A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering th...A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering the effects of large-scale dynamic processes on the trigger of deep convection.The closure,based on dynamic CAPE,is improved accordingly to allow other processes to consume CAPE under the more restricted convective trigger condition.The revised convective parameterization is evaluated with a variable-resolution model setup(110–35 km,refined over East Asia).The Atmospheric Model Intercomparison Project(AMIP)simulations demonstrate that the revised convective parameterization substantially delays the daytime precipitation peaks over most land areas,leading to an improved simulated diurnal cycle,evidenced by delayed and less frequent afternoon precipitation.Meanwhile,changes to the threshold of the trigger function yield a small impact on the diurnal amplitude of precipitation because of the consistent setting of dCAPE-based trigger and closure.The simulated mean precipitation remains reasonable,with some improvements evident along the southern slopes of the Tibetan Plateau.The revised scheme increases convective precipitation at the lower levels of the windward slope and reduces the large-scale precipitation over the upper slope,ultimately shifting the rainfall peak southward,which is in better agreement with the observations.展开更多
In relatively coarse-resolution atmospheric models,cumulus parameterization helps account for the effect of subgridscale convection,which produces supplemental rainfall to the grid-scale precipitation and impacts the ...In relatively coarse-resolution atmospheric models,cumulus parameterization helps account for the effect of subgridscale convection,which produces supplemental rainfall to the grid-scale precipitation and impacts the diurnal cycle of precipitation.In this study,the diurnal cycle of precipitation was studied using the new simplified Arakawa-Schubert scheme in a global non-hydrostatic atmospheric model,i.e.,the Yin-Yang-grid Unified Model for the Atmosphere.Two new diagnostic closures and a convective trigger function were suggested to emphasize the job of the cloud work function corresponding to the free tropospheric large-scale forcing.Numerical results of the 0.25-degree model in 3-month batched real-case simulations revealed an improvement in the diurnal precipitation variation by using a revised trigger function with an enhanced dynamical constraint on the convective initiation and a suitable threshold of the trigger.By reducing the occurrence of convection during peak solar radiation hours,the revised scheme was shown to be effective in delaying the appearance of early-afternoon rainfall peaks over most land areas and accentuating the nocturnal peaks that were wrongly concealed by the more substantial afternoon peak.In addition,the revised scheme enhanced the simulation capability of the precipitation probability density function,such as increasing the extremely low-and high-intensity precipitation events and decreasing small and moderate rainfall events,which contributed to the reduction of precipitation bias over mid-latitude and tropical land areas.展开更多
A global non-hydrostatic atmospheric model, i.e., GRAPES_YY （Global/Regional Assimilation and Prediction System on the Yin-Yang grid）, with a semi-implicit semi-Lagrangian （SISL） dynamical core developed on the Yi...A global non-hydrostatic atmospheric model, i.e., GRAPES_YY （Global/Regional Assimilation and Prediction System on the Yin-Yang grid）, with a semi-implicit semi-Lagrangian （SISL） dynamical core developed on the Yin-Yang grid was coupled with the physical parameterization package of the operational version of GRAPES. A 3.5-yr integration was carried out on an aqua planet to assess the numerical performance of this non-hydrostatic mo- del relative to other models. Specific aspects of precipitation and general circulation under two different sea surface temperature （SST） conditions （CONTROL and FLAT） were analyzed. The CONTROL SST peaked at the equator. The FLAT SST had its maximum gradient at about 20~ latitude, giving a broad equatorial SST maximum in the trop- ics and flat profile approaching the equator. The tropical precipitation showed different propagation features in the CONTROL and FLAT simulations. The CONTROL showed tropical precipitation bands moving eastward with some envelopes of westward convective-scale disturbance. Less organized westward-propagating rainfall cells and bands were seen in the FLAT and the propagation of the tropical wave varied with the SST gradient. The Inter Tropical Convergence Zone （ITCZ）, Hadley cell, and westerly jet core were weaker and more poleward as the SST profile flattened from the CONTROL to FLAT. The climatological structures simulated by GRAPES_YY, such as the distri- bution of precipitation and the large-scale circulation, fell within the bounds from other models. The stronger ITCZ precipitation, accompanied with stronger Hadley cells and convective heating in the CONTROL simulation, may be summed up as a result of stronger parameterized convection and the non-hydrostatic effects in GRAPES_YY. In ad- dition, mechanism of the zonal mean circulation maintaining is analyzed for the different SST patterns referring the transient eddy flux.展开更多
