Effect of shallow convection parametrization on cloud resolving NWP forecasts over the Eastern Mediterranean

Khain, Pavel; Levi, Yoav; Muskatel, Harel; Shtivelman, Alon; Vadislavsky, Elyakom; Stav, Nir

doi:10.1016/j.atmosres.2020.105213

Cited by 10 publications

(7 citation statements)

References 53 publications

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“…This explains why this parameter affects winds at 10 m. Furthermore, XCMF also alters the accumulated precipitation, solar radiation, temperature and relative humidity at 2 m. Indeed, this parameter controls the intensity of the mass flux and consequently the activity of the shallow convection scheme. Thus, as already observed by Khain et al (2021), that activity influences the ascending motion of humidity in the free atmosphere and the humidity available for the microphysics scheme to generate grid-scale precipitation.…”

Section: Influence Of Global Parameters With the Morris Designsupporting

confidence: 62%

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Sensitivity analysis of the convective‐scale AROME model to physical and dynamical parameters

Wimmer

Raynaud

Descamps

et al. 2022

Quart J Royal Meteoro Soc

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A global sensitivity analysis of the convective-scale Application of Research to Operations at Mesoscale (AROME) model is performed in order to determine the most influential parameters on the forecast of different near-surface variables.For that purpose, the Morris method is applied to 21 parameters from six different physical and dynamical parametrization schemes, over different seasons. Results highlight a set of eight parameters with a noticeable influence on most variables, in particular 10 m wind speed and precipitation forecasts. The sensitivity of parameter uncertainties is also examined on different spatio-temporal scales. A clear diurnal cycle of parameters influence is observed in summer, in close connection with the convective activity. In addition, the spatial distribution of parameters influence is mostly consistent with the underlying distribution of weather forecasts. A Sobol' sensitivity analysis, based on surrogate models, mostly confirms Morris conclusions and highlights some interactions between parameters.

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Section: Influence Of Global Parameters With the Morris Designsupporting

confidence: 62%

“…Thus, as already observed by Khain et al . (2021), that activity influences the ascending motion of humidity in the free atmosphere and the humidity available for the microphysics scheme to generate grid‐scale precipitation.…”

Section: Resultsmentioning

confidence: 99%

Sensitivity analysis of the convective‐scale AROME model to physical and dynamical parameters

Wimmer

Raynaud

Descamps

et al. 2022

Quart J Royal Meteoro Soc

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“…This also holds specifically for severe convection during the spring over the Negev Desert (Dayan and Morin, 2006;Armon et al, 2019). The data for the synoptic maps, including sea level pressure (SLP) and upper-level fields and geopotential height (gph), were taken from the NCEP/NCAR (National Center for Environmental Prediction/National Center for Atmospheric Research) reanalysis 1 database at 2.5 • × 2.5 • spatial resolution (Kalnay et al, 1996;Kistler et al, 2001). The data for the mesoscale maps, including wind, relative and potential vorticity, temperature, and relative humidity, are taken from ERA5 European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis database (C3S, 2017, https://cds.climate.copernicus.…”

Section: Methodsmentioning

confidence: 99%

Atmospheric conditions leading to an exceptional fatal flash flood in the Negev Desert, Israel

Dayan

Lensky

Ziv

et al. 2021

Nat. Hazards Earth Syst. Sci.

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Abstract. The study deals with an intense rainstorm that hit the Middle East between 24 and 27 April 2018 and took the lives of 13 people, 10 of them on 26 April during the deadliest flash flood in Tzafit Basin (31.0∘ N, 35.3∘ E), the Negev Desert. The rainfall observed in the southern Negev was comparable to the long-term annual rainfall there, with intensities exceeding a 75-year return period. The timing of the storm, at the end of the rainy season when rain is relatively rare and spotty, raises the question of what the atmospheric conditions were that made this rainstorm one of the most severe late-spring storms. The synoptic background was an upper-level cut-off low that formed south of a blocking high which developed over eastern Europe. The cut-off low entered the Levant near 30∘ N latitude, slowed its movement from ∼10 to <5 m s−1 and so extended the duration of the storm over the region. The dynamic potential of the cut-off low, as estimated by its curvature vorticity, was the largest among the 12 late-spring rainstorms that occurred during the last 33 years. The lower levels were dominated by a cyclone centred over north-western Saudi Arabia, producing north-westerly winds that advected moist air from the Mediterranean inland. During the approach of the storm, the atmosphere over Israel became unstable, with instability indices reaching values favourable for thunderstorms (e.g. CAPE>1500 J kg−1, LI=4 K) and the precipitable water reaching 30 mm. The latter is explained by lower-level moisture advection from the Mediterranean and an additional contribution of mid-level moist air transport entering the region from the east. Three major rain centres were active over Israel during 26 April, only one of them was orographic and the other two were triggered by instability and mesoscale cyclonic centres. The build-up of the instability is explained by a negative upper-level temperature anomaly over the region caused by a northerly flow east of a blocking high that dominated eastern Europe and ground warming during several hours under clear skies. The intensity of this storm is attributed to an amplification of a mid-latitude disturbance which produced a cut-off low with its implied high relative vorticity, low upper-level temperatures and slow progression. All these, combined with the contribution of moisture supply, led to intense moist convection that prevailed over the region for 3 successive days.

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“…The 20-member ensemble simulations were performed by C3-ENS RCPE, operationally used at the Israeli Meteorological Service (IMS) since November 2020 (Khain et al, 2022). C3-ENS is running twice daily over the Eastern Mediterranean (EM) domain (25 E-39 E/26 N-36 N; D1 in Figure 1), and to our knowledge, is the first operational RCPE used over this region.…”

Section: Modelmentioning

confidence: 99%

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

Khain,

Shtivelman,

Levi

et al. 2023

Meteorological Applications

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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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Effect of shallow convection parametrization on cloud resolving NWP forecasts over the Eastern Mediterranean

Cited by 10 publications

References 53 publications

Sensitivity analysis of the convective‐scale AROME model to physical and dynamical parameters

Sensitivity analysis of the convective‐scale AROME model to physical and dynamical parameters

Atmospheric conditions leading to an exceptional fatal flash flood in the Negev Desert, Israel

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

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