Improvement of seasonal forecast correction by using weather regimes

In order to develop seasonal forecast applications, raw forecast data generally need to be corrected to remove their systematic errors and drifts in time. In the climate community, methods based on quantile mapping techniques are quite common for their easy implementation. In the framework of the SECLI-FIRM project, we have tested a refinement of quantile mapping by conditioning the correction to weather regimes, in order to take large-scale circulation into account. For that purpose, we have used ADAMONT, a tool originally developed by M&#233;t&#233;o-France to correct climate projection scenarios. It was applied on four C3S seasonal forecast models over Europe, using ERA5 as a reference. Three parameters were treated at daily time-step: 2-metre temperature, precipitation and 10-metre wind-speed.One of the main objectives of this study was to better understand the role weather regimes can play, if/when/where/for which parameter we gain in quality and predictability. For instance, a series of experiments were conducted on an idealized case of &#8220;perfect forecasts&#8221; of weather regimes, to point out the maximum benefits we could expect from the method.Another focus of research was to test some strategies to optimize the positive impact of the introduction of weather regimes, by selecting members in one model ensemble or by using a multi-model approach. The selection was based on a sub-sampling of the best members in terms of weather regime frequency forecast, in order to determine the needed precision of weather regime forecast, for it to be useful in the correction.We will present the main results of this work and some operational perspectives.

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Seasonal Forecasts of the Twentieth Century

Bulletin of the American Meteorological Society ◽

10.1175/bams-d-19-0019.1 ◽

2020 ◽

Vol 101 (8) ◽

pp. E1413-E1426 ◽

Cited By ~ 2

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.

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The impact of ENSO and the Atlantic Multidecadal Variability (AMV) on the upper tropospheric large scale flow in the PRIMAVERA models.

10.5194/egusphere-egu2020-18113 ◽

2020 ◽

Author(s):

Paolo Ghinassi ◽

Federico Fabiano ◽

Virna L. Meccia ◽

Susanna Corti

Keyword(s):

Rossby Wave ◽

Large Scale ◽

Rossby Waves ◽

Wave Activity ◽

Transient Wave ◽

Weather Regime ◽

Weather Regimes ◽

The Pacific ◽

Large Scale Flow ◽

The Impact

Rossby waves play a fundamental role for both climate and weather. They are in fact associated with heat, momentum and moisture transport across large distances and with different types of weather at the surface. Assessing how they are represented in climate models is thus of primary importance to understand both predictability and the present and future climate. In this study we investigate how ENSO and the AMV affect the large scale flow pattern in the upper troposphere of the Northern Hemisphere, using reanalysis data and data from the PRIMAVERA simulations.The upper tropospheric large scale flow is investigated in terms of the Rossby wave activity associated with persistent and recurrent patterns over the Pacific-North American and Euro-Atlantic regions during winter, the so called weather regimes. In order to quantify the vigour of Rossby wave activity associated with each weather regime we make use of a recently developed diagnostic based on Finite Amplitude Local Wave Activity in isentropic coordinates, partitioning the total wave activity into the stationary and transient components. The former is associated with quasi-stationary, planetary Rossby waves, whereas the latter is associated with synoptic scale Rossby wave packets. This allows one to quantify the contribution from stationary versus transient eddies in the total Rossby wave activity linked to each weather regime.In this study we explore how ENSO and the AMV affect both the weather regimes frequencies and the upper tropospheric waviness in the Pacific and Atlantic storm tracks, respectively. Furthermore we analyse how both the stationary and transient wave activity component modulate the onset and transition between different regimes.

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Rossby wave activity associated with Euro-Atlantic weather regimes in the PRIMAVERA historical runs.

10.5194/egusphere-egu21-9605 ◽

2021 ◽

Author(s):

Paolo Ghinassi ◽

Federico Fabiano ◽

Susanna Corti

Keyword(s):

