scholarly journals Tropopause referenced ozone climatology and inter-annual variability (1994–2003) from the MOZAIC programme

2006 ◽  
Vol 6 (4) ◽  
pp. 1033-1051 ◽  
Author(s):  
V. Thouret ◽  
J.-P. Cammas ◽  
B. Sauvage ◽  
G. Athier ◽  
R. Zbinden ◽  
...  
Keyword(s):  
Large Scale ◽  
Strong Positive Correlation ◽  
Tropopause Height ◽  
Atmospheric Variability ◽  
Automatic Equipment ◽  
Upper Troposphere ◽  
Annual Variability ◽  
The North ◽  
Nao Index ◽  
The North Atlantic Oscillation

Abstract. The MOZAIC programme collects ozone and water vapour data using automatic equipment installed on board five long-range Airbus A340 aircraft flying regularly all over the world since August 1994. Those measurements made between September 1994 and August 1996 allowed the first accurate ozone climatology at 9–12 km altitude to be generated. The seasonal variability of the tropopause height has always provided a problem when constructing climatologies in this region. To remove any signal from the seasonal and synoptic scale variability in tropopause height we have chosen in this further study of these and subsequent data to reference our climatology to the altitude of the tropopause. We define the tropopause as a mixing zone 30 hPa thick across the 2 pvu potential vorticity surface. A new ozone climatology is now available for levels characteristic of the upper troposphere (UT) and the lower stratosphere (LS) regardless of the seasonal variations of the tropopause over the period 1994–2003. Moreover, this new presentation has allowed an estimation of the monthly mean climatological ozone concentration at the tropopause showing a sine seasonal variation with a maximum in May (120 ppbv) and a minimum in November (65 ppbv). Besides, we present a first assessment of the inter-annual variability of ozone in this particular critical region. The overall increase in the UTLS is about 1%/yr for the 9 years sampled. However, enhanced concentrations about 10–15 % higher than the other years were recorded in 1998 and 1999 in both the UT and the LS. This so-called "1998–1999 anomaly" may be attributed to a combination of different processes involving large scale modes of atmospheric variability, circulation features and local or global pollution, but the most dominant one seems to involve the variability of the North Atlantic Oscillation (NAO) as we find a strong positive correlation (above 0.60) between ozone recorded in the upper troposphere and the NAO index. A strong anti-correlation is also found between ozone and the extremes of the Northern Annular Mode (NAM) index, attributing the lower stratospheric variability to dynamical anomalies. Finally this analysis highlights the coupling between the troposphere, at least the upper one, and the stratosphere, at least the lower one.

scholarly journals Tropopause referenced ozone climatology and inter-annual variability (1994–2003) from the MOZAIC programme

2005 ◽  
Vol 5 (4) ◽  
pp. 5441-5488 ◽  
Author(s):  
V. Thouret ◽  
J.-P. Cammas ◽  
B. Sauvage ◽  
G. Athier ◽  
R. Zbinden ◽  
...  
Keyword(s):  
Large Scale ◽  
Strong Positive Correlation ◽  
Tropopause Height ◽  
Atmospheric Variability ◽  
Automatic Equipment ◽  
Upper Troposphere ◽  
Annual Variability ◽  
The North ◽  
Nao Index ◽  
The North Atlantic Oscillation

Abstract. The MOZAIC programme collects ozone and water vapour data using automatic equipment installed on board five long-range Airbus A340 aircraft flying regularly all over the world since August 1994. Those measurements made between September 1994 and August 1996 allowed the first accurate ozone climatology at 9–12 km altitude to be generated. The seasonal variability of the tropopause height has always provided a problem when constructing climatologies in this region. To remove any signal from the seasonal and synoptic scale variability in tropopause height we have chosen in this further study of these and subsequent data to reference our climatology to the altitude of the tropopause. We define the tropopause as a mixing zone 30 hPa thick across the 2 pvu potential vorticity surface. A new ozone climatology is now available for levels characteristic of the upper troposphere (UT) and the lower stratosphere (LS) regardless of the seasonal variations of the tropopause over the period 1994–2003. More over, this new presentation has allowed an estimation of the monthly mean climatological ozone concentration at the tropopause showing a sine seasonal variation with a maximum in May (120 ppbv) and a minimum in November (65 ppbv). Besides, we present a first assessment of the inter-annual variability of ozone in this particular critical region. The overall increase in the UTLS is about 1%/yr for the 9 years sampled. However, enhanced concentrations about 10–15% higher than the other years were recorded in 1998 and 1999 in both the UT and the LS. This so-called "1998–1999 anomaly'' may be attributed to a combination of different processes involving large scale modes of atmospheric variability, circulation features and local or global pollution, but the most dominant one seems to involve the variability of the North Atlantic Oscillation (NAO) as we find a strong positive correlation (above 0.60) between ozone recorded in the upper troposphere and the NAO index. A strong anti-correlation is also found between ozone and the Northern Annular Mode (NAM) index, attributing the lower stratospheric variability to dynamical anomalies. Finally this analysis highlights the coupling between the troposphere, at least the upper one, and the stratosphere, at least the lower one.

