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CN-122021083-A - Atmospheric numerical simulation method based on multiphase water conservation constraint and application thereof

CN122021083ACN 122021083 ACN122021083 ACN 122021083ACN-122021083-A

Abstract

The invention relates to the technical field of atmospheric science and numerical computation, and discloses an atmospheric numerical simulation method based on multi-phase water substance conservation constraint and application thereof, wherein the method is oriented to the evolution computation of cloud micro-physical parameterization of an atmospheric numerical mode on each phase water substance under the conditions of discrete grids and discrete time steps. The method comprises the steps of obtaining density and speed fields of each component in a grid unit, constructing a mass ratio variable normalized by wet air density, defining a growth rate of a unit volume in unit time, representing a phase change source sink by a component continuous equation, establishing a coupling discrete updating rule according to an accurate evolution equation of the mass ratio, calculating a ratio residual error corresponding to a total water substance growth rate residual error and an equivalent conservation expression, and obtaining a corrected growth rate meeting conservation constraint through consistency correction so as to write back and update the mass ratio field. The method can inhibit water material balance drift, reduce phase distribution errors under the condition of mixed phase cloud, and is suitable for numerical weather forecast and regional numerical simulation.

Inventors

  • YU YUBIN
  • LIU SHIJUN
  • ZHAO DAJUN
  • WANG TIANSHU

Assignees

  • 中国气象局气象干部培训学院

Dates

Publication Date
20260512
Application Date
20260415

Claims (12)

