Attenuation coefficients of ultraviolet and photosynthetically active wavelengths in the waters of Heron Reef, Great Barrier Reef, Australia

2012 ◽  
Vol 63 (2) ◽  
pp. 142 ◽  
Author(s):  
Kelvin J. Michael ◽  
Cameron J. Veal ◽  
Manuel Nunez
Keyword(s):  
Great Barrier Reef ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Ultraviolet Spectrum ◽  
Barrier Reef ◽  
Attenuation Coefficients ◽  
Wind Speeds ◽  
Underwater Irradiance ◽  
Order Factor ◽  
Highly Correlated

Variation in subsurface solar radiation has been identified as a second-order factor in coral bleaching. This study examines transmission of radiation at Heron Reef (southern Great Barrier Reef, Australia) testing the hypotheses that spectral transmission is independent of location, season and solar zenith angle. In June and December 2004, 132 underwater irradiance profiles were collected at six ultraviolet wavelengths (305, 313, 320, 340, 380, 395 nm) and photosynthetically-active radiation (PAR) to estimate spectral diffuse attenuation coefficients Kd(λ). Mean Kd(λ) decreased through the ultraviolet spectrum (0.435 m–1 at 305 nm to 0.115 m–1 at 395 nm) whereas mean Kd(PAR) was 0.129 m–1. Ultraviolet Kd(λ) values were highly correlated with each other, but less well correlated with Kd(PAR). Kd(λ) values were larger inside than outside Heron Lagoon, both across all wavelengths and at individual wavelengths. Similarly, Kd(λ) values were significantly larger in December than June. These results are consistent with greater resuspension and transport of particulates in Heron Lagoon at higher wind speeds. Kd(λ) values were not dependent on solar zenith angle. The implications are that location and season must be accounted for when setting Kd(λ) values to calculate spectral irradiances affecting corals at Heron Reef.

scholarly journals A Laboratory Experiment for the Statistical Evaluation of Aerosol Retrieval (STEAR) Algorithms

2019 ◽  
Vol 11 (5) ◽  
pp. 498 ◽  
Author(s):  
Gregory Schuster ◽  
W. Espinosa ◽  
Luke Ziemba ◽  
Andreas Beyersdorf ◽  
Adriana Rocha-Lima ◽  
...  
Keyword(s):  
Particle Size ◽  
Laboratory Experiment ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Size Distributions ◽  
Shape Factors ◽  
Highly Correlated ◽  
Single Scatter ◽  
Absorption Measurements

We have developed a method for evaluating the fidelity of the Aerosol Robotic Network (AERONET) retrieval algorithms by mimicking atmospheric extinction and radiance measurements in a laboratory experiment. This enables radiometric retrievals that use the same sampling volumes, relative humidities, and particle size ranges as observed by other in situ instrumentation in the experiment. We use three Cavity Attenuated Phase Shift (CAPS) monitors for extinction and University of Maryland Baltimore County’s (UMBC) three-wavelength Polarized Imaging Nephelometer (PI-Neph) for angular scattering measurements. We subsample the PI-Neph radiance measurements to angles that correspond to AERONET almucantar scans, with simulated solar zenith angles ranging from 50 ∘ to 77 ∘ . These measurements are then used as input to the Generalized Retrieval of Aerosol and Surface Properties (GRASP) algorithm, which retrieves size distributions, complex refractive indices, single-scatter albedos, and bistatic LiDAR ratios for the in situ samples. We obtained retrievals with residuals less than 8% for about 90 samples. Samples were alternately dried or humidified, and size distributions were limited to diameters of less than 1.0 or 2.5 μ m by using a cyclone. The single-scatter albedo at 532 nm for these samples ranged from 0.59 to 1.00 when computed with CAPS extinction and Particle Soot Absorption Photometer (PSAP) absorption measurements. The GRASP retrieval provided single-scatter albedos that are highly correlated with the in situ single-scatter albedos, and the correlation coefficients ranged from 0.916 to 0.976, depending upon the simulated solar zenith angle. The GRASP single-scatter albedos exhibited an average absolute bias of +0.023–0.026 with respect to the extinction and absorption measurements for the entire dataset. We also compared the GRASP size distributions to aerodynamic particle size measurements, using densities and aerodynamic shape factors that produce extinctions consistent with our CAPS measurements. The GRASP effective radii are highly correlated (R = 0.80) and biased under the corrected aerodynamic effective radii by 1.3% (for a simulated solar zenith angle of θ ∘ = 50 ∘ ); the effective variance indicated a correlation of R = 0.51 and a relative bias of 280%. Finally, our apparatus was not capable of measuring backscatter LiDAR ratios, so we measured bistatic LiDAR ratios at a scattering angle of 173 degrees. The GRASP bistatic LiDAR ratios had correlations of 0.71 to 0.86 (depending upon simulated θ ∘ ) with respect to in situ measurements, positive relative biases of 2–10%, and average absolute biases of 1.8–7.9 sr.