scholarly journals Heavy Rainfall and Landslide Event in January 1831 at the Pedregoso Mountains (Cabeza Del Buey, SW Spain)

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 544 ◽  
Author(s):  
Juan Pedro García-Garrido ◽  
María Cruz Gallego ◽  
Teodoro Palacios ◽  
Ricardo M. Trigo ◽  
José Manuel Vaquero
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Meteorological Data ◽  
Triggering Mechanism ◽  
Sw Spain ◽  
The North ◽  
Nao Index ◽  
Landslide Event ◽  
High Precipitation ◽  
The North Atlantic Oscillation

In this work, a landslide event that took place on January 1831 at the Pedregoso Mountains, Cabeza del Buey, SW Spain, is described. This landslide had not been documented to date and was only described in the local press. This event involved an estimated amount of dislodged material in the order of 104 m3. The amount of meteorological data is very scarce as the event occurred before the setting up of the national meteorological service in Spain. However, data from the relatively near location of SW Iberia suggest that the landslide was preceded by a prolonged period of unusually high precipitation totals and that this intense wet period is compatible with the large-scale atmospheric configuration in the winter of 1829–1830. In fact, the North Atlantic Oscillation (NAO) index for that winter achieved one of the most negative values observed in the bicentennial period spanning 1821 to 2019. This multidisciplinary work represents the first attempt to report and describe the main triggering mechanism for an historical landslide in the Extremadura region that is similar to other great historical landslides which have already been documented for other locations in Spain.

How well do seasonal forecasts reproduce European winter storm clustering and its relationship to large-scale climate drivers?

2020 ◽  
Author(s):  
Michael Angus ◽  
Gregor Leckebusch
Keyword(s):  
Statistical Model ◽  
Large Scale ◽  
Seasonal Forecast ◽  
Decision Makers ◽  
Seasonal Forecasts ◽  
Annual Variability ◽  
The North ◽  
Explained Variance ◽  
The North Atlantic Oscillation ◽  
Insight Into

<div>The inter-annual variability of the European windstorm season is dependent on a number of large-scale climate drivers and conditions, for example the North Atlantic Oscillation. For seasonal forecasts to provide valuable information to decision makers about the potential severity of the winter windstorm season, they must capture this relationship between large-scale climate drivers and seasonal windstorm frequency in advance. Here, we examine the performance of the latest state of the art ECMWF seasonal forecast product (SEAS5) in capturing this climate response. We apply a statistical model previously shown to well reproduce the explained behaviour of European windstorms from large-scale climate drivers (Walz et al. 2018) to SEAS5, and examine the choice of statistically significant drivers. The model applied is a stepwise Poisson regression approach to account for serial clustering within inter-annual variability of windstorms, the resultant of which categorizes each windstorm season as either active, neutral or inactive. In particular, we focus on the European region where the explained variance of the statistical model in observations is highest (Walz et al. 2018), the British Isles. In addition to comparing the performance of the model in SEAS5 and in observations, we examine which relationships are not recreated in the seasonal forecast successfully from a dynamical perspective, to provide further insight into the current ability of seasonal forecasts to represent European windstorm inter-annual variability.</div><div> </div><div>Reference:</div><div>Walz, M. A., Befort, D. J., Kirchner‐Bossi, N. O., Ulbrich, U., & Leckebusch, G. C. (2018). Modelling serial clustering and inter‐annual variability of European winter windstorms based on large‐scale drivers. <em>International Journal of Climatology</em>, <em>38</em>(7), 3044-3057.</div>

scholarly journals A Regime View of the North Atlantic Oscillation and Its Response to Anthropogenic Forcing

