February 20, 2025
Journal Article

Examining future changes in coastal low-level jet properties offshore California through dynamical downscaling

Abstract

The coastal low-level jet, or CLLJ, is a synoptically-forced meteorological feature frequently present offshore the western United States (U.S.). Characterized by a wind speed maximum that resides at the top of the marine boundary layer, the CLLJ is largely controlled by the location and strength of the North Pacific High (NPH) as well as the coastal geometry. Considering the rich wind resource available in this offshore region, the U.S. Department of Energy identified wind energy lease areas offshore California and deployed two wind lidar buoys near Morro Bay and Humboldt. Despite our relatively good understanding of the fundamental mechanisms responsible for large-scale CLLJ properties offshore the western U.S., future changes in CLLJ characteristics are less clear. To address this research challenge, and ultimately to better inform future wind turbine deployments, we use dynamically downscaled simulations of three global climate models (GCMs). The self-organizing map technique is applied to the model outputs for a historical and two future climate periods to show the range of NPH regimes that support CLLJ conditions during the warm seasons as well as the subtle contribution from land-falling cyclones approaching the mainland during the cold seasons. Compared to the historical period, the three downscaled GCMs agree that CLLJ conditions will become more (less) prevalent from central California northward (southward). Less agreement is found with respect to future changes in maximum CLLJ wind speeds and CLLJ heights. However, after considering model biases present during the historical period, wind speeds between the models are actually more similar during the 2070-2095 period than during the historical period. The potential combination of more frequent CLLJ conditions characterized by relatively consistent wind speeds occurring at lower heights across northern California suggests that the Humboldt lease area may be ideal for a long-term wind turbine deployment.

Published: February 20, 2025

Citation

Juliano T., S. McGinnis, S. McGinnis, M.S. Bukovsky, Y. Liu, T. Brummet, and S.E. Haupt, et al. 2025. Examining future changes in coastal low-level jet properties offshore California through dynamical downscaling. Environmental Research Letters 20, no. 3:Art. No. 034023. PNNL-SA-199511. doi:10.1088/1748-9326/adb16b

Research topics