Long-term variability of oceanographic data at the Port Hacking 50-metre station

1977 ◽  
Vol 28 (1) ◽  
pp. 57 ◽  
Author(s):  
SD Hahn ◽  
DJ Rochford ◽  
JS Godfrey
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Inorganic Phosphate ◽  
Time Interval ◽  
Seasonal Cycles ◽  
Oceanographic Variables ◽  
Oceanographic Data ◽  
Annual Means

Measurements of water temperature, salinity, dissolved oxygen, nitrate and inorganic phosphate have been made at the Port Hacking 50-m station which is about 30 km south of Sydney and 5 km offshore. This paper reports an analysis of the data obtained between 1942 and 1972. Mean seasonal cycles of each of these variables have been evaluated for the time interval, as well as the annual means for each year. Shorter period fluctuations are studied by cross correlating the monthly anomalies of the various oceanographic variables.

scholarly journals RESEARCH OF LONG-TERM SEASONAL VARIABILITY OF TEMPERATURE AND SALINITY IN THE SEA OF AZOV FOR THE PERIOD 1913–2018

2020 ◽  
Vol 1 (5) ◽  
pp. 220-223
Author(s):  
D.M. Shukalo ◽  
◽  
T.Y. Shul’ga ◽  
Keyword(s):  
Water Temperature ◽  
Cold Water ◽  
The Black Sea ◽  
Sea Of Azov ◽  
Summer Period ◽  
Marine Hydrophysical Institute ◽  
The Sea Of Azov ◽  
Azov Sea ◽  
Oceanographic Data

One of the most demanded directions of oceanographic problems is the study of long-term variability and modeling of future climatic changes and also the possibility of obtaining continuous information on the thermohaline structure of the sea based on the joint use of remote sensing data and the results of assimilation modeling. In current paper, research, of the Sea of Azov for the period 1913–2018 was carried out. We used the data of contact measurements from the oceanographic data base of the SSC RAS, Atlas of climate change in large marine ecosystems of the Northern Hemisphere, as well as data from the oceanographic data bank of the Marine Hydrophysical Institute RAS. Based on the analysis of the information, the calculation of the average monthly temperature and salinity was carried out, the periods of anomalous temperature were revealed, the periods of salinization and desalination of the Azov Sea also were noted. Data analysis made possibility to identify intrasecular climate fluctuations. Abnormally cold water temperature in winter was noted in the periods: 1926–1932, 1951– 1956, 2003–2012. In turn, the abnormally warm water temperature in winter, which was recorded in the periods: 1935–1939, 1958–1972, 1983–1992. by accompanied a cold spring-summer period. During the last five years the spring-summer period is characterized by an increased water temperature of the Azov Sea. The long-term variability of the salinity of the Sea of Azov significantly depends on the inflow of saltier waters of the Black Sea and river runoff. Due to these circumstances, the Sea of Azov is characterized by periods of salinization and desalination: the period of salinization was recorded from 1955 to 1973, a shorter period of desalination falls on 2003–2018. On average, the value of the ratio between the mean monthly salinity values during these periods is 2,2 times.

scholarly journals Dissolved oxygen and water temperature dynamics in lowland rivers over various timescales

2015 ◽  
Vol 63 (4) ◽  
pp. 353-363 ◽  
Author(s):  
Agnieszka Rajwa-Kuligiewicz ◽  
Robert J. Bialik ◽  
Paweł M. Rowiński
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Environmental Variability ◽  
Physical Factors ◽  
Lowland Rivers ◽  
Physical Conditions ◽  
The Impact ◽  
Floodplain Hydrology ◽  
Oxygen Dynamics

