scholarly journals Vorticity-divergence semi-Lagrangian global atmospheric model SL-AV20: dynamical core

2017 ◽  
Vol 10 (5) ◽  
pp. 1961-1983 ◽  
Author(s):  
Mikhail Tolstykh ◽  
Vladimir Shashkin ◽  
Rostislav Fadeev ◽  
Gordey Goyman
Keyword(s):  
Numerical Solutions ◽  
Climate Modeling ◽  
Region Of Interest ◽  
Weather Forecast ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Test Case ◽  
Medium Range Weather Forecast ◽  
Variable Resolution ◽  
Dynamical Core

Abstract. SL-AV (semi-Lagrangian, based on the absolute vorticity equation) is a global hydrostatic atmospheric model. Its latest version, SL-AV20, provides global operational medium-range weather forecast with 20 km resolution over Russia. The lower-resolution configurations of SL-AV20 are being tested for seasonal prediction and climate modeling. The article presents the model dynamical core. Its main features are a vorticity-divergence formulation at the unstaggered grid, high-order finite-difference approximations, semi-Lagrangian semi-implicit discretization and the reduced latitude–longitude grid with variable resolution in latitude. The accuracy of SL-AV20 numerical solutions using a reduced lat–lon grid and the variable resolution in latitude is tested with two idealized test cases. Accuracy and stability of SL-AV20 in the presence of the orography forcing are tested using the mountain-induced Rossby wave test case. The results of all three tests are in good agreement with other published model solutions. It is shown that the use of the reduced grid does not significantly affect the accuracy up to the 25 % reduction in the number of grid points with respect to the regular grid. Variable resolution in latitude allows us to improve the accuracy of a solution in the region of interest.

scholarly journals Vorticity-Divergence semi-Lagrangian Global Atmospheric Model SL-AV20: Dynamical Core

2016 ◽  
Author(s):  
Mikhail Tolstykh ◽  
Vladimir Shashkin ◽  
Rostislav Fadeev ◽  
Gordey Goyman
Keyword(s):  
Numerical Solutions ◽  
Climate Modeling ◽  
Region Of Interest ◽  
Weather Forecast ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
Medium Range Weather Forecast ◽  
Variable Resolution ◽  
Dynamical Core ◽  
Global Atmospheric Model

Abstract. SL-AV (Semi-Lagranginan Absolute Vorticity) is a global atmospheric model. Its latest version SL-AV20 provides global operational medium-range weather forecast with 20 km resolution over Russia. The lower resolution configurations of SL-AV20 are being tested for seasonal prediction and climate modeling. The article presents the model dynamical core. Its main features are vorticity-divergence formulation at the unstaggered grid, high-order finite-difference approximations, semi-Lagrangian semi-implicit discretization and the reduced latitude-longitude grid with variable resolution in latitude. The accuracy of SL-AV20 numerical solutions using reduced lat-lon grid and the variable resolution in latitude is tested with two idealized testcases. The results agree well with other published model solutions. It is shown that the use of the reduced grid having up to 25 % less grid points than the regular grid does not significantly affect the accuracy. Variable resolution in latitude allows to improve the accuracy of solution in the region of interest.

How sensitive is the sub-seasonal prediction to the choice of dynamical cores in the atmospheric model?

2020 ◽  
Author(s):  
Ha-Rim Kim ◽  
Baek-Min Kim ◽  
Sang-Yoon Jun ◽  
Yong-Sang Choi
Keyword(s):  
North America ◽  
Prediction Model ◽  
Seasonal Prediction ◽  
Atmospheric Model ◽  
The Arctic ◽  
Late Winter ◽  
Grid System ◽  
Early Winter ◽  
Dynamical Core ◽  
The One

<p>This study investigates the prediction skill of the sub-seasonal prediction model that can depend on the choice of dynamical cores: the finite volume (FV) dynamical core on a latitude-longitude grid system versus spectral element (SE) dynamical core on a cubed-sphere grid system. Recent researches showed that the SE dynamical core on a uniform grid system increases parallel scalability and removes the need for polar filters mitigating uncertainty in climate prediction, particularly for the Arctic region. However, it remains unclear whether the choice of dynamical cores can actually yield significant skill changes or not. To tackle this issue, we implemented a sub-seasonal prediction model based on the Community Atmospheric Model version 5 (CAM5) by incorporating the above two dynamical cores with virtually the same physics schemes. Sub-seasonal prediction skills of the SE dynamical core and FV dynamical core are verified with ERA-interim reanalysis during the early winter (November – December) and the late winter (January – February) from 2001/2002 to 2017/2018. The prediction skills of the two different dynamical cores were significantly different regardless of the virtually same physics schemes. In the ocean, the predictability of the SE dynamical core is similar to the FV dynamical core, mostly because of our simulation configuration imposing the same boundary and initial conditions at the surface. Notable differences in the one-month predictability between the two cores are found for the wintertime Arctic and mid-latitudes, particularly over North America and Eurasia continents. With the one-month lead, SE dynamical core exhibited higher predictability over North America in late winter, whereas the FV dynamical core showed relatively higher predictability in East Asia and Eurasia in early winter. One of the reasons for these differences may be the different manifestations of Arctic-midlatitudes linkage in the two dynamical cores; the SE dynamical core captures warmer Arctic and colder mid-latitudes relatively well than the FV dynamical core. Therefore, we conclude that the careful choice of dynamical cores of sub-seasonal prediction models is needed.</p>