  1. 1. An atmospheric numerical simulation method based on multiphase water conservation constraint is characterized by at least comprising the following steps: SS1 at the beginning of each time step, the density rho λ and the velocity field of each component of the multiphase mixed atmosphere of each grid unit of the area to be simulated are obtained Wherein the subscript lambda comprises d, v, w, i which respectively represents dry air, water vapor, liquid water and solid water, the wet air density rho=ρ d ＋ρ v ,ρ d is calculated to be the dry air density, ρ v is the water vapor density, and the mass ratio q μ =ρ μ /ρ of each phase water substance is calculated, wherein q μ 、ρ μ is the mass ratio and the density of each phase water substance, and the subscript mu comprises v, w and i; SS2 defining the mass m μ and m μ =ρ μ . Alpha. Of each phase of water substance in the grid cell control volume alpha, and defining the corresponding growth rate s μ per unit volume and unit time Wherein the subscript mu comprises v, w, i and t as time, and simultaneously the dry air growth rate s d and s d = 0 are restrained, and the density evolution relation of the water substances in each phase state is established based on a component continuous equation S μ is taken as a quality source sink item caused by phase change and phase transition; SS3 in time step Deltat, according to the accurate evolution equation of the mass ratio of the water substances in each phase Construct the corresponding discrete update quantity Deltaq μ and And accordingly obtain the corresponding predicted mass ratio And is also provided with ; SS4 calculating residual R s and R s =s v +s w +s i of the total water substance growth rate, wherein s v 、s w 、s i is the growth rate of water vapor, liquid water and solid water in unit volume and unit time, and constructing a residual R q of the ratio based on the equivalent conservation expression of the water substance mass conservation equation Wherein the equivalent conservation expression is Wherein q v 、q w 、q i is the mass ratio of water vapor, liquid water and solid water respectively; SS5. Determining the corrected growth rate of the aqueous phase material according to the constraint R s =0 and R q =0 Wherein the subscript μ comprises v, w, i, and Recalculating delta q μ instead of s μ to obtain corresponding corrected discrete update amount Then the mass ratio of the water substances in each phase state after the time step is finished is obtained And is also provided with ; And SS6, repeatedly executing the steps SS 1-SS 5 for the subsequent time steps, and outputting the space-time distribution of the mass ratio q μ of each phase of water substance in the target simulation period and the corresponding residual R s 、R q .
  2. 2. The method according to claim 1, wherein in step SS1, after obtaining the densities ρ λ of the components and calculating the wet air density ρ, multiphase mixed air densities ρ s and ρ s =ρ d +ρ v +ρ w +ρ i are defined, wherein ρ d 、ρ v 、ρ w 、ρ i is dry air, respectively, Water vapor, liquid water, The density of solid water, the total water mass density ρ t and ρ t =ρ v +ρ w +ρ i are defined, the total water mass ratio q t and q t =ρ t /ρ are constructed according to the total water mass density ρ t and ρ t =ρ v +ρ w +ρ i , the dry air mass ratio q d and q d =ρ d /ρ are constructed simultaneously, the mass ratio consistency constraint is established based on the mass ratio definition relation, and q d +q v =1、q t =q v +q w +q i is realized, wherein q d 、q v 、q w 、q i is dry air, Water vapor, liquid water, The mass ratio of the solid water and the mass ratio q s and q s =q d +q v +q w +q i and q s =1+q w +q i of the multiphase mixed atmosphere relative to the wet air are further constructed, and q s is used as the subsequent conservation diagnosis, An additional constraint variable for error analysis or numerical inspection calculates the amount of deviation of q s in each time step and performs a reconciliation process on ρ d 、ρ v 、ρ w 、ρ i or q v 、q w 、q i calculated therefrom when the amount of deviation exceeds a preset tolerance.
  3. 3. The method according to claim 1, wherein in step SS2, the growth rate s μ of each phase of water substance is composed of the phase change and phase transition mass flux outputted by the cloud micro-physical parameterization scheme, and is organized according to mass conservation transfer pairs, so that the water vapor to liquid transfer and the water vapor to liquid transfer, and the water vapor to solid transfer are respectively represented by source and sink terms with opposite signs, and simultaneously the freezing and thawing processes between the liquid and the solid are written into s w and s i with opposite signs, so that s v +s w +s i = 0 is satisfied in the same grid unit, and the phase transition is ensured to change only each phase component without introducing additional mass sources.
  4. 4. A method according to claim 1 or 3, wherein in step SS2, in addition to establishing the component continuous equation of each phase of the water substance, a total continuous equation is established based on the total mass conservation of the multiphase mixed atmosphere so that the multiphase mixed atmosphere density ρ s satisfies the velocity field Conservation relation of variation and accordingly pair And (3) carrying out consistency check on the calculation result of the component continuous equation, and when the total continuous equation is inconsistent with the dispersion term of the component continuous equation, synchronously updating the component continuous equation by adopting the same dispersion term.
  5. 5. The method according to claim 2, wherein in step SS3, the mass-ratio accurate evolution equation is developed into three phase update rules according to the vapor growth rate coupling mode, so that the vapor mass ratio satisfies the following conditions The liquid water mass ratio satisfies The solid water mass ratio satisfies And respectively constructing corresponding discrete increments in the time step delta t to embody nonlinear coupling constraint of the growth rate of the liquid phase and the solid phase relative to the vapor phase.
  6. 6. The method according to claim 5, wherein in step SS4, in addition to calculating the total water mass growth rate residual R s and the duty cycle residual R q , the amount of change Δq t in the total water mass duty cycle q t in time step Δt is calculated, and Δq t is used in combination with R s for conservation diagnosis, wherein R s is used for characterizing water mass transfer conservation per unit volume per unit time, Δq t is used for characterizing duty cycle change with wet air density as a reference, and when Δq t is not zero and R s is zero, it is determined that there is duty cycle change due to density change or transportation process rather than mass non-conservation due to phase transition in the time step.
  7. 7. The method of claim 6, wherein steps SS3, SS5 set q i =0 for the warm cloud gas-liquid two-phase condition, and construct a gas-liquid two-phase update constraint based on the nonlinear coupling relationship of the mass-to-ratio definition framework in time step Δt, such that the liquid water mass-to-ratio increment Δq w and the water vapor mass-to-ratio increment Δq v satisfy a correspondence containing a denominator correction term, which is determined by q v and q w from the beginning of the current time step, instead of simply setting Δq w and Δq v as linear approximations of opposite sign.
  8. 8. The method of claim 7, wherein steps SS3, SS5 introduce the non-gaseous water content q wi and q wi =q w +q i for the gas-liquid-solid three-phase coexistence condition, and construct the relationship between q wi and q v as a constraint relationship in time step based on q t or q wi initiated in time step as a determination condition of the integration constant, so that the corrected growth rate satisfies the coupling evolution law constrained by the initial water content ratio condition while satisfying R s =0 and R q =0.
  9. 9. The method of claim 8, wherein in step SS5, the growth rate is corrected Obtained by iterative consistence solution, wherein in the iterative process, updated R s and R q are used as convergence criteria, and the correction growth rate is substituted into step SS3 for recalculating delta q μ and updating And ending the iteration after R s 、R q simultaneously meets the convergence condition.
  10. 10. The method of claim 9, wherein in step SS6, in addition to outputting the space-time distribution of the mass ratio q μ of each phase of water substance and the residual R s 、R q , R s and R q are accumulated and counted in the simulation period to form a conservation drift diagnosis quantity, and the conservation drift diagnosis quantity and the space-time distribution of q μ are written into a storage medium according to grid indexes and time indexes for subsequent time step reading and for conservation evaluation and numerical debugging of the cloud micro-physical parameterization scheme.
  11. 11. A computer program product comprising computer instructions for performing the steps of the atmospheric numerical simulation method based on the multi-phase conservation of water mass constraint of any one of claims 1 to 10.
  12. 12. A computer-readable storage medium, on which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements the steps of the atmospheric numerical simulation method based on the conservation constraint of multiphase water mass according to any one of claims 1 to 10.

