TIME-SLICE: Developing observation techniques for estimating convective mass flux through rapid, adaptive sampling 

While understanding convective processes is critical for prediction of severe weather and cloud properties, observing convective mass flux at convective-scales is difficult using traditional techniques. The NASA INvestigation of Convective UpdraftS (INCUS) mission will quantify convective mass flux from a convoy of three Ka-band radars using a unique time-differencing approach. In order to develop the necessary observational approaches to calibrate and validate the INCUS products, preliminary testing was performed using data collected under the umbrella of the Testing of INCUS Measurements Experiment - Suborbital preLaunch Investigation of Convective Evolution (TIME-SLICE) campaigns. The focus of TIME-SLICE is to leverage existing and low-cost instruments to experiment with rapid sampling of ground assets to derive vertical motions and reflectivity time differences. TIME-SLICE Colorado (TIME-SLICE-CO) was conducted in the northern Front Range of Colorado during the summer of 2024. During the two months of intensive operations, the Colorado State University CHIVO C-band radar scanned convection using the Multisensor Agile Adaptive Sampling (MAAS) framework, which uses ancillary information to select and follow targets of interest and then scan with RHIs with 30 s frequency. Additionally, a site with multiple frequencies of vertically pointing radars and ground instruments collected continuous data. Lessons learned from this preliminary testing highlighted the need for both priority sampling over the ground site by MAAS as well as larger coverage of convection by multiple scanning radars to broaden the coverage of vertical velocity retrievals and account for horizontal advection. Building on the lessons from TIME-SLICE-CO, a follow-on campaign was held in North Alabama during summer 2025. TIME-SLICE Alabama (TIME-SLICE-AL) extends the objectives of TIME-SLICE to the variety of convection in the Alabama region while employing novel phased-array radar (PAR) sampling in concert with a high concentration of pre-existing instruments. In TIME-SLICE-AL, two X-band PARs, the Stony Brook University (SBU) SKYLER-2 radar and the SBU ROARS radar, were positioned alongside The University of Alabama in Huntsville (UAH) C-band ARMOR radar, operating in a rapid (30-second) RHI mode, all coordinated within the MAAS to autonomously sample a large number of convective clouds. Additionally, novel 3D observations of updrafts were collected by tilting the SKYLER PAR vertically. These innovative new sampling techniques and combined observations allow for rapid quantification of radar reflectivity time differences coincident with Doppler-derived vertical motion estimates, and the development of a large, rich case database. Further, existing assets deployed at the UAH Severe Weather Institute and Radar & Lightning Laboratories site, including a disdrometer and the new Ka Profiling Radar (KaPR), and at the nearby US Department of Energy ARM Mobile Facility 3 in the Bankhead National Forest, provide additional context to the primary radar observations. In this presentation, we will provide an overview of the TIME-SLICE-CO and -AL campaigns, present several of the cases captured, highlight some of the early novel science results, and apply the knowledge gained to the validation efforts for the INCUS mission.