Author: AOML Communications

Performance of an improved TKE-based eddy-diffusivity mass-flux (EDMF) PBL scheme in 2021 hurricane forecasts from Hurricane Analysis and Forecast System. Image of a scientific paper.

Performance of an Improved TKE-Based Eddy-Diffusivity Mass-Flux (EDMF) PBL Scheme in 2021 Hurricane Forecasts from the Hurricane Analysis and Forecast System

Chen, X., Hazelton, A., Marks, F. D., Alaka Jr, G. J., & Zhang, C. (2023). Performance of an Improved TKE-Based Eddy-Diffusivity Mass-Flux (EDMF) PBL Scheme in 2021 Hurricane Forecasts from the Hurricane Analysis and Forecast System. Weather and Forecasting, 38(2), 321-336.

Abstract: Continuous development and evaluation of planetary boundary layer (PBL) parameterizations in hurricane conditions are crucial for improving tropical cyclone (TC) forecasts. A turbulence kinetic energy (TKE)-based eddy-diffusivity mass-flux (EDMF-TKE) PBL scheme, implemented in NOAA’s Hurricane Analysis and Forecast System (HAFS), was recently improved in hurricane conditions using large-eddy simulations. This study evaluates the performance of HAFS TC forecasts with the original (experiment HAFA) and modified EDMF-TKE (experiment HAFY) based on a large sample of cases during the 2021 North Atlantic hurricane season…

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An Improved One-Dimensional Bending Angle Forward Operator for the Assimilation of Radio Occultation Profiles in the Lower Troposphere. Image of scientific paper.

An Improved One-Dimensional Bending Angle Forward Operator for the Assimilation of Radio Occultation Profiles in the Lower Troposphere

Cucurull, L., & Purser, R. J. (2023). An improved one-dimensional bending angle forward operator for the assimilation of radio occultation profiles in the lower troposphere. Monthly Weather Review, 151(5), 1093-1108.

Abstract: Under very large vertical gradients of atmospheric refractivity, which are typical at the height of the planetary boundary layer, the assimilation of radio occultation (RO) observations into numerical weather prediction (NWP) models presents several serious challenges. In such conditions, the assimilation of RO bending angle profiles is an ill-posed problem, the uncertainty associated with the RO observations is higher, and the one-dimensional forward operator used to assimilate these observations has several theoretical deficiencies. As a result, a larger percentage of these RO observations are rejected at the NWP centers by existing quality control procedures, potentially limiting the benefits of this data type to improve weather forecasting in the lower troposphere…

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Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Image of the scientific paper

Observed Relationships Between Tropical Cyclone Vortex Height, Intensity, and Intensification Rate

DesRosiers, A. J., Bell, M. M., Klotzbach, P. J., Fischer, M. S., & Reasor, P. D. (2023). Observed relationships between tropical cyclone vortex height, intensity, and intensification rate. Geophysical Research Letters, 50(8), e2022GL101877.

Abstract: As a tropical cyclone (TC) intensifies, the tangential wind field expands vertically and increases in magnitude. Observations and modeling support vortex height as an important TC structural characteristic. The Tropical Cyclone Radar Archive of Doppler Analyses with Recentering data set provides kinematic analyses for calculation of the height of the vortex (HOV) in observed storms. Analyses are azimuthally-averaged with tangential wind values taken along the radius of maximum winds. A threshold-based technique is used to determine the HOV. A fixed threshold HOV strongly correlates with current intensity. A dynamic HOV metric quantifies vertical decay of tangential wind with reduced dependency on intensity. Statistically significant differences are present between dynamic HOV values in groups of steady-state, intensifying, and rapidly-intensifying cases categorized by subsequent changes in pressure.

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NOAA Corps officers on the bridge of NOAA vessel, Nancy Foster, navigating out at sea.

May 22nd is the NOAA Commissioned Officer Corps (NOAA Corps) 106th Birthday!

The NOAA Commissioned Officer Corps is one of the nation’s eight uniformed services and its officers are an integral part of the National Oceanic and Atmospheric Administration (NOAA). With approximately 330 officers and growing, the NOAA Corps supports nearly all of NOAA’s programs and missions. The combination of commissioned service and scientific expertise makes these officers uniquely capable of leading some of NOAA’s most important initiatives.

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A very large amount of orange/brown seaweed (sargassum) washed up on the coastline.

Extreme climate event in North Atlantic may have kicked off Sargassum explosion a decade ago

When massive mounds of golden-brown seaweed began piling up on beaches throughout the Caribbean and West Africa in summer of 2011, the question of where it came from probably mattered less to residents and businesses than how they were going to get rid of it. Certainly, few would have connected the Sargassum seaweed invasion to the extremely snowy 2010-11 winter in the eastern United States. But according to a hypothesis proposed by a team of NOAA AOML-led scientists in 2020, the two phenomena share an origin story: an extremely strong and long-lasting shift of the North Atlantic Oscillation into its negative phase back in 2010.

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Photo of Sargassum Floating in Open Water. Photo Credit: Credit: NOAA Teacher at Sea Program, NOAA Ship OREGON II Blue economy

Massive bloom of seaweed in tropical Atlantic raises the risk for Caribbean, Gulf, and Florida beach impacts in coming months

Earlier this year, ocean scientists raised an alert about the large amount of seaweed drifting in the tropical Atlantic this spring. Experts warned that the region’s annual spring bloom of Sargassum—a free-floating brown macroalgae from the North Atlantic that suddenly appeared in large quantities in the tropics in 2011— was the densest observed in March since scientists began tracking the phenomenon with satellite images twenty years ago. Excessive amounts of Sargassum raise the chances that large mats will break free from the prevailing currents and wash ashore later this spring and summer in the Caribbean, Gulf of America, and around Florida.

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Eddies in the Caribbean Sea Influence the Prediction of the Loop Current in the Gulf of America  

A recent study by scientists at NOAA’s Atlantic Oceanographic and Meteorological Laboratory (AOML) in collaboration with partners at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science used a numerical modeling approach to investigate the impact of the eddy field in the Caribbean Sea on Loop Current predictions downstream in the Gulf of America. They found that eddy activity in the Caribbean Sea is crucial for the accurate prediction of eddy shedding by the Loop Current.

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