Does the ECMWF IFS Convection Parameterization with Stochastic Physics Correctly Reproduce Relationships between Convection and the Large-Scale State?

Abstract Important questions concerning parameterization of tropical convection are how should subgrid-scale variability be represented and which large-scale variables should be used in the parameterizations? Here the statistics of observational data in Darwin, Australia, are compared with those of short-term forecasts of convection made by the European Centre for Medium-Range Weather Forecasts Integrated Forecast System. The forecasts use multiplicative-noise stochastic physics (MNSP) that has led to many improvements in weather forecast skill. However, doubts have recently been raised about whether MNSP is consistent with observations of tropical convection. It is shown that the model can reproduce the variability of convection intensity for a given large-scale state, both with and without MNSP. Therefore MNSP is not inconsistent with observations, and much of the modeled variability arises from nonlinearity of the deterministic part of the convection scheme. It is also shown that the model can reproduce the lack of correlation between convection intensity and large-scale CAPE and an entraining CAPE, even though the convection parameterization assumes that deep convection is more intense when the vertical temperature profile is more unstable, with entrainment taken into account. Relationships between convection and large-scale convective inhibition and vertical velocity are also correctly captured.

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Scientific motivation for ADM/Aeolus mission

EPJ Web of Conferences ◽

10.1051/epjconf/201817602008 ◽

2018 ◽

Vol 176 ◽

pp. 02008

Author(s):

Erland Källén

Keyword(s):

Weather Forecast ◽

Weather Forecasts ◽

Weather And Climate ◽

Medium Range ◽

Forecast Models ◽

Tropical Areas ◽

Global Coverage ◽

Wind Lidar ◽

Wind Profiles

The ADM/Aeolus wind lidar mission will provide a global coverage of atmospheric wind profiles. Atmospheric wind observations are required for initiating weather forecast models and for predicting and monitoring long term climate change. Improved knowledge of the global wind field is widely recognised as fundamental to advancing the understanding and prediction of weather and climate. In particular over tropical areas there is a need for better wind data leading to improved medium range (3-10 days) weather forecasts over the whole globe.

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Four Years of Tropical ERA-40 Vorticity Maxima Tracks. Part I: Climatology and Vertical Vorticity Structure

Monthly Weather Review ◽

10.1175/2008mwr2390.1 ◽

2008 ◽

Vol 136 (11) ◽

pp. 4301-4319 ◽

Cited By ~ 22

Author(s):

Brandon Kerns ◽

Kantave Greene ◽

Edward Zipser

Keyword(s):

Large Scale ◽

Easterly Waves ◽

Weather Forecasts ◽

East Pacific ◽

Cloud Clusters ◽

Geographical Separation ◽

Medium Range ◽

Strong Gradient ◽

Upper Level ◽

Vorticity Structure

Abstract Using the 40-yr European Centre for Medium-Range Weather Forecasts Re-Analysis (ERA-40), vorticity maxima (VM) have been manually tracked and classified as developing and nondeveloping. The VM are identified on Hovmöller plots for June–October 1998–2001, within 0°–35°N, 140°–10°W. Over 600 low-level and midlevel VM are tracked. The ERA-40 VM track climatology compares favorably with previous knowledge about easterly waves. Some new results have also been found. The VM are not equivalent to easterly waves, so it is important to distinguish between the large-scale wave and the embedded VM. Unlike waves, individual VM leaving Africa generally do not survive to cross the entire Atlantic. Unlike waves, which can cross Central America, most individual east Pacific VM originate in the east Pacific. Genesis productivity is defined as the fraction of nontropical cyclone VM that eventually develop. It reaches 50% in the eastern North Pacific (EPAC) and 30% in the Atlantic, where there is geographical separation between the locations of maximum nondeveloping and pregenesis track density. There is a strong gradient in daily genesis potential (DGP) near 10°N, associated with weaker upper-level anticyclonic vorticity equatorward of 10°N. The maximum genesis productivity is obtained north of 10°N, where the upper-anticyclonic vorticity and DGP are higher. Finally, there is no obvious distinction in VM strength between developing VM prior to genesis and nondeveloping VM. A major factor is the minimum vorticity threshold for VM as opposed to cloud clusters.

