Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

Kozubek, Michal; Laštovička, Jan; Križan, P.

doi:10.5194/angeo-32-353-2014

Cited by 7 publications

(13 citation statements)

References 26 publications

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“…The differences are larger at higher latitudes. This result agrees with previous studies (Labitzke and Kunze, 2009;Labitzke and van Loon, 1988) in which higher latitudes are more affected by changes in solar activity. The analysis of the meridional component does not show any specific features, so we can conclude that solar activity mainly affects the total horizontal wind and its zonal component.…”

Section: Discussionsupporting

confidence: 94%

“…The impact of the 11-year solar cycle, sometimes in combination with the QBO, on the stratosphere has been described in many papers (e.g. Salby and Callahan, 2000;Labitzke and Kunze, 2009;Limpasuvan et al, 2004;Naito and Hirota, 1997;Labitzke and van Loon, 1988). The influence of solar activity on the total horizontal wind as well as the meridional component is shown in Table 3.…”

Section: Discussionmentioning

confidence: 99%

“…According to Kozubek et al (2014), stratospheric winds from the NCEP/NCAR reanalysis are better for long-term trend analysis than those from ERA-40 and ERA-Interim reanalyses -if we take into account the length of the available period. Neither ERA-40, nor ERA-Interim, nor MERRA separately cover the whole period 1958-2012.…”

Section: Methodsmentioning

confidence: 99%

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Northern Hemisphere stratospheric winds in higher midlatitudes: longitudinal distribution and long-term trends

2015

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Section: Discussionsupporting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

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Northern Hemisphere stratospheric winds in higher midlatitudes: longitudinal distribution and long-term trends

2015

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“…Comparison of individual days between reanalysis and Prague-Libus radiosonde observations provided only a small number of days with substantially different winds, e.g. for comparisons NCEP/NCAR versus Prague-Libus it was on average 1 day per year for the 10 hPa level (Kozubek et al, 2014). We found a similar agreement also for MERRA data.…”

Section: Methodssupporting

confidence: 78%

“…Kozubek et al (2014) compared winds from NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research), ERA-40 and ERA-Interim reanalysis with local winds measured by radiosondes launched in the reanalysis grid point 50 • N, 15 • E (station Prague-Libus). As for wind climatology, a good agreement was found among reanalyses and with Prague-Libus observations both in summer and winter for the whole period 1979-2012.…”

Section: Methodsmentioning

confidence: 99%

Longitudinal structure of stationary planetary waves in the middle atmosphere – extraordinary years

2018

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Abstract. One important but little studied factor in the middle atmosphere meridional circulation is its longitudinal structure. Kozubek et al. (2015) disclosed the existence of the two-cell longitudinal structure in meridional wind at 10 hPa at higher latitudes in January. This two-cell structure is a consequence of the stratospheric stationary wave SPW1 in geopotential heights. Therefore here the longitudinal structure in geopotential heights and meridional wind is analysed based on MERRA data over 1979-2013 and limited NOGAPS-ALPHA data in order to find its persistence and altitudinal dependence with focus on extraordinary years. The SPW1 in geopotential heights and related two-cell structure in meridional wind covers the middle stratosphere (lower boundary ∼ 50 hPa), upper stratosphere and most of the mesosphere (almost up to about 0.01 hPa). The two-cell longitudinal structure in meridional wind is a relatively persistent feature; only 9 out of 35 winters (Januaries) display more complex structure. Morphologically the deviation of these extraordinary Januaries consists in upward propagation of the second (Euro-Atlantic) peak (i.e. SPW2 structure) to higher altitudes than usually, mostly up to the mesosphere. All these Januaries occurred under the positive phase of PNA (Pacific North American) index but there are also other Januaries under its positive phase, which behave in an ordinary way. The decisive role in the existence of extraordinary years (Januaries) appears to be played by the SPW filtering by the zonal wind pattern. In all ordinary years the mean zonal wind pattern in January allows the upward propagation of SPW1 (Aleutian peak in geopotential heights) up to the mesosphere but it does not allow the upward propagation of the EuroAtlantic SPW2 peak to and above the 10 hPa level. On the other hand, the mean zonal wind filtering pattern in extraordinary Januaries is consistent with the observed pattern of geopotential heights at higher altitudes.

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Dynamical Consistency of Reanalysis Datasets in the Extratropical Stratosphere

2016

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Reanalysis data provide a good estimate of global atmospheric temperature and wind fields. However, the available reanalysis datasets reveal nonnegligible discrepancies in their mean state and temporal variability. In this study, the quality of eight reanalysis datasets is evaluated by examining their dynamical consistency in the extratropical stratosphere. The dynamical consistency is quantified by computing the residual of the zonal-mean momentum equation. The residual is generally small in the lower stratosphere, especially at and below 30 hPa, but increases significantly aloft in both hemispheres poleward of 45°, where the effect of parameterized gravity wave drag becomes important. However, at most levels, a large difference in the residual is found among the datasets. This interdata difference is mainly caused by an uncertainty in the Coriolis torque. The non-quasigeostrophic terms, such as those associated with the vertical motion, also play a nonnegligible role when the polar vortex accelerates or decelerates. The latest reanalysis datasets exhibit smaller residuals than their earlier counterparts. For example, ERA-Interim is dynamically more consistent than ERA-40. This improvement over the generations is largely attributed to a better representation of the Coriolis torque. This is not likely achieved by the increase in satellite data observations over the past few decades. In fact, the dynamical consistency is only weakly sensitive to the analysis period. Instead, model-specific factors, such as data assimilation technique, model resolution, and physics, likely play a crucial role in improving the dynamical consistency.

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Differences in mid-latitude stratospheric winds between reanalysis data and versus radiosonde observations at Prague

Cited by 7 publications

References 26 publications

Northern Hemisphere stratospheric winds in higher midlatitudes: longitudinal distribution and long-term trends

Northern Hemisphere stratospheric winds in higher midlatitudes: longitudinal distribution and long-term trends

Longitudinal structure of stationary planetary waves in the middle atmosphere – extraordinary years

Dynamical Consistency of Reanalysis Datasets in the Extratropical Stratosphere

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