scholarly journals 20-year LiDAR observations of stratospheric sudden warming over a mid-latitude site, Observatoire de Haute Provence (OHP; 44° N, 6° E): case study and statistical characteristics

2007 ◽  
Vol 7 (6) ◽  
pp. 15739-15779 ◽  
Author(s):  
D. V. Charyulu ◽  
V. Sivakumar ◽  
H. Bencherif ◽  
G. Kirgis ◽  
A. Hauchecorne ◽  
...  
Keyword(s):  
Winter Season ◽  
Reanalysis Data ◽  
Statistical Characteristics ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Sudden Warming ◽  
Rayleigh Lidar ◽  
Environmental Prediction ◽  
Lidar Observations ◽  
Biennial Oscillation

Abstract. The present study delineates the characteristics of Stratospheric Sudden Warming (SSW) events observed over the Observatoire de Haute Provence (OHP: 44° N, 6° E). The study uses 20 years of Rayleigh LiDAR temperature measurements for the period, 1982–2001, which corresponds to 2629 daily temperature profiles. Characteristics of warming events, such as type of warming (major and minor), magnitude of warming, height of occurrence and day period of occurrence are presented with emphasis on wave propagation and isentropic transport conditions. The major and minor warming events are classified with respect to temperature increase and reversal in the zonal wind direction in the polar region using reanalysis data from the National Centre for Environmental Prediction (NCEP). SSWs occur with a mean frequency of 2.15 events per winter season. The percentage of occurrence of major and minor warming events are found to be ~23% and ~77%, respectively. The observed major and minor SSW is associated with a descent of the stratopause layer by −6 to 6 km range. The heights of occurrences of major SSWs are distributed between 38 km and 54 km with magnitudes in the 12.2–35.7 K temperature range, while minor SSW occurrences appear in the 42–54 km range, closer to the usual stratopause layer (~47 km) and with a slightly larger range of temperature magnitude (10.2–32.8 K). The observed major and minor events are examined in connection with Quasi-Biennial Oscillation (QBO) phases.

scholarly journals Analysis of Arctic Spring Ozone Anomaly in the Phases of QBO and 11-year Solar Cycle for 1979–2011

2021 ◽  
Author(s):  
Yousuke Yamashita ◽  
Hideharu Akiyoshi ◽  
Masaaki Takahashi
Keyword(s):  
Solar Cycle ◽  
Climate Model ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Spring ◽  
The Arctic ◽  
Negative Anomaly ◽  
Late Winter ◽  
Quasi Biennial Oscillation ◽  
Biennial Oscillation

Arctic ozone amount in winter to spring shows large year-to-year variation. This study investigates Arctic spring ozone in relation to the phase of quasi-biennial oscillation (QBO)/the 11-year solar cycle, using satellite observations, reanalysis data, and outputs of a chemistry climate model (CCM) during the period of 1979–2011. For this duration, we found that the composite mean of the Northern Hemisphere high-latitude total ozone in the QBO-westerly (QBO-W)/solar minimum (Smin) phase is slightly smaller than those averaged for the QBO-W/Smax and QBO-E/Smax years in March. An analysis of a passive ozone tracer in the CCM simulation indicates that this negative anomaly is primarily caused by transport. The negative anomaly is consistent with a weakening of the residual mean downward motion in the polar lower stratosphere. The contribution of chemical processes estimated using the column amount difference between ozone and the passive ozone tracer is between 10–20% of the total anomaly in March. The lower ozone levels in the Arctic spring during the QBO-W/Smin years are associated with a stronger Arctic polar vortex from late winter to early spring, which is linked to the reduced occurrence of sudden stratospheric warming in the winter during the QBO-W/Smin years.

scholarly journals Stratospheric semi-decadal oscillations in NCEP data

2008 ◽  
Vol 26 (8) ◽  
pp. 2143-2157 ◽  
Author(s):  
H. G. Mayr ◽  
J. G. Mengel ◽  
F. T. Huang ◽  
E. R. Talaat ◽  
E. R. Nash ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Data Analysis ◽  
Temperature Data ◽  
Spectral Features ◽  
Altitude Range ◽  
Quasi Biennial Oscillation ◽  
Atmospheric Research ◽  
Zonal Winds ◽  
Environmental Prediction ◽  
Biennial Oscillation

