The Effects of Vertical Grid Resolution on the Representation of a Convective Environment

Abstract:

In a pre-convective environment, modeled atmospheric conditions can be presented as discrete indices, which serve as valuable resources both in forecasting potential severe weather events and also in assessing changes in convective potential over time. However, the value of these indices may depend on the vertical resolution of the simulation that is used to do the calculation. Upper-air radiosonde sounding data from various research campaigns (e.g., PECAN, DC3, TRMM-LBA, etc) in both midlatitude and tropical convective regimes are analyzed and later interpolated to the pressure levels in a range of atmospheric reanalysis and operational models. Indices such as CAPE, CIN, bulk shear, and strength of capping inversion are then calculated using both the raw sounding and the interpolated soundings. Not surprisingly, results show that the degraded vertical resolution of the model impacts these indices. This presentation will quantify just how much the indices are impacted, and how the model bias changes in different convective regimes. As operational soundings are rarely representative of the convective environment, we need model soundings to investigate convective potential; implications of biases caused by varied vertical resolutions will be discussed in this context.