scholarly journals Evaluation of wet troposphere path delays from atmospheric reanalyses and radiometers and their impact on the altimeter sea level

2014 ◽  
Vol 11 (3) ◽  
pp. 1613-1642 ◽  
Author(s):  
J.-F. Legeais ◽  
M. Ablain ◽  
S. Thao
Keyword(s):  
Sea Level ◽  
Spatial Scales ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Path Delay ◽  
Medium Range Weather Forecast ◽  
The Mean ◽  
Microwave Radiometers

Abstract. The assessment of long-term errors in altimeter sea level measurements is essential for studies related to the mean sea level (MSL) evolution. One of the main contributors to the long-term sea level uncertainties is the correction of the altimeter range from the wet troposphere path delay, which is provided by onboard microwave radiometers for the main altimeter missions. The wet troposphere correction (WTC) derived from the operational European Centre for Medium-Range Weather Forecast (ECMWF) atmospheric model is usually used as a reference for comparison with the radiometer WTC. However, due to several improvements of the processing, this model is not homogenous over the altimetry period (from 1993 onwards), preventing the detection of errors in the radiometer WTC, especially in the first altimetry decade. In this study, we determine the quality of WTC provided by the operational ECMWF atmospheric model in comparison with the fields derived from the ERA Interim (ECMWF) and the National Centers for Environmental Predictions/National Center for Atmospheric Research (NCEP/NCAR) reanalyses. Separating our analyses on several temporal and spatial scales, we demonstrate that ERA Interim provides the best modeled WTC for the altimeter sea level at climate scales. This allows us to better evaluate the radiometer WTC errors, especially for the first altimetry decade (1993–2002), and thus to improve the altimeter MSL error budget. This work also demonstrates the relevance of the feed-backs that the "altimetry" and "atmosphere" communities can bring to each other.

scholarly journals Evaluation of wet troposphere path delays from atmospheric reanalyses and radiometers and their impact on the altimeter sea level

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 893-905 ◽  
Author(s):  
J.-F. Legeais ◽  
M. Ablain ◽  
S. Thao
Keyword(s):  
Sea Level ◽  
Spatial Scales ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Path Delay ◽  
Medium Range Weather Forecast ◽  
The Mean ◽  
Microwave Radiometers

Abstract. The assessment of long-term errors in altimeter sea level measurements is essential for studies related to the mean sea level (MSL) evolution. One of the main contributors to the long-term sea level uncertainties is the correction of the altimeter range from the wet troposphere path delay, which is provided by onboard microwave radiometers for the main altimeter missions. The wet troposphere correction (WTC) derived from the operational European Centre for Medium-Range Weather Forecast (ECMWF) atmospheric model is usually used as a reference for comparison with the radiometer WTC. However, due to several improvements in the processing, this model is not homogenous over the altimetry period (from 1993 onwards), preventing the detection of errors in the radiometer WTC, especially in the first altimetry decade. In this study, we determine the quality of WTC provided by the operational ECMWF atmospheric model in comparison with the fields derived from the ERA-Interim (ECMWF) and the National Centers for Environmental Predictions/National Center for Atmospheric Research (NCEP/NCAR) reanalyses. Separating our analyses on several temporal and spatial scales, we demonstrate that ERA-Interim provides the best modeled WTC for the altimeter sea level at climate scales. This allows us to better evaluate the radiometer WTC errors, especially for the first altimetry decade (1993–2002), and thus to improve the altimeter MSL error budget. This work also demonstrates the relevance of the interactions between the "altimetry" and "atmosphere" communities, since the expertise of each is of benefit to the other.

scholarly journals A Multiscale Dynamical Model in a Dry-Mass Coordinate for Weather and Climate Modeling: Moist Dynamics and Its Coupling to Physics

