Several years of surface wave observations in the Chukchi Sea reveal wave groups are a common feature in open water and ice-covered conditions. The strength of the groupiness, here characterized by the group factor, is well correlated with the characteristic wave steepness, the spectral bandwidth, and the Benjamin-Feir Index. The general finding is enhanced groupiness in ice. However, the trends with wave characteristics are opposite from ice to open water, and suggest different mechanisms. In ice, groupiness increases with decreasing steepness, increasing bandwidth, and decreasing Benjamin-Feir Index. In open water, the trends indicate that both linear superposition of phase-coherent waves and nonlinear behaviour are important for the generation of wave groups. We hypothesize that in ice-covered conditions, directional spreading reduces the effective bandwidth in the dominant wave direction, possibly due to modified four-wave nonlinear transfer spreading high-frequency energy to lateral directions. This reduced effective bandwidth is then conducive to enhanced group formation by linear superposition. However, an increased high-frequency noise floor of the in-ice observations would also be consistent with the observed increase in omni-directional bandwidth. Without directional measurements, neither of these two processes can be favoured with certainty.

在楚科奇海进行的数年表面波观测表明，波群是开放水域和冰雪覆盖条件下的共同特征。此处以群因子为特征的群聚强度与特征波陡度，光谱带宽和本杰明·菲尔指数具有很好的相关性。总的发现是增强了冰上的分组性。但是，从冰到开阔水域，具有波动特征的趋势是相反的，并暗示了不同的机制。在冰中，随着陡度的降低，带宽的增加以及本杰明·费尔指数的降低，群体性会增加。在开阔水域中，趋势表明，相干波的线性叠加和非线性行为都对波群的产生很重要。我们假设在冰雪覆盖的条件下，定向扩展会减小主波方向上的有效带宽，这可能是由于修改后的四波非线性传输将高频能量扩展到横向。然后，这种减小的有效带宽有助于通过线性叠加来增强基团形成。但是，冰内观测的高频本底噪声的增加也将与观测到的全向带宽的增加一致。如果没有定向测量，这两个过程都无法确定地受到青睐。在冰上观测中增加的高频本底噪声也将与观测到的全向带宽的增加一致。如果没有定向测量，这两个过程都无法确定地受到青睐。在冰上观测中增加的高频本底噪声也将与观测到的全向带宽的增加一致。如果没有定向测量，这两个过程都无法确定地受到青睐。