Abstract. An analysis of the National Centers for Environmental Prediction (NCEP)/National Center for Atmospheric Research (NCAR) data is presented to provide a more complete description of the stratospheric 5-year semi-decadal (SD) oscillation (Mayr et al., 2007). The zonal-mean temperature and zonal wind data from the Atmospheric Research R-1 analysis are employed, covering the years from 1962 to 2002 in the altitude range from 10 to 30 km. For diagnostic purposes, the data are separated into the hemispherically symmetric and anti-symmetric components, and spectral analysis is applied to identify the signatures of the SD oscillations. Through the synthesis or filtering of spectral features, the SD modulations of the annual oscillation (AO) and quasi-biennial oscillation (QBO) are delineated. In agreement with the earlier findings, the magnitude of the SD oscillation is more pronounced when the 30-month QBO dominates during the years from 1975 to 1995. This is consistent with results from a numerical model, which shows that such a QBO generates the SD oscillation through interaction with the 12-month AO. In the zonal winds, the SD oscillation in the NCEP data is confined to equatorial latitudes, where it modulates the symmetric AO and QBO by about 5 m/s below 30 km. In the temperature data, the effect is also seen around the equator, but it is much larger at polar latitudes where the SD oscillation produces variations as large as 2 K. Our data analysis indicates that the SD oscillation is mainly hemispherically symmetric, and it appears to originate at equatorial latitudes where most of the energy resides.

scholarly journals Influence of the Quasi-Biennial Oscillation on the Extratropical Winter Stratosphere in an Atmospheric General Circulation Model and in Reanalysis Data

2010 ◽  
Vol 67 (5) ◽  
pp. 1402-1419 ◽  
Author(s):  
James A. Anstey ◽  
Theodore G. Shepherd ◽  
John F. Scinocca
Keyword(s):  
Zonal Wind ◽  
General Circulation ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Empirical Orthogonal Functions ◽  
Vertical Profiles ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Polar Vortex ◽  
Atmospheric General Circulation ◽  
Biennial Oscillation

Abstract The interannual variability of the stratospheric polar vortex during winter in both hemispheres is observed to correlate strongly with the phase of the quasi-biennial oscillation (QBO) in tropical stratospheric winds. It follows that the lack of a spontaneously generated QBO in most atmospheric general circulation models (AGCMs) adversely affects the nature of polar variability in such models. This study examines QBO–vortex coupling in an AGCM in which a QBO is spontaneously induced by resolved and parameterized waves. The QBO–vortex coupling in the AGCM compares favorably to that seen in reanalysis data [from the 40-yr ECMWF Re-Analysis (ERA-40)], provided that careful attention is given to the definition of QBO phase. A phase angle representation of the QBO is employed that is based on the two leading empirical orthogonal functions of equatorial zonal wind vertical profiles. This yields a QBO phase that serves as a proxy for the vertical structure of equatorial winds over the whole depth of the stratosphere and thus provides a means of subsampling the data to select QBO phases with similar vertical profiles of equatorial zonal wind. Using this subsampling, it is found that the QBO phase that induces the strongest polar vortex response in early winter differs from that which induces the strongest late-winter vortex response. This is true in both hemispheres and for both the AGCM and ERA-40. It follows that the strength and timing of QBO influence on the vortex may be affected by the partial seasonal synchronization of QBO phase transitions that occurs both in observations and in the model. This provides a mechanism by which changes in the strength of QBO–vortex correlations may exhibit variability on decadal time scales. In the model, such behavior occurs in the absence of external forcings or interannual variations in sea surface temperatures.

scholarly journals Subseasonal midlatitude prediction skill following Quasi-Biennial Oscillation and Madden–Julian Oscillation activity

