Thursday, April 27, 2017

Combined with standard observations, underwater gliders lead to improved hurricane forecasts

Captured here by NOAA's GOES East satellite on October 2014, Gonzalo was a rapidly-intensifying hurricane in the North Atlantic. (Credit: NOAA)

A study published as an early online version on Weather and Forecasting concluded that combining standard ocean observations (satellite, ship-based, buoys, drifters) with underwater glider data produces the best hurricane intensity and ocean forecasts. 

Dong et al. analyzed hurricane Gonzalo in 2014 in the Atlantic using a NOAA high resolution coupled atmospheric-ocean model. The simulation shows how the ocean data from the gliders helped initialize the model and identify ocean conditions contributing to intensification, thus reducing the error in intensity forecast by 50%. 

This study was supported by the CPO Ocean Observation and Monitoring Division.


Read the paper:   Dong, J., R. Domingues, G. Goni, G. Halliwell, H. Kim, S. Lee, M. Mehari, F. Bringas, J. Morell, & L. Pomales (2017). Impact of assimilating underwater glider data on Hurricane Gonzalo (2014) forecast. Weather Forecasting, 0. doi: 10.1175/WAF-D-16-0182.1

Abstract:

The initialization of ocean conditions is essential to coupled tropical cyclone (TC) forecasts. This study investigates the impact of ocean observations assimilation, particularly underwater glider data, on high-resolution coupled TC forecasts. Using the coupled Hurricane Weather Research and Forecasting (HWRF) - Hybrid Coordinate Ocean Model (HYCOM) system, numerical experiments are performed by assimilating underwater glider observations alone and with other standard ocean observations for the forecast of Hurricane Gonzalo (2014). The glider observations are able to provide valuable information on sub-surface ocean thermal and saline structure, even with their limited spatial coverage along the storm track and relatively small amount of data assimilated. Through the assimilation of underwater glider observations, the pre-storm thermal and saline structures of initial upper ocean conditions are significantly improved near the location of glider observations, though the impact is localized due to the limited coverage of glider data. The ocean initial conditions are best represented when both the standard ocean observations and the underwater glider data are assimilated together. The barrier layer and the associated sharp density gradient in the upper ocean are successfully represented in the ocean initial conditions only with the use of underwater glider observations. The upper ocean temperature and salinity forecasts in the first 48 hours are improved by assimilating both underwater glider and standard ocean observations. The assimilation of glider observations alone does not make large impact on the intensity forecast due to their limited coverage along the storm track. The 126-hour intensity forecast of Hurricane Gonzalo is improved moderately through assimilating both underwater glider data and standard ocean observations.

Thursday, April 13, 2017/Categories: Climate Observation Division, General News, Climate.gov RSS

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