Abstract The impact of floodplain hydrology on the in-stream dissolved oxygen dynamics and the relation between dissolved oxygen and water temperature are investigated. This has been done by examining the time series of dissolved oxygen and water temperature coupled with meteorological and hydrological data obtained from two lowland rivers having contrasting hydrological settings. Spectral analysis of long-term oxygen variations in a vegetated river revealed a distinct scaling regime with slope ‘–1’ indicating a self-similar behaviour. Identical slopes were obtained for water temperature and water level. The same power-law behaviour was observed for an unvegetated river at small timescales revealing the underlying scaling behaviour of dissolved oxygen regime for different types of rivers and over various time scales. The results have shown that the oxygenation of a vegetated river is strongly related to its thermal regime and flow conditions. Moreover, analysis of short-term fluctuations in the unvegetated river demonstrated that physical factors such as rainfall and backwaters play a substantial role in the functioning of this ecosystem. Finally, the results show that the relation between water temperature and dissolved oxygen concentration at the diurnal timescale exhibits a looping behaviour on the variable plot. The findings of this study provide an insight into the sensitivity of rivers to changing hydro-physical conditions and can be useful in the assessment of environmental variability.

scholarly journals Dissolved oxygen stratification in a small lake depending on water temperature and density and wind impact

2021 ◽  
Vol 937 (3) ◽  
pp. 032019
Author(s):  
N Palshin ◽  
G Zdorovennova ◽  
T Efremova ◽  
S Bogdanov ◽  
A Terzhevik ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Wind Load ◽  
Density Stratification ◽  
Wind Regime ◽  
Independent Variables ◽  
Decomposition Of Organic Matter ◽  
Do Concentration ◽  
Weak Stratification

Abstract The dissolved oxygen (DO) is one of the most important parameters in lakes ecosystem. Variability of DO in lakes is associated with the absorption of oxygen due to the decomposition of organic matter and chemical reactions and the release of oxygen as a result of photosynthesis. The DO concentration also depends on seasonal changes in water temperature and mixing regime. The aim of this work is to assess the influence of seasonal thermal and density stratification on the DO stratification in a small mesotrophic lake and to develop a regression DO model, with water temperature and density and characteristics of wind regime as independent variables. Long-term measurements of water temperature and DO in small Karelian Lake Vendyurskoe in 2007-2020 were used. At the stage of spring-summer heating, three periods are considered when the water column was in the state of homothermy (May 15-June 15), weak stratification (July 15-August 15), and strong stratification (July 15-August 15). The wind load (number of days with wind speed more than 3 m/s for each period) was analysed based on the weather station Petrozavodsk data. As a result of multiple regression analysis, taking into account the wind load, dependences of DO stratification on water temperature stratification (R2 = 0.51) and water density stratification (R2 = 0.61) are found. Obtained regression DO models can be used for solving various environmental tasks.

scholarly journals Evaluation of oxythermal metrics and benchmarks for the protection of cisco (Coregonus artedi) habitat quality and quantity in Wisconsin lakes

2018 ◽  
Vol 75 (4) ◽  
pp. 600-608 ◽  
Author(s):  
John Lyons ◽  
Timothy P. Parks ◽  
Kristi L. Minahan ◽  
Aaron S. Ruesch
Keyword(s):  
Dissolved Oxygen ◽  
Great Lakes ◽  
Water Temperature ◽  
Water Column ◽  
Laurentian Great Lakes ◽  
Great Lakes Region ◽  
Wide Range ◽  
Coregonus Artedi ◽  
Oxygenated Water

