Tropical convection and precipitation over the equatorial pacific ocean are key elements of the entire planets climate system

The National Oceanic and Atmospheric Administration awarded Colorado State University $762,266 under the Climate and Atmospheric Research program (CFDA 11.431) on September 1, 2026, to deploy a dual-polarimetric sea-based precipitation radar during the TEPEX-C field experiment in the equatorial Pacific Ocean.

Colorado State University's Sea-POL radar will be deployed aboard the NOAA Ship Ronald H. Brown to collect three-dimensional observations of cloud and precipitation structure inside convective systems over open ocean. The radar dataset will support microphysical and kinematic characterization of tropical convection and precipitation, with processing to generate high-fidelity spatial maps of precipitation rate. A multi-institutional team of tropical and radar meteorologists will collect and quality-control the novel dataset, enabling observationally based analysis of connections between rainfall and ocean surface salinity changes. Work is performed in Fort Collins, Colorado, with a period of performance from September 1, 2026, through August 31, 2028.

Where and when convection forms over the pacific can impact weather all over earth. Decades of increasingly advanced in situ and remote sensing observations have yielded valuable insights about the structure of convective systems and the variability of precipitation in the tropics. However, many of the processes that govern the development of convection are not well understood, largely because observing them is difficult. As a result, these processesand their global impactsare still not well represented in weather and climate prediction systems. Moist convection occurs ubiquitously on spatial scales smaller and time frames shorter than modern satellite observations can detect, plus few satellite observations of convection are able to reveal detailed information about structures inside clouds. However, surface-based precipitation radarswhile limited in the area they can observecan sample three-dimensional volumes inside clouds and precipitation every few minutes and on grids of tens to hundreds of meters. Therefore, they are a critical tool for understanding how clouds and precipitation play a role in the coupled ocean-atmospheric system over the pacific. For this project, colorado state universitys sea-POL radar will be deployed on the NOAA ship ronald h. Brown during the tepex-c field experiment. This dual-polarimetric radar is specially designed for deployment on sea-faring research vessels and is capable of providing important microphysical and kinematic observations inside clouds. A diverse, multi-institutional team of tropical and radar meteorologists will collect and quality control a novel radar dataset for the open ocean in the equatorial pacific. High fidelity spatial maps of precipitation rate will also be produced from the data, permitting more observationally based connections between rainfall and changes in ocean surface salinity. The radar will operate around the clock during the cruise, allowing IT to sample diurnal variability in cloud properties and precipitation. Synergy with other ship and satellite observations will help connect the cloud structures and precipitation observed by the radar to surface and boundary layer variability on time scales as short as diurnal and as long as subseasonal. The observations collected by sea-POL will provide one piece of critical information about what promotes precipitation and how ocean surface and rainfall from moist convection interact and feed back onto one another. As part of tepex-c, sea-POL will directly support noaas precipitation prediction grand challenge (ppgc) and future efforts to improve weather and climate prediction as IT will provide insight into critical microphysical, boundary layer, and convective processes that are not well represented in modern numerically integrated or neural network prediction systems.