scholarly journals Objective Center-Finding Algorithm for Tropical Cyclones in Numerical Models

Atmosphere ◽  
2019 ◽  
Vol 10 (7) ◽  
pp. 376 ◽  
Author(s):  
Chengwu Zhao ◽  
Junqiang Song ◽  
Hongze Leng ◽  
Juan Zhao
Keyword(s):  
High Resolution ◽  
Tropical Cyclones ◽  
Numerical Models ◽  
Small Scale ◽  
Two Dimensional ◽  
Model Data ◽  
Centroid Algorithm ◽  
Resolution Model ◽  
High Resolution Model ◽  
Resolution Simulation

Precise center-detection of tropical cyclones (TCs) is critical for dynamic analysis in high resolution model data. The existence of both smaller scale perturbations and larger scale circulations could reduce the accuracy of center positioning. In this study, an objective center-finding algorithm is developed based on a two-dimensional Fourier filter and a vorticity centroid algorithm. This proposed algorithm is able to automatically adjust its parameters according to the scale of the target vortex instead of using artificially prescribed parameters in previous research. What’s more, this new algorithm has been optimized and validated by a hundred idealized vortexes with different sizes and small-scale perturbations. A high-resolution simulation of Typhoon Soudelor (2015) was used to evaluate the performance of the new algorithm, and the proposed objective center-finding algorithm was found able to detect a precise and reliable center.

scholarly journals High Resolution Model Intercomparison Project (HighResMIP)

2016 ◽  
Author(s):  
R. J. Haarsma ◽  
M. Roberts ◽  
P. L. Vidale ◽  
C. A. Senior ◽  
A. Bellucci ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Computational Cost ◽  
Horizontal Resolution ◽  
Small Scale ◽  
Model Intercomparison ◽  
Resolution Model ◽  
Intercomparison Project ◽  
High Resolution Model ◽  
The Impact

Abstract. Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest the possibility for significant changes in both large-scale aspects of circulation, as well as improvements in small-scale processes and extremes. However, such high resolution global simulations at climate time scales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centers and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other MIPs. Increases in High Performance Computing (HPC) resources, as well as the revised experimental design for CMIP6, now enables a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950-2050, with the possibility to extend to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulation. HighResMIP thereby focuses on one of the CMIP6 broad questions: “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.

scholarly journals High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP6

2016 ◽  
Vol 9 (11) ◽  
pp. 4185-4208 ◽  
Author(s):  
Reindert J. Haarsma ◽  
Malcolm J. Roberts ◽  
Pier Luigi Vidale ◽  
Catherine A. Senior ◽  
Alessio Bellucci ◽  
...  
Keyword(s):  
High Resolution ◽  
Large Scale ◽  
Computational Cost ◽  
Horizontal Resolution ◽  
Small Scale ◽  
Model Intercomparison ◽  
Resolution Model ◽  
Intercomparison Project ◽  
High Resolution Model ◽  
The Impact

Abstract. Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest both the possibility of significant changes in large-scale aspects of circulation as well as improvements in small-scale processes and extremes. However, such high-resolution global simulations at climate timescales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centres and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other model intercomparison projects (MIPs). Increases in high-performance computing (HPC) resources, as well as the revised experimental design for CMIP6, now enable a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal-resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950–2050, with the possibility of extending to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulations. HighResMIP thereby focuses on one of the CMIP6 broad questions, “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges.

scholarly journals Effect of Horizontal Resolution on the Simulation of Tropical Cyclones in the Chinese Academy of Sciences FGOALS-f3 Climate System Model

2021 ◽  
Author(s):  
Jinxiao Li ◽  
Qing Bao ◽  
Yimin Liu ◽  
Lei Wang ◽  
Jing Yang ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclones ◽  
Horizontal Resolution ◽  
System Model ◽  
Climate System Model ◽  
Chinese Academy Of Sciences ◽  
Resolution Model ◽  
Intercomparison Project ◽  
High Resolution Model ◽  
Academy Of Sciences

