A time-split nonhydrostatic atmospheric model for weather research and forecasting applications

Skamarock, William C.; Klemp, Joseph B.

doi:10.1016/j.jcp.2007.01.037

Cited by 1,994 publications

(1,365 citation statements)

References 41 publications

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“…Representative classes of time-integration schemes embedded in the GL method consist of implicit multistep methods such as Adams-Moulton (AM) [22] and backward differentiation (BDF) methods [13,20,21], implicit multistage Runge-Kutta schemes such as diagonally (DIRK) and singly-diagonally (SDIRK) implicit Runge-Kutta schemes [3,19,59], explicit multistep methods, such as leapfrog and Adams-Bashforth methods [28,43], explicit Runge-Kutta schemes, such as the fourthorder Runge-Kutta scheme [55] and partitioned methods, such as Implicit-Explicit (IMEX) schemes, whereby the operators are linearized in some fashion with-e.g., two Butcher tableaux, one explicit and one implicit [5,40,106]. While EBTI schemes are widely used in computational fluid dynamics, especially in the engineering sector [18,52], their adoption in the weather and climate communities has been less widespread, with SE schemes [54,88,107] and horizontally-explicit vertically-implicit schemes [8,40,63]-i.e., schemes where the horizontal direction is treated explicitly and the vertical is treated implicitly-becoming more prominent but still confined mainly to research and limited-area models (with very few exceptions-see Table 1). Within this context, Eq.…”

Section: Eulerian-based Time-integration (Ebti)mentioning

confidence: 99%

“…A SE approach has been adopted in a number of active research and operational limited-area atmospheric models: the JMA's non-hydrostatic Mesoscale Model (JMA-NHM) continues to use a leapfrog-based approach for the long time-step integrations, but includes some low-order advection components in the short time-step computations to improve the computational stability [79,80]. Other groups have moved towards single-time-level, multistage explicit Runge-Kutta schemes to integrate the slow components-both the COSMO [6,7] and WRF [56,88] models use a 3-stage 3rd-order Runge-Kutta (RK) scheme for integrating the slow components, retaining the forward-backward and trapezoidal schemes (previously described) for the fast components (following the analyses of RK methods for timesplitting in [108,109]). Figure 3b illustrates the 3-stage RK-based approach.…”

Section: Split-explicit Schemesmentioning

confidence: 99%

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Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Mengaldo

Wyszogrodzki

Diamantakis

et al. 2018

Arch Computat Methods Eng

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The continuous partial differential equations governing a given physical phenomenon, such as the Navier-Stokes equations describing the fluid motion, must be numerically discretized in space and time in order to obtain a solution otherwise not readily available in closed (i.e., analytic) form. While the overall numerical discretization plays an essential role in the algorithmic efficiency and physically-faithful representation of the solution, the time-integration strategy commonly is one of the main drivers in terms of cost-to-solution (e.g., time-or energy-to-solution), accuracy and numerical stability, thus constituting one of the key building blocks of the computational model. This is especially true in time-critical applications, including numerical weather prediction (NWP), climate simulations and engineering. This review provides a comprehensive overview of the existing and emerging time-integration (also referred to as time-stepping) practices used in the operational global NWP and climate industry, where global refers to weather and climate simulations performed on the entire globe. While there are many flavors of time-integration strategies, in this review we focus on the most widely adopted in NWP and climate centers and we emphasize the reasons why such numerical solutions were adopted. This allows us to make some considerations on future trends in the field such as the need to balance accuracy in time with substantially enhanced time-to-solution and associated implications on energy consumption and running costs. In addition, the potential for the co-design of time-stepping algorithms and underlying high performance computing hardware, a keystone to accelerate the computational performance of future NWP and climate services, is also discussed in the context of the demanding operational requirements of the weather and climate industry.

