◽  
Vol 65 (2) ◽  
pp. 242-248 ◽  
Author(s):  
Louie Marincovich ◽  
William J. Zinsmeister
Keyword(s):  
Atlantic Ocean ◽  
South Dakota ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Ellesmere Island ◽  
Marine Mollusks ◽  
Molluscan Fauna ◽  
Northern Atlantic ◽  
Northern Alaska ◽  
Northern Atlantic Ocean

The gastropod Drepanochilus pervetus (Stanton) and the bivalve Cytrodaria rutupiensis (Morris) occur in the Mount Moore Formation at Strathcona Fiord, west-central Ellesmere Island, northern Canada. They are the first marine mollusks identified from the Eureka Sound Group of the Canadian arctic islands. These mollusks correlate with Paleocene faunas of the Cannonball Formation of North Dakota and South Dakota, the Prince Creek Formation of northern Alaska, the Barentsburg Formation of Svalbard, and the Thanet and Oldhaven Formations of southeastern England. These occurrences imply that the earliest Tertiary Arctic Ocean molluscan fauna was compositionally distinct from coeval faunas of the northern Atlantic Ocean.

Arctic meteorological operations and counter-operations during world War II

Polar Record ◽  
1983 ◽  
Vol 21 (135) ◽  
pp. 559-567 ◽  
Author(s):  
Franz Selinger ◽  
Alexander Glen
Keyword(s):  
World War Ii ◽  
Atlantic Ocean ◽  
The United States ◽  
Northern Europe ◽  
Free Access ◽  
World War ◽  
The North ◽  
The North Sea ◽  
Northern Atlantic ◽  
Northern Atlantic Ocean

By autumn 1940 the first round of fighting in World War II was over. In northern Europe, German forces occupied Poland, Norway and Denmark. Both sides recognized that further operations demanded naval and air superiority in northern waters. Germany needed free access to the Atlantic Ocean through the North Sea; Britain had to prevent that access, which threatened the lifeline to the United States. More than ever before, it became essential for both sides to have meteorological information from the northern Atlantic Ocean area. Germany's need was especially acute, for the routes for her shipping from ports in Scandinavia traversed enemy-patrolled waters, where foul weather was essential for evasion.

scholarly journals Development of a New Ship Adaptive Weather Routing Model Based on Seakeeping Analysis and Optimization

2020 ◽  
Vol 8 (4) ◽  
pp. 270 ◽  
Author(s):  
Silvia Pennino ◽  
Salvatore Gaglione ◽  
Anna Innac ◽  
Vincenzo Piscopo ◽  
Antonio Scamardella
Keyword(s):  
Weather Forecast ◽  
Wave Model ◽  
Sea State ◽  
Model Based ◽  
Weather Routing ◽  
Route Length ◽  
Seakeeping Analysis ◽  
Northern Atlantic ◽  
Optimum Route ◽  
Northern Atlantic Ocean

This paper provides a new adaptive weather routing model, based on the Dijkstra shortest path algorithm, aiming to select the optimal route that maximizes the ship performances in a seaway. The model is based on a set of ship motion-limiting criteria and on the weather forecast maps, providing the sea state conditions the ship is expected to encounter along the scheduled route. The new adaptive weather routing model is applied to optimize the scheduled route in the Northern Atlantic Ocean of the S175 containership, assumed as a reference vessel, based on the weather forecast data provided by the Global WAve Model (GWAM). In the analysis, both wave and combined wind/swell wave conditions are embodied to investigate the incidence on the optimum route assessment. Furthermore, the effect of the vessel speed on the optimum route detection is also investigated. Current results clearly show that it is possible to achieve appreciable improvements, up to 50% of the ship seakeeping performances, without excessively increasing the route length and the voyage duration.

scholarly journals Estimating the Uncertainty in a Regional Climate Model Related to Initial and Lateral Boundary Conditions

2005 ◽  
Vol 18 (7) ◽  
pp. 917-933 ◽  
Author(s):  
Wanli Wu ◽  
Amanda H. Lynch ◽  
Aaron Rivers
Keyword(s):  
Boundary Conditions ◽  
Climate Model ◽  
Initial Conditions ◽  
Climate Modeling ◽  
Regional Climate ◽  
Regional Climate Modeling ◽  
Regional Model ◽  
Lateral Boundary ◽  
Lateral Boundary Conditions ◽  
The Impact