scholarly journals Subseasonal prediction of the 2020 Great Barrier Reef and Coral Sea marine heatwave

2021 ◽  
Author(s):  
Jessica Ann Benthuysen ◽  
Grant A. Smith ◽  
Claire M. Spillman ◽  
Craig R. Steinberg
Keyword(s):  
Great Barrier Reef ◽  
Early Warning Systems ◽  
Spatial Extent ◽  
Lead Times ◽  
Barrier Reef ◽  
Wind Speeds ◽  
Subseasonal Variability ◽  
Coral Sea ◽  
Sea Surface Temperature Anomalies ◽  
System Access

Abstract The 2020 marine heatwave in the Great Barrier Reef and Coral Sea led to mass coral bleaching. Sea surface temperature anomalies reached +1.7°C for the whole of the Great Barrier Reef and Coral Sea and exceeded +2°C across broad regions (referenced to 1990-2012). The marine heatwave reached Category 2 (Strong) and warm anomalies peaked between mid-February and mid-March 2020. The marine heatwave’s peak intensity aligned with regions of reduced cloud cover and weak wind speeds. We used a marine heatwave framework to assess the ability of an operational coupled ocean-atmosphere prediction system (ACCESS-S1) to capture the marine heatwave’s severity, duration, and spatial extent. For initial week predictions, the predicted marine heatwave severity generally agreed with the magnitude and spatial extent of the observed severity for that week. The model ensemble mean did not capture the marine heatwave’s development phase at lead times beyond the first week. The model underestimated the marine heatwave’s spatial extent, which reached up to 95% of the study area with at least Moderate severity and up to 43% with at least Strong severity. However, most forecast ensemble members correctly predicted the period of Strong severity in the first week of the model forecast. The model correctly predicted marine heatwave conditions to persist from mid-February to mid-March but did not capture the end of the marine heatwave. The inability to predict the end of the event and other periods of less skilful prediction were related to subseasonal variability owing to weather systems, including the passage of tropical cyclones not simulated in the model. On subseasonal timescales, evaluating daily to weekly forecasts of ocean temperature extremes is an important step toward implementing methods for developing operational forecast extremes products for use in early warning systems.

scholarly journals Coral reef origins of atmospheric dimethylsulfide at Heron Island, southern Great Barrier Reef, Australia

2016 ◽  
Author(s):  
Hilton B. Swan ◽  
Graham B. Jones ◽  
Elisabeth S. M. Deschaseaux ◽  
Bradley D. Eyre
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Great Barrier Reef ◽  
Cloud Condensation Nuclei ◽  
Dry Season ◽  
Radiation Budget ◽  
Convective Precipitation ◽  
Barrier Reef ◽  
Wet Season ◽  
Wind Speeds

Abstract. Atmospheric dimethylsulfide (DMSa), continually derived from the world’s oceans, is a feed gas for the tropospheric production of new sulfate particles, leading to cloud condensation nuclei that influence the formation and properties of marine clouds, and ultimately the Earth’s radiation budget. Previous studies on the Great Barrier Reef (GBR), Australia, have indicated coral reefs are significant sessile sources of DMSa capable of enhancing the tropospheric DMSa burden mainly derived from phytoplankton in the surface ocean; however, specific evidence of coral reef DMS emissions and their characteristics is lacking. By using on-site automated continuous analysis of DMSa and meteorological parameters at Heron Island in the southern GBR, we show that the coral reef was the source of occasional spikes of DMSa identified above the oceanic DMSa background signal. In most instances, these DMSa spikes were detected at low tide under low wind speeds, indicating they originated from the lagoonal platform reef surrounding the island, although evidence of longer range transport of DMSa from a 70 km stretch of coral reefs in the southern GBR was also observed. The most intense DMSa spike occurred in the winter dry season at low tide when convective precipitation fell onto the aerially exposed platform reef. This co-occurrence of events appeared to biologically shock the coral resulting in a seasonally aberrant extreme DMSa spike concentration of 45.9 nmol m−3 (1122 ppt). Seasonal DMS emission fluxes for the 2012 wet season and 2013 dry season campaigns at Heron Island were 5.0 and 1.4 µmol m−2 d−1, respectively, of which the coral reef was estimated to contribute 4 % during the wet season and 14 % during the dry season to the dominant oceanic flux.

