کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
6383241 1626140 2014 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Shoreline dissipation of infragravity waves
ترجمه فارسی عنوان
از بین رفتن موج شکنی امواج القایی
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات زمین شناسی
چکیده انگلیسی
Infragravity waves (0.005-0.05 Hz) have recently been observed to dissipate a large part of their energy in the short-wave (0.05-1 Hz) surf zone, however, the underlying mechanism is not well understood. Here, we analyse two new field data sets of near-bed pressure and velocity at up to 13 cross-shore locations in ≲2.5m depth on a ≈1:80 and a ≈1:30 sloping beach to quantify infragravity-wave dissipation close to the shoreline and to identify the underlying dissipation mechanism. A frequency-domain Complex Eigenfunction analysis demonstrated that infragravity-wave dissipation was frequency dependent. Infragravity waves with a frequency larger than ≈0.0167-0.0245Hz were predominantly onshore progressive, indicative of strong dissipation of the incoming infragravity waves. Instead, waves with a lower frequency showed the classic picture of cross-shore standing waves with minimal dissipation. Bulk infragravity reflection coefficients at the shallowest position (water depth ≈0.7m) were well below 1 (≈0.20), implying that considerable dissipation took place close to the shoreline. We hypothesise that for our data sets infragravity-wave breaking is the dominant dissipation mechanism close to the shoreline, because the reflection coefficient depends on a normalised bed slope, with the higher infragravity frequencies in the mild-sloping regime where breaking is known to dominate dissipation. Additional numerical modelling indicates that, close to the shoreline of a 1:80 beach, bottom friction contributes to infragravity-wave dissipation to a limited extent, but that non-linear transfer of infragravity energy back to sea-swell frequencies is unimportant.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Continental Shelf Research - Volume 72, 1 January 2014, Pages 73-82
نویسندگان
, , ,