Improving simulations of severe winter storms by initial modification of potential vorticity in sensitive regions

Røsting, Bjørn; Kristjánsson, Jón Egill

doi:10.1256/qj.05.188

Cited by 14 publications

(16 citation statements)

References 36 publications

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“…16a) and the assimilation of the estimated tropopause pressure level with an approximate alignment model (Fig. These broader increments are also in better agreement with the large vertical extent of singular vectors (Røsting and Kristjá nsson 2006). As pointed out in section 3, the vertical structure is broader for the alignment model, which also vertically displaces the upperlevel PV fields (2-PVU and 3-PVU surfaces).…”

Section: Pv Initial Incrementsupporting

confidence: 76%

Data Assimilation of Tropopause Height Using Dry Intrusion Observations

Michel

2010

Monthly Weather Review

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International audienceThis article investigates the problem of initializing upper-level potential vorticity by using the detection of dry intrusions that can be seen in water vapor images. First, a satellite image processing technique has been developed for the identification and tracking of dry intrusions on geostationary satellite images. This technique can also be applied to images derived from model fields through a radiative transfer model. A linking algorithm automatically compares the trajectories of the dry intrusions in the model and in the satellite images. Differences of brightness temperatures are then converted to differences of tropopause height through a simple linear model, which is based on the correlation found in the background. As the scheme is likely to provide observations of the tropopause height, it also suggests that a space-alignment representation of the errors be used. A simple one-dimensional study provides a depiction of the background error covariance in alignment space, which is compared to the traditional approach of background error covariance in amplitude space. An approximate form of the Ertel potential vorticity operator is then used to incorporate pseudo-observations inside a global four-dimensional variational assimilation scheme. A case study of cyclogenesis highlights the difference between the amplitude-space assimilation of potential vorticity values and the alignment space assimilation of the height of the tropopaus

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Section: Pv Initial Incrementsupporting

confidence: 76%

Data Assimilation of Tropopause Height Using Dry Intrusion Observations

Michel

2010

Monthly Weather Review

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“…This method allows the total flow to be obtained by adding the contributions from several PV anomalies, despite the nonlinearity of the Ertel PV (Kristjánsson et al, 1999). The method has also been successfully used by Røsting and Kristjánsson (2006).…”

Section: Pv Inversionmentioning

confidence: 99%

The full life cycle of a polar low over the Norwegian Sea observed by three research aircraft flights

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Kristjánsson

Sætra

et al. 2011

Quart J Royal Meteoro Soc

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“…Concerning PLs induced by baroclinic instability, the cyclogenesis was attributed to upper-level perturbations superimposed on low-level perturbations. After Hoskins et al (1985) elaborated on the application of isentropic potential vorticity in the diagnosis of the upper-level forcing in the development of synoptic-scale cyclones, the approach was used in analysing PL developments (Sunde et al, 1994;Røsting et al, 2003;Røsting and Kristjansson, 2006).…”

Section: Introductionmentioning

confidence: 99%