Cloud microphysics

Lohmann U, Roeckner E (1996) Design and performance of a new cloud microphysics scheme developed for the ECHAM4 general circulation model. Clim Dyn 12 557-572 Mackay D (1991) Multimedia Environmental Models The Fugacity Approach. Lewis Publishers, Chelsea, MI, USA... 

Albrecht, B. A., "Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, 245, 1227-1230(1989). 

Eichel, C., M. Kramer, L. Schiitz, and S. Wurzler, The Water-Soluble Fraction of Atmospheric Aerosol Particles and Its Influence on Cloud Microphysics, J. Geophys. Res., 101, 29499-29510 (1996). 

Albrecht BA (1989) Aerosol, cloud microphysics, and fractional cloudiness. Science 245 1227-1230... 

Brenguier J.-L. Pawlowska H. and Schuller L. (2003). Cloud microphysical and radiative properties for parameterization and satellite monitoring of the indirect effect of aerosol on climate. J. Geophys. Res., 108(D15), CMP6/1-CMP6/14. 

R. Bourayou, G. Mejean, J. Kasparian, M. Rodriguez, E. Salmon, J. Yu, H. Lehmann, B. Stecklum, U. Laux, J. Eisloffel, A. Scholz, A. P. Hatzes, R. Sauerbrey, L. Woste, J.-P. Wolf, White-light filaments for multiparameter analysis of cloud microphysics, Journal of the Optical Society of America 22, 369 (2005)... 

For the realization of all aerosol forcing mechanisms in integrated systems it is necessary to improve not only ACTMs, but also NWP/MetMs. The boundary layer structure and processes, including radiation transfer, cloud development and precipitation must be improved. Convection and condensation schemes need to be adjusted to take the aerosol-cloud microphysical interactions into account, and the radiation scheme needs to be modified to include the aerosol effects. 

All these models predict gases, aerosols, and clouds with varying degrees of complexities in chemical mechanisms and aerosol/cloud microphysics. The history and current status of these models along with other relevant models are reviewed below. 

Improvement of NWP itself by implementation of ACTMs and aerosol/gases forcing/feedback mechanisms into HIRLAM (mostly by online integration, like in Enviro-HIRLAM) as well as by further development of the radiation and cloud microphysics modules to introduce feedback mechanisms. 

For simulation of the aerosol (especially anthropogenic) effects more detailed microphysics in HIRLAM is needed, in the former version it is very difficult to consider all the aerosol indirect effects. The current STRACO (Soft TRAnsition condensation) scheme in HIRLAM (Sass 2002) needs modifications and gives a possibility of developing simpler indirect mechanisms. One of such feedback semi-empirical model was developed in Enviro-HIRLAM by Korsholm et al. (2008b). The new AROMA/HARMONIE cloud scheme (Pinty and Jabouille 1998 Caniaux et al. 1994) is more suitable for implementation of aerosol dynamics and indirect effects of aerosols (CCN) models, but will be more expensive computationally. So, the main focus of our collaboration in this field should be in the improvement of the cloud/microphysics and radiation schemes in HIRLAM. 

At the moment the cloud microphysics-aerosol interaction is included in HIRLAM in a very simple way in the convection schemes, where the cloud condensation nuclei have a lower concentration than over land. Enviro-HIRLAM includes the aerosol dynamics and their indirect effects on meteorology. The use of aerosol may also be prepared by making a 3D field of aerosol that has the characteristics of the currently prescribed values, then the extension to a real 3D distribution of aerosols that can interact with the microphysics is relatively straightforward. Sensitivity studies are needed to understand the relative importance of feedbacks. First experience of Enviro-HIRLAM indicates some sensitivity to effective droplet size modification in radiation and clouds. 

Processes needed aerosol activation/resuspension, cloud microphysics, and hydrometeor dynamics... 

Reduced availability of SO2 would reduce the formation rate of new particles. Further studies are needed to elucidate the combined effect of these reactions of cloud microphysics and radiative forcing. Regions that cloud be affected most by these changes are the large regions of marine stratocumuli, especially the tradewind systems. 

Borensen C, Kirchner U, Scheer V, Vogt R, Zellner R (2000) Mechanism and kinetics of the reactions of NO2 or HNO3 with alumina as a mineral dust model compound. J Phys Chem A 104 5036-5045 Borys RD, Lowenthal DH, Mitchell DL (2000) The relationships among cloud microphysics, chemistry, and precipitation rate in cold mountain clouds. Atmos Environ 34 2593-2602 Bowles RK, McGraw R, Schaaf P, Senger B, Voegel JC, Reiss H. (2000) A molecular based derivation of the nucleation theorem. J Chem Phys 113 4524-4532... 

Water is probably the most important and the most intensely studied substance on Earth. It is the solvent of life and it is also of vital importance in many aspects of our existence, ranging from cloud microphysics to its key role as a solvent in many chemical reactions. The familiar process of water freezing is encountered in many natural and technologically relevant processes. In this contribution, we discuss the applicability of the methods of computational chemistry for the theoretical study of two important phenomena. Namely, we apply the molecular dynamics (MD) simulations to the study of brine rejection from freezing salt solutions and the study of homogeneous nucleation of supercooled water. 

Ervens B., G. Feingold, S. L. Clegg and S. M. Kreidenweis A modeling study of aqueous production of dicarboxyUc acids 2. implications for cloud microphysics., J. Geophys. Res. [Atmos.], 109 (2004) D15, D15206/15201-D15206/15212. 

For a given environment and given entrainment rate e, we need one more equation to close the system, namely, an equation describing the liquid water mixing ratio wL of the drop population. This liquid water content can be calculated if the droplet size distribution is known, such as a simple integral over the distribution. We thus need to derive differential equations for the droplet diameter rate of change dDp/dt. These equations will link the cloud dynamics discussed here with the cloud microphysics discussed in the following sections. 

Also, we take pdep = 0.22. Finally, values of pe ranging from - to 1.0 have been assumed. Essentially, p6 is very uncertain because the cloud microphysics is unknown. Using the above values show that... 

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