Description

Atmospheric numerical simulation method based on multiphase water conservation constraint and application thereof Technical Field The invention belongs to the technical field of atmospheric science and numerical computation, relates to a cloud micro physical parameterization scheme in an atmospheric numerical mode, multi-phase water conservation constraint construction, wet physical source and sink consistency correction and discrete time advancing error suppression, and in particular relates to an atmospheric numerical simulation method based on the multi-phase water conservation constraint and application thereof. Background The atmospheric numerical simulation and climate mode is an important technical means of modern meteorological science research and business weather forecast, and the simulation accuracy directly determines the accuracy of precipitation forecast and the reliable description level of the atmospheric moisture circulation process. In an atmosphere numerical mode system, multiphase variables such as water vapor, cloud water, cloud ice, precipitation particles and the like are usually predicted on grids, and the sub-grid processes such as phase change, collision and growth, sedimentation, turbulent mixing and the like are described by means of cloud micro-physical parameterization (Cloud Microphysics Parameterization). In order to adapt to the power frame, the mode can adopt the characterization modes such as specific humidity, mixing ratio or mass concentration, and the like, and the momentum, heat and water substance equation are coupled under the altitude coordinate or the air pressure coordinate to form a discrete solving system. However, water material balance under three-phase coexistence conditions involves multi-source sink coupling and energy exchange, and the conservation relationship is vulnerable to multiple factors at a discrete level. First, cloud micro-physical schemes often split or update source and sink terms item by item according to the process, and mass transfer between different phases may not be completely symmetrical in value, resulting in accumulation of total water material balance residual errors over time. And simultaneously, the atmospheric compressibility causes density and volume change, and if the conservation amount denominator is inconsistent in selection and conversion relation treatment, the non-closed error is amplified. Thirdly, the spectrum distribution, the falling speed, the re-evaporation, the re-freezing and other processes depend on experience relations, and parameters are sensitive to time steps and resolution, so that inconsistent transmission among scales is easy to cause. In order to reduce the numerical problem caused by unbalance, the prior art generally adopts the means of flux form dispersion, mass conservation type advection format, source sink item amplitude limiting, numerical filtering and the like, and evaluates the wet process error through water vapor balance diagnosis and budget closure inspection. However, under the conditions of strong convection, mixed phase cloud, continuous precipitation and the like, the phase state is frequently converted, the source-sink item amplitude is large, and the phenomena of drift of total water substances, local conservation and destruction, inconsistent energy and water evolution and the like can still occur, so that precipitation magnitude deviation and long-term integral drift are caused. In summary, the existing atmospheric numerical simulation still has insufficient problems in terms of conservation and depiction of multiphase water substances and discrete balance closure, and the stability and precision drop caused by the insufficient problems, so how to effectively improve the numerical consistency and budget closure capability under the conservation constraint of multiphase water substances in the atmospheric numerical simulation is a technical problem to be solved in the art. Disclosure of Invention Object of the invention Aiming at the defects and shortcomings of the prior art, the invention aims to provide an atmospheric numerical simulation method based on multi-phase water conservation constraint and application thereof, which realizes multi-phase water balance closure, reduces long-term integral drift, improves numerical stability, provides a reckonable diagnosis basis for wet process evaluation in numerical weather forecast and climate simulation, reduces dependence on experience amplitude limiting and artificial parameter adjustment on the premise of ensuring calculation efficiency and outputs updated multi-phase field and conservation diagnosis result thereof by introducing verifiable conservation constraint and residual indexes in grid dispersion and time step promotion and implementing consistency coordination and self-adaptive correction on source and sink items such as advection, turbulent mixing, sedimentation and phase change. (II) technical scheme In order to achieve the ai