The cisco (Coregonus artedi) requires cold, well-oxygenated water and is threatened by climate warming and lake eutrophication, especially at the southern edge of its range in the Laurentian Great Lakes region. In this paper, a method is described to assess the quality, quantity, and variability of suitable cisco habitat. Two metrics are proposed to characterize existing cisco oxythermal habitat in this region: water temperature in the water column at a dissolved oxygen of 6 mg/L (TDO6) and “cisco layer thickness” (CLT), the vertical extent of the water column within which water temperature is ≤22.8 °C and dissolved oxygen is ≥6 mg/L. It is proposed that values of TDO6 = 22.8 °C and CLT = 1 m be used as benchmarks to identify cisco lakes with potentially stressful oxythermal habitat. Long-term summer data from 14 Wisconsin cisco lakes with a wide range of limnological characteristics indicated that TDO6 varied from 4.2 to 27.5 °C and CLT from −6.2 to 66.7 m. Cisco abundance across lakes was greater at lower values of TDO6 and higher values of CLT, and non-attainments of the proposed benchmarks were most likely in lakes with remnant or extirpated cisco populations. Non-attainment of benchmarks could occur from late June through September, and three or more samples across the entire summer would be required to have a reasonable probability of detecting a non-attainment in TDO6 or CLT within any given year. Across years, to detect a single year of non-attainment with an 80% level of confidence, two years of sampling would be sufficient for CLT and three years for TD06; to detect more than one non-attaining year, three years of sampling for CLT and six years of sampling for TD06 would be required. Despite relatively high temporal variation in some lakes, the proposed metrics and benchmarks appear to have value for assessing cisco oxythermal habitat in the Great Lakes region.

A study on bioecology of macroalgae, genus Caulerpa in northern Minahasa Waters, North Sulawesi Province

2013 ◽  
Vol 1 (1) ◽  
pp. 26
Author(s):  
Irma Pulukadan ◽  
Rene Ch Keppel ◽  
Grevo S Gerung
Keyword(s):  
Dissolved Oxygen ◽  
Water Temperature ◽  
Raw Materials ◽  
Economic Value ◽  
Algal Growth ◽  
Environmental Parameters ◽  
Caulerpa Racemosa ◽  
Bottom Substrate ◽  
North Sulawesi ◽  
Ecological Aspects

Alga is a marine resource of potential to fisheries and marine sector. It has an important economic value to promote the economy in Indonesia. Nowdays, algae have been used as a relatively high value fisheries commodity since it has been used for food, industrial, pharmaceutical and cosmetic raw materials. This important potential needs to be supported with understanding of its biology and ecology, so that its utilization could increase the livelihood of the coastal villagers. This study was aimed at inventorying and identifying the members of genus Caulerpa found in North Minahasa Regency waters and studying some biological and ecological aspects of the algae in the area. Resuls showed that there were 7 species recorded, Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata,C. lentillifera and C. peltata. Ecologically, the environmental parameters, such as water temperature, salinity, pH, dissolved oxygen, turbidity, were in tolerable ranges for algal growth. Bottom substrate supported the growth of genus Caulerpa as well© Saat ini alga dijadikan sebagai komoditas hasil perikanan dengan nilai ekonomis yang relatif tinggi karena manfaatnya sebagai bahan makanan serta bahan baku industri, farmasi, dan kosmetik. Potensi yang cukup penting ini harus ditunjang dengan ilmu pengetahuan tentang biologi dan ekologi dari alga laut, sehingga pemanfaatannya dapat meningkatkan taraf hidup masyarakat pesisir. Penelitian tentang kajian bioekologi alga makro genus Caulerpa di perairan Minahasa Utara ini dilaksanakan dan diharapkan dapat memberikan informasi ilmiah tentang bioekologi alga makro genus Caulerpa, sehingga dapat dimanfaatkan untuk pengembangan pemanfaatan bagi kepentingan masyarakat pesisir khususnya dan industri alga makro umumnya. Penelitian ini bertujuan untuk menginventarisasi dan mengidentifikasi alga makro genus Caulerpa di perairan Kabupaten Minahasa Utara, dan mengkaji aspek bioekologinya. Hasil penelitian menunjukkan bahwa ditemukan 7 spesies, yaitu Caulerpa racemosa, C. racemosa var. macrophysa, C. sertularioides, C. taxifolia, C. serrulata, C. lentillifera dan C. peltata. Parameter lingkungan seperti suhu, salinitas, pH, oksigen terlarut, tingkat kecerahan air berada pada kisaran yang dapat ditolerir untuk pertumbuhan alga makro, sedangkan substrat juga mendukung pertumbuhan alga makro ini©

scholarly journals Estimation of Ocean Thermal Energy Conversion Resources in the East of Malaysia

