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 What are the prospects for seasonal prediction of the marine environment of the North-west European Shelf?

Ocean Science ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 887-909 ◽  
Author(s):  
Jonathan Tinker ◽  
Justin Krijnen ◽  
Richard Wood ◽  
Rosa Barciela ◽  
Stephen R. Dye
Keyword(s):  
Marine Environment ◽  
Large Scale ◽  
Seasonal Forecast ◽  
The State ◽  
Seasonal Forecasts ◽  
Dynamic Downscaling ◽  
North West ◽  
Annual Variability ◽  
The North ◽  
European Shelf

Abstract. Sustainable management and utilisation of the North-west European Shelf (NWS) seas could benefit from reliable forecasts of the marine environment on monthly to seasonal timescales. Recent advances in global seasonal forecast systems and regional marine reanalyses for the NWS allow us to investigate the potential for seasonal forecasts of the state of the NWS. We identify three possible approaches to address this issue: (A) basing NWS seasonal forecasts directly on output from the Met Office's GloSea5 global seasonal forecast system; (B) developing empirical downscaling relationships between large-scale climate drivers predicted by GloSea5 and the state of the NWS; and (C) dynamically downscaling GloSea5 using a regional model. We show that the GloSea5 system can be inadequate for simulating the NWS directly (approach A). We explore empirical relationships between the winter North Atlantic Oscillation (NAO) and NWS variables estimated using a regional reanalysis (approach B). We find some statistically significant relationships and present a skillful prototype seasonal forecast for English Channel sea surface temperature. We find large-scale relationships between inter-annual variability in the boundary conditions and inter-annual variability modelled on the shelf, suggesting that dynamic downscaling may be possible (approach C). We also show that for some variables there are opposing mechanisms correlated with the NAO, for which dynamic downscaling may improve on the skill possible with empirical forecasts. We conclude that there is potential for the development of reliable seasonal forecasts for the NWS and consider the research priorities for their development.

scholarly journals Improving Meteorological Seasonal Forecasts for Hydrological Modeling in European Winter

2020 ◽  
Vol 59 (2) ◽  
pp. 317-332
Author(s):  
Nicky Stringer ◽  
Jeff Knight ◽  
Hazel Thornton
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Hydrological Modeling ◽  
Strongly Correlated ◽  
Hydrological Models ◽  
Seasonal Forecasts ◽  
The North ◽  
Ensemble Mean ◽  
The North Atlantic Oscillation ◽  
Correlation Skill

AbstractRecent advances in the skill of seasonal forecasts in the extratropics during winter mean they could offer improvements to seasonal hydrological forecasts. However, the signal-to-noise paradox, whereby the variability in the ensemble mean signal is lower than would be expected given its correlation skill, prevents their use to force hydrological models directly. We describe a postprocessing method to adjust for this problem, increasing the size of the predicted signal in the large-scale circulation. This reduces the ratio of predictable components in the North Atlantic Oscillation (NAO) from 3 to 1. We then derive a large ensemble of daily sequences of spatially gridded rainfall that are consistent with the seasonal mean NAO prediction by selecting historical observations conditioned on the adjusted NAO forecasts. Over northern and southwestern Europe, where the NAO is strongly correlated with winter mean rainfall, the variability of the predicted signal in the adjusted rainfall forecasts is consistent with the correlation skill (they have a ratio of predictable components of ~1) and are as skillful as the unadjusted forecasts. The adjusted forecasts show larger predicted deviations from climatology and can be used to better assess the risk of extreme seasonal mean precipitation as well as to force hydrological models.

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 What are the prospects for seasonal prediction of the marine environment of the Northwest European shelf?

2018 ◽  
Author(s):  
Jonathan Tinker ◽  
Justin Krijnen ◽  
Richard Wood ◽  
Rosa Barciela ◽  
Stephen R. Dye
Keyword(s):  
Marine Environment ◽  
Large Scale ◽  
Research Priorities ◽  
Seasonal Forecast ◽  
The State ◽  
Seasonal Forecasts ◽  
Dynamic Downscaling ◽  
Annual Variability ◽  
European Shelf ◽  
Northwest European Shelf

