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WMO-CAS TECHNICAL CONFERENCE, INCHEON, R. KOREA 16-17 NOVEMBER, 2009

WMO-CAS TECHNICAL CONFERENCE, INCHEON, R. KOREA 16-17 NOVEMBER, 2009. IMPACTS ON PHYSICAL AND CHEMICAL PROPERTIES OF A STORM FROM THE TROPICAL-VS-MID-LATITUDE CONTRAST IN INSTABILITY AND HUMIDITY OF THE ENVIRONMENT V.Spiridonov 1 and M.Curic 2

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WMO-CAS TECHNICAL CONFERENCE, INCHEON, R. KOREA 16-17 NOVEMBER, 2009

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  1. WMO-CAS TECHNICAL CONFERENCE, INCHEON, R. KOREA 16-17 NOVEMBER, 2009 IMPACTS ON PHYSICAL AND CHEMICAL PROPERTIES OF A STORM FROM THE TROPICAL-VS-MID-LATITUDE CONTRAST IN INSTABILITY AND HUMIDITY OF THE ENVIRONMENT V.Spiridonov1 and M.Curic2 1 Hydrometeorological Institute Skopje, Macedonia, 2Department of Meteorology, Faculty of Physics, Belgrade Serbia

  2. MODEL FRAMEWORK • The convective cloud model is a three-dimensional, non-hydrostatic, time-dependant, compressible system using the dynamic scheme from Klemp and Wilhelmson (1978). • The thermodynamic energy equation is based on Orville and Kopp (1977) with effects of the snow field added. • Bulk water parameterizations are used for simulation of microphysical processes with detailed scheme from Lin et al. (1983) with a significant improvement proposed by Curic and Janc (1995, 1997). • It takes into account 6 water variables (water vapor, cloud droplets, ice crystals, rain, snow, and graupel). • The graupel hydrometeor class is represented as hail with a density of 0.9 g cm-3. • The equivalent radar reflectivity factors for hail, rain are computed by using equations from Smith et al., (1975) and empirical equation for snow by Sekhon and Srivistava (1970).

  3. MODEL CHEMISTRY • The chemistry module includes 4 species (SO2, SO42-, NH4+, H2O2) and 3 aqueous-phase reactions describing in-cloud sulfate chemistry (Taylor, 1989). • While the mass of aerosol sulfate is predicted, the aerosols do not affect the cloud drop activation. The absorption of chemical species from the gas phase into cloud water and rainwater is determined by either Henry’s law equilibrium (Taylor, 1989), or by diffusion-limited mass transfer between gas and liquid phases to include possible non-equilibrium states, (Barth et al., 2001). • All equilibrium constants and oxidation reactions are temperature dependent according to the van’t-Hoff relation (Seinfeld, 1986). Cloud water and rainwater pH is calculated using the charge balance equation from Taylor (1989). • The model includes a freezing transport mechanism of chemical species based on Rutledge et al. (1986). Thus, when water from one hydrometeor class is transferred to another, the dissolved scalar is transferred to the destination hydrometeor in proportion to the water mass that was transferred. More detailed information’s regarding the hydrodynamic equations, microphysics equations, turbulent closure, chemistry parameterizations and numerical methods could be found in Telenta and Aleksic (1988) and (Spiridonov and Curic, 2003; 2005).

  4. MODEL CONCEPT 1. A THREE-DIMENSIONAL 2. NON-HYDROSTATIC 3. CLOUD RESOLVING 4. COMMPRESIBLE 5. TIME-DEPENDANT

  5. MODEL FRAMEWORK DYNAMICS AND THERMODYNAMICS 1. 2. TURBULENCE 3. MICROPHYSICS 4. CHEMISTRY BOUNDARY CONDITIONS, NUMERICAL TECHNIQUES AND INITIALIZATION 5.

  6. DYNAMICS 1. KLEMP AND WILHELMSON (1978) The momentum equations are derived from Navier-Stokes equations with the aid 2. of moist equation of state 3. Non-dimensional pressure (Exner function) 4. 5.

  7. THE PRESSURE EQUATION 1. DERIVED BY TAKING SUBSTANTIAL DERIVATIVE OF EQ. (2) USING COMPRESSIBLE CONTINUITY EQUATION 2. To eliminate d/dt, and thermodynamic equation to eliminate d/dt. The final equationhas the following form: 3. 4.

  8. THERMODYNAMIC EQUATION 1. The potential temperature is used as a Conservative variable for adiabatic processes 2. The flux-conserving form of the equation is: 3. ’ is specific entropy of moist air; Kh heat eddy coefficient 4.