2020 ◽  
Vol 9 (1) ◽  
pp. 22
Author(s):  
Sathiabama T. T. Thirugnana ◽  
Abu Bakar Jaafar ◽  
Takeshi Yasunaga ◽  
Tsutomu Nakaoka ◽  
Yasuyuki Ikegami ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Energy Conversion ◽  
Thermal Energy ◽  
Biomass Energy ◽  
Relative Depth ◽  
Solar Pv ◽  
Ocean Thermal Energy Conversion ◽  
Thermal Energy Conversion ◽  
Oceanographic Data ◽  
Ocean Thermal Energy

The Malaysian Government has set a target of achieving 20% penetration of Renewable Energy (RE) in the energy mix spectrum by 2025. In order to get closer to the target, Ocean Thermal Energy Conversion (OTEC) aligned with solar PV, biogas and biomass energy sources must be evaluated and comprehended. Hybrid OTEC systems consisting of energy and water production are currently under research and validation. Therefore, for the construction of a commercial OTEC plant, 1 MW or 2.5 MW, the choice of a strategic location or potential site is vital. In this paper, oceanographic data such as seawater temperature, depth, salinity and dissolved oxygen obtained from the Japan Oceanographic Data Center (JODC) for Semporna, Tawau, Kudat, Pulau Layang-Layang and Pulau Kalumpang in Sabah, Malaysia, are reported. The RE available from the Exclusive Economic Zone (EEZ) on the coast of Sabah was estimated based on the JODC data obtained. There were no remarkable differences in temperatures between the five sites, which were reported as approximately 27 °C at the surface and 7 °C at depths below 600 m. The surface salinities below 100 m at those sites were slightly lower than the deeper waters, where the salinity increased up to approximately 34.5 PSU. Dissolved oxygen data from the Pulau Kalumpang site showed a slight increment to approximately 4.7 mL/L at depth intervals below 50 m, before declining steadily to approximately 1.7 mL/L along with the depth. The temperature-salinity profiles of the Malaysian sites were congruent with those of Palau, Kumejima and Okinawa, but not with that of Fiji, where the salinity profile showed a distinct variation at the relative depth (below 200 m). Estimates of RE using two different methods were used to prove the potential of OTEC in Malaysia.

scholarly journals Surface Water Temperature Predictions at a Mid-Latitude Reservoir under Long-Term Climate Change Impacts Using a Deep Neural Network Coupled with a Transfer Learning Approach

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1109
Author(s):  
Nobuaki Kimura ◽  
Kei Ishida ◽  
Daichi Baba
Keyword(s):  
Climate Change ◽  
Surface Water ◽  
Water Temperature ◽  
Transfer Learning ◽  
Air Temperature ◽  
Climate Models ◽  
Temporal Variations ◽  
Training Data ◽  
Surface Water Temperature

Long-term climate change may strongly affect the aquatic environment in mid-latitude water resources. In particular, it can be demonstrated that temporal variations in surface water temperature in a reservoir have strong responses to air temperature. We adopted deep neural networks (DNNs) to understand the long-term relationships between air temperature and surface water temperature, because DNNs can easily deal with nonlinear data, including uncertainties, that are obtained in complicated climate and aquatic systems. In general, DNNs cannot appropriately predict unexperienced data (i.e., out-of-range training data), such as future water temperature. To improve this limitation, our idea is to introduce a transfer learning (TL) approach. The observed data were used to train a DNN-based model. Continuous data (i.e., air temperature) ranging over 150 years to pre-training to climate change, which were obtained from climate models and include a downscaling model, were used to predict past and future surface water temperatures in the reservoir. The results showed that the DNN-based model with the TL approach was able to approximately predict based on the difference between past and future air temperatures. The model suggested that the occurrences in the highest water temperature increased, and the occurrences in the lowest water temperature decreased in the future predictions.

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