The Great Plains Irrigation Experiment—Grainex

In the spring and summer of 2018, two intensive observation periods were conducted in Southeastern Nebraska by the National Center for Atmospheric Research Earth Observing Laboratory (EOL) and the Center for Sever Weather Research (CSWR), NASA's Hydrological Sciences Laboratory and a group of research universities. The objective of the experiment was to obtain an expansive observational data set to investigate the impact of irrigation on land-atmosphere coupling, particularly the diurnal planetary boundary layer evolution, outflow boundary development and evolution, and cloud and precipitation development. Southeastern Nebraska was chosen for its sharp gradient in applied irrigation across the Big Blue River region. The domain is one of the most heavily irrigated regions of the world thanks to the Ogallala Aquifer.

Observing platforms consisted of:

• Two Integrated Sounding System units from EOL to sample the evolution of the boundary layer over the irrigated and non-irrigated regions.
• Twelve Integrated Surface Flux Stations from EOL were deployed in both irrigated and no-irrigated portions of the domain for the collection of land surface conditions and lower atmospheric meteorology.
• Three Doppler on Wheels were deployed from CSWR to establish a domain of dual Doppler observations that straddle the transition zone between the irrigated and non-irrigated regions.
• NASA flew the L-band GREX instrument during the second observation period to obtain spatial heterogeneous and high-resolution soil moisture estimates over the domain.
• A dense network (75 stations) of UAH Environmental Monitoring, Economical Sensor Hubs (EMESH) stations were deployed to acquire meteorology, soil moisture and soil temperature observations.
• Radiosondes were released from the Doppler on Wheels and Sounding System sites every 2 hours from roughly sunrise to sunset.

The authors will present an overview of the experiment, observational results, preliminary modeling studies, and future plans of analysis.