Abstract There is a growing demand for regional-scale climate predictions and assessments. Quantifying the impacts of uncertainty in initial conditions and lateral boundary forcing data on regional model simulations can potentially add value to the usefulness of regional climate modeling. Results from a regional model depend on the realism of the driving data from either global model outputs or global analyses; therefore, any biases in the driving data will be carried through to the regional model. This study used four popular global analyses and achieved 16 driving datasets by using different interpolation procedures. The spread of the 16 datasets represents a possible range of driving data based on analyses to the regional model. This spread is smaller than typically associated with global climate model realizations of the Arctic climate. Three groups of 16 realizations were conducted using the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) in an Arctic domain, varying both initial and lateral boundary conditions, varying lateral boundary forcing only, and varying initial conditions only. The response of monthly mean atmospheric states to the variations in initial and lateral driving data was investigated. Uncertainty in the regional model is induced by the interaction between biases from different sources. Because of the nonlinearity of the problem, contributions from initial and lateral boundary conditions are not additive. For monthly mean atmospheric states, biases in lateral boundary conditions generally contribute more to the overall uncertainty than biases in the initial conditions. The impact of initial condition variations decreases with the simulation length while the impact of variations in lateral boundary forcing shows no clear trend. This suggests that the representativeness of the lateral boundary forcing plays a critical role in long-term regional climate modeling. The extent of impact of the driving data uncertainties on regional climate modeling is variable dependent. For some sensitive variables (e.g., precipitation, boundary layer height), even the interior of the model may be significantly affected.

scholarly journals Lagrangian Eddy Scales in the Northern Atlantic Ocean

2002 ◽  
Vol 32 (9) ◽  
pp. 2425-2440 ◽  
Author(s):  
Rick Lumpkin ◽  
Anne-Marie Treguier ◽  
Kevin Speer
Keyword(s):  
Atlantic Ocean ◽  
Gulf Stream ◽  
Deep Ocean ◽  
High Energy ◽  
Length Scale ◽  
Length Scales ◽  
Near Surface ◽  
Northern Atlantic ◽  
Eddy Field ◽  
Northern Atlantic Ocean

Abstract Eddy time and length scales are calculated from surface drifter and subsurface float observations in the northern Atlantic Ocean. Outside the energetic Gulf Stream, subsurface timescales are relatively constant at depths from 700 m to 2000 m. Length scale and the characteristic eddy speed decrease with increasing depth below 700 m, but length scale stays relatively constant in the upper several hundred meters of the Gulf Stream. It is suggested that this behavior is due to the Lagrangian sampling of the mesoscale field, in limits set by the Eulerian eddy scales and the eddy kinetic energy. In high-energy regions of the surface and near-surface North Atlantic, the eddy field is in the “frozen field” Lagrangian sampling regime for which the Lagrangian and Eulerian length scales are proportional. However, throughout much of the deep ocean interior, the eddy field may be in the “fixed float” regime for which the Lagrangian and Eulerian timescales are nearly equal. This does not necessarily imply that the deep interior is nearly linear, as fixed-float sampling is possible in a flow field of O(1) nonlinearity.

scholarly journals Cloud-Resolving Ensemble Simulations of Mediterranean Heavy Precipitating Events: Uncertainty on Initial Conditions and Lateral Boundary Conditions

2011 ◽  
Vol 139 (2) ◽  
pp. 403-423 ◽  
Author(s):  
Benoît Vié ◽  
Olivier Nuissier ◽  
Véronique Ducrocq
Keyword(s):  
Boundary Conditions ◽  
Case Studies ◽  
Short Range ◽  
Initial Conditions ◽  
Ensemble Prediction ◽  
Lateral Boundary ◽  
Synoptic Scale ◽  
Lateral Boundary Conditions ◽  
Convective Scale ◽  
The Impact

Abstract This study assesses the impact of uncertainty on convective-scale initial conditions (ICs) and the uncertainty on lateral boundary conditions (LBCs) in cloud-resolving simulations with the Application of Research to Operations at Mesoscale (AROME) model. Special attention is paid to Mediterranean heavy precipitating events (HPEs). The goal is achieved by comparing high-resolution ensembles generated by different methods. First, an ensemble data assimilation technique has been used for assimilation of perturbed observations to generate different convective-scale ICs. Second, three ensembles used LBCs prescribed by the members of a global short-range ensemble prediction system (EPS). All ensembles obtained were then evaluated over 31- and/or 18-day periods, and on 2 specific case studies of HPEs. The ensembles are underdispersive, but both the probabilistic evaluation of their overall performance and the two case studies confirm that they can provide useful probabilistic information for the HPEs considered. The uncertainty on convective-scale ICs is shown to have an impact at short range (under 12 h), and it is strongly dependent on the synoptic-scale context. Specifically, given a marked circulation near the area of interest, the imposed LBCs rapidly overwhelm the initial differences, greatly reducing the spread of the ensemble. The uncertainty on LBCs shows an impact at longer range, as the spread in the coupling global ensemble increases, but it also depends on the synoptic-scale conditions and their predictability.

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