2020 ◽  
Vol 1 (1) ◽  
pp. 247-259
Author(s):  
Kirsten J. Mayer ◽  
Elizabeth A. Barnes
Keyword(s):  
Northern Hemisphere ◽  
Rossby Waves ◽  
Prediction Skill ◽  
Lead Times ◽  
Madden Julian Oscillation ◽  
Quasi Biennial Oscillation ◽  
Weather Forecasts ◽  
The Pacific ◽  
Environmental Prediction ◽  
Biennial Oscillation

Abstract. The Madden–Julian Oscillation (MJO) is known to force extratropical weather days to weeks following an MJO event through excitation of stationary Rossby waves, also referred to as tropical–extratropical teleconnections. Prior research has demonstrated that this tropically forced midlatitude response leads to increased prediction skill on subseasonal to seasonal (S2S) timescales. Furthermore, the Quasi-Biennial Oscillation (QBO) has been shown to possibly alter these teleconnections through modulation of the MJO itself and the atmospheric basic state upon which the Rossby waves propagate. This implies that the MJO–QBO relationship may affect midlatitude circulation prediction skill on S2S timescales. In this study, we quantify midlatitude circulation sensitivity and prediction skill following active MJOs and QBOs across the Northern Hemisphere on S2S timescales through an examination of the 500 hPa geopotential height field. First, a comparison of the spatial distribution of Northern Hemisphere sensitivity to the MJO during different QBO phases is performed for European Centre for Medium-Range Weather Forecasts (ECMWF) ERA-Interim reanalysis and ECMWF and the National Centers for Environmental Prediction (NCEP) hindcasts. Secondly, differences in prediction skill in ECMWF and NCEP hindcasts are quantified following MJO–QBO activity. In both hindcast systems, we find that regions across the Pacific, North America, and the Atlantic demonstrate an enhanced MJO impact on prediction skill during strong QBO periods with lead times of 1–4 weeks compared to MJO events during neutral QBO periods.

scholarly journals Role of equatorial planetary and gravity waves in the 2015–16 quasi-biennial oscillation disruption

2020 ◽  
Author(s):  
Min-Jee Kang ◽  
Hye-Yeong Chun ◽  
Rolando R. Garcia
Keyword(s):  
Gravity Waves ◽  
Rossby Waves ◽  
Wave Mode ◽  
Reanalysis Data ◽  
Small Scale ◽  
Negative Wave ◽  
Quasi Biennial Oscillation ◽  
Rossby Wave Breaking ◽  
Wave Forcing ◽  
Biennial Oscillation

Abstract. In February 2016, the descent of the westerly phase of the quasi-biennial oscillation (QBO) was unprecedentedly disrupted by the development of easterly winds. Previous studies have shown that extratropical Rossby waves propagating into the deep Tropics were the major cause of the 2015–16 QBO disruption. However, a large portion of the negative momentum forcing associated with the disruption still stems from equatorial planetary and small-scale gravity waves, which calls for detailed analyses by separating each wave mode compared with climatological QBO cases. Here, the contributions of resolved equatorial planetary waves [Kelvin, Rossby, mixed-Rossby gravity (MRG), and inertia-gravity (IG) waves] and small-scale convective gravity waves (CGWs) obtained from an offline CGW parameterization to the 2015–16 QBO disruption are investigated using MERRA-2 global reanalysis data from October 2015 to February 2016. In October and November 2015, anomalously strong negative forcing by MRG and IG waves weakened the QBO jet at 0°–5° S near 40 hPa, leading to Rossby wave breaking at the QBO jet core in the southern hemisphere. From December 2015 to January 2016, exceptionally strong Rossby waves propagating horizontally (vertically) continuously decelerated the southern (northern) flank of the jet. In February 2016, when the westward CGW momentum flux at the source level was much stronger than its climatology, CGWs began to exert considerable negative forcing at 40–50 hPa near the equator, in addition to the Rossby waves. The enhancement of the negative wave forcing in the Tropics stems mostly from strong wave activity in the troposphere associated with increased convective activity and the strong westerlies (or weaker easterlies) in the troposphere, except that the MRG wave forcing is more likely associated with increased barotropic instability in the lower stratosphere.

scholarly journals Does the coupling of the mesospheric semiannual oscillation with the quasi-biennial oscillation provide predictability of Antarctic sudden stratospheric warmings?

