Modeling dimethylsulphide production in the upper ocean

Dimethylsulphide (DMS) is produced by upper ocean ecosystems and emitted to the atmosphere, where it may have an important role in climate regulation. Several attempts to quantify the role of DMS in climate change have been undertaken in modeling studies. We examine a model of biogenic DMS production and describe its endogenous dynamics and sensitivities. We extend the model to develop a one-dimensional version that more accurately resolves the important processes of the mixed layer in determining the ecosystem dynamics. Comparisons of the results of the one-dimensional model with an empirical relationship that describes the global distribution of DMS, and also with vertical profiles of DMS in the upper ocean measured at the Bermuda Atlantic Time Series, suggest that the model represents the interaction between the biological and physical processes well on local and global scales. Our analysis of the model confirms its veracity and provides insights into the important processes determining DMS concentration in the oceans

Correlation between sea surface temperature and wind speed in Greenland Sea and their relationships with NAO variability

AbstractThe North Atlantic Oscillation (NAO) is one of the major causes of many recent changes in the Arctic Ocean. Generally, it is related to wind speed, sea surface temperature (SST), and sea ice cover. In this study, we analyzed the distributions of and correlations between SST, wind speed, NAO, and sea ice cover from 2003 to 2009 in the Greenland Sea at 10°W to 10°E, 65°N to 80°N. SST reached its peak in July, while wind speed reached its minimum in July. Seasonal variability of SST and wind speed was different for different regions. SST and wind speed mainly had negative correlations. Detailed correlation research was focused on the 75°N to 80°N band. Regression analysis shows that in this band, the variation of SST lagged three months behind that of wind speed. Ice cover and NAO had a positive correlation, and the correlation coefficient between ice cover and NAO in the year 2007 was 0.61. SST and NAO also had a positive correlation, and SST influenced NAO one month in advance. The correlation coefficients between SST and NAO reached 0.944 for the year 2005, 0.7 for the year 2008, and 0.74 for the year 2009 after shifting SST one month later. NAO also had a positive correlation with wind speed, and it also influenced wind speed one month in advance. The correlation coefficients between NAO and wind speed reached 0.783, 0.813, and 0.818 for the years 2004, 2005, and 2008, respectively, after shifting wind speed one month earlier

A revised algorithm for calculating sample concentrations from spectrophotometric absorbances

Standard colorimetric techniques require conversion of measured absorbances to concentrations. When blank absorbances are significant, use of the conventional algorithm under-estimates the true sample concentration. A revised algorithm is presented which allows a more accurate determination of sample concentration

Water quality and phytoplankton dynamics in Moreton Bay, south-eastern Queensland. I. Field survey and satellite data

The water quality of Moreton Bay, a sub-tropical estuarine embayment in south-eastern Queensland, was monitored over a 2-year period. Surveys in situ and ground-truthed satellite imagery were used to describe the temporal and spatial variability in water-quality indicators and the level of eutrophication. Strong east-west gradients in chlorophyll a and water clarity were found. During the study period fluvial discharges, which all enter on the western littoral, were below their long-term averages, and nutrient loading to the bay was dominated by point-source wastewater discharges along the western boundary. The data suggest that although the impact of nutrient loads on the bay's eastern side is mitigated by tidal intrusion of oceanic water, the western areas are already degraded and can be considered mesotrophic to eutrophic. This part of the bay may deteriorate further with the projected future population expansion in the bay's catchment

Water quality and phytoplankton dynamics in Moreton Bay, south-eastern Queensland. II. Mathematical modelling

A coupled hydrodynamic water-quality model of Moreton Bay was developed to enable better management of nutrient loads and to predict eutrophication-related problems. The hydrodynamic submodel was calibrated to available tidal data, and the transport submodel was calibrated to a salinity dataset. A 15-month time-series of field data was used together with historical data to calibrate and validate the water-quality submodel. Model simulations suggest that denitrification removes over half the external N inputs with about one-third exported to the open ocean. Approximately 8% of N and 20% of the P loading accumulates in the sediments. Short-term variations due to hydrodynamic effects tend to mask the seasonal cycle in phytoplankton biomass except at inshore localities. The model predictions confirm the field data that indicate that water quality in the western bay is severely affected while the better flushed eastern region remains relatively unaffected. Future increases in nutrient loading due to population pressure are predicted to extend the severely affected region eastwards. Over most of the bay, algal productivity is N-limited except for the western margins where nutrients are saturating and light availability regulates growth. Model hindcasts suggest that system-wide mean algal production has increased by a factor of ten since European settlement