title: Extracting remotely sensed water quality parameters from shallow intertidal estuaries

authors: Shao, Zhanchao

abstract: Sentinel-2 imagery is potentially ideal for providing a rapid assessment of the ecological condition of estuarine water due to its high temporal and spatial resolution and coverage. However, for optically shallow waters, the problem of isolating the effect of seabed reflectance from the influence of water properties makes it difficult to use the observed surface reflectance to monitor water quality. In this study, we adopt a methodology based on Lyzenga’s model to estimate water quality properties such as the dominant wavelength and diffuse attenuation coefficient (Kd) of shallow estuarine waters. Lyzenga models the observed reflectance (R) using four parameters: total water depth (z), sea-bed reflectance (Rb), water reflectance (Rw) and Kd. If Rb is known a priori and multiple observations of R are available from different total water depths, we show that Lyzenga’s model can be used to estimate the values of the remaining two parameters, Kd and Rw. Observations of R from different water depths can either be taken from the same image at different proximal locations in the estuary (“spatial method”) or from the same pixel observed at different tidal stages (“temporal method”), both assuming homogeneous seabed and water reflectance properties. Tests in our case study estuary show that Kd and Rw can be estimated at water depths less than 6.4 m. We also show that the proximity restriction for the reflectance correction with the temporal method limits outcomes to monthly or seasonal resolution, and the correction with the spatial method performs best at a spatial resolution of 60 m. The Kd extracted from the blue band correlates well with the observed Kd for photosynthetically active radiation (PAR) (r2 = 0.66) (although the relationship is likely to be estuary-specific). The methodology provides a foundation for future work assessing rates of primary production in shallow estuaries on large scales.

text: Extracting remotely sensed water quality parameters from shallow intertidal estuaries Sentinel-2 imagery is potentially ideal for providing a rapid assessment of the ecological condition of estuarine water due to its high temporal and spatial resolution and coverage. However, for optically shallow waters, the problem of isolating the effect of seabed reflectance from the influence of water properties makes it difficult to use the observed surface reflectance to monitor water quality. In this study, we adopt a methodology based on Lyzenga’s model to estimate water quality properties such as the dominant wavelength and diffuse attenuation coefficient (Kd) of shallow estuarine waters. Lyzenga models the observed reflectance (R) using four parameters: total water depth (z), sea-bed reflectance (Rb), water reflectance (Rw) and Kd. If Rb is known a priori and multiple observations of R are available from different total water depths, we show that Lyzenga’s model can be used to estimate the values of the remaining two parameters, Kd and Rw. Observations of R from different water depths can either be taken from the same image at different proximal locations in the estuary (“spatial method”) or from the same pixel observed at different tidal stages (“temporal method”), both assuming homogeneous seabed and water reflectance properties. Tests in our case study estuary show that Kd and Rw can be estimated at water depths less than 6.4 m. We also show that the proximity restriction for the reflectance correction with the temporal method limits outcomes to monthly or seasonal resolution, and the correction with the spatial method performs best at a spatial resolution of 60 m. The Kd extracted from the blue band correlates well with the observed Kd for photosynthetically active radiation (PAR) (r2 = 0.66) (although the relationship is likely to be estuary-specific). The methodology provides a foundation for future work assessing rates of primary production in shallow estuaries on large scales.

year: 2023-01-01

title: Qumran Textiles in the Palestine Exploration Fund, London: Radiocarbon Dating Results

authors: Taylor, Joan E.

subjects: charitable users, trusts and foundations

abstract: Three pieces of fabric from Qumran's Cave 1 have been stored in the Palestine Exploration Fund collection since the 1960s but have hitherto never been tested or re-examined. The fabric is made of linen, and was probably used for wrapping or packing scrolls, or sealing jars. New radiocarbon dating on one piece of fabric indicated a probability of 55% for it being made between 1 and 55 A.D., and a probability of 95.4% that it was made between 50 cal B.C.–80 cal A.D.

text: Qumran Textiles in the Palestine Exploration Fund, London: Radiocarbon Dating Results Three pieces of fabric from Qumran's Cave 1 have been stored in the Palestine Exploration Fund collection since the 1960s but have hitherto never been tested or re-examined. The fabric is made of linen, and was probably used for wrapping or packing scrolls, or sealing jars. New radiocarbon dating on one piece of fabric indicated a probability of 55% for it being made between 1 and 55 A.D., and a probability of 95.4% that it was made between 50 cal B.C.–80 cal A.D.

year: 2005-10

title: Editorial: Special Issue: Ignored no longer: Emerging Indigenous researchers on Indigenous psychologies

authors: Groot, Shiloh Ann Maree

abstract: In this special issue, edited by Mohi, Bridgette, Shiloh, Pat and Darren, we showcase work conducted within several such Indigenous psychologies. This collection of papers from emerging Indigenous scholars reflect a vibrant, healthy and supportive research environment in which conversations relevant to Indigenous peoples are taking place, and where culturally diverse perspectives and methods are valued and accepted. Here, culture is not simply seen as an abstract set of concepts. Culture constitutes a field of human action, meaning making, and self-production. It is through culture that all people construct themselves and make sense of the world (Groot, Hodgetts, Nikora, & Leggat-Cook, 2011; Nikora, Rua, & Te Awekōtuku, 2007).

text: Editorial: Special Issue: Ignored no longer: Emerging Indigenous researchers on Indigenous psychologies In this special issue, edited by Mohi, Bridgette, Shiloh, Pat and Darren, we showcase work conducted within several such Indigenous psychologies. This collection of papers from emerging Indigenous scholars reflect a vibrant, healthy and supportive research environment in which conversations relevant to Indigenous peoples are taking place, and where culturally diverse perspectives and methods are valued and accepted. Here, culture is not simply seen as an abstract set of concepts. Culture constitutes a field of human action, meaning making, and self-production. It is through culture that all people construct themselves and make sense of the world (Groot, Hodgetts, Nikora, & Leggat-Cook, 2011; Nikora, Rua, & Te Awekōtuku, 2007).

year: 2012