Revisiting Sverdrup's critical depth hypothesis

Mapping spatio-temporal dynamics of suspended load in a lagoon before-during-after a cyclone is crucial for monitoring sudden nutrient enrichment and associated processes such as algal blooms and siltation. However, not all cyclones produce similar impact on a coastal lagoon, some trigger algal blooms after passage while others just increase the overall turbidity. Asia’s largest brackish water lagoon, Chilika Lagoon, India was hit by two anniversary-severe cyclones Phailin (12 October 2013) and Hudhud (12 October 2014) recently. Their impacts were analysed with respect to physical, biological and meteorological factors which favour or restrict a phytoplankton bloom after the passage of a storm. Moderate-resolution imaging spectroradiometer surface reflectance data were used to examine the spatio-temporal variability in total suspended sediment (TSS) and chlorophyll-a (Chl-a) concentration pre- and post-cyclone. Comparative results revealed that Phailin was associated with higher rainfall, wind speed and surface runoff compared with Hudhud. These factors contributed to higher TSS concentration in all sectors of the lagoon post-Phailin compared with post-Hudhud. Extreme TSS, limited light, high rainfall and runoff and increased flushing rate post-Phailin restricted the likelihood of a phytoplankton bloom in the lagoon, a commonly reported phenomenon after the passage of a cyclone. In contrast, sufficient light availability due to lower TSS, low runoff and flushing and stable wind supported a phytoplankton bloom post-Hudhud. The observed differential impacts were linked to the individual cyclone’s characteristics such as differences in landfall locations, wind speed, trajectory after the landfall, differences in rainfall rate and surface runoff and speed of passage.

Differential Impact of Anniversary-Severe Cyclones on the Water Quality of a Tropical Coastal Lagoon

Satellite observations of seasonal and regional variability of particulate organic carbon concentration in the Barents Sea

Summary The Nordic and Barents Seas are of special interest for research on climate change, since they are located on the main pathway of the heat transported from low to high latitudes. The Barents Sea is characterized by supreme phytoplankton blooms and large amount of carbon is sequestered here due to biological processes. It is important to monitor the biological variability in this region in order to derive in depth understanding whether the size of carbon reservoirs and fluxes may vary as a result of climate change. In this paper we analyze the 17 years (1998–2014) of particulate organic carbon (POC) concentration derived from remotely sensed ocean color. POC concentrations in the Barents Sea are among the highest observed in the global ocean with monthly mean concentrations in May exceeding 300 mg m −3 . The seasonal amplitude of POC concentration in this region is larger when compared to other regions in the global ocean. Our results indicate that the seasonal increase in POC concentration is observed earlier in the year and higher concentrations are reached in the southeastern part of the Barents Sea in comparison to the southwestern part. Satellite data indicate that POC concentrations in the southern part of the Barents Sea tend to decrease in recent years, but longer time series of data are needed to confirm this observation.

The Faroe shelf spring bloom onset explained by a 'Critical Volume Hypothesis'

John F. Marra1*, Tommy D. Dickey2, Albert J. Plueddemann3, Robert A. Weller3, Christopher S. Kinkade4, and Malgorzata Stramska5 Earth and Environmental Sciences Department, Brooklyn College (CUNY), Brooklyn, NY, USA Ocean Physics Laboratory, University of California Santa Barbara, Santa Barbara, CA, USA Physical Oceanography Department, Woods Hole Oceanographic Institution, Woods Hole, MA, USA NOAA National Ocean Service, Silver Spring, MD 20910, USA Institute of Oceanology of the Polish Academy of Sciences, Sopot 81-712, Poland *Corresponding author: tel: +1 718 951 5000x2594; fax: +1 718 951 4753; e-mail: jfm7780@brooklyn.cuny.edu

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Christopher S. Kinkade

Papers

Phytoplankton bloom phenomena in the North Atlantic Ocean and Arabian Sea