10-Year Warm-Season Doppler Radar Climatology of Horizontal Convective Rolls and Cellular Convection in Central Oklahoma

Horizontal convective rolls (HCRs) and cellular convection (cells) are observed frequently within the convective boundary layer, yet a large data base of HCR and cell events spanning several years has not been previously available to researchers. This data set corrects this gap. Daily information on HCRs and cells from the warm season (April-September) months of 2008 to 2017 have been created over central Oklahoma and are provided in an easy to use Excel spreadsheet. Doppler radar observations from the Twin Lakes (KTLX), Oklahoma, WSR-88D are used to determine the start and end times of HCRs and cells for each day during these 10 years. The start and end times were determined by visual inspection of animated loops of a 1.4 degree elevation angle plan position indicator (PPI) display of radar reflectivity observations between 1200 and 0000 UTC each day. Even in clear air conditions, WSR-88D observations are available roughly every 10 min, providing high temporal sampling of the atmosphere near the radar. There are 1830 days during this 10-year warm-season period and KTLX observations are available on 1807 days. Of these 1807 days, HCRs and/or cells are observed on 1382 days as discussed in Banghoff et al. (2020), with the majority of the days without HCRs and/or cells being days with precipitation. In addition to the start and end times of HCRs and cells, and their transitions, KTLX observations from 2013-2017 are used to determine HCR and cell wavelengths and aspect ratios and HCR orientation angles. Only data from 2013 onward are used for these more detailed analyses owing to the availability of dual-polarization observations starting in 2013 which allow for the estimation of convective boundary layer depth (see Banghoff et al. 2018). An analysis of these data is presented in Banghoff et al. (2020) that includes a careful analysis of the frequency of HCRs and cells, their duration, wavelengths, aspect ratios, and HCR orientation angles. These results are compared to those from earlier studies to set the 10-year climatology into context. With such a lengthy and rich data set, we expect that others will benefit from the daily information on HCRs and cells created as part of our research studies.