  9. THE SUBGRID SCALE PROCESSES SUB-GRID SCALE PARAMETERIZATION BASED ON THE SOLUTION OF THE TURBULENT KINETIC ENERGY (TKE ), DERIVED FROM: 1. MOMENTUM EQUATION (3), FOR INCOMPRESSIBLE FLUID (=const), PERFORMING REYNOLDS AVERAGING ON EACH PROGNOSTIC VARIABLES AND APPLYING FIRST-ORDER CLOSURE TO NEARLY CONSERVATIVE VARIABLES 2. 3. Subgrid-scale kinetic energy per unit mass 4.

  10. TKE TERMS R.H.S. EQ. (7) BUOYANCY 1. SHEAR 2. DIFFUSSION 3. DISSIPATION 4. ’ deviation of vertical velocity ,CD=0.2 empirical value; l=(xyz)1/3 is the appropriate length 5.

  11. CLOUD MICROPHYSICS Bulk cloud microphysics scheme from Lin et al. (1983) 1. 6 water variables (water vapor, cloud droplets, ice crystals, rain, snow and graupel) 2. Cloud water and cloud ice are assumed to be monodisperse, with zero terminal velocities 3. Cloud droplets mass: Mw=4.19x10-9 Cloud crystal mass: Mi=4.19x10-10 4. Rain, hail and snow have Marshall-Palmer type size distributions with fixed intercept parameters 5.

  12. MICROPHYSICS PARAMETERIZATIONS Density of rain, hail and snow are: (1g cm-3; 0.9 g cm-3; 0.1 g cm-3) 1. The density of air is separately calculated 2. These six forms of water substances interact mutually 3. Four continuity equations for the water substances 4. The equivalent radar reflectivity factors for hail and rain are computed on the equations given by Smith et al., (1975) and empirical equation for snow by Sekhon and Srivistava (1970) 5.

  13. MICROPHYSICS (CONTINUE) 1. 2. 3. 4. where Are the mixing ratios for cloud water, cloud ice, rain, hail and snow and water vapor, respectively 5.

  14. MICROPHYSICS (CONTINUE) Kh is the eddy heat diffusion coefficient Km is the eddy momentum diffusion coefficient 1. UR, UG and US are terminal velocities for rain, graupel and snow; PR, PG and PS are production terms 2. 3. Allow coexistence of cloud water and cloud ice in the temperature region of - 40C to 0C Hsie et al. (1980) 4. Condensation and deposition of water vapor produce, cloud water and cloud ice, respectively 5. Conversly, evaporation and sublimation of cloud water and cloud ice maintain saturation

  15. MICROPHYSICS (CONTINUE) Natural cloud ice is initiated by using a Fletcher-type equation for the ice nuclei number concentration 1. Bergeron-Findeisen process transforms some of cloud water into cloud ice, and both into snow 2. Rain is produced by the autoconversion of cloud water, melting of snow and hail, and shedding during wet growth of hail 3. Hail is produced by the auto-conversion of snow, interaction of cloud ice and snow with rain, and by immersion freezing of rain 4. Snow may by produced by the auto-conversion, Bergeron-Findeisen growth of cloud ice, and interaction of cloud ice and rain 5. All types of precipitation elements grow by different forms of accretion

  16. MODEL CHEMISTRY 1. Model chemistry is formulated in terms of continuity equations concentration of the i-th pollutant expressed through mixing ratio in the air, cloud water and cloud ice by ( ) rain( ), graupel or hail ( ) and snow ( ) 2. 3. 4. 5. 6.

  17. MODEL CHEMISTRY SUBGRID CONTRIBUTION 1. REDISTRIBUTION TERMS INDUCED BY MICROPHYSICS CONVERSION PROCESSES 2. GIVEN BY (17) WHERE IS THE RATE OF MICROPHYSICS TRANSFORMATION DERIVED FROM MIC.SCHEME 3. CHEMICAL TRANSFORMATIONS TERMS 4. FALLOUT TERMS (18) 5. During transformation water “w” is considered to lose mass while “i” to gain mass

  18. MASS TRANSFER BETWEEN GAS AND LIQUID PHASES • Absorption of gas phase is determined: • Equilibrium according to Henry’s law; • Mass transfer limitation calculation 1. Gases, (with an effective Henrys law constant 2. in cloud water and rain are assumed to be in equilibrium with the local gas-phase concentrations These liquid-phase concentrations of each chemical component (i) are calculated according to Henry’s law; i.e. 3. Where [i] is in mol i/L H2O (M); KH Henry’s law coefficient (M atm-1); pi partial pressure of the Species “i” given in units atm. 4.

