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  • Wiley  (30)
  • Physics  (30)
  • 1
    Online Resource
    Online Resource
    The ECMWF model climate: recent progress through improved physical parametrizations
    Wiley ; 2010
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 136, No. 650 ( 2010-07), p. 1145-1160
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 136, No. 650 ( 2010-07), p. 1145-1160
    Abstract: The progress achieved since 2005 in simulating today's climate with the European Centre for Medium‐Range Weather Forecasts (ECMWF) model through improved physical parametrizations is described. Results are based on climate integrations at an intermediate horizontal resolution (T L 159) using major model versions employed operationally at ECMWF since June 2005. Recent improvements to the physical parametrization package are shown to substantially reduce long‐standing systematic model deficiencies in the tropical precipitation, convectively coupled tropical waves, and circulation features in the Northern Hemisphere Extratropics including synoptic‐scale variability and Euro‐Atlantic blocking. The climate integrations are augmented by a set of monthly forecast experiments. By considering the atmospheric response in a seamless sense, i.e. from time‐scales of hours to many months, an attempt is made to understand the impact of changes to the convection and radiation schemes. Overall, the largest and mostly beneficial impact results from the introduction of a major revision to the convection scheme made in November 2007. This is true for systematic errors in the Tropics and Extratropics over a wide range of time‐scales as well as for the short‐range and medium‐range deterministic forecast skill over the Northern Hemisphere. Copyright © 2010 Royal Meteorological Society
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v136:650
    DOI: 10.1002/qj.634
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2010
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 2
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    Online Resource
    On the use of a predictor–corrector scheme to couple the dynamics with the physical parametrizations in the ECMWF model
    Wiley ; 2003
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 129, No. 589 ( 2003-01), p. 1217-1236
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 129, No. 589 ( 2003-01), p. 1217-1236
    Abstract: Methods of coupling the time integration of the resolved dynamics with the parametrized processes in atmospheric models are an active development area. Many centres have demonstrated strong sensitivity to variations in the methods of coupling in their models. The European Centre for Medium‐Range Weather Forecasts has recently introduced a revised method of coupling which gives significant forecast benefits. Theoretically, optimal methods are difficult to establish because of the mixture of timescales represented within the parametrizations. Implicit methods are well‐suited to achieving coupling between different processes, but are not practical because of the nonlinear switching present in most parametrization schemes. In this paper we show that a predictor–corrector scheme can give some of the advantages of a fully‐implicit scheme. We show that the use of more than one physics evaluation per time step significantly improves the accuracy in a model problem. We also demonstrate the effect of further iterations which, in principle, would converge towards a fully‐implicit scheme. A second iteration has only a small effect on overall performance, but gives a large reduction in the amount of convection. This indicates that the current formulation of convection is not compatible with this type of integration scheme. Copyright © 2003 Royal Meteorological Society
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Article
    DOI: 10.1256/qj.02.12
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2003
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 3
    Online Resource
    Online Resource
    Numerical prediction of tropical cyclogenesis. Part II: Identification of large‐scale physical processes under the monsoon shear line synoptic pattern
    Wiley ; 2022
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 148, No. 745 ( 2022-04), p. 1965-1982
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 148, No. 745 ( 2022-04), p. 1965-1982
    Abstract: This is the second part of a two‐part study to investigate the numerical prediction of tropical cyclogenesis. Part I presents a comprehensive statistical assessment of the performance of the high‐resolution European Centre for Medium‐Range Weather Forecasts deterministic forecasts in predicting tropical cyclone (TC) genesis over the western North Pacific between 2007 and 2018 using The International Grand Global Ensemble data. Among these forecasts, the ones that predict TC genesis occurring in the monsoon shear line synoptic pattern have the highest 5‐day predicted skill. In this article (Part II), the large‐scale dynamic and thermodynamic variables associated with this type of genesis are examined to identify the physical processes likely responsible for TC genesis. Moist convection appears to be one of the first important factors. Deep convection at the initial time (Day −5) is concentrated near the inner core of the pre‐genesis vortex. In the lower troposphere, the northeasterly flow to the north and southwesterly flow to the south of the pre‐genesis vortex begin to strengthen at Day −4 and Day −3 respectively, and then the maximum wind centres move close to the genesis position (GP) from Day −3 to Day 0. Strong low‐level radial wind and the associated absolute angular momentum (AAM) import develop on Day −4, which effectively forces a transverse circulation and spins up a surface vortex near the GP. The vertical gradients of latent heat release and the decrease in mean‐sea‐level pressure by Day −3 further support the import of low‐level AAM and the development of the low‐level vortex. At the upper levels, an anticyclone moves close to the GP, reducing the vertical wind shear at Day −2, fully establishing the secondary circulation system. The positive feedback between the environmental flow and the internal thermal forcing conditions from Day −2 to the genesis time are also important to genesis.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v148.745