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Predictability of a Mediterranean Tropical-Like Storm Downstream of the Extratropical Transition of Hurricane Helene (2006)

Monthly Weather Review ◽

10.1175/mwr-d-12-00164.1 ◽

2013 ◽

Vol 141 (6) ◽

pp. 1943-1962 ◽

Cited By ~ 13

Author(s):

Florian P. Pantillon ◽

Jean-Pierre Chaboureau ◽

Patrick J. Mascart ◽

Christine Lac

Keyword(s):

Tropical Cyclone ◽

Lead Time ◽

Large Scale ◽

Synoptic Situation ◽

British Isles ◽

Extratropical Transition ◽

Ensemble Forecasts ◽

Weather Forecasts ◽

Warm Core ◽

Medium Range

Abstract The extratropical transition (ET) of a tropical cyclone is known as a source of forecast uncertainty that can propagate far downstream. The present study focuses on the predictability of a Mediterranean tropical-like storm (Medicane) on 26 September 2006 downstream of the ET of Hurricane Helene from 22 to 25 September. While the development of the Medicane was missed in the deterministic forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) initialized before and during ET, it was contained in the ECMWF ensemble forecasts in more than 10% of the 50 members up to 108-h lead time. The 200 ensemble members initialized at 0000 UTC from 20 to 23 September were clustered into two nearly equiprobable scenarios after the synoptic situation over the Mediterranean. In the first and verifying scenario, Helene was steered northeastward by an upstream trough during ET and contributed to the building of a downstream ridge. A trough elongated farther downstream toward Italy and enabled the development of the Medicane in 9 of 102 members. In the second and nonverifying scenario, Helene turned southeastward during ET and the downstream ridge building was reduced. A large-scale low over the British Isles dominated the circulation in Europe and only 1 of 98 members forecasted the Medicane. The two scenarios resulted from a different phasing between Helene and the upstream trough. Sensitivity experiments performed with the Méso-NH model further revealed that initial perturbations targeted on Helene and the upstream trough were sufficient in forecasting the warm-core Medicane at 84- and 108-h lead time.

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Comparison between the Large-Scale Environments of Moderate and Intense Precipitating Systems in the Mediterranean Region

Monthly Weather Review ◽

10.1175/2009mwr2922.1 ◽

2009 ◽

Vol 137 (11) ◽

pp. 3933-3959 ◽

Cited By ~ 38

Author(s):

Beatriz M. Funatsu ◽

Chantal Claud ◽

Jean-Pierre Chaboureau

Keyword(s):

Mediterranean Region ◽

Large Scale ◽

Deep Convection ◽

Extreme Rainfall ◽

Convective Precipitation ◽

Target Area ◽

Weather Forecasts ◽

Microwave Sounding ◽

The Mediterranean ◽

Upper Level

Abstract A characterization of the large-scale environment associated with precipitating systems in the Mediterranean region, based mainly on NOAA-16 Advanced Microwave Sounding Unit (AMSU) observations from 2001 to 2007, is presented. Channels 5, 7, and 8 of AMSU-A are used to identify upper-level features, while a simple and tractable method, based on combinations of channels 3–5 of AMSU-B and insensitive to land–sea contrast, was used to identify precipitation. Rain occurrence is widespread over the Mediterranean in wintertime while reduced or short lived in the eastern part of the basin in summer. The location of convective precipitation shifts from mostly over land from April to August, to mostly over the sea from September to December. A composite analysis depicting large-scale conditions, for cases of either rain alone or extensive areas of deep convection, is performed for selected locations where the occurrence of intense rainfall was found to be important. In both cases, an upper-level trough is seen to the west of the target area, but for extreme rainfall the trough is narrower and has larger amplitude in all seasons. In general, these troughs are also deeper for extreme rainfall. Based on the European Centre for Medium-Range Weather Forecasts operational analyses, it was found that sea surface temperature anomalies composites for extreme rainfall are often about 1 K warmer, compared to nonconvective precipitation conditions, in the vicinity of the affected area, and the wind speed at 850 hPa is also stronger and usually coming from the sea.

