Stephen Bunker: Data Sampling, 23 October 2011

NOAA Teacher at Sea
Stephen Bunker
Aboard R/V Walton Smith
October 20 — 24, 2011

Mission: South Florida Bimonthly Regional Survey
Geographical Area: South Florida Coast and Gulf of Mexico
Date: 23 October 2011

Weather Data from the bridge

Time: 6:23 PM
Wind direction: Northeast
Wind velocity: 5 m/s
Air Temperature: 25° C (77° F)
Clouds: stratocumulus

Science and Technology Log

Collecting data is what science is all about and scientists can measure many different things from the ocean. They generally take these measurements in two different ways: discrete and ongoing samples.

Cheryl is preparing filter samples made from water collected with the CTD. These samples will be frozen and analyzed later in a laboratory on shore.

Discrete sampling means scientists will take samples at different times. When we take measurements at regular intervals, we can compare the data and look for patterns. On the R/V Walton Smith we take discrete samples each time the CTD is lowered. At approximately every two weeks RV Walton Smith will revisit the same location and collect data again. These bi-monthly data samples will let the scientists compare the data and look for patterns.

Remember when we collected weather data in class? We were also doing discrete sampling. We collected weather data from the morning and afternoon each school day. We would record precipitation, wind velocity and direction, air temperature, barometric pressure, and cloud types. Remember the pattern we noticed? When the afternoon temperature was cooler than the morning, we would have precipitation the next day.

Pump and valve system used for water sampling

Here is the pipes, valves and instruments used to take ongoing samples of surface water.

Ongoing sampling is also done on the R/V Walton Smith. On the fore, port (the left front) side of the ship, ocean water is continually sucked into some pipes. This surface water is continually pumped through instruments and water chemistry data is collected.

This continual data sampling is recorded on a computer and graphs can be made for  different characteristics of water chemistry. When continual data is graphed, the graphs have a smoother shape than they would with discrete samples.

Initially I thought that we were just collecting data each time we stopped to lower the CTD. Actually we had been collecting data throughout the entire voyage.

Kuan is monitoring his ongoing data collection of dissolved inorganic carbon.

Kuan, one of the scientists on our cruise, was measuring the amount of dissolved inorganic carbon in the ocean. The process of doing this has typically been a discrete sampling process that involves chemically analyzing water samples, Kuan has developed an instrument that would take ongoing water samples and measure the amount of dissolved inorganic carbon continually.

His instrument would tap into the water pipes above and take ongoing samples throughout the trip. He also wrote a computer program that would record, calculate, and graph the quantity of dissolved inorganic carbon. He even collects GPS data so he can tell where in the ocean his samples were taken. His experiment, I learned, is cutting-edge science or something that hasn’t been tried before.

Personal Log

I hadn’t realized the close connection there is between our earth’s atmosphere and its oceans. I understood how the ocean temperatures and currents  affect our weather systems. But, I didn’t understand how on a micro scale this happens as well. The ocean will exchange (absorb and give off) carbon dioxide and many other molecules with the air.

Why is it important to understand how the ocean and atmosphere interact? We often hear how greenhouse gasses are contributing to climate change. Carbon dioxide, considered a greenhouse gas, is one of the inorganic carbon molecules absorbed and given off by the oceans. When it is absorbed, it can make the ocean slightly more acidic which could harm the micro organisms that are in the ocean food chain

Understanding the interaction between atmosphere and ocean will help us understand why some areas of the earths ocean absorb more carbon dioxide and others don’t.