2010 ◽  
Vol 23 (6) ◽  
pp. 1291-1307 ◽  
Author(s):  
Tim Woollings ◽  
Abdel Hannachi ◽  
Brian Hoskins ◽  
Andrew Turner
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Anthropogenic Forcing ◽  
The Third ◽  
The North ◽  
Nao Index ◽  
Future Behavior ◽  
Real Change ◽  
The North Atlantic Oscillation

Abstract The distribution of the daily wintertime North Atlantic Oscillation (NAO) index in the 40-yr ECMWF Re-Analysis (ERA-40) is significantly negatively skewed. Dynamical and statistical analyses both suggest that this skewness reflects the presence of two distinct regimes—referred to as “Greenland blocking” and “subpolar jet.” Changes in both the relative occurrence and in the structure of the regimes are shown to contribute to the long-term NAO trend over the ERA-40 period. This is contrasted with the simulation of the NAO in 100-yr control and doubled CO2 integrations of the third climate configuration of the Met Office Unified Model (HadCM3). The model has clear deficiencies in its simulation of the NAO in the control run, so its predictions of future behavior must be treated with caution. However, the subpolar jet regime does become more dominant under anthropogenic forcing and, while this change is small it is clearly statistically significant and does represent a real change in the nature of NAO variability in the model.

scholarly journals Trends in compound extremes of air temperature and precipitation in Eastern Europe

2021 ◽  
Author(s):  
Elena Vyshkvarkova ◽  
Olga Sukhonos
Keyword(s):  
Eastern Europe ◽  
North Atlantic Oscillation ◽  
Air Temperature ◽  
North Atlantic ◽  
Large Scale ◽  
The North ◽  
Temperature And Precipitation ◽  
Atmosphere System ◽  
Daily Data ◽  
The North Atlantic Oscillation

Abstract The spatial distribution of compound extremes of air temperature and precipitation was studied over the territory of Eastern Europe for the period 1950–2018 during winter and spring. Using daily data on air temperature and precipitation, we calculated the frequency and trends of the four indices – cold/dry, cold/wet, warm/dry and warm/wet. Also, we studying the connection between these indices and large-scale processes in the ocean-atmosphere system such as North Atlantic Oscillation, East Atlantic Oscillation and Scandinavian Oscillation. The results have shown that positive trends in the region are typical of the combinations with the temperatures above the 75th percentile, i.e., the warm extremes in winter and spring. Negative trends were obtained for the cold extremes. Statistically significant increase in the number of days with warm extremes was observed in the northern parts of the region in winter and spring. The analysis of the impacts of the large-scale processes in oceans-atmosphere system showed that the North Atlantic Oscillation index has a strong positive and statistically significant correlation with the warm indices of compound extremes in the northern part of Eastern Europe in winter, while the Scandinavian Oscillation shows the opposite picture.

scholarly journals Polar Mesoscale Cyclone Climatology for the Nordic Seas Based on ERA-Interim

2018 ◽  
Vol 31 (6) ◽  
pp. 2511-2532 ◽  
Author(s):  
Clio Michel ◽  
Annick Terpstra ◽  
Thomas Spengler
Keyword(s):  
North Atlantic ◽  
Selection Criteria ◽  
Large Scale ◽  
Sea Ice Extent ◽  
Nordic Seas ◽  
The North ◽  
Cold Air Outbreak ◽  
Low Level Jet ◽  
Large Scale Flow ◽  
The North Atlantic Oscillation

Polar mesoscale cyclones (PMCs) are automatically detected and tracked over the Nordic seas using the Melbourne University algorithm applied to ERA-Interim. The novelty of this study lies in the length of the dataset (1979–2014), using PMC tracks to infer relationships to large-scale flow patterns, and elucidating the sensitivity to different selection criteria when defining PMCs and polar lows and their genesis environments. The angle between the ambient mean and thermal wind is used to distinguish two different PMC genesis environments. The forward shear environment (thermal and mean wind have the same direction) features typical baroclinic conditions with a temperature gradient at the surface and a strong jet stream at the tropopause. The reverse shear environment (thermal and mean wind have opposite directions) features an occluded cyclone with a barotropic structure throughout the entire troposphere and a low-level jet. In contrast to previous studies, PMC occurrence features neither a significant trend nor a significant link with the North Atlantic Oscillation and the Scandinavian blocking (SB), though the SB negative pattern seems to promote reverse shear PMC genesis. The sea ice extent in the Nordic seas is not associated with overall changes in PMC occurrence but influences the genesis location. Selected cold air outbreak indices and the temperature difference between the sea surface and 500 hPa (SST − T500) show no robust link with PMC occurrence, but the characteristics of forward shear PMCs and their synoptic environments are sensitive to the choice of the SST − T500 threshold.

