title: Effects of surfzone wave transformation on swash dynamics

authors: Guedes, Rafael Marcondes Carvalho

subjects: swash

abstract: Swash oscillations on two natural beaches were measured to show that the shape and magnitude of energy spectra can be largely dependent on processes occurring inside the surfzone. The observations took place on a steep, intermediate beach on the east coast (Tairua Beach), and a low-sloping, dissipative beach located on the west coast of New Zealand (Ngarunui Beach, Raglan), and aimed at improving the understanding of the effects of wave breaking, beach slope, and nonlinear wave interactions on the swash oscillations. These problems were addressed by analysing datasets obtained from field experiments undertaken at these two sites.
A field experiment at Tairua Beach showed that swash oscillations were critically dependent on the stage of the tide which controlled the degree of wave energy dissipation over the sandbar crest. Under mild, near-constant offshore wave conditions, the presence of a sandbar and the tidally-controlled water depth over its crest determined whether most of the incoming waves broke before reaching the shoreline. This forced a change in the pattern of wave energy dissipation across the surfzone between low and high tide, which was reflected by changes to swash elevation (runup) on time-scales of a few hours. Significant runup height Rs, defined as 4 times the standard deviation of the waterline time series, varied by a factor of 2 between low tide, when most of the waves were breaking over the sandbar and high tide, when the waves were barely breaking. The increase in wave energy dissipation during low tide was associated with changes in swash maxima distribution, decrease in mean swash period and increasing energy at infragravity frequencies (0.004–0.05 Hz). Bispectral analysis suggested this infragravity modulation might be connected with the presence of secondary waves at the shoreline.
Swash oscillations at Tairua were not homogeneous along the beach. Alongshore variability in Rs of up to 78% was observed and was mainly driven by changes in the sea-swell (0.05–0.4 Hz) band of the swash. This variability was predominantly controlled by alongshore changes in beach face slope, although alongshore patterning in wave breaking over the sandbar caused alongshore changes in wave dissipation and also resulted in alongshore swash variation in the sea-swell bandwidth. At infragravity frequencies, alongshore swash variability was not well associated either with changes in beach slope or wave breaking and was possibly linked to the presence of low-mode edge waves, observed from frequency-wavenumber spectra of the swash time series.
A final experiment was conducted to understand the surfzone control on incident and infragravity runup on a gently-sloping beach. The observations showed that runup saturation at infragravity frequencies can occur under mild offshore energy conditions if the beach slope is sufficiently gentle. Infragravity saturation was observed for higher-frequency (> 0.025–0.035 Hz) infragravity waves, where typically less than 5% of the (linear) energy flux was reflected from the beach and where, similar to the sea-swell band, the swash energy was independent of offshore wave energy. The infragravity frequency range of saturation was determined by the tide, with saturation extending to lower frequencies at low tide when the local beach face slope over the concave-shaped profile was gentler. Runup was strongly dominated by infragravity frequencies, which accounted on average for 96% of the runup variance, and its energy levels were entirely consistent with strong infragravity wave dissipation observed in the surfzone, particularly when including the nonlinear contributions to the wave energy fluxes. Our observations show evidence of nonlinear interactions involving infragravity and high-frequency, harmonic waves, and suggest that these harmonics could play a role in the wave energy balance near the shoreline on low-sloping, dissipative beaches.

text: Effects of surfzone wave transformation on swash dynamics Swash oscillations on two natural beaches were measured to show that the shape and magnitude of energy spectra can be largely dependent on processes occurring inside the surfzone. The observations took place on a steep, intermediate beach on the east coast (Tairua Beach), and a low-sloping, dissipative beach located on the west coast of New Zealand (Ngarunui Beach, Raglan), and aimed at improving the understanding of the effects of wave breaking, beach slope, and nonlinear wave interactions on the swash oscillations. These problems were addressed by analysing datasets obtained from field experiments undertaken at these two sites.
A field experiment at Tairua Beach showed that swash oscillations were critically dependent on the stage of the tide which controlled the degree of wave energy dissipation over the sandbar crest. Under mild, near-constant offshore wave conditions, the presence of a sandbar and the tidally-controlled water depth over its crest determined whether most of the incoming waves broke before reaching the shoreline. This forced a change in the pattern of wave energy dissipation across the surfzone between low and high tide, which was reflected by changes to swash elevation (runup) on time-scales of a few hours. Significant runup height Rs, defined as 4 times the standard deviation of the waterline time series, varied by a factor of 2 between low tide, when most of the waves were breaking over the sandbar and high tide, when the waves were barely breaking. The increase in wave energy dissipation during low tide was associated with changes in swash maxima distribution, decrease in mean swash period and increasing energy at infragravity frequencies (0.004–0.05 Hz). Bispectral analysis suggested this infragravity modulation might be connected with the presence of secondary waves at the shoreline.
Swash oscillations at Tairua were not homogeneous along the beach. Alongshore variability in Rs of up to 78% was observed and was mainly driven by changes in the sea-swell (0.05–0.4 Hz) band of the swash. This variability was predominantly controlled by alongshore changes in beach face slope, although alongshore patterning in wave breaking over the sandbar caused alongshore changes in wave dissipation and also resulted in alongshore swash variation in the sea-swell bandwidth. At infragravity frequencies, alongshore swash variability was not well associated either with changes in beach slope or wave breaking and was possibly linked to the presence of low-mode edge waves, observed from frequency-wavenumber spectra of the swash time series.
A final experiment was conducted to understand the surfzone control on incident and infragravity runup on a gently-sloping beach. The observations showed that runup saturation at infragravity frequencies can occur under mild offshore energy conditions if the beach slope is sufficiently gentle. Infragravity saturation was observed for higher-frequency (> 0.025–0.035 Hz) infragravity waves, where typically less than 5% of the (linear) energy flux was reflected from the beach and where, similar to the sea-swell band, the swash energy was independent of offshore wave energy. The infragravity frequency range of saturation was determined by the tide, with saturation extending to lower frequencies at low tide when the local beach face slope over the concave-shaped profile was gentler. Runup was strongly dominated by infragravity frequencies, which accounted on average for 96% of the runup variance, and its energy levels were entirely consistent with strong infragravity wave dissipation observed in the surfzone, particularly when including the nonlinear contributions to the wave energy fluxes. Our observations show evidence of nonlinear interactions involving infragravity and high-frequency, harmonic waves, and suggest that these harmonics could play a role in the wave energy balance near the shoreline on low-sloping, dissipative beaches.

