Impact of climate variability on an east Australian bay

Abstract

The climate along the subtropical east coast of Australia is changing significantly. Rainfall has decreased by about 50 mm per decade and temperature increased by about 0.1 C per decade during the last fifty years. These changes are likely to impact upon episodes of hypersalinity and the persistence of inverse circulations, which are often characteristic features of the coastal zone in the subtropics and are controlled by the balance between evaporation, precipitation, and freshwater discharge. In this study, observations and results from a general ocean circulation model are used to investigate how current climate trends have impacted upon the physical characteristics of the Hervey Bay, Australia. During the last two decades, mean precipitation in Hervey Bay deviates by 13 % from the climatology . In the same time, the river discharge is reduced by 23 %. In direct consequence, the frequency of hypersaline and inverse conditions has increased. Moreover, the salinity flux out of the bay has increased and the evaporation induced residual circulation has accelerated. Contrary to the drying trend, the occurrence of severe rainfalls, associated with floods, leads to short-term fluctuations in the salinity. These freshwater discharge events are used to estimate a typical response time for the bay.

Is the East Australian Current causing a marine ecological hot-spot and an important fisheries near Fraser Island, Australia?

“…Previous analysis of three extreme river discharge events in the Hervey Bay region found that the freshwater plume-impacted coastal zone of the inner-shelf extends only a few kilometres from the coast (Gräwe et al, 2010). Water depth is well below the 40 m threshold previously introduced.…”

“…It was hypothesised that strong bottom Ekman layer flux resulted in the observed uplift of nutrient-rich (phosphate, nitrate and silicate) water onto the shelf. Gräwe et al (2010) found evidence of a sporadic upwelling event just to the north of Sandy Cape at 24.5 o S in hydrography data from a Hervey Bay survey during December 2007. Rossi et al (2014) focused their analysis of eastern coastal upwelling on a region south of 28 o S using 10 years of remotely sensed wind data.…”

La influencia de la descarga del Canal del Dique en los niveles del mar de la Bahía de Cartagena-Colombia

“…El cambio climático es generalmente asociado al incremento de la temperatura, ya que éste es un parámetro básico medible; éste también causa cambios en los patrones del viento [9] [10], en la intensidad o frecuencia de tormentas [11] [12]; así como también de la lluvia y de la escorrentía [5] [13]. Aunque no se ha llegado a un consenso sobre la actividad futura de la actividad de El Niño [14] [15], recientemente encontraron, después de hacer 79 simulaciones de doce diferentes modelos climáticos, acoplando el océano y la atmósfera, y evaluando seis diferentes escenarios del IPCC, un incremento en el número de anomalías del tipo La Niña en el sector del océano Pacífico a partir del 2050.…”

Potential effects of climate change on Australian estuaries and fish utilising estuaries: a review

“…Recent studies have also suggested that Hervey Bay (Queensland) has inverse salinity throughout most of the year and that such conditions may persist with drought (Ribbe 2006;Gräwe et al 2010). Inverse salinity in northern Australia is likely only during the dry season and will depend on rainfall changes associated with climate change.…”

“…In northern Australia, altered rainfall and river flows are suggested to be more important factors as a consequence of climate change than are increases in temperature (Hobday et al 2008). Reduced river flows have already occurred in eastern Australia (Gräwe et al 2010). The direct human use of water resources (e.g.…”