    DOI: 10.1002/qj.4288
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2022
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 4
    Online Resource
    Online Resource
    Underlying physical mechanisms of winter precipitation extremes over India's high mountain region
    Wiley ; 2024
    In:  Quarterly Journal of the Royal Meteorological Society
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley
    Abstract: Extreme precipitation events (EPEs) are among the most pervasive weather hazards in the western Himalayan region (WHR), posing widespread damage to life, infrastructure, and agriculture. This study investigates the synoptic and large‐scale characteristics linked to winter precipitation extremes over the WHR. EPEs are identified as events surpassing the 95 th percentile threshold. A composite analysis is employed using two reanalyses—the fifth‐generation European Centre for Medium‐Range Weather Forecasts Reanalysis (ERA5) and the Indian Monsoon Data Assimilation and Analysis (IMDAA)—to elucidate the synoptic conditions conducive to EPEs. Our findings suggest that EPEs in the WHR are linked to an intensified subtropical westerly jet, characteristically shifted to south than normal. Enhanced kinetic energy in the upper troposphere, attributed to increased baroclinic instability, reinforces moisture convergence and strengthens synoptic‐scale circulation, triggering deep convection and supporting EPEs. Notably, the interplay of pronounced Rossby waves sinking over the WHR and regional orography significantly modulates the intensity of western disturbances (WDs). Employing clustering analysis, we observed that the strongest EPEs are linked to anomalous vorticity in the upper to middle troposphere, together with deep convection via strengthened WDs, suggesting the potential role of large‐scale influences. Using Lagrangian method, we identify that the Arabian Sea is the primary moisture source for EPEs in the WHR. We further delved into the role of large‐scale connections and EPEs through quasi‐resonant amplification (QRA) analysis. The findings unveil distinct QRA fingerprints in meridional temperature gradients along with notably magnified, quasi‐stationary midlatitude planetary waves characterized by zonal wave numbers 6/7/8 (baroclinic waves) contributing to EPEs. Overall, our results highlight the underlying physical mechanisms for winter precipitation extremes, emphasizing QRA's role in amplifying planetary waves and promoting EPEs, underscoring the WHR's vulnerability to evolving climatic conditions.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Article
    DOI: 10.1002/qj.4661
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2024
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 5
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    Towards a high‐resolution regional reanalysis for the European CORDEX domain
    Wiley ; 2015
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 141, No. 686 ( 2015-01), p. 1-15
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 141, No. 686 ( 2015-01), p. 1-15
    Abstract: Atmospheric reanalyses covering the European region are mainly available as part of relatively coarse global reanalyses. The aim of this article is to present the development and evaluation of a next generation regional reanalysis for the European CORDEX EUR‐11 domain with a horizontal grid spacing of approximately 6 km. In this context, a reanalysis is understood to be an assimilation of heterogeneous observations with a physical model such as a numerical weather prediction (NWP) model. The reanalysis system presented here is based on the NWP model COSMO by the German Meteorological Service (Deutscher Wetterdienst) using a continuous nudging scheme. In order to assess the added value of data assimilation, a dynamical downscaling experiment has been conducted, i.e. an identical model set‐up but without data assimilation. Both systems have been evaluated for a 1 year test period, employing standard measures such as analysis increments, biases, or log‐odds ratios, as well as tests for distributional characteristics. An important aspect is the evaluation from different perspectives and with independent measurements such as satellite infrared brightness temperatures using forward operators, integrated water vapour from GPS stations, and ceilometer cloud cover. It can be shown that the reanalysis better resolves local extreme events; this is basically an effect of the higher spatio‐temporal resolution, as known from dynamical downscaling approaches. However, an important criterion for regional reanalyses is the coherence with independent observations of high temporal and spatial resolution, resulting in significant improvement over dynamical downscaling. The system is intended to become operational within a year, continuously reprocessing and evaluating longer time periods. The reanalysis data are planned to become available to the research community within a year.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.2015.141.issue-686
    DOI: 10.1002/qj.2486
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 6
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    Online Resource
