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Seminar: Relating Observed Marine Boundary Layer Cells, Rolls, or Their Absence to Surface Layer Stratification Using Sentinel-1 SAR Data

10 November 2021 @ 3:30 pm - 4:30 pm

SAR images indicating the 3 MABL states

Dr. Justin Stopa
Assistant Professor
Department of Ocean and Resources Engineering
University of Hawai’i at Mānoa

Zoom Meeting Link:
Meeting ID: 935 9608 7383
Passcode: OREseminar
https://hawaii.zoom.us/j/93596087383

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 (20×20 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<Ri<-0.002), and stable (Ri>-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.

 

Seminar: Relating Observed Marine Boundary Layer Cells, Rolls, or Their Absence to Surface Layer Stratification Using Sentinel-1 SAR Data

Details

Date:
10 November 2021
Time:
3:30 pm - 4:30 pm
Event Category:
Event Tags:
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Venue

https://hawaii.zoom.us/j/93596087383
View Venue Website

Organizer

ORE Department
Phone:
1 (808) 956-7572
Email:
adminore@hawaii.edu
View Organizer Website