English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We use radiances collected from space by the Infrared Atmospheric SounderInterferometer (IASI) when looking down at ocean surfaces during the day toremotely determine the probability distribution of wave slopes. This isachieved by using about 300 channels between 3.6 and 4.0 $\mu$m and aphysically-based approach which properly takes the contribution of thereflected solar radiation into account. Based on about 150 millionobservations, the same number of wave-slope probabilities are retrieved forwind speeds up to 15 m/s. We revisit and discuss the methodology proposed byCox and Munk (CM) to derive their celebrated wave-slope probabilitydistribution function (pdf) from photographs of the sun glitter. We propose anoriginal and robust approach for accurate retrievals of the 7 parametersappearing in the Gram-Charlier representation of the pdf. Our results for themean square slopes are fully compatible with those of CM, and with the morerecent results by Br\'eon and Henriot, but our lower uncertainties enable us topoint out departures from the linear wind-speed dependencies and a slightoverestimation of the upwind MSS described by the linear fit of CM at moderatewind speed. Our skewness and kurtosis coefficients show clear influences of thewind speed, with a steady decrease of the former and the alongwind kurtosiscoefficient being maximal at moderate wind speeds, features that CM could notpoint out due to the limitations of their measurements. We revisit therenormalization procedure employed by CM to obtain the complete variances fromtruncated pdf and show that it imposes stringent conditions on the kurtosiscoefficients that allow us to determine them accurately, with wind-dependentvalues specific to the local sea state.

Revisiting the Cox and Munk wave-slope statistics using IASI observations of the sea surface