    Validating and improving the uncertainty assumptions for the assimilation of ocean‐colour‐derived chlorophyll a into a marine biogeochemistry model of the Northwest European Shelf Seas
    Wiley ; 2023
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 149, No. 750 ( 2023-01), p. 300-324
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 149, No. 750 ( 2023-01), p. 300-324
    Abstract: The correct specification of all sources of uncertainty is critical to the success of data assimilation (DA) in improving the realism and accuracy of forecasts and reanalyses. This work focuses on improving the uncertainty assumptions made during the assimilation of ocean‐colour‐derived chlorophyll into an operational marine coupled physical–biogeochemical DA system, which produces daily biogeochemistry forecasts on the Northwest European Shelf Seas. Analysis of the observation–model misfits shows significant biases in chlorophyll , which vary strongly with season. The behaviour of these misfits agrees well with previous studies and can be attributed to systematic errors within the coupled model. Diagnostic metrics, used frequently within numerical weather prediction, are applied to separate out the random component of the observation and model errors, allowing for the derivation of new error covariance matrices. These new error covariance matrices are then modified to account for the biases in the model that cannot be treated explicitly within the operational DA system. This has the effect of inflating both the error variances and the correlation length‐scales. Experiments show that the new error covariances can result in significant improvements in the accuracy of the analysis and forecast. In particular, the new error covariance matrices reduce the bias in the spring phytoplankton bloom present when using the previous error covariances. Validation against independent glider observations in the North Sea also shows reductions in bias in chlorophyll and oxygen that extend below the surface to the depth of the mixed layer. Accounting for the biases in the model in the error correlations can lead to much larger improvements than not accounting for them; however, there are also regions where large degradations are seen that may indicate model instabilities. This may be improved by estimating the bias separately for the different regions on the shelf.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v149.750
    DOI: 10.1002/qj.4408
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 7
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    Online Resource
    The influence of aggregation and statistical post‐processing on the subseasonal predictability of European temperatures
    Wiley ; 2020
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 146, No. 731 ( 2020-07), p. 2654-2670
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 146, No. 731 ( 2020-07), p. 2654-2670
    Abstract: The succession of European surface weather patterns has limited predictability because disturbances quickly transfer to the large‐scale flow. Some aggregated statistics, however, such as the average temperature exceeding a threshold, can have extended predictability when adequate spatial scales, temporal scales and thresholds are chosen. This study benchmarks how the forecast skill horizon of probabilistic 2‐m temperature forecasts from the subseasonal forecast system of the European Centre for Medium‐Range Weather Forecasts (ECMWF) evolves with varying scales and thresholds. We apply temporal aggregation by rolling‐window averaging and spatial aggregation by hierarchical clustering. We verify 20 years of re‐forecasts against the E‐OBS dataset and find that European predictability extends at maximum into the fourth week. Simple aggregation and standard statistical post‐processing extend the forecast skill horizon with two and three skilful days on average, respectively. The intuitive notion that higher levels of aggregation capture large‐scale and low‐frequency variability and can therefore tap into extended predictability holds in many cases. However, we show that the effect can be saturated and that there exist regional optimums beyond which extra aggregation reduces the forecast skill horizon. We expect such windows of predictability to result from specific physical mechanisms that only modulate and extend predictability locally. To optimize subseasonal forecasts for Europe, aggregation should thus be limited in certain cases.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v146.731
    DOI: 10.1002/qj.3810
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2020
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
    SSG: 14
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  • 8
    Online Resource
    Online Resource
    Subseasonal predictability of onset, duration, and intensity of European heat extremes
    Wiley ; 2023
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 149, No. 750 ( 2023-01), p. 84-101
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 149, No. 750 ( 2023-01), p. 84-101