scholarly journals Large-Scale Flow and the Long-Lasting Blocking High over Russia: Summer 2010

2012 ◽  
Vol 140 (9) ◽  
pp. 2967-2981 ◽  
Author(s):  
Andrea Schneidereit ◽  
Silke Schubert ◽  
Pavel Vargin ◽  
Frank Lunkeit ◽  
Xiuhua Zhu ◽  
...  
Keyword(s):  
Heat Wave ◽  
Large Scale ◽  
Wave Structure ◽  
Arctic Region ◽  
Stationary Wave ◽  
Boreal Summer ◽  
Atmospheric Variability ◽  
The North ◽  
Blocking High ◽  
Large Scale Flow

Abstract Several studies show that the anomalous long-lasting Russian heat wave during the summer of 2010, linked to a long-persistent blocking high, appears mainly as a result of natural atmospheric variability. This study analyzes the large-scale flow structure based on the ECMWF Re-Analysis Interim (ERA-Interim) data (1989–2010). The anomalous long-lasting blocking high over western Russia including the heat wave occurs as an overlay of a set of anticyclonic contributions on different time scales. (i) A regime change in ENSO toward La Niña modulates the quasi-stationary wave structure in the boreal summer hemisphere supporting the eastern European blocking. The polar Arctic dipole mode is enhanced and shows a projection on the mean blocking high. (ii) Together with the quasi-stationary wave anomaly, the transient eddies maintain the long-lasting blocking. (iii) Three different pathways of wave action are identified on the intermediate time scale (~10–60 days). One pathway commences over the eastern North Pacific and includes the polar Arctic region; another one runs more southward and crossing the North Atlantic, continues to eastern Europe; a third pathway southeast of the blocking high describes the downstream development over South Asia.

Increased frequency of Eurasian double jets linked to summer heat extremes in Europe

2021 ◽  
Author(s):  
Efi Rousi ◽  
Kai Kornhuber ◽  
Goratz Beobide Arsuaga ◽  
Fei Luo ◽  
Dim Coumou
Keyword(s):  
Zonal Wind ◽  
Large Scale ◽  
Driving Forces ◽  
Linear Regression Analysis ◽  
Reanalysis Data ◽  
Self Organizing Maps ◽  
Upper Troposphere ◽  
The North ◽  
Heat Extremes ◽  
Different Levels

<p>Persistent summer extremes, such as heatwaves and droughts, can have considerable impacts on nature and societies. There is evidence that weather persistence has increased in Europe over the past decades, in association to changes in atmosphere dynamics, but uncertainties remain and the driving forces are not yet well understood. </p><p>Particularly for Europe, the jet stream may affect surface weather significantly by modulating the North Atlantic storm tracks. Here, we examine the hypothesis that high-latitude warming and decreased westerlies in summer result in more double jets, consisting of two distinct maxima of the zonal wind in the upper troposphere, over the Eurasian sector. Previous work has shown that such double jet states are related to persistent blocking-like circulation in the mid-latitudes. </p><p>We adapt a dynamical perspective of heat extreme trends by looking at large scale circulation and in particular, changes in the zonal mean zonal wind in different levels of the upper troposphere. We define clusters of jet states with the use of Self-Organizing Maps and analyze their characteristics. We find an increase in frequency and persistence of a cluster of double jet states for the period 1979-2019 during July-August (in ERA5 reanalysis data). Those states are linked to increased surface temperature and more frequent heatwaves compared to climatology over western, central, and northern Europe. Significant positive double jet anomalies are found to be dominant in the days preceding and/or coinciding with some of the most intense historical heatwaves in Europe, such as those of 2003 and 2018. A linear regression analysis shows that the increase in frequency and persistence of double jet states may explain part of the strong upward trend in heat extremes over these European regions.</p>

scholarly journals Response of Extreme Precipitation to Urbanization over the Netherlands