Spatial Distribution ◽

High Resolution ◽

Rossby Wave ◽

Large Scale ◽

Wave Activity ◽

Large Scale Circulation ◽

Temporal Behaviour ◽

Weather Regime ◽

Weather Regimes ◽

Isentropic Coordinates

In this study we aim to assess how the upper tropospheric Rossby wave activity is represented in the PRIMAVERA models. The low and high resolution historical coupled simulations will be compared with ERA5 reanalysis (spanning the 1979-2014 period) to enlighten model deficiencies in representing the spatial distribution and temporal evolution of Rossby wave activity and to emphasize the benefits of increased resolution. Our analysis focuses on the wintertime large scale circulation over the Euro-Atlantic sector. A diagnostic based on Local Wave Activity (LWA) in isentropic coordinates is used to identify Rossby waves and to quantify their amplitude. LWA is partitioned into its stationary and transient components, to distinguish the contribution from planetary versus synoptic scale waves (i.e. wave packets). This diagnostic is then combined with another one to identify persistent and recurrent large scale circulation patterns, the so called weather regimes. Weather regimes in the Euro-Atlantic sector are identified with the usual approach of EOF decomposition and k-mean clustering applied to daily anomalies of Montgomery streamfunction, in order to have a consistent framework with LWA (which is defined in isentropic coordinates). A composite of transient LWA is realised for each weather regime to obtain the spatial distribution of Rossby wave activity associated with each weather regime.Results show a marked intermodel variability in the ability of reproducing the correct (i.e. the one observed in reanalysis data) LWA distribution. Many of the models in fact fails to reproduce the localized (in space) maxima of LWA associated with each weather regime and to distribute LWA over a larger region compared to reanalysis. High resolution helps to correct this bias in the majority of the models, in particular in those where the low-resolution LWA distribution was already close to reanalysis. Finally, the temporal behaviour of the spatially averaged LWA in the examined period is discussed.

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Tropical Cyclones in European Seasonal Forecast Models

10.5194/egusphere-egu2020-2552 ◽

2020 ◽

Author(s):

Kevin Hodges ◽

Daniel Befort ◽

Antje Weisheimer

Keyword(s):

Tropical Cyclones ◽

North Atlantic ◽

North Pacific ◽

Western North Pacific ◽

Large Scale ◽

Seasonal Forecast ◽

The North ◽

Forecast Models ◽

The North Atlantic ◽

Stochastic Physics

This study assesses the representation of Tropical Cyclones (TC) in an ensemble of seasonal forecast models from five different centres (ECMWF, UK Met Office, DWD, CMCC, M&#233;t&#233;o-France). Northern Hemispheric Tropical Cyclones are identified using a widely applied objective Tropical Cyclone tracking algorithm based on relative vorticity fields. Analyses for three different aspects are carried out: 1) assessment of the skill of the ensemble to predict&#160; the TC frequencies over different ocean basins, 2) analyse the dependency between the model's ability to represent TCs and large-scale biases and 3) assess the impact of stochastic physics and horizontal resolution on TC frequency.For the July to October season all seasonal forecast models initialized in June are skilful in predicting the observed inter-annual variability of TC frequency over the North Atlantic (NA). Similarly, the models initialized in May show significant skill over the Western North Pacific (WNP) for the season from June to October. Further to these significant positive correlations over the NA, it is found that most models are also able to discriminate between inactive and active seasons over this region. However, despite these encouraging results, especially&#160; for skill over the NA, most models suffer from large biases. These biases are not only related to biases in the large-scale circulation but also to the representation of intrinsic model uncertainties and the relatively coarse resolution of current seasonal forecasts. At ECMWF model uncertainty is accounted for by the use of stochastic physics, which has been shown to improve forecasts on seasonal time-scales in previous studies. Using a set of simulations conducted with the ECMWF SEAS5 model, the effects of stochastic physics and resolution on the representation of Tropical Cyclones on seasonal time-scales are assessed. Including stochastic physics increases the number of TCs over all ocean basins, but especially over the North Atlantic and Western North Pacific.

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Flow-dependent sub-seasonal forecast skill for Atlantic-European weather regimes and its relation to planetary- to synoptic-scale processes

10.5194/egusphere-egu21-12124 ◽

2021 ◽

Author(s):

Dominik Büeler ◽

Jan Wandel ◽

Julian F. Quinting ◽

Christian M. Grams

Keyword(s):

Large Scale ◽

Life Cycles ◽

Forecast Skill ◽

Synoptic Scale ◽

Atmospheric Variability ◽

Weather Regime ◽

Weather Regimes ◽

Weather Forecasts ◽

Conveyor Belts ◽

Warm Conveyor Belts

<div>Sub-seasonal numerical weather forecasts (10 &#8211; 60 days) primarily aim to predict the evolution of the large-scale circulation and its associated surface weather on continent- and multi-daily scales. In the extratropics, this atmospheric variability is depicted best by so-called weather regimes. Here, we assess the ability of sub-seasonal reforecasts of the European Centre for Medium-Range Weather Forecasts (ECMWF) to predict 7 year-round weather regimes in the Atlantic-European region. We first investigate how well the forecasts reproduce frequency, length, and transitions of the weather regime life cycles. We then show that the average forecast skill horizon varies by several days for different weather regimes, seasons, and initial planetary-scale flow states. In a final part, we provide first insight into how synoptic-scale processes, more specifically warm conveyor belts, and their inherent intrinsic predictability limit might affect this flow-dependent sub-seasonal weather regime forecast skill.</div>