Monitoring Larval Fluxes through the Surf Zones of Australian Coral Reefs

1996 ◽  
Vol 47 (2) ◽  
pp. 383 ◽  
Author(s):  
P Doherty ◽  
J McIlwain
Keyword(s):  
Great Barrier Reef ◽  
Western Australia ◽  
Larval Fish ◽  
Fish Fauna ◽  
Barrier Reef ◽  
Larval Supply ◽  
Short Term ◽  
Highly Correlated ◽  
North Western ◽  
Pelagic Juveniles

The first successful trials with stationary 'crest' nets to monitor the nocturnal fluxes of larval fish crossing reef margins in both eastern and western Australia are described. Lengthy deployments were possible on Ningaloo Reef, north-western Australia, because that system is topographically suitable: i.e. a fringing barrier reef where surf produces a constant flow into a coastal lagoon. Sampling on 85 nights between October 1994 and March 1995 revealed a rich larval fish fauna (56474 individuals) dominated by pelagic juveniles nearing settlement stage. Variations in the daily catches of replicate nets (200 m apart) were highly correlated, showing the suitability of this technique for monitoring larval supply. Another trial (five nights) was made at One Tree Reef, southern Great Barrier Reef. On nocturnal flood tides, when rising water first spilled into the lagoon, triplicate nets caught many presettlement fish (47797 individuals) in this flow. The behaviour of some taxa clearly assisted their transport through the surf. Despite the successful short-term deployments at One Tree, there may be limited potential to deploy this gear elsewhere on the Great Barrier Reef because of unsuitable flow regimes.

scholarly journals Coral reef origins of atmospheric dimethylsulfide at Heron Island, southern Great Barrier Reef, Australia

2017 ◽  
Vol 14 (1) ◽  
pp. 229-239 ◽  
Author(s):  
Hilton B. Swan ◽  
Graham B. Jones ◽  
Elisabeth S. M. Deschaseaux ◽  
Bradley D. Eyre
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Great Barrier Reef ◽  
Cloud Condensation Nuclei ◽  
Dry Season ◽  
Radiation Budget ◽  
Convective Precipitation ◽  
Barrier Reef ◽  
Wet Season ◽  
Wind Speeds

Abstract. Atmospheric dimethylsulfide (DMSa), continually derived from the world's oceans, is a feed gas for the tropospheric production of new sulfate particles, leading to cloud condensation nuclei that influence the formation and properties of marine clouds and ultimately the Earth's radiation budget. Previous studies on the Great Barrier Reef (GBR), Australia, have indicated coral reefs are significant sessile sources of DMSa capable of enhancing the tropospheric DMSa burden mainly derived from phytoplankton in the surface ocean; however, specific environmental evidence of coral reef DMS emissions and their characteristics is lacking. By using on-site automated continuous analysis of DMSa and meteorological parameters at Heron Island in the southern GBR, we show that the coral reef was the source of occasional spikes of DMSa identified above the oceanic DMSa background signal. In most instances, these DMSa spikes were detected at low tide under low wind speeds, indicating they originated from the lagoonal platform reef surrounding the island, although evidence of longer-range transport of DMSa from a 70 km stretch of coral reefs in the southern GBR was also observed. The most intense DMSa spike occurred in the winter dry season at low tide when convective precipitation fell onto the aerially exposed platform reef. This co-occurrence of events appeared to biologically shock the coral resulting in a seasonally aberrant extreme DMSa spike concentration of 45.9 nmol m−3 (1122 ppt). Seasonal DMS emission fluxes for the 2012 wet season and 2013 dry season campaigns at Heron Island were 5.0 and 1.4 µmol m−2 day−1, respectively, of which the coral reef was estimated to contribute 4 % during the wet season and 14 % during the dry season to the dominant oceanic flux.

Management of Water Quality in the Great Barrier Reef Marine Park

1989 ◽  
Vol 21 (2) ◽  
pp. 31-38 ◽  
Author(s):  
Simon Woodley
Keyword(s):  
Water Quality ◽  
Coral Reef ◽  
Great Barrier Reef ◽  
Barrier Reef ◽  
Management Issue ◽  
Reef System ◽  
Marine Park ◽  
World Heritage List ◽  
The World ◽  
Coral Reef System

The Great Barrier Reef is the largest coral reef system in the world. It is recognised and appreciated worldwide as a unique environment and for this reason has been inscribed on the World Heritage List. The Reef is economically-important to Queensland and Australia, supporting substantial tourism and fishing industries. Management of the Great Barrier Reef to ensure conservation of its natural qualities in perpetuity is achieved through the establishment of the Great Barrier Reef Marine Park. The maintenance of water quality to protect the reef and the industries which depend on it is becoming an increasingly important management issue requiring better knowledge and possibly new standards of treatment and discharge.

Sign in / Sign up

Export Citation Format

Share Document