ORE Seminar: Relating Marine Boundary Layer to Surface Layer Stratification

November 10, 3:30pm - 4:30pm
Mānoa Campus, Zoom Meeting, Please see description for Meeting ID and Passcode

We live in the layer of the atmosphere that extends upward from the ground to a typical height of 1 km. This lower portion of the atmosphere interacts with the ocean and exchanges gas and heat which drives the weather and climate. Datasets describing the lower portion of the atmosphere in the open ocean are sparse. We are motivated to fill this data gap by proposing a marine atmospheric boundary layer state indicator (MABL-SI). The MABL-SI detects stable, near stable, and unstable MABL states, depending on the synthetic aperture radar (SAR) image texture and spectral information from a large catalog of high resolution (5 m) Sentinel-1 SAR images (20x20 km) globally. In particular, we use image texture classification scores from a machine learning algorithm (convolutional neural network) to indicate the three MABL states. The three classes are roughly defined as images that lack any signature of surface wind variability, cases of evident wind streaks, and 3D variation attributed to microscale convection. The bulk Richardson number (Ri) derived from collocated ERA5 surface analyses provides a reference to compare our MABL-SI estimates. Using both Sentinel-1 satellites for 2016-2019, we discriminate between unstable (Ri<-0.012), near neutral (-0.012-0.002) relative to ERA5. The regional patterns of MABL states between ERA5 and independent observations from SAR are strikingly similar and change between unstable and near neutral stability at seasonal and basin scales is clearly resolved by Sentinel-1. The S-1 MABL-SI is a new satellite-based indicator of the MABL stability that has implications for weather modeling, air-sea interaction research, and gridded air-sea flux products. This seminar will be given by Dr. Justin Stopa, Assistant Professor in the Department of Ocean and Resources Engineering. Zoom Meeting ID: 935 9608 7383, Passcode: OREseminar


Event Sponsor
Ocean and Resources Engineering, Mānoa Campus

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