Environmental Monitoring – March

UDT exhibition for undersea defense from May 26-28
UDT features a three-day exhibition packed with organisations operating in undersea defence and security domains.

2018 Global Temps
Fourth Highest on Record

The release of provisional figures for the average global temperature in 2018 sho ws the long-term warming trend has continued. Professor Tim Osborn of the University of East Anglia’s Climatic Research Unit, which provides data used in the analysis by the World Meteorological Organization (WMO), said the warming caused by these greenhouse gas emissions is already clear at the global scale.

The WMO provisional Statement on the State of the Climate in 2018 shows the average global temperature in 2018 is set to be the fourth highest on record. The 20 warmest years on record have been in the past 22 years, with the top four in the past four years.

Osborn cites the burning of coal, oil and gas as resulting in the emission of 1.5 trillion tonnes of carbon dioxide to the Earth’s atmosphere. The warming caused by these greenhouse gas emissions has knock-on effects for regional climates and the severity of weather events.

Sea Level Variations
In Disko Bay

Dr. David Holland of New York University, in collaboration with Dr. Natalya Gomez at McGill University, is leading an investigation of sea level variations in the Disko Bay region of western Greenland. A shore-based system compares the direct arrival of GPS signals to the signals reflected off the sea surface to obtain sea level. The presence of sea ice and icebergs complicate the measurements. A shore-mounted camera provides information about the surroundings and the presence of sea ice and icebergs when there is daylight. Underwater sonar devices can supplement the camera-based observations and eliminate the dependence on daylight to characterize the ice.

An ASL ice-profiling sonar (IPS) was chosen to make ice-draft measurements at two sites located within 150 m of shore in water depths of 20 to 30 m. In the 2019 field season, the team will service the shore-based and mooring-based instruments and recover the data.

Hypoxic Dead Zones
Found in Urban Streams

A new Duke University-led study reveals that hypoxic dead zones also occur in freshwater urban streams. Researchers measured dissolved oxygen concentrations, light levels, water chemistry and stream flow in six streams draining urban watersheds in Durham and Raleigh, North Carolina, from 2015 to 2017. They used the data to model the growth of algae and oxygen-consuming bacteria in the streams and examine the frequency at which dissolved oxygen concentrations dropped below 2 mg per liter—the danger point for fish and other aquatic organisms.

Streams draining developed areas are subject to intense, erosive storm flows when roads and stormwater pipes rapidly route runoff into streams during storms, without allowing the water to infiltrate into the soil. Erosion caused by these intense flows changed the shape of some stream channels to such an extent that water essentially stopped flowing in them during late summer. They became a series of pools containing high levels of nutrient runoff and organic matter, including nitrogen from leaking sewer pipes, fertilizer and pet waste. The elevated nutrient levels spurred greater consumption of dissolved oxygen by bacteria in the water, causing the pools to become hypoxic until the next storm flushed them out.

Dam building and other human alterations that stop the flow of water make these freshwater ecosystems particularly vulnerable to hypoxia, with negative implications for biodiversity.

Improved Cyclone Modeling
Helps Infrastructure Design

It is hard to predict precisely where and how severely cyclones are likely to affect a particular location. Cyclones are erratic weather phenomena, and the historical data available are often not sufficiently detailed for accurate predictions.

HR Wallingford scientists have developed a method to expand the data set for specific sites, allowing for much more precise modeling of likely future cyclone events. In a study, cyclones were modeled using TELEMAC-2D and SWAN open-source software to predict surge and wave conditions at a particular site for each cyclone (https://youtu.be/wpiX3Qzu6bo).

The new Probabilistic Cyclone Modeling Tool uses statistical methods in combination with surge and wave modeling. This can be used to inform the design of coastal infrastructure such as seawalls and breakwaters to match the conditions of a specific site.

pH Sensors at Experimental
Aquaculture Site

Three meters below the surface of Washington State’s Hood Canal, the very first SeapHOx V2s hummed along next to an experimental sugar kelp farm. In a previous life, these SeapHOxes were among the first SeaFET V1s.

When Sea-Bird Scientific made the decision to upgrade the line of pH sensors to the SeaFET V2, these early instruments were readily available for upgrades. Engineers pulled the original boards out of these instruments, fitted them with all new hardware, and combined them with a 37-SMP-ODO to form the first alpha “SeapHOx V2.”

The aquaculture site itself is an experiment to identify if sugar kelp farming can help sequester carbon to combat ocean acidification, funded by the Paul Allen Foundation and led by the Puget Sound Restoration Fund.

The SeapHOx V2s were joined by a 16plusV2 CTD, chlorophyll sensors, current meters and another colorimetric pH sensor.

Researchers are still analyzing the data for the larger aquaculture project. For Sea-Bird Scientific, the successful deployment provided a trove of field validation data from the prototype sensors.