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Upscale Error Growth in a High-Resolution Simulation of a Summertime Weather Event over Europe*

Monthly Weather Review ◽

10.1175/mwr-d-14-00140.1 ◽

2015 ◽

Vol 143 (3) ◽

pp. 813-827 ◽

Cited By ~ 52

Author(s):

Tobias Selz ◽

George C. Craig

Keyword(s):

Large Scale ◽

Slow Growth ◽

Deep Convection ◽

Baroclinic Instability ◽

Weather Forecast ◽

Initial Growth ◽

Error Growth ◽

Geostrophic Adjustment ◽

Large Growth ◽

Conditional Instability

Abstract The growth of small-amplitude, spatially uncorrelated perturbations has been studied in a weather forecast of a 4-day period in the summer of 2007, using a large domain covering Europe and the eastern Atlantic and with explicitly resolved deep convection. The error growth follows the three-stage conceptual model of Zhang et al., with rapid initial growth (e-folding time about 0.5 h) on all scales, relaxing over about 20 h to a slow growth of the large-scale perturbations (e-folding time 12 h). The initial growth was confined to precipitating regions, with a faster growth rate where conditional instability was large. Growth in these regions saturated within 3–10 h, continuing for the longest where the precipitation rate was large. While the initial growth was mainly in the divergent part of the flow, the eventual slow growth on large scales was more in the rotational component. Spectral decomposition of the disturbance energy showed that the rapid growth in precipitating regions projected onto all Fourier components; however, the amplitude at saturation was too small to initiate the subsequent large-scale growth. Visualization of the disturbance energy showed it to expand outward from the precipitating regions at a speed corresponding to a deep tropospheric gravity wave. These results suggest a physical picture of error growth with a rapidly growing disturbance to the vertical mass transport in precipitating regions that spreads to the radius of deformation while undergoing geostrophic adjustment, eventually creating a balanced perturbation that continues to grow through baroclinic instability.

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One million feet view of Level-2 Processing Facility managed at European Centre for Medium-Range Weather Forecasts (ECMWF)

10.5194/egusphere-egu2020-2391 ◽

2020 ◽

Author(s):

Rakesh Prithiviraj

Keyword(s):

Wind Profile ◽

European Space Agency ◽

Weather Forecast ◽

System Perspective ◽

Weather Forecasts ◽

European Centre ◽

Ground Segment ◽

Processing Facility ◽

Medium Range ◽

Level 2

Title: One million feet view of Level-2 Processing Facility managed at European Centre for Medium-Range Weather Forecasts (ECMWF)Authors: Rakesh Prithiviraj, Ioannis Mallas, Cristiano Zanna&#160;Affiliation of authors: European Centre for Medium-Range Weather Forecasts (ECMWF)Abstract text Launched in August 2018, European Space Agency&#8217;s Aeolus satellite mission measures Earth's wind profile from space. The Aeolus ground segment mainly comprises of: &#8226; Flight Operations Segment (FOS) to monitor and control Aeolus satellite and the instrument onboard,&#160; &#8226; Payload Data Ground Segment (PDGS) for the acquisition and systematic generation of Level-1A and Level-1B products and&#160; &#8226; Level-2 Processing Facility (L2PF) at ECMWF for the generation and dissemination of Level-2B and Level-2C products.&#160;ECMWF is both a research institute and a 24/7 operational service, producing global numerical weather predictions and other data for our Member and Co-operating States and the broader community. ECMWF relies on its atmospheric model and data assimilation system which is called the Integrated Forecasting System (IFS) to make weather predictions. ECMWF has one of the largest supercomputer facilities and meteorological data archives in the world.This talk focusses on the Aeolus L2PF facility at ECMWF providing an overview of the processing infrastructure, relevant dataflows, monitoring system and presents the technical/system perspective of Aeolus L2PF in the context of weather forecast. The L2PF facility receives L1B data from Aeolus PDGS and systematically generates and disseminates L2B products and L2C products. The centre is also responsible for the generation of meteorological auxiliary data which is one of the critical inputs for the L2B generation. &#160;The talk also shows various components at ECMWF that work together to achieve more than 99% L2B completeness. The components include ECMWF Production Data Store (ECPDS), ECMWF's High Performance Computing Facility (HPCF) and L2PF cluster.&#160;The talk concludes with references to tests carried out at ECMWF that have demonstrated that new wind profile observations from Aeolus satellite significantly improve weather forecasts, particularly in the southern hemisphere and the tropics. Because the positive impact of Aeolus on the weather predictions, Aeolus data is expected to be part of the operational weather forecast system at ECMWF in January 2020.

