The NGEE Arctic Rainfall Simulator: Deployment to the Kougarok Fire Complex

In FY 2022, NGEE Arctic researchers at Los Alamos National Laboratory (LANL) developed a rainfall simulator to study the hydrothermal response of permafrost landscapes to discrete rainfall events. During the design phase of NARS, Advanced Terrestrial Simulator (ATS) model simulations were used to estimate ideal rainfall rates and durations to inform rainfall experiments on permafrost landscapes. In September and October of 2022, NARS was deployed to the Kougarok Fire Complex on the Seward Peninsula of Alaska to study soil organic layer interflow discharge rates following a simulated 100-year storm event. During the field campaign, 293 L (48.83 mm) of simulated rain was delivered to a 2 × 3 m plot over 40 min, the equivalent of a 100-year storm event for this region of Alaska. A specially designed flume was used to measure interflow discharge rates from the soil’s organic layer, which was 15 to 20 cm thick, underlain with a confining mineral soil layer, and overlain with well-defined tussocks. Interflow discharge from the organic layer began 6 min after the beginning of the simulation and continued for 68 min after the rainfall ceased. The measured interflow discharge rates, cumulative rainfall, and cumulative discharge are shown in Figure 2. Interflow discharge samples were collected and returned to LANL for geochemical analysis and are currently being processed. Efforts to parameterize ATS for high-resolution modeling of this simulated 100-year storm event are also underway.