2019 ◽  
Vol 58 (4) ◽  
pp. 645-661 ◽  
Author(s):  
Vahid Rahimpour Golroudbary ◽  
Yijian Zeng ◽  
Chris M. Mannaerts ◽  
Zhongbo Su
Keyword(s):  
The Netherlands ◽  
Extreme Precipitation ◽  
Large Scale ◽  
Daily Precipitation ◽  
Atmospheric Air ◽  
The North ◽  
Circulation Types ◽  
Return Levels ◽  
Air Temperatures ◽  
The North Atlantic Oscillation

AbstractKnowledge of the response of extreme precipitation to urbanization is essential to ensure societal preparedness for the extreme events caused by climate change. To quantify this response, this study scales extreme precipitation according to temperature using the statistical quantile regression and binning methods for 231 rain gauges during the period of 1985–2014. The positive 3%–7% scaling rates were found at most stations. The nonstationary return levels of extreme precipitation are investigated using monthly blocks of the maximum daily precipitation, considering the dependency of precipitation on the dewpoint, atmospheric air temperatures, and the North Atlantic Oscillation (NAO) index. Consideration of Coordination of Information on the Environment (CORINE) land-cover types upwind of the stations in different directions classifies stations as urban and nonurban. The return levels for the maximum daily precipitation are greater over urban stations than those over nonurban stations especially after the spring months. This discrepancy was found by 5%–7% larger values in August for all of the classified station types. Analysis of the intensity–duration–frequency curves for urban and nonurban precipitation in August reveals that the assumption of stationarity leads to the underestimation of precipitation extremes due to the sensitivity of extreme precipitation to the nonstationary condition. The study concludes that nonstationary models should be used to estimate the return levels of extreme precipitation by considering the probable covariates such as the dewpoint and atmospheric air temperatures. In addition to the external forces, such as large-scale weather modes, circulation types, and temperature changes that drive extreme precipitation, urbanization could impact extreme precipitation in the Netherlands, particularly for short-duration events.

scholarly journals Impacts of large-scale atmospheric circulation changes due to winter sea-ice retreat on Black Carbon transport and deposition to the Arctic

2016 ◽  
Author(s):  
Luca Pozzoli ◽  
Srdan Dobricic ◽  
Simone Russo ◽  
Elisabetta Vignati
Keyword(s):  
Sea Ice ◽  
Atmospheric Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Southern Oscillation ◽  
The Arctic ◽  
The North ◽  
Ice Retreat ◽  
The North Atlantic Oscillation ◽  
Sea Ice Retreat

Abstract. Winter warming and sea ice retreat observed in the Arctic in the last decades determine changes of large scale atmospheric circulation pattern that may impact as well the transport of black carbon (BC) to the Arctic and its deposition on the sea ice, with possible feedbacks on the regional and global climate forcing. In this study we developed and applied a new statistical algorithm, based on the Maximum Likelihood Estimate approach, to determine how the changes of three large scale weather patterns (the North Atlantic Oscillation, the Scandinavian Blocking, and the El Nino-Southern Oscillation), associated with winter increasing temperatures and sea ice retreat in the Arctic, impact the transport of BC to the Arctic and its deposition. We found that the three atmospheric patterns together determine a decreasing winter deposition trend of BC between 1980 and 2015 in the Eastern Arctic while they increase BC deposition in the Western Arctic. The increasing trend is mainly due to the more frequent occurrences of stable high pressure systems (atmospheric blocking) near Scandinavia favouring the transport in the lower troposphere of BC from Europe and North Atlantic directly into to the Arctic. The North Atlantic Oscillation has a smaller impact on BC deposition in the Arctic, but determines an increasing BC atmospheric load over the entire Arctic Ocean with increasing BC concentrations in the upper troposphere. The El Nino-Southern Oscillation does not influence significantly the transport and deposition of BC to the Arctic. The results show that changes in atmospheric circulation due to polar atmospheric warming and reduced winter sea ice significantly impacted BC transport and deposition. The anthropogenic emission reductions applied in the last decades were, therefore, crucial to counterbalance the most likely trend of increasing BC pollution in the Arctic.

Sign in / Sign up

Export Citation Format

Share Document