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Stochastic and Perturbed Parameter Representations of Model Uncertainty in Convection Parameterization*

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-14-0250.1 ◽

2015 ◽

Vol 72 (6) ◽

pp. 2525-2544 ◽

Cited By ~ 37

Author(s):

H. M. Christensen ◽

I. M. Moroz ◽

T. N. Palmer

Keyword(s):

Model Uncertainty ◽

Ensemble Prediction ◽

Uncertain Parameters ◽

Convection Scheme ◽

Weather Forecasts ◽

Probabilistic Forecasts ◽

Medium Range ◽

Estimation System ◽

Convection Parameterization ◽

Parameter Scheme

Abstract It is now acknowledged that representing model uncertainty in atmospheric simulators is essential for the production of reliable probabilistic forecasts, and a number of different techniques have been proposed for this purpose. This paper presents new perturbed parameter schemes for use in the European Centre for Medium-Range Weather Forecasts (ECMWF) convection scheme. Two types of scheme are developed and implemented. Both schemes represent the joint uncertainty in four of the parameters in the convection parameterization scheme, which was estimated using the Ensemble Prediction and Parameter Estimation System (EPPES). The first scheme developed is a fixed perturbed parameter scheme, where the values of uncertain parameters are varied between ensemble members, but held constant over the duration of the forecast. The second is a stochastically varying perturbed parameter scheme. The performance of these schemes was compared to the ECMWF operational stochastic scheme, stochastically perturbed parameterization tendencies (SPPT), and to a model that does not represent uncertainty in convection. The skill of probabilistic forecasts made using the different models was evaluated. While the perturbed parameter schemes improve on the stochastic parameterization in some regards, the SPPT scheme outperforms the perturbed parameter approaches when considering forecast variables that are particularly sensitive to convection. Overall, SPPT schemes are the most skillful representations of model uncertainty owing to convection parameterization.

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An update on global atmospheric ice estimates from satellite observations and reanalyses

10.5194/acp-2018-275 ◽

2018 ◽

Cited By ~ 1

Author(s):

David Ian Duncan ◽

Patrick Eriksson

Keyword(s):

General Circulation ◽

Large Scale ◽

Principal Component ◽

Diurnal Variability ◽

Weather Forecasts ◽

Earth Observing System ◽

Current State ◽

Medium Range ◽

Ice Water ◽

Modern Era

Abstract. This study assesses the global distribution of mean atmospheric ice mass from current state-of-the-art estimates and its variability on daily and seasonal timescales. Ice water path (IWP) retrievals from active and passive satellite platforms are compared and analysed against estimates from two reanalysis datasets, ERA5 (European Centre for Medium-range Weather Forecasts Reanalysis 5) and MERRA-2 (Modern-era Retrospective Reanalysis for Research and Applications 2). Large discrepancies in IWP exist between the satellite datasets themselves, making validation of the model results problematic and indicating that progress towards consensus on the distribution of atmospheric ice has been limited. Comparing the datasets, zonal means of IWP exhibit similar shapes but differing magnitudes. Diurnal analysis centred on A-Train overpasses shows homologous structures in some regions, but the degree and sign of the variability varies widely; the reanalyses exhibit noisier and higher amplitude diurnal variability than borne out by the satellite estimates. Spatial structures governed by the atmospheric general circulation are fairly consistent across the datasets, as principal component analysis shows that the patterns of seasonal variability line up well between the datasets but disagree in severity. These results underscore the limitations of the current Earth observing system with respect to atmospheric ice, as the level of consensus between observations is mixed. The large-scale variability of IWP is relatively consistent, whereas disagreements on diurnal variability and global means point to varying microphysical assumptions in retrievals and models alike that seem to underlie the biggest differences.

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How much snow falls in the world's mountains? A first look at mountain snowfall estimates in A-train observations and reanalyses

The Cryosphere ◽

10.5194/tc-14-3195-2020 ◽

2020 ◽

Vol 14 (9) ◽

pp. 3195-3207

Author(s):

Anne Sophie Daloz ◽

Marian Mateling ◽

Tristan L'Ecuyer ◽

Mark Kulie ◽

Norm B. Wood ◽

...

