Impacts of irrigated and non-irrigated land use on convective environments and related diagnostic variables during GRAINEX in Nebraska, USA

Authors: WHITESEL, DANIEL - University Of Nebraska; MAHMOOD, REZAUL - University Of Nebraska; Flanagan, Paul; PHILLIPS, CHRISTOPHER - University Of Alabama; PIELKE SR, ROGER - University Of Colorado; NAIR, UDAYSANKAR - University Of Alabama; RAPPIN, ERIC - Western Kentucky University

Submitted to: Journal of Hydrometeorology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2025
Publication Date: N/A
Citation: N/A

Interpretive Summary: While the knowledge gap into the impacts of the surface on the atmosphere are becoming more well known due to ongoing research, gaps still exist especially when it comes to observed impacts. Using data from a field campaign in Nebraska, this study computed numerous atmospheric metrics related to convection. The goal of this study was to quantify the impacts of irrigation and a transition from irrigation to non-irrigated crops on the convective environment. The results of this study show that irrigation caused an environment more favorable for convection on most days, particularly when irrigation was at its peak during the later portion of the field campaign. Overall, this work presents a first of its kind investigation into the impacts of irrigation on the convective environment using a field based observed data with a high number of observed data points per day.

Technical Abstract: Land use land cover change (LULCC) caused by irrigation impacts weather and climate. The Great Plains Irrigation Experiment (GRAINEX) aims to understand the impacts of irrigated and non-irrigated land uses on convective environment. To the best of authors’ knowledge, this paper is the first of this type of study that analyzed convective environments over irrigated and non-irrigated land use during early and peak growing seasons under variety of atmospheric conditions, using observed rawinsonde data from GRAINEX and convective diagnostic variables. These variables include CAPE, CIN, mixed-layer CAPE (MLCAPE), mixed-layer CIN (MLCIN), most-unstable CAPE (MUCAPE), most-unstable CIN (MUCIN), Lifted Index, Showalter Index, K-index, Total-Totals index, bulk shear, storm relative helicity, precipitable water (PWAT), dewpoint depression, and environmental lapse rates (ELR) Rawinsonde observations were categorized by, for example, irrigated versus non-irrigated, morning versus afternoon, cloudy versus non-cloudy day, early [Intensive Observation Period 1 (IOP1)] versus peak (IOP2) growing season (when irrigation also become widespread). Irrigated land use and irrigation impacts many of these diagnostic variables. For example, it was found that CAPE and MUCAPE were higher over irrigated land use compared to non-irrigated for most categories. PWAT was found to be higher over irrigated land use, especially during clear days and peak growing season (IOP2) when irrigation is widespread. Dew point depression was lower over irrigated areas and particularly during IOP2. We suggest that LULCC driven by irrigation impacts convective environments and favors convective developments. Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer.