Sea surface temperature (SST) anomalies at 140 w affect societally and economically relevant seasonal and subseasonal precipitation in the continental US

The National Oceanic and Atmospheric Administration (NOAA) awarded Oregon State University $908,709 under the Climate and Atmospheric Research program (CFDA 11.431) on September 1, 2025, to conduct oceanographic and atmospheric observations in the equatorial Pacific Ocean at 140°W. The project, which runs through August 31, 2028, will generate detailed measurements of the vertical structure of wind, temperature, and moisture in the free troposphere, as well as profiles of turbulent kinetic energy and vertical fluxes of momentum, temperature, and humidity through the marine atmospheric boundary layer (MABL). These observations will document how sea surface temperature anomalies at 140°W are communicated through the atmospheric boundary layer via deep mixing processes and transmitted northward over strong sea surface temperature gradients, ultimately influencing Northern Hemisphere winter storm tracks and precipitation patterns relevant to continental U.S. weather prediction.

The project will employ rawinsonde observations, Doppler lidar, and Raman lidar instrumentation deployed from a research vessel to measure atmospheric and turbulent processes across the region between the equatorial cold tongue and the intertropical convergence zone. Through partnership with Universität Hohenheim (sub-awarded funding on February 3, 2026), the project contributes to the TEPEX-E (Tropical Eastern Pacific Exploration) research initiative focused on stratification processes over the cold tongue. The observational data and process-level understanding generated will support improved subseasonal and seasonal precipitation forecasting for the United States by clarifying the atmospheric mechanisms through which remote equatorial Pacific Ocean conditions influence continental weather systems.

Equatorial pacific ocean winds change ocean thermocline depth. Unlike further east, the thermocline at 140 w is deep and disconnected from the surface mixed layer, so diurnal-subseasonal variations of currents communicate the thermocline depth variations to the surface through deep mixing. The marine atmospheric boundary layer (mabl) conducts thermal and humidity anomalies from the ocean to deep atmospheric convection. Deep atmospheric convective heating from warm SST anomalies modifies the northern hemisphere winter storm track and US precipitation. Summary of work to be completed: this project proposes to make observations of the vertical structure of wind, temperature, and moisture in the free troposphere, and the profiles of turbulent kinetic energy (TKE), vertical fluxes of momentum, temperature, and humidity through the mabl near the equator at 140 w. The mabl blows northward over strong SST gradients, over a distance easily traversed by a research vessel. The gradients modulate atmospheric horizontal and vertical fluxes of moisture and temperature. The project will make rawinsonde observations of the wind, temperature, humidity of the troposphere, between the equatorial cold tongue and the northern intertropical convergence zone (itcz). IT will also continuously measure mean wind profiles with doppler lidar, and turbulent-scale eddies of temperature, humidity, and vertical wind in the mabl with raman and doppler lidar. The project will observe horizontal transports in the mabl, and the vertical and turbulent processes and fluxes responsible for them.