Keyword(s):

Large Scale ◽

Critical Factor ◽

Weather Forecasts ◽

Cloud Radar ◽

Regional Trends ◽

Medium Range ◽

America South ◽

Alpine Environments ◽

Modern Era ◽

Factor Governing

Abstract. CloudSat estimates that 1773 km3 of snow falls, on average, each year over the world's mountains. This amounts to 5 % of the global snowfall accumulations. This study synthetizes mountain snowfall estimates over the four continents containing mountains (Eurasia, North America, South America and Africa), comparing snowfall estimates from a new satellite cloud-radar-based dataset to those from four widely used reanalyses: Modern-Era Retrospective analysis for Research and Applications (MERRA), MERRA-2, Japanese 55-year Reanalysis (JRA-55), and European Center for Medium-Range Weather Forecasts Re-Analysis (ERA-Interim). Globally, the fraction of snow that falls in the world's mountains is very similar between all these independent datasets (4 %–5 %), providing confidence in this estimate. The fraction of snow that falls in the mountains compared to the continent as a whole is also very similar between the different datasets. However, the total of snow that falls globally and over each continent – the critical factor governing freshwater availability in these regions – varies widely between datasets. The consensus in fractions and the dissimilarities in magnitude could indicate that large-scale forcings may be similar in the five datasets, while local orographic enhancements at smaller scales may not be captured. This may have significant implications for our ability to diagnose regional trends in snowfall and its impacts on snowpack in rapidly evolving alpine environments.

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Downscaling Dinâmico sobre o Nordeste do Brasil Utilizando um Modelo Climático Regional: Impacto de Diferentes Parametrizações na Precipitação Simulada (Dynamic Downscaling over Northeast Brazil Using a Regional Climate Model: Impact of Different ...)

Revista Brasileira de Geografia Física ◽

10.26848/rbgf.v6i4.233091 ◽

2013 ◽

Vol 6 (4) ◽

pp. 995 ◽

Cited By ~ 1

Author(s):

Vanessa De Almeida Dantas ◽

Ana Cleide Bezerra Amorim ◽

Micejane Da Silva Costa ◽

Cláudio Moisés Santos e Silva

Keyword(s):

Large Scale ◽

Tropical Rainfall Measuring Mission ◽

Rainfall Simulation ◽

Cumulus Parameterization ◽

Scale Model ◽

Dynamic Downscaling ◽

Tropical Rainfall ◽

Weather Forecasts ◽

European Centre ◽

Medium Range

Estudos utilizando modelos regionais na realização de downscaling dinâmico tem se mostrado adequado para reproduzir a escala local de uma região. Neste sentido, o presente estudo teve como objetivo analisar a sensibilidade de simulação da precipitação para o ano de 2009 na região do Nordeste Brasileiro (NEB) utilizando três esquemas de parametrização cumulus disponíveis no modelo RegCM4, a saber: Anthes Kuo (Kuo), Grell com fechamento Fristish Chappell (GFC) e MIT-Emmanuel (EM). Como condição inicial e de contorno de grande escala foram usadas informações do modelo European Centre for Medium-Range Weather Forecasts (ECMWF), especificamente o produto ERA_interim. Dados do projeto Tropical Rainfall Measuring Mission (TRMM) foram usados para a avaliação da precipitação simulada. Testes e parâmetros estatísticos foram usados como métrica na avaliação das simulações. Verificou-se que o modelo consegue representar de forma adequada a precipitação quando comparada aos dados do TRMM. Os experimentos que mais se aproximaram das observações foram GFC e EM. O RegCM4 subestimou a precipitação no NEB no início de março e superestimando em meados de julho. Entretanto, é possível afirmar que o modelo é capaz de reproduzir bem a variabilidade do clima, na região do NEB, após alguns ajustes utilizando diferentes tipos parametrizações para os trópicos. ABSTRACT Studies using regional models in performing dynamic downscaling have been adequate to reproduce the local scale of a region. In this sense, the present study aimed to analyze the sensitivity of rainfall simulation for the year 2009 in the Brazilian Northeast (NEB) using three cumulus parameterization schemes available in RegCM4 model, namely: Anthes Kuo (Kuo) Grell closure Fristish Chappell (GFC), and MIT-Emmanuel (EM). As a condition of initial and boundary large scale model information were used European Centre for Medium-Range Weather Forecasts (ECMWF), specifically the product ERA_interim. Project data Tropical Rainfall Measuring Mission (TRMM) were used for the evaluation of simulated rainfall. Testing and statistical parameters were used as a metric in evaluating simulations. It was found that the model can adequately represent the precipitation compared with data from TRMM. The experiments that came closer to the observations were GFC and EM. The RegCM4 underestimated precipitation in the NEB in early March and overestimating in mid-July. However, we can say that the model is able to reproduce well the climate variability in the region of the NEB, after some adjustments using different parameterizations for the tropics. Keywords: RegCM4, Kuo, Grell, Emanuel

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