Response of the Ross Ice Shelf, Antarctica, to ocean gravity-wave forcing
Response of the Ross Ice Shelf, Antarctica, to ocean gravity-wave forcing
复制标题
南极洲罗斯冰架对海洋重力波强迫的响应
作者：
P. Bromirski;R. Stephen
摘要：将近前地震台 RIS2 的罗斯冰架（RIS，南极洲）响应与板状冰山 B15A 上收集的地震仪数据以及罗斯岛斯科特基地 (SBA) 和干谷万达湖 (VNDA) 附近的陆基地震台进行比较，可以识别由重力波强迫产生的 RIS 特定信号，包括气象驱动的风波、涌浪、次重力 (IG) 波和海啸波。 RIS 的振动响应随季节以及重力波强迫的频率和幅度而变化。 RIS 对IG 波和涌浪冲击的响应比在SBA 和VNDA 观察到的要大得多。近冰锋地震台 RIS2 的频谱峰值集中在 0.5 Hz 附近，该峰值在 4 月份海冰抑制膨胀时持续存在，可能是 RIS 的主要共振或特征频率。高振幅膨胀事件会激发相对宽带的信号，这些信号可能是断裂事件（冰震）。 2 月至 4 月，垂直和水平传感器在 8-12 Hz 频段内的相干性变化，加上 4 月海冰受潮膨胀时在 10 Hz 附近出现的光谱峰值，表明南半球冬季（夏季）月份较低（较高）的温度会影响信号传播特性，从而影响 RIS 的机械特性。
Abstract Comparison of the Ross Ice Shelf (RIS, Antarctica) response at near-front seismic station RIS2 with seismometer data collected on tabular iceberg B15A and with land-based seismic stations at Scott Base on Ross Island (SBA) and near Lake Vanda in the Dry Valleys (VNDA) allows identification of RIS-specific signals resulting from gravity-wave forcing that includes meteorologically driven wind waves and swell, infragravity (IG) waves and tsunami waves. The vibration response of the RIS varies with season and with the frequency and amplitude of the gravity-wave forcing. The response of the RIS to IG wave and swell impacts is much greater than that observed at SBA and VNDA. A spectral peak at near-ice-front seismic station RIS2 centered near 0.5 Hz, which persists during April when swell is damped by sea ice, may be a dominant resonance or eigenfrequency of the RIS. High-amplitude swell events excite relatively broadband signals that are likely fracture events (icequakes). Changes in coherence between the vertical and horizontal sensors in the 8–12 Hz band from February to April, combined with the appearance of a spectral peak near 10 Hz in April when sea ice damps swell, suggest that lower (higher) temperatures during austral winter (summer) months affect signal propagation characteristics and hence mechanical properties of the RIS.