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Section: Eulerian-based Time-integration (Ebti)mentioning

confidence: 99%

Section: Split-explicit Schemesmentioning

confidence: 99%

Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Mengaldo

Wyszogrodzki

Diamantakis

et al. 2018

Arch Computat Methods Eng

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“…Winds were taken from a custom downscaling of NCEP NFL boundary conditions using the WRF model (Skamarock et al, 2008) to a sub-4 km grid size. Drift scenarios were run by stepping forward in time from hypothetical sites and times of mortality.…”

Section: Analysis For Toxins (Pst/ast)mentioning

confidence: 99%

Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom

Häussermann

Beddington

Cassis

et al. 2017

Preprint

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While large mass mortality events (MMEs) are well known for toothed whales, they have been rare in baleen whales due to their less gregarious behaviour. Although in most cases the cause of mortality has not been conclusively identified, some baleen whale mortality events have been linked to bio-oceanographic conditions, such as harmful algal blooms (HABs). In southern Chile, HABs can be triggered by the ocean-atmosphere phenomenon El Niño. The frequency of the strongest El Niño events is increasing due to climate change. In March 2015, by far the largest reported mass mortality of baleen whales took place in a gulf in southern Chile. Here we show that the synchronous death of at least 343, primarily sei, whales can be attributed to HABs during a building El Niño. Although considered an oceanic species, the sei whales died while feeding near to shore in previously unknown large aggregations. This provides evidence of new feeding grounds for the species. The combination of older and newer remains of whales in the same area indicate that MMEs have occurred more than once in recent years. Large HABs and reports of marine mammal MMEs along the north-east Pacific coast may indicate similar processes in both hemispheres. Increasing MMEs through HABs may become a serious concern in the conservation of endangered whale species.

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“…MM5 is the fifth-generation NCAR/Penn State non-hydrostatic mesoscale model [Dudhia et al, 2002] and WRF is the Weather Research and Forecast model [Skamarock et al, 2008]. The surface forcing was created with a horizontal resolution of 9 km using MM5 for 1978-2006 and then using WRF with the same spatial resolution for 2007-2013.…”

Section: Necofsmentioning

confidence: 99%

Surface circulation in Block Island Sound and adjacent coastal and shelf regions: A FVCOM-CODAR comparison

Sun

Chen

Beardsley

et al. 2016

Progress in Oceanography

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CODAR-derived surface currents in Block Island Sound over the period of June 2000 throughSeptember 2008 were compared to currents computed using the Northeast Coastal Ocean Forecast System (NECOFS). The measurement uncertainty of CODAR-derived currents, estimated using statistics of a screened nine-year time series of hourly-averaged flow field, ranged from 3-7 cm/s in speed and 4°-14° in direction. The CODAR-derived and model-computed kinetic energy spectrum densities were in good agreement at subtidal frequencies, but the NECOFS-derived currents were larger by about 28% at semi-diurnal and diurnal tidal frequencies. The short-term (hourly to daily) current variability was dominated by the semidiurnal tides (predominantly the M 2 tide), which on average accounted for ~87% of the total kinetic energy. The diurnal tidal and subtidal variability accounted for ~4% and ~9% of the total kinetic energy, respectively. The monthly-averaged difference between the CODAR-derived and model-computed velocities over the study area was 6 cm/s or less in speed and 28° or less in direction over the study period. An EOF analysis for the low-frequency vertically-averaged model current field showed that the water transport in the Block Island Sound region was dominated by modes 1 and 2, which accounted for 89% and 7% of the total variance, respectively. Mode 1 represented a relatively stationary spatial and temporal flow pattern with a magnitude that varied with season. Mode 2 was characterized mainly by a secondary cross-shelf flow and a relatively strong along-shelf flow. Process-oriented model experiments indicated that the relatively stationary flow pattern found in mode 1 was a result of tidal rectification and its magnitude changed with seasonal stratification. Correlation analysis between the flow and wind stress suggested that the cross-shelf water transport and its 3 temporal variability in mode 2 were highly correlated to the surface wind forcing. The mode 2 derived onshore and offshore water transport, and was consistent with wind-driven Ekman theory.The along-shelf water transport over the outer shelf, where a large portion of the water flowed from upstream Nantucket Shoals, was not highly correlated to the surface wind stress.

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A time-split nonhydrostatic atmospheric model for weather research and forecasting applications

Cited by 1,994 publications

References 41 publications

Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Current and Emerging Time-Integration Strategies in Global Numerical Weather and Climate Prediction

Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom

Surface circulation in Block Island Sound and adjacent coastal and shelf regions: A FVCOM-CODAR comparison

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