Effect of Two-Way Air–Sea Coupling in High and Low Wind Speed Regimes

Abstract

A recent advance in the Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) is described and used to study two-way air-sea coupling and its impact on two different weather scenarios. The first case examines the impact of a hurricane-induced cold ocean wake on simulated changes in the structure of Hurricane Katrina. The second case investigates the effect of wind-and current-induced island wakes and their impact on the local electromagnetic (EM) and acoustic propagation characteristics in the Southern California Bight region. In the Katrina case, both the atmosphere and ocean show a strong response from airsea interaction. The model results show that wind-induced turbulent mixing, vertical advection, and horizontal advection are the three primary causes of the development of the trailing cold ocean wake. A distinct spatial separation is seen in these three primary forcing terms that are generating the bulk of the cooling in the ocean mixed layer. An asymmetric tropical cyclone structure change has been documented in detail from a more realistic, full physics, and tightly coupled model. These changes include a broadening of the eye, a reduced radius of hurricane-force wind, and a pronounced inner-core dry slot on the west side of the storm. In the island wake experiment, many finescale variations in the wind, current, and static stability structure resulting from the two-way interaction are described. These variations take the form of narrow vorticity and temperature anomalies that are found to reside in the ocean and atmosphere well downwind from the Channel Islands. Upwind differences in the lower-atmospheric wind and thermal structure also arise and are found to have a small impact on the lee-flow structure and EM characteristics of the southernmost Channel Islands.

Ocean Response to CINDY/DYNAMO MJOs in Air-Sea-Coupled COAMPS

“…Details about the atmospheric model can be found in Hodur (1997) and Chen et al (2003), and the application of the coupled model has been given by Chen et al (2010); Jensen et al (2011). COAMPS was also used in a fully coupled configuration for the simulation of a 2009 MJO event by Shinoda et al (2013a).…”

Tropical Cyclone Prediction Using COAMPS-TC

“…The Coupled Boundary Layer Air-Sea Transfer (CBLAST) field program (Black et al, 2007) processes (e.g., Bao et al, 2000;Bender et al, 2007;Chen et al, 2007Chen et al, , 2010. The coupling to an ocean-circulation model can improve the storm intensity forecast through a more realistic representation of storm-induced cooling in the upper ocean and sea surface.…”

“…The COAMPS-TC system is composed of data quality control, analysis, initialization, and forecast model subcomponents (Doyle et al, 2011) The COAMPS-TC system has the capability to operate in a fully coupled air-sea interaction mode (Chen et al, 2010Doyle, et al, 2011) Charnock parameter (Moon et al, 2004) that is a function of wave age and wind speed. A sea spray parameterization (Fairall et al, 1994(Fairall et al, , 2009Bao et al, 2011) In a seminal study, Powell et al (2003) analyzed data from GPS dropwindsondes deployed from aircraft into hurricanes; they found that the mean wind Both surface drag and sea spray processes play major roles in regulating energy exchange at the air-sea James D. Doyle (james.doyle@nrlmry.navy.mil interface.…”

The UKC2 regional coupled environmental prediction system

“…Pullen et al, 2006Pullen et al, , 2007Chen et al, 2010;Sandery et al, 2010;Warner et al, 2010;Renault et al, 2012;Carniel et al, 2016;Ličer et al, 2016;Bruneau and Toumi, 2016) and operational applications (e.g. Pellerin et al, 2004;Smith et al, 2013;Durnford et al, 2017) to improve the representation of feedbacks in simulations and predictions of the Earth System.…”