Bio-optical characterization and light availability parameterization in Uummannaq Fjord and Vaigat–Disko Bay (West Greenland)

L Holinde,O Zielinski

doi:10.5194/os-12-117-2016

Abstract

Abstract. This study investigated the bio-optical conditions of Uummannaq Fjord and Vaigat–Disko Bay, two neighboring, semi-enclosed coastal systems in West Greenland. Though close to each other, the systems differ in their hydrographic structure influencing the bio-optical conditions and, subsequently, the biological activities. Both systems showed high inorganic suspended particulate matter (SPMi) concentrations near river runoff or meltwater influxes (max. of 15.28 mg L−1 at the surface) and low colored dissolved organic matter (aCDOM@350nm, < 1.50 m−1) abundance throughout the systems. High chlorophyll levels (as an indicator of phytoplankton biomass) were measured in the Vaigat (max. of 11.44 µg L−1), which represents the outflow arm of Disko Bay. Light penetration depth as indicated by the 1 % depth of photosynthetically available radiation (PAR) was dominated by chlorophyll and SPMi alike, ranging from 12.2 to 41.2 m. Based on these characteristics, an effective two-component parameterization for the diffuse attenuation coefficient kPAR was developed in order to model light penetration depth as a relevant factor for bio-optical studies in Arctic environments under glacial meltwater influence.

Highlights

Greenland’s coastal systems are strongly influenced by their ocean and land boundaries
We investigated the distribution of chlorophyll a (Chl a), inorganic suspended particulate matter (SPMi), and colored dissolved organic matter (CDOM), and determined the resulting light penetration depth of the photosynthetically available radiation (PAR) based on field observations
In this study we present the findings of a physical-bio-optical investigation of Uummannaq Fjord and the Vaigat–Disko Bay system, two embayments on the western coast of Greenland

Summary

Introduction

Greenland’s coastal systems are strongly influenced by their ocean and land boundaries. Land-based influences include freshwater influx from glacial meltwater or river runoff (Straneo and Cenedese, 2015), while oceanic influences include adjacent waters from the Nordic Seas, Baffin Bay and coastal currents. Climate-driven warming significantly affects the hydrography of these coastal systems through glacial melting and freshwater runoff, and Disko Bay (West Greenland, Andersen, 1981), which is fed by the Jakobshavn Isfjord, is especially subject to these dynamics (Hansen et al, 2012). The expedition coincided with an increase in Jakobshavn Isbræ glacier melting activity as reported by Joughin et al (2014) and an unprecedented surface melt of the Greenland ice sheet in 2012 (Nghiem et al, 2012)

Objectives

Methods

Results

Discussion

Conclusion