Premium
The seasonal evolution of high vertical‐mode internal waves in a deep reservoir
Author(s) -
Vidal Javier,
Rueda Francisco J.,
Casamitjana Xavier
Publication year - 2007
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2007.52.6.2656
Subject(s) - seiche , stratification (seeds) , thermocline , internal wave , forcing (mathematics) , geology , thermal stratification , oceanography , mode (computer interface) , climatology , oscillation (cell signaling) , mixed layer , structural basin , thermal , internal tide , atmospheric sciences , geophysics , meteorology , geomorphology , geography , seed dormancy , botany , germination , genetics , dormancy , computer science , biology , operating system
The causal mechanism and seasonal evolution of the internal wave field in a deep, warm, monomictic reservoir are examined through the analysis of field observations and numerical techniques. The study period extends from the onset of thermal stratification in the spring until midsummer in 2005. During this time, wind forcing was periodic, with a period of 24 h (typical of land‐sea breezes), and the thermal structure in the lake was characterized by the presence of a shallow surface layer overlying a thick metalimnion, typical of small to medium sized reservoirs with deep outtakes. Basin‐scale internal seiches of high vertical mode (ranging from mode V3 to V5) were observed in the metalimnion. The structure of the dominant modes of oscillation changed as stratification evolved on seasonal timescales, but in all cases, their periods were close to that of the local wind forcing (i.e., 24 h), suggesting a resonant response. Nonresonant oscillatory modes of type V1 and V2 became dominant after large frontal events, which disrupted the diurnal periodicity of the wind forcing.