Takahashi 구름모형에서의 얼음입자 충돌효율 개선
Implementation of Improved Ice Particle Collision Efficiency in Takahashi Cloud Model
1
조회
0
다운로드
0
인용
0
참고문헌
키워드
초록
The collision efficiency data for collision between graupel or hail particles and cloud drops that take into account the differences of particle density are applied to the Takahashi cloud model. The original setting assumes that graupel or hail collision efficiency is the same as that of the cloud drops of the same volume. The Takahashi cloud model is run with the new collision efficiency data and the results are compared with those with the original. As an initial condition,a thermodynamic profile that can initiate strong convection is provided. Three different CCN concentration values and therefore three initial cloud drop spectra are prescribed that represent maritime (CCN concentration = 300 cm−3), continental (1000 cm−3) and extreme continental (5000 cm−3) air masses to examine the aerosol effects on cloud and precipitation development. Increase of CCN concentration causes cloud drop sizes to decrease and cloud drop concentrations to increase. However, the concentration of ice particles decreases with the increase of CCN concentration because small drops are difficult to freeze. These general trends are well captured by both model runs (one with the new collision efficiency data and the other with the original) but there are significant differences: with the new data, the development of cloud and raindrop formation are delayed by (1) decrease of ice collision efficiency, (2) decrease of latent heat from riming process and (3) decrease of ice crystals generated by ice multiplication. These results indicate that the model run with the original collision efficiency data overestimates precipitation rates.
Abstract
The collision efficiency data for collision between graupel or hail particles and cloud drops that take into account the differences of particle density are applied to the Takahashi cloud model. The original setting assumes that graupel or hail collision efficiency is the same as that of the cloud drops of the same volume. The Takahashi cloud model is run with the new collision efficiency data and the results are compared with those with the original. As an initial condition,a thermodynamic profile that can initiate strong convection is provided. Three different CCN concentration values and therefore three initial cloud drop spectra are prescribed that represent maritime (CCN concentration = 300 cm−3), continental (1000 cm−3) and extreme continental (5000 cm−3) air masses to examine the aerosol effects on cloud and precipitation development. Increase of CCN concentration causes cloud drop sizes to decrease and cloud drop concentrations to increase. However, the concentration of ice particles decreases with the increase of CCN concentration because small drops are difficult to freeze. These general trends are well captured by both model runs (one with the new collision efficiency data and the other with the original) but there are significant differences: with the new data, the development of cloud and raindrop formation are delayed by (1) decrease of ice collision efficiency, (2) decrease of latent heat from riming process and (3) decrease of ice crystals generated by ice multiplication. These results indicate that the model run with the original collision efficiency data overestimates precipitation rates.
참고문헌 (25)
- Andreae, M. O, "Smoking rain clouds over the Amazon", Science, 303, pp.1337~1342 (2004)
- Auer, A. H. Jr., "Observations of ice crystal nucleation by droplet freezing in natural cloud", J. Atmos. Sci., 28, pp.285~290 (1971)
- Beheng, K, "Numerical simulation of graupel development", J. Atmos. Sci., 35, pp.683689~ (1978)
- Berry, E. X, "Cloud droplet growth by collection", J. Atmos. Sci., 24, pp.688~701 (1967)
- Flossmann, A. I., "A theoretical study of the wet removal of atmospheric pollutants. Part 1: The redistribution of aerosol particles captured through nucleation and impaction scavenging by growing cloud drops", J. Atmos. Sci, 42, pp.583~606 (1985)
- Hallet, J., "Production of secondary ice particles during the riming process", Nature, 249, pp.26~28 (1974)
- Hudson, J. G, "Maritime-continental drizzle contrasts in small cumuli", J. Atmos.Sci, 58, pp.915~926 (2001)
- Johnson, D.B, "On the relative efficiency of coalescence and riming", J. Atmos. Sci, 44, pp.1671~1680 (1987)
- Khain, A, "Notes on state-of-the-art investigations of aerosol effects on precipitation: a critical review", Environ. Res. Lett, 4, pp.015004~ (2009)
- Johnson, D.B, A, "Simulation of precipitation formation in the Eastern Mediterranean coastal zone using a spectral microphysics cloud ensemble model", Atmos. Res, 43, pp.77~110 (1996)
- Johnson, D.B, "Some effects of cloudaerosol interaction on cloud microphysics structure and precipitation formation: Numerical experiments with a spectral microphysics cloud ensemble model", Atmos. Res., 52, pp.195220~ (1999)
- Johnson, D.B, "Collision Rate of Small Graupel and Water Drops", J. Atmos. Sci., 58, pp.2571~2595 (2001)
- Klett, J. D., "Theoretical collision efficiencies of cloud droplets at small Reynolds number", J. Atmos. Sci., 30, pp.107~117 (1973)
- Kovetz, A, "The effect of coalescence and condensation on rain formation in a cloud of finite vertical extent", J. Atmos. Sci., 26, pp.1060~1065 (1969)
- Macklin, W. C, "The density and structure of ice formed by accretion", Quart. J. Roy. Meteor. Soc, 88, pp.30~50 (1962)
- Mason, B. J., "On the melting of hailstones", Quart. J. Roy. Meteor. Soc., 80, pp.209~216 (1956)
- Nakaya, U., "Snow Crystals, Natural and Artificial", pp.510~ (1954), Harvard University Press
- Rosenfeld, D., "TRMM Observed First Direct Evidence of Smoke from Forest Fires Inhibiting Rainfall", Geophys. Res. Lett, 26, pp.3105~3108 (1999)
- Shafrir, O, "Collision efficiencies of two spheres falling in a viscous medium", J. Geophys. Res, 68, pp.4141~4148 (1963)
- Takahashi, T., "Hail in an axisymmetric cloud model", J. Atmos. Sci, 33, pp.579~1601 (1976)
- Takahashi, T, "Warm rain, giant nuclei and chemical balance", J. Atmos. Sci, 33, pp.269~286 (1976)
- Ice nuclei relative to formation of hail, "Vali, G.", Stormy Weather Group, McGill University, 51~, pp.Sci. Rept. MW-58, (1968)
- Yang, H. J., "Effects of Cloud Condensation Nuclei on Convective Cloud and Precipitation Developments under Different Thermodynamic Conditions: a Modeling and Observational Study", Atmos. Res, 86, pp.207~224 (2007)
- Yum, S. S, "Maritime", continental microphysical contrast in stratus, 2002, pp.54, 61~73
- Yum, S. S, "Springtime cloud condensation nuclei concentrations on the west coast of Korea", GEOPHYSICAL RESEARCH LETTERS, 32, pp.94~101 (2005), doi : 10. 1029[DOI]