  19. MASS TRANSFER BETWEEN GAS AND LIQUID PHASES All equilibrium constants and oxidation reactions are temperature dependent according to van’t-Hoff’s relation 1. where H increase of enthalpy induced by chemical reactions, KT0 is the equilibrium constant at standard temperature and R 2. However, a chemical species not attain equilibrium on the time scale of cloud model due to the slow mass transfer between phases. In that case a fully kinetic calculation of gas dissolution in cloud drops and raindrops is applied in the model 3. 4. Where qd,i,a is the rate of molar mixing ratio of gas species inside dropswith diameter to that in the air; KH* effective Henrys’s law coefficient; Dg,I diffusivity of gases “i”, P partial pressure; Nsh,i mass ventilation index;  factor as function of Knudsen number; yi sticking coefficient 5.

  20. MASS TRANSFER BETWEEN CLOUD HYDROMETEORS After dissolution into cloud water and rain follows: transfer of a soluble compound through microphysical processes 1. The present model includes: frezing transport mechanism of chemical species 2. It is assumed that dissolved compounds are retained during conversion of liquid drops to frozen hydrometeors 3. Melting of ice, snow or hail transfer the dissolved matter to cloud water and rain 4. During sublimation of hail and snow, dissolved scalar is retain in the hail or snow unless all hydrometeor mass is converted to gas phase 5.

  21. SULFATE CHEMISTRY PARAMETERIZATION The chemistry module includes sulfate chemistry from (Taylor, 1989) both inside and outside clouds 1. The absorbtion of chemical species from the gas phase into cloud water and rain is determined: Hentry’s law equilibrium (Taylor, 1989), or Diffusion limited mass transfer (Barth et al., 2001) 2. Equilibrium constants and oxidation reactions are temperature dependent, van’t-Hoff relation (Seifeld, 1986) 3. 4. The model includes a freezing transport mechanizm of chemical species (Rutledge et al. 1986); i.e. water from one hydrometeor class is transferred another, The dissolved chemical scalar is tranaferred to the destination hydrometeor in proportion to the water mass that was transferred 5.

  22. SCHEMATIC OF MICROPHYSICS AND CHEMISTRY-RELATED CONVERSIONS FOR SO4-2 IN AIR AND IN DIFFERENT WATER CATEGORIES

  23. SCHEMATIC OF MICROPHYSICS- AND CHEMISTRY-RELATED CONVERSIONS FOR H2O2, SO2 AND O3 IN AIR AND IN DIFFERENT WATER CARRIERS

  24. SULFATE CHEMISTRY PARAMETERIZATION Cloud water and rainwater pH is calculated using the charge balance equation from (Taylor, 1989)

  25. BOUNDARY CONDITIONS Boundary conditions are specified along all sides of the integration domain since the computations take place within a finite model domain 1. Along the bottom of the model domain the normal velocity w is set to zero 2. The open top boundary condition is applied in the model in order to eliminate strong internal gravity waves (Klemp and Durran, 1983) 3. The lateral boundaries are open and time-dependant, so that disturbances can pass through with minimal reflection 4. Two different cases with regard to the wind velocity are considered, after Durran [1981] 5.

  26. BOUNDARY CONDITIONS When the velocity component normal to the boundary is directed inside the domain (inflow boundary), normal derivatives are set to zero 1. At outflow boundaries, the normal velocity component is advected out through the boundary with an estimated propagation speed which is averaged in the vertical, and weighted at each level by the approximate local amplitude of the wave 2. Boundary conditions for the pressure are calculated from other boundary values to maintain consistency 3.

  27. NUMERICAL TECHNIQUES Model equations are solved on a standard spatially staggered grid 1. All velocity components are defined at one-half grid interval , while scalar variables are defined at the mid point of each grid 2. The horizontal and vertical advection terms are calculated by centered fourth- and second-order differences, respectively 3. Since the model equations are compressible, a time splitting procedure is applied to achieve numerical efficiency 4. With this procedure the sound wave terms are solved separately using a smaller time step, while all other processes are treated with a larger time step , which is appropriate to the time scales of physical interest. 5.

  28. NUMERICAL TECHNIQUES The scalar prognostic equations, except the pressure equation, are solved from t-t to t+tby a single leap-frog step 1. The terms which are not responsible for sound wave generation in the equations of motion and the pressure equation, are evaluated at the central time level t 2. Wind and pressure prognostic variables are stepped forward from t-t to t+t with forward time differencing with the small time step 3. In grid points adjacent to lateral boundaries, the normal horizontal advection terms are approximated using second-order differences instead of the fourth-order ones used elsewhere 4. At lateral boundaries the normal derivatives for all prognostic variables are calculated with first-order accuracy, through one-sided differences lagged at time to provide stability 5.

