Dataset Information

Global coastal attenuation of wind-waves observed with radar altimetry.

ABSTRACT: Coastal studies of wave climate and evaluations of wave energy resources are mainly regional and based on the use of computationally very expensive models or a network of in-situ data. Considering the significant wave height, satellite radar altimetry provides an established global and relatively long-term source, whose coastal data are nevertheless typically flagged as unreliable within 30 km of the coast. This study exploits the reprocessing of the radar altimetry signals with a dedicated fitting algorithm to retrieve several years of significant wave height records in the coastal zone. We show significant variations in annual cycle amplitudes and mean state in the last 30 km from the coastline compared to offshore, in areas that were up to now not observable with standard radar altimetry. Consequently, a decrease in the average wave energy flux is observed. Globally, we found that the mean significant wave height at 3 km off the coast is on average 22% smaller than offshore, the amplitude of the annual cycle is reduced on average by 14% and the mean energy flux loses 38% of its offshore value.

SUBMITTER: Passaro M

PROVIDER: S-EPMC8217570 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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Publications

Global coastal attenuation of wind-waves observed with radar altimetry.

Passaro Marcello M Hemer Mark A MA Quartly Graham D GD Schwatke Christian C Dettmering Denise D Seitz Florian F

Nature communications 20210621 1

Coastal studies of wave climate and evaluations of wave energy resources are mainly regional and based on the use of computationally very expensive models or a network of in-situ data. Considering the significant wave height, satellite radar altimetry provides an established global and relatively long-term source, whose coastal data are nevertheless typically flagged as unreliable within 30 km of the coast. This study exploits the reprocessing of the radar altimetry signals with a dedicated fitt ...[more]

PMID: 34155219

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Project description:Abstract Gravity waves (GWs) generated by tropical convection are important for the simulation of large?scale atmospheric circulations, for example, the quasi?biennial oscillation (QBO), and small?scale phenomena like clear?air turbulence. However, the simulation of these waves still poses a challenge due to the inaccurate representation of convection, and the high computational costs of global, cloud?resolving models. Methods combining models with observations are needed to gain the necessary knowledge on GW generation, propagation, and dissipation so that we may encode this knowledge into fast parameterized physics for global weather and climate simulation or turbulence forecasting. We present a new method suitable for rapid simulation of realistic convective GWs. Here, we associate the profile of latent heating with two parameters: precipitation rate and cloud top height. Full?physics cloud?resolving WRF simulations are used to develop a lookup table for converting instantaneous radar precipitation rates and echo top measurements into a high?resolution, time?dependent latent heating field. The heating field from these simulations is then used to force an idealized dry version of the WRF model. We validate the method by comparing simulated precipitation rates and cloud tops with scanning radar observations and by comparing the GW field in the idealized simulations to satellite measurements. Our results suggest that including variable cloud top height in the derivation of the latent heating profiles leads to better representation of the GWs compared to using only the precipitation rate. The improvement is especially noticeable with respect to wave amplitudes. This improved representation also affects the forcing of GWs on large?scale circulation. Key Points Use of an idealized numerical model forced with radar?derived latent heat profiles to simulate convective gravity waves in the tropics Relating latent heat to rain rate and echo top height leads to improved representation of tropical GWs compared to satellite observations Approach could improve prediction of tropical gravity waves for weather forecasting and climate applications

Dataset Information

Global coastal attenuation of wind-waves observed with radar altimetry.

Publications

Global coastal attenuation of wind-waves observed with radar altimetry.

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