Abstract. The effects of horizontal resolution on the simulation of tropical cyclones were studied using the Chinese Academy of Sciences FGOALS-f3 climate system model from the High-Resolution Model Intercomparison Project (HighResMIP) for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Both the low-resolution (approximately 100 km resolution) FGOALS-f3 model (FGOALS-f3-L) and the high-resolution (approximately 25 km resolution) FGOALS-f3 (FGOALS-f3-H) model were used to achieve the standard Tier1 experiment required by the HighResMIP. FGOALS-f3-L and FGOALS-f3-H have the same model parameterizations with exactly the same parameters. The only differences between the two models are the horizontal resolution and the time step. The performance of FGOALS-f3-H and FGOALS-f3-L in simulating tropical cyclones was evaluated with the observation firstly. FGOALS-f3-H (25 km resolution) simulated more realistic distributions of the formation, movement and intensity of the climatology of tropical cyclones than FGOALS-f3-L at 100 km resolution. The seasonal cycles of the number of tropical cyclones increased by about 50 % at the higher resolution and better matched the observed values in the peak month, especially in the eastern Pacific, northern Atlantic, southern Indian and southern Pacific oceans. The simulated variabilities of the number of tropical cyclones and the accumulated cyclone energy were both significantly improved from FGOALS-f3-L to FGOALS-f3-H over most of the ocean basins on the interannual timescale. The characteristics of the tropical cyclones (e.g., the average lifetime, the wind–pressure relationship and the horizontal structure) were more realistic in the simulation using the high-resolution model. The possible physical linkage between the performance of the tropical cyclone simulation and the horizontal resolution were revealed by further analyses. The improvement in the Madden–Julian oscillation from FGOALS-f3-H contributed to the realistic simulation of tropical cyclones. The genesis potential index and the vorticity, relative humidity, maximum potential intensity and the wind shear terms were used to diagnose the effects of the resolution. The current insufficiencies and future directions of improvement for the simulation of tropical cyclones and the potential applications of the FGOALS-f3-H model in the sub-seasonal to seasonal prediction of tropical cyclones are discussed.

Exploring a Variable-Resolution Modeling Approach within a Global Nonhydrostatic Dynamical Core

2020 ◽  
Author(s):  
Yihui Zhou ◽  
Yi Zhang ◽  
Zhuang Liu ◽  
Jian Li ◽  
Rucong Yu
Keyword(s):  
High Resolution ◽  
Climate Models ◽  
Computational Cost ◽  
Cost Effective ◽  
Small Scale ◽  
Variable Resolution ◽  
Dynamical Core ◽  
Modeling Approach ◽  
Resolution Model ◽  
Resolution Simulation

<p>High-resolution numerical weather and climate models have a great advantage in both prediction and simulation for their ability to resolve small-scale systems, but suffer from expensive computational cost. The aim of this study is to explore a cost-effective variable-resolution modeling approach within a newly developed global nonhydrostatic dynamical core based on an unstructured mesh. We provide a size-controllable formulation of hierarchical refinement mode by an adapted density function for more realistic high-resolution simulations. The dynamical core is tested regarding both dry and moist atmosphere to evaluate variable-resolution simulations against quasi-uniform ones. In baroclinic wave tests, the variable-resolution model, which owns much less grid points, captures a comparable fine-scale fluid structure with the high-resolution quasi-uniform one in the refinement region. In the coarse region, the result of the variable-resolution simulation matches that of the low-resolution quasi-uniform one, which contributes to smaller global errors of the variable-resolution simulation. A series of sensitivity tests regarding parameters of the hierarchical refinement mode validate the high stability of the variable-resolution model to preserve the intensity and vertical structure of tropical cyclones moving through the transition zone. The variable-resolution modeling lays a strong foundation for potential improvement of regional high-resolution simulations.</p>

scholarly journals Multi-platform model assessment in the Western Mediterranean Sea: impact of downscaling on the surface circulation and mesoscale activity

2019 ◽  
Vol 70 (2) ◽  
pp. 273-288 ◽  
Author(s):  
Eva Aguiar ◽  
Baptiste Mourre ◽  
Mélanie Juza ◽  
Emma Reyes ◽  
Jaime Hernández-Lasheras ◽  
...  
Keyword(s):  
High Resolution ◽  
Data Assimilation ◽  
Western Mediterranean ◽  
Small Scale ◽  
Model Assessment ◽  
Mesoscale Structures ◽  
Western Mediterranean Basin ◽  
Surface Circulation ◽  
Resolution Model ◽  
High Resolution Model