2020 ◽  
Vol 148 (7) ◽  
pp. 2671-2699 ◽  
Author(s):  
Yi Zhang ◽  
Jian Li ◽  
Rucong Yu ◽  
Zhuang Liu ◽  
Yihui Zhou ◽  
...  
Keyword(s):  
Weather Forecasting ◽  
Climate Modeling ◽  
Equations Of Motion ◽  
Dry Mass ◽  
Dynamical Model ◽  
Test Case ◽  
Tracer Transport ◽  
Efficient Manner ◽  
Dynamical Core ◽  
Vertical Coordinate

Abstract A multiscale dynamical model for weather forecasting and climate modeling is developed and evaluated in this study. It extends a previously established layer-averaged, unstructured-mesh nonhydrostatic dynamical core (dycore) to moist dynamics and parameterized physics in a dry-mass vertical coordinate. The dycore and tracer transport components are coupled in a mass-consistent manner, with the dycore providing time-averaged horizontal mass fluxes to passive transport, and tracer transport feeding back to the dycore with updated moisture constraints. The vertical mass flux in the tracer transport is obtained by reevaluating the mass continuity equation to ensure compatibility. A general physics–dynamics coupling workflow is established, and a dycore–tracer–physics splitting strategy is designed to couple these components in a flexible and efficient manner. In this context, two major physics–dynamics coupling strategies are examined. Simple-physics packages from the 2016 Dynamical Core Model Intercomparison Project (DCMIP2016) experimental protocols are used to facilitate the investigation of the model behaviors in idealized moist-physics configurations, including cloud-scale modeling, weather forecasting, and climate modeling, and in a real-world test-case setup. Performance evaluation demonstrates that the model is able to produce reasonable sensitivity and variability at various spatiotemporal scales. The consideration and implications of different physics–dynamics coupling options are discussed within this context. The appendix provides discussion on the energetics in the continuous- and discrete-form equations of motion.

A Non-hydrostatic Variable Resolution Atmospheric Model in ACME

2018 ◽  
Author(s):  
David Matthew Hall ◽  
Mark Taylor ◽  
Paul Ullrich ◽  
Carol Woodward
Keyword(s):  
Atmospheric Model ◽  
Variable Resolution

scholarly journals A Comparison between One-Step and Two-Step Nesting Strategy in the Dynamical Downscaling of Regional Climate Model COSMO-CLM at 2.2 km Driven by ERA5 Reanalysis

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 260
Author(s):  
Mario Raffa ◽  
Alfredo Reder ◽  
Marianna Adinolfi ◽  
Paola Mercogliano
Keyword(s):  
Regional Climate Model ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Spatial Scales ◽  
Regional Climate ◽  
Weather Forecast ◽  
Medium Range Weather Forecast ◽  
Spatial And Temporal Scales ◽  
Starting Point ◽  
One Step

Recently, the European Centre for Medium Range Weather Forecast (ECMWF) has released a new generation of reanalysis, acknowledged as ERA5, representing at the present the most plausible picture for the current climate. Although ERA5 enhancements, in some cases, its coarse spatial resolution (~31 km) could still discourage a direct use of precipitation fields. Such a gap could be faced dynamically downscaling ERA5 at convection permitting scale (resolution < 4 km). On this regard, the selection of the most appropriate nesting strategy (direct one-step against nested two-step) represents a pivotal issue for saving time and computational resources. Two questions may be raised within this context: (i) may the dynamical downscaling of ERA5 accurately represents past precipitation patterns? and (ii) at what extent may the direct nesting strategy performances be adequately for this scope? This work addresses these questions evaluating two ERA5-driven experiments at ~2.2 km grid spacing over part of the central Europe, run using the regional climate model COSMO-CLM with different nesting strategies, for the period 2007–2011. Precipitation data are analysed at different temporal and spatial scales with respect to gridded observational datasets (i.e., E-OBS and RADKLIM-RW) and existing reanalysis products (i.e., ERA5-Land and UERRA). The present work demonstrates that the one-step experiment tendentially outperforms the two-step one when there is no spectral nudging, providing results at different spatial and temporal scales in line with the other existing reanalysis products. However, the results can be highly model and event dependent as some different aspects might need to be considered (i.e., the nesting strategies) during the configuration phase of the climate experiments. For this reason, a clear and consolidated recommendation on this topic cannot be stated. Such a level of confidence could be achieved in future works by increasing the number of cities and events analysed. Nevertheless, these promising results represent a starting point for the optimal experimental configuration assessment, in the frame of future climate studies.

scholarly journals Detection and thermal description of medicanes from numerical simulation