The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework al...The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework allowing easy switching between a one-dimensional(1D)and a three-dimensional(3D)time-independent reference state is developed for the semi-implicit semi-Lagrangian solver in a global non-hydrostatic atmospheric model on Yin–Yang grids.The 3D reference state is introduced with consideration of additional horizontal gradient terms of referencestate terms,which is different from the 1D reference state.It is characterized by reduced magnitude of deviations,more accurate pressure gradient force,as well as alleviated numerical noise.Four idealized benchmark tests and multiple full-physics real-case forecasts are carried out to assess the impact of the 3D and 1D reference states.The 3D reference state shows significant advantages in the simulation of atmospheric transport and wave propagation in the idealized experiments.In the real-case forecasts,batched forecasts from June to August 2021 show a comprehensive improvement in medium-range prediction by using the 3D reference state.The new scheme achieves an enhanced prediction skill for large-scale circulation and extends the effective forecast period by 0.8 days in the Northern Hemisphere.展开更多
The corona virus disease 2019(COVID-19)has emerged as a fatal virus.This deadly virus has taken the whole world into clutches and many people have embraced death due to this invincible bug.The death toll is rising wit...The corona virus disease 2019(COVID-19)has emerged as a fatal virus.This deadly virus has taken the whole world into clutches and many people have embraced death due to this invincible bug.The death toll is rising with every tick of time.The aspiration behind this article is to discover the preventive measure that should be taken to cope with this intangible enemy.We study the prime notions of novel sort of topology accredited Pythagorean m-polar fuzzy topology along with its prime attributes.We slightly amend the well-acknowledged multi-criteria decision analysis tool TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution)to befit the proposed multi-criteria group decision making(MCGDM)problem of exploring the most effective method for curing from COVID-19 employing the proposed model.展开更多
基金supported by the National Key R&D Program of China on the Monitoring,Early Warning,and Prevention of Major Natural Disasters(Grant Nos.2018YFC1507005 and 02017YFC1502202)。
文摘A double-plume convective parameterization scheme is revised to improve the precipitation simulation of a global model(Global-to-Regional Integrated Forecast System;GRIST).The improvement is achieved by considering the effects of large-scale dynamic processes on the trigger of deep convection.The closure,based on dynamic CAPE,is improved accordingly to allow other processes to consume CAPE under the more restricted convective trigger condition.The revised convective parameterization is evaluated with a variable-resolution model setup(110–35 km,refined over East Asia).The Atmospheric Model Intercomparison Project(AMIP)simulations demonstrate that the revised convective parameterization substantially delays the daytime precipitation peaks over most land areas,leading to an improved simulated diurnal cycle,evidenced by delayed and less frequent afternoon precipitation.Meanwhile,changes to the threshold of the trigger function yield a small impact on the diurnal amplitude of precipitation because of the consistent setting of dCAPE-based trigger and closure.The simulated mean precipitation remains reasonable,with some improvements evident along the southern slopes of the Tibetan Plateau.The revised scheme increases convective precipitation at the lower levels of the windward slope and reduces the large-scale precipitation over the upper slope,ultimately shifting the rainfall peak southward,which is in better agreement with the observations.
基金supported by the National Natural Science Foundation of China(Grant Nos.42375153,42075151).
文摘In relatively coarse-resolution atmospheric models,cumulus parameterization helps account for the effect of subgridscale convection,which produces supplemental rainfall to the grid-scale precipitation and impacts the diurnal cycle of precipitation.In this study,the diurnal cycle of precipitation was studied using the new simplified Arakawa-Schubert scheme in a global non-hydrostatic atmospheric model,i.e.,the Yin-Yang-grid Unified Model for the Atmosphere.Two new diagnostic closures and a convective trigger function were suggested to emphasize the job of the cloud work function corresponding to the free tropospheric large-scale forcing.Numerical results of the 0.25-degree model in 3-month batched real-case simulations revealed an improvement in the diurnal precipitation variation by using a revised trigger function with an enhanced dynamical constraint on the convective initiation and a suitable threshold of the trigger.By reducing the occurrence of convection during peak solar radiation hours,the revised scheme was shown to be effective in delaying the appearance of early-afternoon rainfall peaks over most land areas and accentuating the nocturnal peaks that were wrongly concealed by the more substantial afternoon peak.In addition,the revised scheme enhanced the simulation capability of the precipitation probability density function,such as increasing the extremely low-and high-intensity precipitation events and decreasing small and moderate rainfall events,which contributed to the reduction of precipitation bias over mid-latitude and tropical land areas.