AbstractIn numerical ocean modeling, dynamical downscaling is the approach consisting in generating high-resolution regional simulations exploiting the information from coarser resolution models for initial and boundary conditions. Here we evaluate the impacts of downscaling the 1/16o (~ 6–7 km) CMEMS Mediterranean reanalysis model solution into a high-resolution 2-km free-run simulation over the Western Mediterranean basin, focusing on the surface circulation and mesoscale activity. Multi-platform observations from satellite-borne altimeters, high-frequency radar, fixed moorings, and gliders are used for this evaluation, providing insights into the variability from basin to coastal scales. Results show that the downscaling leads to an improvement of the time-averaged surface circulation, especially in the topographically complex area of the Balearic Sea. In particular, the path of the Balearic current is improved in the high-resolution model, also positively affecting transports through the Ibiza Channel. While the high-resolution model produces a similar number of large eddies as CMEMS Med Rea and altimetry, it generates a much larger number of small-scale eddies. Looking into the variability, in the absence of data assimilation, the high-resolution model is not able to properly reproduce the observed phases of mesoscale structures, especially in the southern part of the domain. This negatively affects the representation of the variability of the surface currents interacting with these eddies, highlighting the importance of data assimilation in the high-resolution ocean model in this region to constrain the evolution of these mesoscale structures.

scholarly journals Stochastic parameterization of shallow cumulus convection estimated from high-resolution model data

2012 ◽  
Vol 27 (1-2) ◽  
pp. 133-148 ◽  
Author(s):  
Jesse Dorrestijn ◽  
Daan T. Crommelin ◽  
A. Pier. Siebesma ◽  
Harm J. J. Jonker
Keyword(s):  
High Resolution ◽  
Cumulus Convection ◽  
Model Data ◽  
Shallow Cumulus ◽  
Resolution Model ◽  
High Resolution Model

scholarly journals Effect of horizontal resolution on the simulation of tropical cyclones in the Chinese Academy of Sciences FGOALS-f3 climate system model

2021 ◽  
Vol 14 (10) ◽  
pp. 6113-6133
Author(s):  
Jinxiao Li ◽  
Qing Bao ◽  
Yimin Liu ◽  
Lei Wang ◽  
Jing Yang ◽  
...  
Keyword(s):  
High Resolution ◽  
Tropical Cyclones ◽  
Horizontal Resolution ◽  
System Model ◽  
Climate System Model ◽  
Chinese Academy Of Sciences ◽  
Resolution Model ◽  
Intercomparison Project ◽  
High Resolution Model ◽  
Academy Of Sciences

Abstract. The effects of horizontal resolution on the simulation of tropical cyclones were studied using the Chinese Academy of Sciences Flexible Global Ocean–Atmosphere–Land System Finite-Volume version 3 (FGOALS-f3) climate system model from the High-Resolution Model Intercomparison Project (HighResMIP) for the Coupled Model Intercomparison Project phase 6 (CMIP6). Both the low-resolution (about 100 km resolution) FGOALS-f3 model (FGOALS-f3-L) and the high-resolution (about 25 km resolution) FGOALS-f3 (FGOALS-f3-H) models were used to achieve the standard Tier 1 experiment required by HighResMIP. FGOALS-f3-L and FGOALS-f3-H have the same model parameterizations with the exactly the same parameters. The only differences between the two models are the horizontal resolution and the time step. The performance of FGOALS-f3-H and FGOALS-f3-L in simulating tropical cyclones was evaluated using observations. FGOALS-f3-H (25 km resolution) simulated more realistic distributions of the formation, movement and intensity of the climatology of tropical cyclones than FGOALS-f3-L at 100 km resolution. Although the number of tropical cyclones increased by about 50 % at the higher resolution and better matched the observed values in the peak month, both FGOALS-f3-L and FGOALS-f3-H appear to replicate the timing of the seasonal cycle of tropical cyclones. The simulated average and interannual variabilities of the number of tropical cyclones and the accumulated cyclone energy were both significantly improved from FGOALS-f3-L to FGOALS-f3-H over most of the ocean basins. The characteristics of tropical cyclones (e.g., the average lifetime, the wind–pressure relationship and the horizontal structure) were more realistic in the simulation using the high-resolution model. The possible physical linkage between the performance of the tropical cyclone simulation and the horizontal resolution were revealed by further analyses. The improvement in the response between the El Niño–Southern Oscillation and the number of tropical cyclones and the accumulated cyclone energy in FGOALS-f3 contributed to the realistic simulation of tropical cyclones. The genesis potential index and the vorticity, relative humidity, maximum potential intensity and the wind shear terms were used to diagnose the effects of resolution. We discuss the current insufficiencies and future directions of improvement for the simulation of tropical cyclones and the potential applications of the FGOALS-f3-H model in the subseasonal to seasonal prediction of tropical cyclones.

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