2021 ◽  
Author(s):  
Viktoria J. Nordström ◽  
Annika Seppälä
Keyword(s):  
Lower Stratosphere ◽  
Reanalysis Data ◽  
Stratospheric Warming ◽  
Early Winter ◽  
Sudden Stratospheric Warming ◽  
Quasi Biennial Oscillation ◽  
Westerly Winds ◽  
Low Latitudes ◽  
Biennial Oscillation ◽  
Semiannual Oscillation

Abstract. During September 2019 there was a sudden stratospheric warming over Antarctica, which brought disruption to the usually stable winter vortex. The mesospheric winds reversed and temperatures in the stratosphere rose by over 50 K. Whilst this was only the second SSW in the Southern Hemisphere (SH), the other having occurred in 2002, its Northern counterpart experiences about six per decade. Currently, an amplification of atmospheric waves during winter is thought to trigger SSWs. However, our understanding remains incomplete, especially in regards to its occurrence in the SH. Here, we investigate the interaction of two equatorial atmospheric modes, the Quasi Biennial Oscillation (QBO) and the Semiannual Oscillation (SAO) during the SH winters of 2019 and 2002. Using MERRA-2 reanalysis data we find that the two modes interact at low latitudes during their easterly phases in the early winter, forming a zero wind line that stretches from the lower stratosphere into the mesosphere. This influences the meridional wave guide, resulting in easterly momentum being deposited in the mesosphere throughout the polar winter, reducing the magnitude of the westerly winds. As the winter progresses these features descend into the stratosphere, until SSW conditions are reached. We find similar behaviour in two other years leading to delayed dynamical disruptions later in the spring. The timing and magnitude of the SAO and the extent of the upper stratospheric easterly QBO signal, that results in the SAO-QBO interaction, was found to be unique in these years, when compared to the years with a similar QBO phase. We propose that this early winter behaviour may be a key physical process in decelerating the mesospheric winds which may precondition the Southern atmosphere for a SSW. Thus the early winter equatorial upper stratosphere-mesosphere together with the polar mesosphere may provide critical early clues to an imminent SH SSW.

scholarly journals Equatorial annual oscillation with QBO-driven 5-year modulation in NCEP data

2007 ◽  
Vol 25 (1) ◽  
pp. 37-45 ◽  
Author(s):  
H. G. Mayr ◽  
J. G. Mengel ◽  
F. T. Huang ◽  
E. R. Nash
Keyword(s):  
Spectral Analysis ◽  
Zonal Wind ◽  
Lower Stratosphere ◽  
Circumstantial Evidence ◽  
High Latitudes ◽  
Time Intervals ◽  
Quasi Biennial Oscillation ◽  
Temperature Variations ◽  
Environmental Prediction ◽  
Biennial Oscillation

Abstract. An analysis is presented of the stratospheric zonal wind and temperature variations supplied by the National Center for Environmental Prediction (NCEP). The derived zonal-mean variations are employed. Stimulated by modeling studies, the data are separated into the hemispherically symmetric and anti-symmetric components, and spectral analysis is applied to study the 12-month annual oscillation (AO) and the quasi-biennial oscillation (QBO). For data samples that cover as much as 40 years, the zonal wind results reveal a pronounced 5-year modulation of the symmetric AO in the lower stratosphere, which is confined to equatorial latitudes. This modulation is also seen in the temperature variations but extends to high latitudes, qualitatively consistent with published model results. A comparison between different time intervals of the data indicates that the signature of the 5-year oscillation is larger when the QBO of 30 months is more pronounced. Thus there is circumstantial evidence that this particular QBO period is involved in generating the oscillation as was shown in a modeling study (Mayr et al., 2000). In agreement with the model, the spectral analysis also reveals a weak anti-symmetric 5-year oscillation in the zonal wind data, which could interact with the strong anti-symmetric AO to produce the modulation of the symmetric AO. The 30-month QBO is well suited to be synchronized by, and phase-locked to, the equatorial semi-annual oscillation (SAO), and this may explain why this QBO periodicity and its 5-year spin-off are observed to persist for many cycles.

