Global Wave Hindcasts Using the Observation‐Based Source Terms: Description and Validation

Abstract

Global wave hindcasts are developed using the third generation spectral wave model WAVEWATCH III with the observation-based source terms (ST6) and a hybrid rectilinear-curvilinear, irregular-regular-irregular grid system (approximately at 0.25 0.25   ). Three distinct global hindcasts are produced: (a) a long-term hindcast forced by the ERA5 conventional winds 10 U and (b) two short-term hindcasts (2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019) driven by the NCEP climate forecast system (CFS)v2 10 U and the ERA5 neutral winds 10,neu U, respectively. The input field for ice is sourced from the Ocean and Sea Ice Satellite Application Facility (OSI SAF) sea-ice concentration climate data records. These wave simulations, together with the driving wind forcing, are validated against extensive in-situ observations and satellite altimeter records. The performance of the ST6 wave hindcasts shows promising results across multiple wave parameters, including the conventional wave characteristics (e.g., wave height s H and wave period) and high-order spectral moments (e.g., the surface Stokes drift and mean square slope). The ERA5-based simulations generally present lower random errors, but the CFS-based run represents extreme sea states (e.g., 10 s H  m) considerably better. Novel wave parameters available in our hindcasts, namely the dominant wave breaking probability, wave-induced mixed layer depth, freak wave indexes and wavespreading factor, are further described and briefly discussed. Inter-comparisons of s H from the long-term (41 years) wave hindcast, buoy measurements and two different calibrated altimeter data sets highlight the inconsistency in these altimeter records arising from different calibration methodology. Significant errors in the low-frequency bins (period T  s) for both wave energy and directionality call for further model development.Plain Language Summary Ocean surface waves are fundamentally important for ocean engineering design, ship navigation, air-sea exchange of gas, heat, momentum and energy, upper ocean dynamics, and remote sensing of the ocean. Spectral wave modeling is an indispensable tool to estimate sea state information. In this study, we present new global wave hindcasts developed using the stateof-the-art model physics and numerics and the modern reanalysis winds and satellite sea ice records. It is demonstrated through validation against in-situ observations and altimeter records that the global wave hindcasts perform well across multiple parameters. Meanwhile, intercomparisons of wave height from the long-term hindcast, buoys, and altimeters reveal inconsistency and potential inhomogeneity in these different data sets. The wave hindcasts we developed, in combination with global wave databases published previously, will form a large ensemble of realizations of historical evolution of sea states simulated with distinct wave physics and wind forcing, which will help quantify sea states in real oceans more accurately. LIU ET AL.

A Comparison of Multiple Approaches to Study the Modulation of Ocean Waves Due To Climate Variability

“…The present study adopted the WW3 global wave hindcast developed by Q. Liu et al. (2021), which covers the period 1979–2020. In the present study, only data over the period 1981–2020 were used.…”

“…In this study, the WW3 global wave hindcast of Q. Liu et al. (2021) was used, as both the ERA5 reanalysis winds used to force the model and the wave hindcast results have been extensively validated.…”

A Two‐Part Model for Wave‐Sea Ice Interaction: Attenuation and Break‐Up

“…This source-term package represents the physical processes of wind-wave interaction, whitecapping (dissipation due to breaking) and wave-turbulence interaction (swell dissipation), and has its roots in field and laboratory observations and experiments. CDFAC, the ST6 parameter to account for wind field biases, is set to CDFAC = 1.08 as in Liu et al (2021).…”

“…CDFAC, the ST6 parameter to account for wind field biases, is set to CDFAC = 1.08 as in Liu et al. (2021).…”

Evaluation of Spectral Wave Models Physics as Applied to a 100‐Year Southern Hemisphere Extra‐Tropical Cyclone Sea State

“…To model the waves generated by the April 2021 ETC we use a three-grid global wave model set up, originally proposed by Rogers and Linzell (2018) and already tested and implemented by Liu et al (2021) for a WW3/ERA5 forced 40-year hindcast and by Meucci et al (2023) for 140-year continuous wind-wave climate future projections. The inputs to the WW3 three-grid model are the ERA5 hourly 10-m neutral wind components and the daily sea ice concentration at 0.25° horizontal resolution globally.…”