Abstract. Sustainable management and utilisation of the Northwest European Shelf Seas (NWS) could benefit from reliable forecasts of the marine environment on monthly-to-seasonal timescales. Recent advances in global seasonal forecast systems, and regional marine reanalyses for the NWS, allow us to investigate the potential for seasonal forecasts of the state of the NWS. We identify three possible approaches to address this issue: A) basing NWS seasonal forecasts directly on output from the Met Office’s GloSea5 global seasonal forecast system; B) developing empirical downscaling relationships between large-scale climate drivers predicted by GloSea5, and the state of the NWS; and C) dynamically downscaling GloSea5 using a regional model. We reject A) after showing that the GloSea5 system is inadequate for simulating the NWS directly. Turning to B), we explore empirical relationships between the winter North Atlantic Oscillation (NAO), and NWS variables estimated using a regional reanalysis. We find some statistically significant relationships, and present a skilful prototype seasonal forecast for English Channel sea surface temperature. We then consider the potential of C). We find large scale relationships between inter-annual variability in the boundary conditions and inter-annual variability modelled on the shelf, suggesting that dynamic downscaling may be possible. We also show that for some variables there are opposing mechanisms correlated to the NAO, for which dynamic downscaling may improve on the skill possible with empirical forecasts. We conclude that there is potential for the development of reliable seasonal forecasts for the NWS, and consider the research priorities for their development.

scholarly journals Seasonal Forecasts of the Twentieth Century

2020 ◽  
Vol 101 (8) ◽  
pp. E1413-E1426 ◽  
Author(s):  
Antje Weisheimer ◽  
Daniel J. Befort ◽  
Dave MacLeod ◽  
Tim Palmer ◽  
Chris O’Reilly ◽  
...  
Keyword(s):  
Twentieth Century ◽  
Large Scale ◽  
Seasonal Forecast ◽  
Forecast Skill ◽  
Seasonal Forecasts ◽  
Climate Anomalies ◽  
Global Circulation Models ◽  
Skill Scores ◽  
Physically Based ◽  
Forecast Models

Abstract Forecasts of seasonal climate anomalies using physically based global circulation models are routinely made at operational meteorological centers around the world. A crucial component of any seasonal forecast system is the set of retrospective forecasts, or hindcasts, from past years that are used to estimate skill and to calibrate the forecasts. Hindcasts are usually produced over a period of around 20–30 years. However, recent studies have demonstrated that seasonal forecast skill can undergo pronounced multidecadal variations. These results imply that relatively short hindcasts are not adequate for reliably testing seasonal forecasts and that small hindcast sample sizes can potentially lead to skill estimates that are not robust. Here we present new and unprecedented 110-year-long coupled hindcasts of the next season over the period 1901–2010. Their performance for the recent period is in good agreement with those of operational forecast models. While skill for ENSO is very high during recent decades, it is markedly reduced during the 1930s–1950s. Skill at the beginning of the twentieth century is, however, as high as for recent high-skill periods. Consistent with findings in atmosphere-only hindcasts, a midcentury drop in forecast skill is found for a range of atmospheric fields, including large-scale indices such as the NAO and the PNA patterns. As with ENSO, skill scores for these indices recover in the early twentieth century, suggesting that the midcentury drop in skill is not due to a lack of good observational data. A public dissemination platform for our hindcast data is available, and we invite the scientific community to explore them.

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.

Building a Low-Manned Production Installation: Considerations for Rotating Equipment, Electrical & Automation Systems, and Digitalization

2021 ◽  
Author(s):  
Elgonda LaGrange
Keyword(s):  
Oil And Gas ◽  
Cost Savings ◽  
Decision Makers ◽  
The North ◽  
Automation Systems ◽  
The North Sea ◽  
Rotating Equipment ◽  
Using Data ◽  
Areas Of Interest ◽  
Insight Into

Abstract Nearly all oil and gas operators and engineering companies in the offshore sector today are engaged in programs to advance concepts for low-manned and/or normally unattended production installations (NUIs). When it comes to the design of these facilities, topsides rotating equipment and electrical, instrumentation, control, and telecommunications (EICT) packages represent key areas of interest for decision-makers, owing to the significant impact they can have on required manning levels. Over the past decade, the author's company has worked closely with major Operators in the U.S. and the North Sea to look at how existing technologies can be applied in these areas to safely facilitate de-manning of both brownfields and greenfields. This paper provides insight into these efforts. It also presents projected manpower and cost savings from de-manning, using data derived from both studies and real-world projects.

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.

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