2014 ◽  
Vol 14 (5) ◽  
pp. 1059-1070 ◽  
Author(s):  
M. A. Picornell ◽  
J. Campins ◽  
A. Jansà
Keyword(s):  
Numerical Simulation ◽  
Thermal Structure ◽  
Weather Prediction ◽  
Weather Forecast ◽  
Small Scale ◽  
Medium Range Weather Forecast ◽  
Warm Core ◽  
Strong Winds ◽  
Nwp Model ◽  
Ecmwf Model

Abstract. Tropical-like cyclones rarely affect the Mediterranean region but they can produce strong winds and heavy precipitations. These warm-core cyclones, called MEDICANES (MEDIterranean hurriCANES), are small in size, develop over the sea and are infrequent. For these reasons, the detection and forecast of medicanes are a difficult task and many efforts have been devoted to identify them. The goals of this work are to contribute to a proper description of these structures and to develop some criteria to identify medicanes from numerical weather prediction (NWP) model outputs. To do that, existing methodologies for detecting, characterizating and tracking cyclones have been adapted to small-scale intense cyclonic perturbations. First, a mesocyclone detection and tracking algorithm has been modified to select intense cyclones. Next, the parameters that define the Hart's cyclone phase diagram are tuned and calculated to examine their thermal structure. Four well-known medicane events have been described from numerical simulation outputs of the European Centre for Medium-Range Weather Forecast (ECMWF) model. The predicted cyclones and their evolution have been validated against available observational data and numerical analyses from the literature.

scholarly journals Toward a Weather-Based Forecasting System for Fire Blight and Downy Mildew

Atmosphere ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 484 ◽  
Author(s):  
Ana Firanj Sremac ◽  
Branislava Lalić ◽  
Milena Marčić ◽  
Ljiljana Dekić
Keyword(s):  
Downy Mildew ◽  
Fire Blight ◽  
Meteorological Data ◽  
Weather Prediction ◽  
Weather Forecast ◽  
Atmospheric Model ◽  
Plasmopara Viticola ◽  
Forecasting System ◽  
Nwp Model ◽  
The Impact

The aim of this research is to present a weather-based forecasting system for apple fire blight (Erwinia amylovora) and downy mildew of grapevine (Plasmopara viticola) under Serbian agroecological conditions and test its efficacy. The weather-based forecasting system contains Numerical Weather Prediction (NWP) model outputs and a disease occurrence model. The weather forecast used is a product of the high-resolution forecast (HRES) atmospheric model by the European Centre for Medium-Range Weather Forecasts (ECMWF). For disease modelling, we selected a biometeorological system for messages on the occurrence of diseases in fruits and vines (BAHUS) because it contains both diseases with well-known and tested algorithms. Several comparisons were made: (1) forecasted variables for the fifth day are compared against measurements from the agrometeorological network at seven locations for three months (March, April, and May) in the period 2012–2018 to determine forecast efficacy; (2) BAHUS runs driven with observed and forecast meteorology were compared to test the impact of forecasted meteorological data; and (3) BAHUS runs were compared with field disease observations to estimate system efficacy in plant disease forecasts. The BAHUS runs with forecasted and observed meteorology were in good agreement. The results obtained encourage further development, with the goal of fully utilizing this weather-based forecasting system.

scholarly journals Two decades of in-situ temperature measurements in the upper troposphere and lowermost stratosphere from IAGOS long-term routine observation

2017 ◽  
Author(s):  
Florian Berkes ◽  
Patrick Neis ◽  
Martin G. Schultz ◽  
Ulrich Bundke ◽  
Susanne Rohs ◽  
...  
Keyword(s):  
Weather Forecast ◽  
Global Scale ◽  
Temperature Trend ◽  
Data Set ◽  
Medium Range Weather Forecast ◽  
Upper Troposphere ◽  
Temperature Trends ◽  
Geographical Regions

Abstract. Despite several studies on temperature trends in the tropopause region, a comprehensive understanding of the evolution of temperatures in this climate-sensitive region of the atmosphere remains elusive. Here we present a unique global-scale, long-term data set of high-resolution in-situ temperature data measured aboard passenger aircraft within the European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System, www.iagos.org). This data set is used to investigate temperature trends within the global upper troposphere and lowermost stratosphere (UTLS) for the period 1995 to 2012 in different geographical regions and vertical layers of the UTLS. The largest amount of observations is available over the North Atlantic. Here, a neutral temperature trend is found within the lowermost stratosphere. This contradicts the temperature trend in the European Centre for Medium Range Weather Forecast (ECMWF) ERA-Interim reanalysis, where a significant (95 % confidence) temperature increase of +0.56 K/decade is obtained. Differences between trends derived from observations and reanalysis data can be traced back to changes in the temperature bias between observation and model data over the studied period. This study demonstrates the value of the IAGOS temperature observations as anchor point for the evaluation of reanalyses and its suitability for independent trend analyses.

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