Evolution of the Stratosphere during Northern Winter 1991/92 as Diagnosed from U.K. Meteorological Office Analyses

O’Neill, A.; Grose, W. L.; Pope, V. D.; Maclean, Hector; Swinbank, Richard

doi:10.1175/1520-0469(1994)051<2800:eotsdn>2.0.co;2

Cited by 61 publications

(39 citation statements)

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“…The UKMO data have been widely used to describe the state of the stratosphere (e.g. O'Neill et al, 1994;Chshyolkova et al, 2005Chshyolkova et al, , 2006Chshyolkova et al, , 2007Manson et al, 2008). In this paper, we use UKMO temperatures and horizontal wind components to describe the state of winter stratospheric circulation and polar vortex.…”

Section: Ukmo Datamentioning

confidence: 99%

Vertical and interhemispheric links in the stratosphere-mesosphere as revealed by the day-to-day variability of Aura-MLS temperature data

et al. 2009

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Abstract. The coupling processes in the middle atmosphere have been a subject of intense research activity because of their effects on atmospheric circulation, structure, variability, and the distribution of chemical constituents. In this study, the day-to-day variability of Aura-MLS (Microwave Limb Sounder) temperature data are used to reveal the vertical and interhemispheric coupling processes in the stratosphere-mesosphere during four Northern Hemisphere winters (2004/2005-2007/2008). The UKMO (United Kingdom Meteorological Office) assimilated data and mesospheric winds from MF (medium frequency) radars are also applied to help highlight the coupling processes.In this study, a clear vertical link can be seen between the stratosphere and mesosphere during winter months. The coolings and reversals of northward meridional winds in the polar winter mesosphere are often observed in relation to warming events (Sudden Stratospheric Warming, SSW for short) and the associated changes in zonal winds in the polar winter stratosphere. An upper-mesospheric cooling usually precedes the beginning of the warming in the stratosphere by 1-2 days.Inter-hemispheric coupling has been identified initially by a correlation analysis using the year-to-year monthly zonal mean temperature. Then the correlation analyses are performed based upon the daily zonal mean temperature. From the original time sequences, significant positive (negative) correlations are generally found between zonal mean temperatures at the Antarctic summer mesopause and in the ArcCorrespondence to: X. Xu (xix303@mail.usask.ca) tic winter stratosphere (mesosphere) during northern midwinters, although these correlations are dominated by the low frequency variability (i.e. the seasonal trend). Using the short-term oscillations (less than 15 days), the statistical result, by looking for the largest magnitude of correlation within a range of time-lags (0 to 10 days; positive lags mean that the Antarctic summer mesopause is lagging), indicates that the temporal variability of zonal mean temperature at the Antarctic summer mesopause is also positively (negatively) correlated with the polar winter stratosphere (mesosphere) during three (2004/2005, 2005/2006, and 2007/2008) out of the four winters. The highest value of the correlation coefficient is over 0.7 in the winter-stratosphere for the three winters. The remaining winter (2006/2007) has more complex correlations structures; correspondingly the polar vortex was distinguished this winter. The time-lags

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Section: Ukmo Datamentioning

confidence: 99%

Vertical and interhemispheric links in the stratosphere-mesosphere as revealed by the day-to-day variability of Aura-MLS temperature data

et al. 2009

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“…MetO data are widely used and shown to be very helpful in studies of the stratospheric region. In particular, O'Neill et al (1994) successfully used the MetO data to study the evolution of the NH stratosphere during winter 1991/92. We have also used MetO data in conjunction with TOMS (Total Ozone Mapping Spectrometer) and MF radar data in earlier studies (Chshyolkova et al, 2005).…”

Section: Meto Datamentioning

confidence: 99%

Polar vortex evolution during Northern Hemispheric winter 2004/05

Chshyolkova

Manson²,

Meek³

et al. 2007

Ann. Geophys.