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ASSESSMENT OF MAXIMUM INSTANT DISCHARGE OF VARIOUS FREQUENCY AT UNGAUGED MOUNTAINOUS RIVER KHEMCHIK (TUVA REPUBLIC) BASED ON MATHEMATICAL MODELLING

Engineering survey ◽

10.25296/1997-8650-2019-13-2-36-51 ◽

2019 ◽

Vol 13 (2) ◽

pp. 36-51 ◽

Cited By ~ 2

Author(s):

O. M. Makarieva ◽

N. V. Nesterova ◽

G. P. Yampolsky ◽

E. Y. Kudymova

Keyword(s):

Coniferous Forest ◽

Frequency Interval ◽

Time Step ◽

Model Calculations ◽

Runoff Formation ◽

Emergency Situations ◽

Daily Streamflow ◽

Standard Methodology ◽

Maximum Elevation ◽

Daily Time Step

Abstract: the article presents the results of application of distributed deterministic hydrological model Hydrograph for estimation of maximum discharge values of different frequency at the ungauged catchment of the Khemchik River (Khemchik village, Tuva Republic). The catchment area is 1750 km2 , the average and maximum elevation — 2200 and 3600 m, respectively. Due to the lack of detailed information, a schematization of the catchment and the parameterization of the model are proposed, based on general ideas about the water balance and the processes of runoff formation of the main landscapes — rocky talus, coniferous forest and steppe. Parameters and algorithms are verified based on the results of streamflow modeling at two studied catchments: the Tapsy River — Kara-Khol (302 km2 ) and the Khemchik River — Iyme (25500 km2 ). Modelling of runoff formation processes with daily time step for the Khemchik River — Khemchik village was conducted for the period 1966–2012 using observational data at Teeli meteorological station. For the transition from daily to instant discharges, the dependence of the observed values of instant and daily streamflow at the studied gauges has been applied. On the basis of simulated discharge series, the frequency curve was built and the obtained curve was compared with the calculation data according to the standard methodology SP 33-101-2003 “Determination of the main calculated hydrological characteristics” using the analogue river. Simulated maximum instant discharges for entire frequency interval of up to 1% are 1.3–5 times higher than the values obtained by standard methodology SP 33-101-2003. The results of model calculations is indirectly confirmed by the evidences of regular flooding of the Khemchik village provided by the Ministry of Emergency Situations of the Tuva Republic, which is not predicted by the values obtained by the standard methods.

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Knowledge and awareness about MERS-CoV among the dental students in Chennai

International Journal of Research in Pharmaceutical Sciences ◽

10.26452/ijrps.v11ispl1.3091 ◽

2020 ◽

Vol 11 (SPL1) ◽

pp. 847-851

Author(s):

Nithyanandham Masilamani ◽

Dhanraj Ganapathy

Keyword(s):

College Students ◽

Large Scale ◽

Preventive Measures ◽

Positive Impact ◽

Educational Programs ◽

Dental Students ◽

Professional Organizations ◽

Cross Sectional Survey ◽

Cross Sectional ◽

Mode Of Transmission

Middle East Respiratory Syndrome (MERS) induced by new ß coronavirus MERS-(CoV) had first been described in Saudi Arabia in September 2012. MERS-CoV communication inside the population is often identified with clustered households and cramped communal spaces. The purpose of the study is to assess the knowledge and awareness of MERS-CoV among dental students in India. This was a questionnaire-based cross-sectional survey of 100 dental college students in Chennai. The self-designed questionnaires contained ten questions focused on the knowledge and awareness of MERS-CoV amongst dental college students. Questionnaires were circulated through an online website survey planet. After the responses were received from 100 participants, data were collected and analyzed, .87% are aware of MERS-CoV through media 13% from professional channels. 84%are aware of the clinical manifestation of MERS-CoV. 81%Are aware of the mode of transmission of MERS-CoV. 76%are aware of the preventive measures against MERS -CoV.68%. Are aware of the incubation period of MERS-CoV. 74%aware of PCR as a diagnostic test for MERS-CoV. This study concluded that dental students had strong awareness and knowledge of MERS. Also, there are a few differences in information and behaviours that require change. Large-scale health educational programs on MERS also should be facilitated by professional organizations to expand their reach and to strengthen knowledge to have a positive impact on their behaviour.