  29. NUMERICAL TECHNIQUES-CHEMISTRY The model chemistry also included the time splitting procedure, using ratios of the time step n1, n2, n3, n4 and n5 of a given process (e.g., advection, subgrid scale, microphysical, the dissociation, oxidation or other aqueous phase reaction term) to the base time step Dt, Wang and Chang (1993a) 1. The advection scheme for chemicals is mainly based on Bott (1989), using nonoscillatory method by Smolarkiewicz and Grabowski (1990) 2. More detailed information about the cloud model and the chemistry submodels could be found in studies by Telenta and Aleksic (1988) and Spiridonov and Curic (2003,2005,2006) 3.

  30. MODEL INITIALIZATION Initial impulse for convection is an ellipsoidal warm bubble of the form 1. for 2. where 3. Here, the subscript c refers to the location of the center of the perturbation 4. 5. While x*, y*, z* are radial dimensions of the bubble

  31. THE MAIN MOTIVATION OF THE STUDY • CONVECTIVE PROCESSING OF TRACE GAS SPECIES AND AEROSOLS IS AN IMPORTANT MEANS OF MOVING CHEMICAL CONSTITUENTS RAPIDLY BETWEEN THE BOUNDARY LAYER AND FREE TROPOSPHERE, AND IS ALSO AN EFFECTIVE WAY OF CLEANSING THE ATMOSPHERE THROUGH WET DEPOSITION. • BECAUSE OF THESE TWO PROCESSES, THE EFFECT OF CONVECTION ON CHEMICAL SPECIES AND AEROSOLS IS CRITICAL TO OUR UNDERSTANDING OF CHEMISTRY-CLIMATE STUDIES, AIR QUALITY STUDIES, AND THE EFFECTS OF ACIDIC PRECIPITATION ON THE EARTH'S SURFACE. • IT IS INTERESTING TO STUDY THE IMPACTS ON PHYSICAL AND CHEMICAL PROPERTIES OF CONVECTIVE CLOUDS FROM THE TROPICAL-VS-MID-LATITUDE CONTRAST IN INSTABILITY AND HUMIDITY OF THE ENVIRONMENT. • IT IS ALSO IMPORTANT TO ANALYSE THE RELATIVE IMPORTANCE OF SCAVENGING, OXIDATION AND ICE PHASE PROCESSES IN SULFATE PRODUCTION AND WET REMOVAL IN SUCH TYPE OF CLOUDS.

  32. MODEL INITIALIZATION Continental environemnt Tropical environment

  33. THERMODYNAMIC PARAMETERS

  34. INITIALIZATION OF CHEMICAL SPECIESINCLUDED IN SULFATE PRODUCTION

  35. PHYSICAL PROPERTIES OF CLOUDS

  36. MICROPHYSICAL PROPERTIES OF CLOUDS

  37. RAINFALL AND RADAR REFLECTIVITY

  38. DISTRIBUTION OF CHEMICALS

  39. pH-FACTOR

  40. THE MEAN TRANSFER RATES OF THE MICROPHYSICAL PROCESSES AVERAGED OVER 2 H SIMULATION PERIOD

  41. THE MEAN CHEMICAL CONVERSION RATES OF SULFATE (KG KG-1 S-1) AVERAGED OVER 2H SIMULATION PERIOD (POLLUTED BACKGROUND)

  42. THE MEAN CHEMICAL CONVERSION RATES OF SULFATE (KG KG-1 S-1) AVERAGED OVER 2 H SIM. PERIOD (NON-POLLUTED BACKGROUND)

  43. SULFUR INTEGRATED CLOUD BASE FLUX AND PRECIPITATION MASS

  44. THE REL. CONTRIBUTION IN (%) OF THE TOTAL SULFUR MASS REMOVED BY WET DEPOSITION FOR MID-LATITUDE COTINENTAL AND TROPICAL NON-POLLUTED AND POLLUTED BACKGROUND

  45. RELATIVE CONTRIBUTION (CONTINUE) overestimate underestimate

  46. SULFATE AEROSOL AND CLOUD -TROPICAL CASE

  47. CLOUD +SULFATE AEROSOLS (CONT. CASE)

  48. COMPARATIVE ANALYSIS RADAR REFLECTIVITY-CONTINENTAL CASE

  49. COMPARATIVE ANALYSIS RADAR REF. AND RAINFALL-TROPICAL CASE

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