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Abstract. As a part of the project "Atmospheric Wave Influences upon the Winter Polar Vortices (0-100 km)" of the CAWSES program, data from meteor and Medium Frequency radars at 12 locations and MetO (UK Meteorological Office) global assimilated fields have been analyzed for the first campaign during the Northern Hemispheric winter of 2004/05. The stratospheric state has been described using the conventional zonal mean parameters as well as Q-diagnostic, which allows consideration of the longitudinal variability.The stratosphere was cold during winter of 2004/05, and the polar vortex was relatively strong during most of the winter with relatively weak disturbances occurring at the end of December and the end of January. For this winter the strongest deformation with the splitting of the polar vortex in the lower stratosphere was observed at the end of February. Here the results show strong latitudinal and longitudinal differences that are evident in the stratospheric and mesospheric data sets at different stations. Eastward winds are weaker and oscillations with planetary wave periods have smaller amplitudes at more poleward stations. Accordingly, the occurrence, time and magnitude of the observed reversal of the zonal mesospheric winds associated with stratospheric disturbances depend on the local stratospheric conditions. In general, compared to previous years, the winter of 2004/05 could be characterized by weak planetary wave activity at stratospheric and mesospheric heights.

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“…Lagrangian transport has been demonstrated for generating high resolution fields from PV (e.g. O'Neill et al, 1994;Fairlie et al, 1997;Flentje et al, 2000;Dragani et al, 2002), global model tracer fields (e.g. Methven and Hoskins, 1999;Evans et al, 2000;Methven et al, 2001Methven et al, , 2003 and gridded satellite data (e.g.…”

Section: Introductionmentioning

confidence: 99%

Refinements in the use of equivalent latitude for assimilating sporadic inhomogeneous stratospheric tracer observations, 1: Detecting transport of Pinatubo aerosol across a strong vortex edge

Good

Pyle

2004

Atmos. Chem. Phys.

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Abstract. The use of PV equivalent latitude for assimilating stratospheric tracer observations is discussed -with particular regard to the errors in the equivalent latitude coordinate, and to the assimilation of sparse data. Some example measurements are assimilated: they sample the stratosphere sporadically and inhomogeneously. The aim was to obtain precise information about the isentropic tracer distribution and evolution as a function of equivalent latitude. Precision is important, if transport across barriers like the vortex edge are to be detected directly. The main challenges addressed are the errors in modelled equivalent latitude, and the non-ideal observational sampling. The methods presented allow first some assessment of equivalent latitude errors and a picture of how good or poor the observational coverage is. This information determines choices in the approach for estimating as precisely as possible the true equivalent latitude distribution of the tracer, in periods of good and poor observational coverage. This is in practice an optimisation process, since better understanding of the equivalent latitude distribution of the tracer feeds back into a clearer picture of the errors in the modelled equivalent latitude coordinate. Error estimates constrain the reliability of using equivalent latitude to make statements like "this observation samples air poleward of the vortex edge" or that of more general model-measurement comparisons. The approach is demonstrated for groundbased lidar soundings of the Mount Pinatubo aerosol cloud, focusing on the 1991-92 arctic vortex edge between 475-520 K. Equivalent latitude is estimated at the observation times and locations from Eulerian model tracers initialised with PV and forced by UK Meteorological Office analyses. With the model formulation chosen, it is shown that tracer transport of a few days resulted in an error distribution that Correspondence to: P. Good (pgood@meteo.noa.gr) was much closer to Gaussian form, although the mean error was not significantly affected. The analysis of the observations revealed a small amount of irreversible transport of aerosol across the vortex edge during late January 1992, coincident with a strongly disturbed vortex.

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Evolution of the Stratosphere during Northern Winter 1991/92 as Diagnosed from U.K. Meteorological Office Analyses

Cited by 61 publications

References 0 publications

Vertical and interhemispheric links in the stratosphere-mesosphere as revealed by the day-to-day variability of Aura-MLS temperature data

Vertical and interhemispheric links in the stratosphere-mesosphere as revealed by the day-to-day variability of Aura-MLS temperature data

Polar vortex evolution during Northern Hemispheric winter 2004/05

Refinements in the use of equivalent latitude for assimilating sporadic inhomogeneous stratospheric tracer observations, 1: Detecting transport of Pinatubo aerosol across a strong vortex edge

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