year: 2012

title: Empathy, connectedness and organisation

authors: Pavlovich, Kathryn

subjects: connectedness

abstract: In this paper, we conceptually explore the role of empathy as a connectedness organising mechanism. We expand ideas underlying positive organisational scholarship and examine leading-edge studies from neuroscience and quantum physics that give support to our claims. The perspective we propose has profound implications regarding how we organise and how we manage. First, we argue that empathy enhances connectedness through the unconscious sharing of neuro-pathways that dissolves the barriers between self and other. This sharing encourages the integration of affective and cognitive consciousness which facilitates the ability to find common ground for solution building. Second, empathy enhances connectedness through altruistic action. In giving to others, feelings of joy and harmony are activated. This in turn allows personal freedom to be enriched and transcendence from the rational ego-self is reduced to develop a more expansive, integrated and enlightened state underlying connectedness. Finally, empathy enhances connectedness which results in sharing the quantum field of coherence where there is little separation between self and other. This means living beyond self-interest in a coherent world based upon interdependent wholeness rather than atomization and separation. Empathy allows us to find that state of coherent connectedness.

text: Empathy, connectedness and organisation In this paper, we conceptually explore the role of empathy as a connectedness organising mechanism. We expand ideas underlying positive organisational scholarship and examine leading-edge studies from neuroscience and quantum physics that give support to our claims. The perspective we propose has profound implications regarding how we organise and how we manage. First, we argue that empathy enhances connectedness through the unconscious sharing of neuro-pathways that dissolves the barriers between self and other. This sharing encourages the integration of affective and cognitive consciousness which facilitates the ability to find common ground for solution building. Second, empathy enhances connectedness through altruistic action. In giving to others, feelings of joy and harmony are activated. This in turn allows personal freedom to be enriched and transcendence from the rational ego-self is reduced to develop a more expansive, integrated and enlightened state underlying connectedness. Finally, empathy enhances connectedness which results in sharing the quantum field of coherence where there is little separation between self and other. This means living beyond self-interest in a coherent world based upon interdependent wholeness rather than atomization and separation. Empathy allows us to find that state of coherent connectedness.

year: 2011

title: Sweet as – the [ADJ + as] intensifier construction in Māori English/ Aotearoa English.

authors: Calude, Andreea S.

abstract: We introduce the Waikato Māori English Conversation (MEC) corpus, which consists of 43 dyadic conversations between 49 young adults who self-recorded informal conversations with close friends, in their own homes, with no topic of conversation specified (83 hours of dialogue; nearly 800,000 words). The resulting materials are colloquial and unstructured, capturing a wider range of pragmatic and stylistic modes than is possible in a standard sociolinguistic interview. Here, we report on one such feature, the [ADJ + as] construction, for example: ‘sorry some of the questions are like awkward as’ and ‘that caused a big as drama eh’. This intensifier construction has been identified as a distinctive New Zealand English (NZE) innovation, yet little has been written about this it. However, the Waikato MEC corpus presents the opportunity to analyse the construction in a more systematic manner and to fill existing gaps in analyses of Māori English grammar.

text: Sweet as – the [ADJ + as] intensifier construction in Māori English/ Aotearoa English. We introduce the Waikato Māori English Conversation (MEC) corpus, which consists of 43 dyadic conversations between 49 young adults who self-recorded informal conversations with close friends, in their own homes, with no topic of conversation specified (83 hours of dialogue; nearly 800,000 words). The resulting materials are colloquial and unstructured, capturing a wider range of pragmatic and stylistic modes than is possible in a standard sociolinguistic interview. Here, we report on one such feature, the [ADJ + as] construction, for example: ‘sorry some of the questions are like awkward as’ and ‘that caused a big as drama eh’. This intensifier construction has been identified as a distinctive New Zealand English (NZE) innovation, yet little has been written about this it. However, the Waikato MEC corpus presents the opportunity to analyse the construction in a more systematic manner and to fill existing gaps in analyses of Māori English grammar.

year: 2025