Tahun Terbit

1982

No. Panggil

B SOE k

Several hypotheses exist that describe phytoplankton spring blooms in temperate and subpolar oceans: the critical depth, shoaling mixed layer (ML), critical turbulence, onset of stratification and disturbance-recovery hypotheses. These theories appear to be mutually exclusive and none of them describe the annual cycle of phytoplankton biomass. Here, we present a model of the annual cycle in phy…

Pulse amplitude-modulated (PAM) fluorometry was used to obtain rapid light curves (RLCs) for phytoplankton from small Canadian lakes of varying water clarity, including metalimnetic communities from two clear lakes. RLCs were measured before and after exposure to a number of experimental spectra containing ultraviolet radiation (UVR) and photosynthetically active radiation (PAR). Photochemical …

High-melt areas of glaciers and ice sheets foster a rich spectrum of ambient seismicity. These signals not only shed light on source mechanisms (e.g. englacial fracturing, water flow, iceberg detachment, basal motion) but also carry information about seismic wave propagation within glacier ice. Here, we present two approaches to measure and potentially monitor phase velocities of high-frequency…

Predation is considered an important source of mortality for plankton, but documenting variation in planktonic predation, particularly across interacting environmental cycles, remains logistically difficult, thus our understanding remains limited. To test for the combined effects of prey life history stage, diel or light level phase (including crepuscular periods) and seasonal upwelling on the…

Microseismic monitoring from large arrays using migration-based detection and location techniques is limited by detections of false positive events, which are the interpretation of spurious/noisy signals as real events. Therefore, semblance has been considered to differentiate between false positive and true events. However, semblance by itself is not suitable for variable signals such as those…

Asymptotic expressions are derived for electromagnetic fields induced by arbitrarily oriented electric and magnetic dipoles in a laterally isotropic stratified medium. Considering that the leading terms, which describe the airwave, decay in accordance with the same geometric law whether the source is a horizontal electric or magnetic dipole, it is suggested to use a transmitter, which combines…

In presence of large wavelength-scale shear-velocity variations in the Earth, acoustic waveform inversion may not be sufficient even when inverting long-offset data to retrieve the long-to-intermediate wavelengths of the compressional velocity. An acoustic modelling does not always correctly represent the compressional/primary waves when tuning effects and energy conversion between compression…

Protistan grazers and viruses are major agents of mortality in marine microbial communities with substantially different implications for food-web dynamics, carbon cycling and diversity maintenance.While grazers and viruses are typically studied independently, their impacts on microbial communities may be complicated by direct and indirect interactions of their mortality effects. Using a modif…

In the Umbria–Marche (Central Italy) region an important earthquake sequence occurred in 1997, characterized by nine earthquakes with magnitudes in the range between 5 and 6, that caused important damages and causalities. In the present paper, we separately estimate intrinsic and scatteringQ−1 parameters, using the classical multiple lapse time window analysis (MLTWA) approach in the a…