Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members

Abstract Nowadays, several global ensembles (GEs) which consist of several tens of members are being run operationally. In order to locally improve the probabilistic forecasts, various forecasting centers and research institutes utilize the GEs as initial and boundary conditions to drive regional co...

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Main Authors: Pavel Khain, Alon Shtivelman, Yoav Levi, Anat Baharad, Eyal Amitai, Yizhak Carmona, Elyakom Vadislavsky, Amit Savir, Nir Stav
Format: Article
Language:English
Published: Wiley 2023-07-01
Series:Meteorological Applications
Subjects:
Online Access:https://doi.org/10.1002/met.2137
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author Pavel Khain
Alon Shtivelman
Yoav Levi
Anat Baharad
Eyal Amitai
Yizhak Carmona
Elyakom Vadislavsky
Amit Savir
Nir Stav
author_facet Pavel Khain
Alon Shtivelman
Yoav Levi
Anat Baharad
Eyal Amitai
Yizhak Carmona
Elyakom Vadislavsky
Amit Savir
Nir Stav
author_sort Pavel Khain
collection DOAJ
description Abstract Nowadays, several global ensembles (GEs) which consist of several tens of members are being run operationally. In order to locally improve the probabilistic forecasts, various forecasting centers and research institutes utilize the GEs as initial and boundary conditions to drive regional convection permitting ensembles (RCPEs). RCPEs demand significant computer resources and often a limited number of ensemble members is affordable, which is smaller than the size of the driving GE. Since each RCPE member obtains the initial and boundary conditions from a specific GE member, there are many options to select the GE members. The study uses the European Centre for Medium‐Range Weather Forecasts (ECMWF) GE consisting of 50 members, to drive 20 members of COSMO model RCPE over the Eastern Mediterranean. We compare various approaches for automatic selection of the GE members and propose several optimal methods, including a random selection, which consistently lead to a better performance of the driven RCPE. The comparison includes verification of near surface variables and precipitation using various verification metrics. The results are validated using several methods of model physics perturbation. Besides the selection of the optimal ensemble configurations, we show that at high precipitation intensities spatial up‐scaling is recommended in order to obtain useful probabilistic forecasts.
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spelling doaj.art-b486e991595d4c3f97aa226b1799cb942023-08-30T05:11:03ZengWileyMeteorological Applications1350-48271469-80802023-07-01304n/an/a10.1002/met.2137Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving membersPavel Khain0Alon Shtivelman1Yoav Levi2Anat Baharad3Eyal Amitai4Yizhak Carmona5Elyakom Vadislavsky6Amit Savir7Nir Stav8The Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelThe Israel Meteorological Service Bet‐Dagan IsraelAbstract Nowadays, several global ensembles (GEs) which consist of several tens of members are being run operationally. In order to locally improve the probabilistic forecasts, various forecasting centers and research institutes utilize the GEs as initial and boundary conditions to drive regional convection permitting ensembles (RCPEs). RCPEs demand significant computer resources and often a limited number of ensemble members is affordable, which is smaller than the size of the driving GE. Since each RCPE member obtains the initial and boundary conditions from a specific GE member, there are many options to select the GE members. The study uses the European Centre for Medium‐Range Weather Forecasts (ECMWF) GE consisting of 50 members, to drive 20 members of COSMO model RCPE over the Eastern Mediterranean. We compare various approaches for automatic selection of the GE members and propose several optimal methods, including a random selection, which consistently lead to a better performance of the driven RCPE. The comparison includes verification of near surface variables and precipitation using various verification metrics. The results are validated using several methods of model physics perturbation. Besides the selection of the optimal ensemble configurations, we show that at high precipitation intensities spatial up‐scaling is recommended in order to obtain useful probabilistic forecasts.https://doi.org/10.1002/met.2137ensembleNWPprobabilistic forecastspread skill ratio
spellingShingle Pavel Khain
Alon Shtivelman
Yoav Levi
Anat Baharad
Eyal Amitai
Yizhak Carmona
Elyakom Vadislavsky
Amit Savir
Nir Stav
Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
Meteorological Applications
ensemble
NWP
probabilistic forecast
spread skill ratio
title Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
title_full Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
title_fullStr Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
title_full_unstemmed Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
title_short Optimizing convection‐permitting ensemble via selection of the coarse ensemble driving members
title_sort optimizing convection permitting ensemble via selection of the coarse ensemble driving members
topic ensemble
NWP
probabilistic forecast
spread skill ratio
url https://doi.org/10.1002/met.2137
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