基金Supported by the National Natural Science Foundation of China(41575103 and 91637210)Chinese Academy of Meteorological Sciences Research Project Funds(2015Z002 and 2018KJ039)
文摘A global non-hydrostatic atmospheric model, i.e., GRAPES_YY （Global/Regional Assimilation and Prediction System on the Yin-Yang grid）, with a semi-implicit semi-Lagrangian （SISL） dynamical core developed on the Yin-Yang grid was coupled with the physical parameterization package of the operational version of GRAPES. A 3.5-yr integration was carried out on an aqua planet to assess the numerical performance of this non-hydrostatic mo- del relative to other models. Specific aspects of precipitation and general circulation under two different sea surface temperature （SST） conditions （CONTROL and FLAT） were analyzed. The CONTROL SST peaked at the equator. The FLAT SST had its maximum gradient at about 20~ latitude, giving a broad equatorial SST maximum in the trop- ics and flat profile approaching the equator. The tropical precipitation showed different propagation features in the CONTROL and FLAT simulations. The CONTROL showed tropical precipitation bands moving eastward with some envelopes of westward convective-scale disturbance. Less organized westward-propagating rainfall cells and bands were seen in the FLAT and the propagation of the tropical wave varied with the SST gradient. The Inter Tropical Convergence Zone （ITCZ）, Hadley cell, and westerly jet core were weaker and more poleward as the SST profile flattened from the CONTROL to FLAT. The climatological structures simulated by GRAPES_YY, such as the distri- bution of precipitation and the large-scale circulation, fell within the bounds from other models. The stronger ITCZ precipitation, accompanied with stronger Hadley cells and convective heating in the CONTROL simulation, may be summed up as a result of stronger parameterized convection and the non-hydrostatic effects in GRAPES_YY. In ad- dition, mechanism of the zonal mean circulation maintaining is analyzed for the different SST patterns referring the transient eddy flux.
基金Supported by the National Natural Science Foundation of China(42375153,42075151,and 42205157).
文摘The definition of a reference state close to the realistic atmosphere in an atmospheric model is essential for deriving prognostic deviations and improving numerical accuracy.In this study,a new dynamical framework allowing easy switching between a one-dimensional(1D)and a three-dimensional(3D)time-independent reference state is developed for the semi-implicit semi-Lagrangian solver in a global non-hydrostatic atmospheric model on Yin–Yang grids.The 3D reference state is introduced with consideration of additional horizontal gradient terms of referencestate terms,which is different from the 1D reference state.It is characterized by reduced magnitude of deviations,more accurate pressure gradient force,as well as alleviated numerical noise.Four idealized benchmark tests and multiple full-physics real-case forecasts are carried out to assess the impact of the 3D and 1D reference states.The 3D reference state shows significant advantages in the simulation of atmospheric transport and wave propagation in the idealized experiments.In the real-case forecasts,batched forecasts from June to August 2021 show a comprehensive improvement in medium-range prediction by using the 3D reference state.The new scheme achieves an enhanced prediction skill for large-scale circulation and extends the effective forecast period by 0.8 days in the Northern Hemisphere.
文摘The corona virus disease 2019(COVID-19)has emerged as a fatal virus.This deadly virus has taken the whole world into clutches and many people have embraced death due to this invincible bug.The death toll is rising with every tick of time.The aspiration behind this article is to discover the preventive measure that should be taken to cope with this intangible enemy.We study the prime notions of novel sort of topology accredited Pythagorean m-polar fuzzy topology along with its prime attributes.We slightly amend the well-acknowledged multi-criteria decision analysis tool TOPSIS(Technique for Order of Preference by Similarity to Ideal Solution)to befit the proposed multi-criteria group decision making(MCGDM)problem of exploring the most effective method for curing from COVID-19 employing the proposed model.
