Convective weather is the primary cause of national airspace delay. A significant fraction of these delays is due specifically to en route weather. The most severe en route convective weather delays occur in crowded corridors such as the Great Lakes corridor from Chicago to New York. It is of particular importance within these high traffic regions that traffic managers have access to accurate and realistic en route weather depiction products in order to minimize convective weather delays.

The Corridor Integrated Weather System (CIWS) first began providing en route weather products for the Great Lakes corridor during the 2001 summer storm season. As part of this system, CIWS provides a precipitation product created by converting Level II reflectivity data from several NEXRAD radars to vertically integrated liquid water (VIL). It has previously been demonstrated that weather depictions based upon the complete vertical examination of radar precipitation echoes fundamentally implied by VIL are more representative of actual weather characteristics than depictions based upon composite radar reflectivity. Specifically, VIL provides a more accurate portrayal of convection than composite reflectivity by way of improved mitigation of bright-band contamination and less exaggeration of convective intensity.

The focus of this investigation is to compare the CIWS 1-km VIL precipitation product to the established, widely utilized, Weather and Radar Processor (WARP) 2-km Base-Scan Radar Reflectivity Mosaic (BRRM) product for en route traffic management applications. Similar to comparison results between VIL and composite reflectivity, it is demonstrated that weather depictions in an operational environment based upon VIL are more realistic than WARP base-scan reflectivity mosaics. VIL is less susceptible to radar bright-banding effects than WARP BRRM, thus providing a better representation of the convective weather field. Moreover, WARP BRRM exhibits a tendency to inflate the peak intensity of convection, as base-scan measurements of strong, near-surface convective cores may be unrepresentative to en route traffic managers concerned with high-altitude air traffic. Finally, differences between the representations of convection by each product are quantified in terms of relative impacts on high-altitude jetways. This jetway impact analysis illustrates how VIL characteristics help reduce weather impact false alarms during convective events where functional airspace may already be limited.

* This work was sponsored by the Federal Aviation Administration under Air Force Contract No. F19628-00-C-0002. The views expressed are those of the authors and do not reflect the official policy or position of the U.S. Government. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the US Government.