Beta gyres in global analysis fields

Kim, Sun‐Hee; Kwon, Hyun-Han; Elsberry, Russell L.

doi:10.1007/s00376-009-8109-4

Cited by 7 publications

(4 citation statements)

References 16 publications

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“…Thus, how the steering flow of Shanshan is influenced by perturbations to the initial condition vorticity in various experiments is investigated in this subsection. To acquire large-scale environmental flows and remove the TC-scale circulation, the Lanczos filtering (Kim et al 2009) is employed to calculate the 850-250-hPa DLM winds for different experiments. The similar way to perform the Lanczos filtering as in Kim et al (2009) is adopted in this study.…”

Section: Deep-layer-mean Windsmentioning

confidence: 99%

“…To acquire large-scale environmental flows and remove the TC-scale circulation, the Lanczos filtering (Kim et al 2009) is employed to calculate the 850-250-hPa DLM winds for different experiments. The similar way to perform the Lanczos filtering as in Kim et al (2009) is adopted in this study. The total field can be separated into a large-scale environmental field and a TC-scale field by the Lanczos filtering.…”

Section: Deep-layer-mean Windsmentioning

confidence: 99%

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Validation and Interpretation of Adjoint-Derived Sensitivity Steering Vector as Targeted Observation Guidance

Chen

et al. 2011

Mon. Wea. Rev.

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The adjoint-derived sensitivity steering vector (ADSSV) has been proposed and applied as a guidance for targeted observation in the field programs for improving tropical cyclone predictability, such as The Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign (T-PARC). The ADSSV identifies sensitive areas at the observing time to the steering flow at the verifying time through adjoint calculation. In addition, the ability of the ADSSV to represent signals of influence from synoptic systems such as the midlatitude trough and the subtropical high prior to the recurvature of Typhoon Shanshan (2006) has also been demonstrated.In this study, the impact of initial perturbations associated with the high or low ADSSV sensitivity on model simulations is investigated by systematically perturbing initial vorticity fields in the case of Shanshan. Results show that experiments with the perturbed initial conditions located in the high ADSSV area (i.e., the midlatitude trough and the subtropical high) lead to more track deflection relative to the unperturbed control run than experiments with perturbations in the low sensitivity area. The evolutions of the deep-layer-mean steering flow and the direction of the ADSSV are compared to provide conceptual interpretation and validation on the physical meaning of the ADSSV. Concerning the results associated with the perturbed regions in high sensitivity regions, the variation of the steering flow within the verifying area due to the initial perturbations is generally consistent with that of the direction of the ADSSV. In addition, the bifurcation between the ADSSV and the steering change becomes larger with the increased integration time. However, the result for the perturbed region in the low-sensitivity region indicates that the steering change does not have good agreement with the ADSSV. The large initial perturbations to the low-sensitivity region may interact with the trough to the north due to the nonlinearity, which may not be accounted for in the ADSSV. Furthermore, the effect of perturbations specifically within the sensitive vertical layers is investigated to validate the vertical structure of the ADSSV. The structure of kinetic energy shows that the perturbation associated with the trough (subtropical high) specifically in the mid-to-upper (mid-to-lower) troposphere evolves similarly to that in the deep-layer troposphere, leading to comparable track changes. A sensitivity test in which perturbations are locally introduced in a higher-sensitivity area is conducted to examine the different impact as compared to that perturbed with the broader synoptic feature.

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Section: Deep-layer-mean Windsmentioning

confidence: 99%

Section: Deep-layer-mean Windsmentioning

confidence: 99%

Validation and Interpretation of Adjoint-Derived Sensitivity Steering Vector as Targeted Observation Guidance

Chen

et al. 2011

Mon. Wea. Rev.

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“…Here, the Lanczos filtering developed and studied by Kim et al (2009) is used to separate the total wind into the background flow and the residual from which the symmetric and asymmetric circulations are calculated. Here, the Lanczos filtering developed and studied by Kim et al (2009) is used to separate the total wind into the background flow and the residual from which the symmetric and asymmetric circulations are calculated.…”

Section: B Modifications Of the Steering Flow And Symmetric And Asymmentioning

confidence: 99%

Using TIGGE Data to Diagnose Initial Perturbations and Their Growth for Tropical Cyclone Ensemble Forecasts

Yamaguchi

Majumdar

2010

Monthly Weather Review

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Ensemble initial perturbations around Typhoon Sinlaku (2008) produced by ECMWF, NCEP, and the Japan Meteorological Agency (JMA) ensembles are compared using The Observing System Research and Predictability Experiment (THORPEX) Interactive Grand Global Ensemble (TIGGE) data, and the dynamical mechanisms of perturbation growth associated with the tropical cyclone (TC) motion are investigated for the ECMWF and NCEP ensembles. In the comparison, it is found that the vertical and horizontal distributions of initial perturbations as well as the amplitude are quite different among the three NWP centers before, during, and after the recurvature of Sinlaku. In addition, it turns out that those variations cause a difference in the TC motion not only at the initial time but also during the subsequent forecast period. The ECMWF ensemble exhibits relatively large perturbation growth, which results from 1) the baroclinic energy conversion in a vortex, 2) the baroclinic energy conversion associated with the midlatitude waves, and 3) the barotropic energy conversion in a vortex. Those features are less distinctive in the NCEP ensemble. A statistical verification shows that the ensemble spread of TC track predictions in NCEP (ECMWF) is larger than ECMWF (NCEP) for 1-(3-) day forecasts on average. It can be inferred that while the ECMWF ensemble starts from a relatively small amplitude of initial perturbations, the growth of the perturbations helps to amplify the ensemble spread of tracks. On the other hand, a relatively large amplitude of initial perturbations seems to play a role in producing the ensemble spread of tracks in the NCEP ensemble.

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“…Li & Wang (1994), and also with observational data analyses e.g. Kim, Kwon & Elsberry (2009). As time goes on, a Rossby-wave tail develops in the south-eastern sector with respect to the core of the vortex.…”

Section: Instabilities Of Hurricane-like Vortices and Their Evolutionmentioning

confidence: 99%

Evolution, propagation and interactions with topography of hurricane-like vortices in a moist-convective rotating shallow-water model

Rostami

Zeitlin

2020

J. Fluid Mech.

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Beta gyres in global analysis fields

Cited by 7 publications

References 16 publications

Validation and Interpretation of Adjoint-Derived Sensitivity Steering Vector as Targeted Observation Guidance

Validation and Interpretation of Adjoint-Derived Sensitivity Steering Vector as Targeted Observation Guidance

Using TIGGE Data to Diagnose Initial Perturbations and Their Growth for Tropical Cyclone Ensemble Forecasts

Evolution, propagation and interactions with topography of hurricane-like vortices in a moist-convective rotating shallow-water model

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