Properly parameterizing the effects of convection is still a challenging problem for Numerical Weather Prediction (NWP) applications. There are many different parameterizations for deep and shallow convection that try to make use of the current understanding of the complicated physics and dynamics of convective clouds to express the interaction between the larger scale flow and the convective clouds in simple "parameterized" terms. This "parameterization problem" gets even more complicated as the horizontal resolution in NWP model decreases to scales in which a clear scale separation no longer exists. These "gray scales" for convective parameterizations are scales on which the WRF model will be widely applied.

Finally, the introduction of atmospheric chemistry into NWP models is an additional complication for convective applications, especially if the parameterized treatment of convection is "online". Assumptions that are of lesser importance for meteorological simulations (some up to now maybe totally neglected) could be of great importance for chemistry applications. In a consistent "online" employment, the treatment for both meteorological as well as chemical applications should be the same. While this may require the introduction of more degrees of freedom into the different schemes, it may also be a great opportunity to uncover errors in convective parameterizations that previously were difficult to detect.

In this workshop we will discuss some of the existing meteorological parameterizations of deep and shallow convection. We will also discuss the needs of the atmospheric chemistry community (e.g. mass conservation, parameterization of vertical transport and its sensitivity, wet deposition). Finally ideas with respect to "gray scales"  will be given consideration.