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Accidental Sustainability

10.1093/oso/9780198706977.003.0005 ◽

2017 ◽

Author(s):

Geoffrey Jones

Keyword(s):

Large Scale ◽

Negative Impact ◽

Positive Impact ◽

Organic Food ◽

The United States ◽

Air Travel ◽

Business Leaders ◽

Natural Beauty ◽

And Diffusion ◽

Whole Foods

This chapter examines the scaling and diffusion of green entrepreneurship between 1980 and the present. It explores how entrepreneurs and business leaders promoted the idea that business and sustainability were compatible. It then examines the rapid growth of organic foods, natural beauty, ecological architecture, and eco-tourism. Green firms sometimes grew to a large scale, such as the retailer Whole Foods Market in the United States. The chapter explores how greater mainstreaming of these businesses resulted in a new set of challenges arising from scaling. Organic food was now transported across large distances causing a negative impact on carbon emissions. More eco-tourism resulted in more air travel and bigger airports. In other industries scaling had a more positive impact. Towns were major polluters, so more ecological buildings had a positive impact.

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Yearly evolution of Euro-Atlantic weather regimes and of their sub-seasonal predictability

Climate Dynamics ◽

10.1007/s00382-021-05679-y ◽

2021 ◽

Author(s):

Nicola Cortesi ◽

Verónica Torralba ◽

Llorenó Lledó ◽

Andrea Manrique-Suñén ◽

Nube Gonzalez-Reviriego ◽

...

Keyword(s):

Annual Cycle ◽

Winter Season ◽

Skill Score ◽

Seasonal Forecast ◽

Forecast Skill ◽

Seasonal Forecasts ◽

Sea Level Pressure ◽

Weather Regimes ◽

Start Dates ◽

Weekly Frequency

AbstractIt is often assumed that weather regimes adequately characterize atmospheric circulation variability. However, regime classifications spanning many months and with a low number of regimes may not satisfy this assumption. The first aim of this study is to test such hypothesis for the Euro-Atlantic region. The second one is to extend the assessment of sub-seasonal forecast skill in predicting the frequencies of occurrence of the regimes beyond the winter season. Two regime classifications of four regimes each were obtained from sea level pressure anomalies clustered from October to March and from April to September respectively. Their spatial patterns were compared with those representing the annual cycle. Results highlight that the two regime classifications are able to reproduce most part of the patterns of the annual cycle, except during the transition weeks between the two periods, when patterns of the annual cycle resembling Atlantic Low regime are not also observed in any of the two classifications. Forecast skill of Atlantic Low was found to be similar to that of NAO+, the regime replacing Atlantic Low in the two classifications. Thus, although clustering yearly circulation data in two periods of 6 months each introduces a few deviations from the annual cycle of the regime patterns, it does not negatively affect sub-seasonal forecast skill. Beyond the winter season and the first ten forecast days, sub-seasonal forecasts of ECMWF are still able to achieve weekly frequency correlations of r = 0.5 for some regimes and start dates, including summer ones. ECMWF forecasts beat climatological forecasts in case of long-lasting regime events, and when measured by the fair continuous ranked probability skill score, but not when measured by the Brier skill score. Thus, more efforts have to be done yet in order to achieve minimum skill necessary to develop forecast products based on weather regimes outside winter season.

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Agricultural Technical Efficiency of Smallholder Farmers in Ethiopia: A Stochastic Frontier Approach

Land ◽

10.3390/land10030246 ◽

2021 ◽

Vol 10 (3) ◽

pp. 246

Author(s):

Markose Chekol Zewdie ◽

Michele Moretti ◽

Daregot Berihun Tenessa ◽

Zemen Ayalew Ayele ◽

Jan Nyssen ◽

...

Keyword(s):

Technical Efficiency ◽

Crop Production ◽

Large Scale ◽

Positive Impact ◽

Smallholder Farmers ◽

Stochastic Frontier ◽

Crop Productivity ◽

Small Scale ◽

Stochastic Frontier Approach ◽

Small Scale Irrigation

In the past decade, to improve crop production and productivity, Ethiopia has embarked on an ambitious irrigation farming expansion program and has introduced new large- and small-scale irrigation initiatives. However, in Ethiopia, poverty remains a challenge, and crop productivity per unit area of land is very low. Literature on the technical efficiency (TE) of large-scale and small-scale irrigation user farmers as compared to the non-user farmers in Ethiopia is also limited. Investigating smallholder farmers’ TE level and its principal determinants is very important to increase crop production and productivity and to improve smallholder farmers’ livelihood and food security. Using 1026 household-level cross-section data, this study adopts a technology flexible stochastic frontier approach to examine agricultural TE of large-scale irrigation users, small-scale irrigation users and non-user farmers in Ethiopia. The results indicate that, due to poor extension services and old-style agronomic practices, the mean TE of farmers is very low (44.33%), implying that there is a wider room for increasing crop production in the study areas through increasing the TE of smallholder farmers without additional investment in novel agricultural technologies. Results also show that large-scale irrigation user farmers (21.05%) are less technically efficient than small-scale irrigation user farmers (60.29%). However, improving irrigation infrastructure shifts the frontier up and has a positive impact on smallholder farmers’ output.

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