    Abstract: Successful weather forecasts on subseasonal time‐scales can support societal preparedness and mitigate the impacts of extreme events. Heatwaves in particular can, in certain cases, be predicted on time‐scales of several weeks in advance. Heatwave predictability is commonly assessed in terms of heatwave intensity. In addition to heatwave intensity, we assess the predictability of heatwave onset and duration, which are crucial components of early‐warning systems and emergency preparedness plans. The forecast skill of heatwaves is investigated over the European region in the subseasonal forecasting system of the European Centre for Medium‐Range Weather Forecasts (ECMWF). The heatwaves are first detected in ERA‐Interim reanalysis data over the period 1998–2017 and then allocated into six clusters in the following regions: Black Sea (BSea), Russia (Ru), Western Europe (WEu), North Sea (NSea), Scandinavia (Sc), and Eastern Europe (EEu). The European regions with the highest predictability in heatwave onset and duration are the clusters Ru, Sc, and NSea. The WEu cluster has the lowest bias in heatwave intensity and is found to be the most predictable region in terms of the number of heatwave events with predictable intensity at lead week 2. Heatwave intensity is generally found to be the most predictable characteristic of European heatwaves, being predictable by the model ensemble mean up to lead times of 3 weeks. Furthermore, this analysis identifies the most predictable heatwaves, allowing for a further investigation of the physical mechanisms and heatwave characteristics leading to enhanced heatwave forecast skill over different European regions.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v149.750
    DOI: 10.1002/qj.4394
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2023
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 9
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    The essential ingredients leading to the explosive growth stage of the European wind storm Lothar of Christmas 1999
    Wiley ; 2010
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 136, No. 648 ( 2010-04), p. 638-652
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 136, No. 648 ( 2010-04), p. 638-652
    Abstract: Key dynamical ingredients leading to the explosive growth stage of the extratropical wind storm Lothar (24–26 December 1999) are identified by performing numerical sensitivity experiments using the Météo‐France operational model. This stage suddenly occurred when the surface cyclone crossed the upper‐level jet in its exit region. The model is shown to capture quite well the whole process by starting the forecast 12 h before the start of the explosive growth stage. A first set of experiments consists of revisiting the role of humidity and other physical processes. A run suppressing latent heating does not exhibit any cyclone growth, similar to a previous study by other authors. However, a frictionless dry adiabatic run, i.e. when latent heating processes and dissipation terms are both suppressed, is shown to reproduce the timing and the location of the rapid intensification stage but not its intensity (which is overestimated). Moist processes are thus crucial because they compensate for the dissipation terms, but the vertical coupling between the surface cyclone and the upper‐level jet can be reproduced and interpreted in terms of frictionless dry adiabatic interactions, at least for conceptual purposes. All the other numerical experiments have the full physics of the model and only differ in their initial conditions. The modification of the flow is performed using a recently developed potential vorticity inversion method. Upper‐level high‐frequency anomalies are shown to have only a moderate impact on the rapid deepening of the surface cyclone. Other experiments are conducted to look at the sensitivity to the strength of the upper‐level jet, to the intensity of the low‐level baroclinicity, to the location of the jet exit and finally to the shape, amplitude and location of the low‐level cyclone. The location of the explosive growth stage depends primarily on the position of the low‐frequency jet exit while its intensity and even its existence is strongly sensitive to the low‐level background baroclinicity and to the properties of the incipient surface cyclone itself. Copyright © 2010 Royal Meteorological Society
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v136:648
    DOI: 10.1002/qj.585
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2010
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
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  • 10
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    Online Resource
    Revision of the Stochastically Perturbed Parametrisations model uncertainty scheme in the Integrated Forecasting System
    Wiley ; 2021
    In:  Quarterly Journal of the Royal Meteorological Society Vol. 147, No. 735 ( 2021-01), p. 1364-1381
    Details
    In: Quarterly Journal of the Royal Meteorological Society, Wiley, Vol. 147, No. 735 ( 2021-01), p. 1364-1381
    Abstract: The Stochastically Perturbed Parametrisations scheme (SPP) represents model uncertainty in numerical weather prediction by introducing stochastic perturbations into the physical parametrisation schemes. The perturbations are constructed in such a way that the internal consistency of the physical parametrisation schemes is preserved. We developed a revised version of SPP for the Integrated Forecasting System of the European Centre for Medium‐Range Weather Forecasts (ECMWF). The revised version introduces perturbations to additional quantities and modifies the probability distributions sampled by the scheme. Medium‐range ensemble forecasts with the revised SPP are considerably more skilful than ensemble forecasts with the original implementation of SPP. The revised version of SPP is similar, in terms of forecast skill, to the Stochastically Perturbed Parametrisation Tendency scheme (SPPT), which is currently used to represent model uncertainty in the operational ECMWF ensemble forecasts.
    Type of Medium: Online Resource
    ISSN: 0035-9009 , 1477-870X
    URL: Issue
    URL: Article
    DOI: 10.1002/qj.v147.735
    DOI: 10.1002/qj.3978
    RVK:
    UA 1000
    RVK:
    UA 7650
    Language: English
    Publisher: Wiley
    Publication Date: 2021
    detail.hit.zdb_id: 3142-2
    detail.hit.zdb_id: 2089168-4
    SSG: 14
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