SAO-QBO Coupling before the 2019 and 2002 Southern Sudden Stratospheric Warmings

2021 ◽  
Author(s):  
Viktoria Nordström ◽  
Annika Seppälä
Keyword(s):  
Lower Stratosphere ◽  
Reanalysis Data ◽  
Stratospheric Warming ◽  
Early Winter ◽  
Sudden Stratospheric Warming ◽  
Quasi Biennial Oscillation ◽  
Westerly Winds ◽  
Low Latitudes ◽  
Biennial Oscillation ◽  
Semiannual Oscillation

<p>During September 2019 there was a sudden stratospheric warming over Antarctica, which brought disruption to the usually stable winter vortex. The mesospheric winds reversed and temperatures in the stratosphere rose by over 50~K. Whilst this was only the second SSW in the Southern Hemisphere (SH), the other having occurred in 2002, its Northern counterpart experiences about six per decade. Currently, an amplification of atmospheric waves during winter is thought to trigger SSWs. Our understanding, however, remains incomplete, especially with regards to its occurrence in the SH. Here, we investigate the interaction of two equatorial atmospheric modes, the Quasi Biennial Oscillation (QBO) and the Semiannual Oscillation (SAO) during the SH winters of 2019 and 2002. Using MERRA-2 reanalysis data we find that the two modes interact at low latitudes during their easterly phases in the early winter, forming a zero wind line that stretches from the lower stratosphere into the mesosphere. This influences the meridional wave guide, resulting in easterly momentum being deposited in the mesosphere throughout the polar winter, reducing the magnitude of the westerly winds. As the winter progresses these features descend into the stratosphere, until SSW conditions are reached. We find similar behaviour in two other years leading to delayed dynamical disruptions later in the spring. The timing and magnitude of the SAO and the extent of the upper stratospheric easterly QBO signal, that results in the SAO-QBO interaction, was found to be unique in these years, when compared to the years with a similar QBO phase. We propose that this early winter behaviour may be a key physical process in decelerating the mesospheric winds which may precondition the Southern atmosphere for a SSW. Thus the early winter equatorial upper stratosphere-mesosphere together with the polar mesosphere may provide critical early clues to an imminent SH SSW.</p>

scholarly journals Lidar observations of middle atmosphere temperature variability

1995 ◽  
Vol 13 (6) ◽  
pp. 648-655 ◽  
Author(s):  
G. P. Gobbi ◽  
C. Souprayen ◽  
F. Congeduti ◽  
G. Di Donfrancesco ◽  
A. Adriani ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Middle Atmosphere ◽  
Atmospheric Temperature ◽  
Temperature Variability ◽  
Quasi Biennial Oscillation ◽  
Temperature Trends ◽  
Atmosphere Temperature ◽  
Reference Atmosphere ◽  
Lidar Observations ◽  
Biennial Oscillation

Abstract. We discuss 223 middle atmosphere lidar temperature observations. The record was collected at Frascati (42°N–13°E), during the 41-month period January 1989-May 1992, corresponding to the maximum of solar cycle 22. The choice of this interval was aimed at minimizing the temperature variability induced by the 11-year solar cycle. The average climatology over the 41-month period and comparison with a reference atmosphere (CIRA86) are presented. Monthly temperature variability over the full period, during opposite quasi-biennial oscillation phases and on a short-term scale (0.5–4 h), is analyzed. Results indicate the 50–55-km region as less affected by variability caused by the natural phenomena considered in the analysis. Due to this minimum in natural noise characterizing the atmospheric temperature just above the stratopause, observations of that region are well suited to the detection of possible temperature trends induced by industrial activities.

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