General characteristics of stratospheric singular vectors

Errico, Ronald M.; Gelaro, Ronald; Novakovskaia, Elena; Todling, Ricardo

doi:10.1127/0941-2948/2007/0245

Cited by 3 publications

(12 citation statements)

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“…An initial SV structure with with global horizontal scales was also found by Errico et al (2007) during the January 2006 wavenumber 1 SSW event. Their results showed that longitudinally separated initial SV structures can converge to similar final structures.…”

Section: Discussionmentioning

confidence: 90%

“…We selected the final optimization domain in the polar stratosphere to target SV structures in the stratosphere specifically. This work extended the cases examined by Hartmann et al (1996) and Errico et al (2007) by studying SVs during a major wave number 2 SSW event and by tracking changes in diagnostics, such as EP flux vectors, and the downward progression of the zonal mean zonal wind as influenced by SV perturbations.…”

Section: Discussionmentioning

confidence: 96%

“…They found lower secondary SV energy peaks when using a higher 3.5 hPa top system and optimizing in the top nine levels; however, the SV energy still peaked at the top model level. Errico et al (2007) used a higher top system (0.01 hPa) optimized Errico et al (2007).…”

Section: Vertical and Horizontal Structure Of Singular Vectorsmentioning

confidence: 99%

“…SV analysis allows for perturbation growth on nonzonal, time-changing flows and has been used in a number of applications related to perturbation growth, especially to baroclinic instability in the troposphere (Lorenz, 1965;Farrell, 1990;Buizza et al, 1993;Molteni and Palmer, 1993;Buizza and Montani, 1999). Stratospheric SV structures and properties have been examined by Hartmann et al (1996), Errico et al (2007), Barkmeijer et al (2008) and de Vries et al (2011). Hartmann et al (1996) found stratospheric SV perturbations that propagated poleward into the stratospheric jet as well as SV perturbations in regions of reversed potential vorticity gradient, the planetary wave-breaking regions; however, their study was limited to 10 hPa in altitude and to periods during which the stratospheric polar vortex was relatively undisturbed.…”

Section: Introductionmentioning

confidence: 99%

“…Hartmann et al (1996) found stratospheric SV perturbations that propagated poleward into the stratospheric jet as well as SV perturbations in regions of reversed potential vorticity gradient, the planetary wave-breaking regions; however, their study was limited to 10 hPa in altitude and to periods during which the stratospheric polar vortex was relatively undisturbed. Errico et al (2007) examined three cases of stratospheric SV perturbations with a system that extended into the lower mesosphere, including a case during the major SSW event of January 2006, and found that non-local (large horizontal scale) initial SV structures, when separated into distinct longitudinal sectors, could still produce the same final SV patterns as when taken together.…”

Section: Introductionmentioning

confidence: 99%

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Singular vectors and their nonlinear evolution during the January 2009 stratospheric sudden warming

Coy

Reynolds

2013

Quart J Royal Meteoro Soc

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The evolution and structure of stratospheric singular vectors (SVs) during the major stratospheric sudden warming (SSW) of January 2009 are investigated. SV analyses, optimized for growth at stratospheric levels over 72 h, were examined for selected dates before and during the SSW. It was found that the initial and final SV fields have larger horizontal structures during the SSW event than before the SSW event. A high-altitude forecast model was initialized with perturbations taken from the initial time SV structures and integrated for 144 h to study growth and nonlinear changes in a highly disturbed polar vortex. When large-amplitude initial SV perturbations were forecast during the SSW, large changes occurred in the descent of the SSW event and poleward focusing of the Eliassen-Palm fluxes. Examination of the development of SV analysis suggests that stratospheric SV growth occurs through wave-action conservation as initial SV perturbations propagate into the polar vortex jet.

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Section: Discussionmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 96%

Section: Vertical and Horizontal Structure Of Singular Vectorsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Singular vectors and their nonlinear evolution during the January 2009 stratospheric sudden warming

Coy

Reynolds

2013

Quart J Royal Meteoro Soc

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Adjoint Estimation of the Variation in Model Functional Output due to the Assimilation of Data

Daescu

Todling

2009

Monthly Weather Review

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A parametric approach to the adjoint estimation of the variation in model functional output due to the assimilation of data is considered as a tool to analyze and develop observation impact measures. The parametric approach is specialized to a linear analysis scheme and it is used to derive various high-order approximation equations. This framework includes the Kalman filter and incremental three-and fourdimensional variational data assimilation schemes implementing a single outer loop iteration. Distinction is made between Taylor series methods and numerical quadrature methods. The novel quadrature approximations require minimal additional software development and are suitable for testing and implementation at operational numerical weather prediction centers where a data assimilation system (DAS) and the associated adjoint DAS are in place. Their potential use as tools for observation impact estimates needs to be further investigated. Preliminary numerical experiments are provided using the fifth-generation NASA Goddard Earth Observing System (GEOS-5) atmospheric DAS.

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Comparing Two Approaches for Assessing Observation Impact

Todling

2013

Monthly Weather Review

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Langland and Baker introduced an approach to assess the impact of observations on the forecasts. In that approach, a state-space aspect of the forecast is defined and a procedure is derived ultimately relating changes in the aspect with changes in the observing system. Some features of the state-space approach are to be noted: the typical choice of forecast aspect is rather subjective and leads to incomplete assessment of the observing system, it requires availability of a verification state that is in practice correlated with the forecast, and it involves the adjoint operator of the entire data assimilation system and is thus constrained by the validity of this operator. This article revisits the topic of observation impacts from the perspective of estimation theory. An observation-space metric is used to allow inferring observation impact on the forecasts without the limitations just mentioned. Using differences of observation-minus-forecast residuals obtained from consecutive forecasts leads to the following advantages: (i) it suggests a rather natural choice of forecast aspect that directly links to the data assimilation procedure, (ii) it avoids introducing undesirable correlations in the forecast aspect since verification is done against the observations, and (iii) it does not involve linearization and use of adjoints. The observation-space approach has the additional advantage of being nearly cost free and very simple to implement. In its simplest form it reduces to evaluating the statistics of observationminus-background and observation-minus-analysis residuals with traditional methods. Illustrations comparing the approaches are given using the NASA Goddard Earth Observing System.

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General characteristics of stratospheric singular vectors

Cited by 3 publications

References 0 publications

Singular vectors and their nonlinear evolution during the January 2009 stratospheric sudden warming

Singular vectors and their nonlinear evolution during the January 2009 stratospheric sudden warming

Adjoint Estimation of the Variation in Model Functional Output due to the Assimilation of Data

Comparing Two Approaches for Assessing Observation Impact

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