Salinity Matters (final)

Salinity Matters (final)
Created by: Carla Companion

In this activity, you will study the variation in concentration of dissolved salt (a.k.a. "salinity"). In addition, you will analyze water temperature and air temperature to discover how these have changed over the past 30 days. Video and interactive concept maps will provide a "bigger picture" view of ocean salinity and how it affects the water cycle, ocean circulation, and climate.

Introduction

"Water, water, everywhere but not a drop to drink" describes over 97% of Earth's water: too salty for human consumption. Since humans generally live on land and can access fresh water from lakes and rivers, it may seem irrelevant to study the saltiness of water. But no matter where you live, you are connected to the ocean: the freshwater that you drink once evaporated from our salty seas. And the ocean is connected to you through watersheds and estuaries. In this activity, you will study data from estuaries, the important transition areas that straddle the land and the sea. You will study the past 30 days of data from two stations: one closer to a river source and another located closer to the ocean. From these examples, you see how salinity, air temperature, tides and water temperatures change within estuaries. You will then "go out to sea" by investigating two concept maps, along with images and videos connected to them. The concept maps will cover the big picture of how ocean salinity changes over time and key connections to water cycle, ocean currents and climate. The evidence presented in this activity -- time-series data, video and concept maps -- will help you develop a written explanation of the important connections between fresh water, salt water, estuaries, the ocean, and you.

Background

The photorealistic image at right depicts the major elements of the water cycle, including major reservoirs for freshwater (i.e., atmosphere and land) and salt water (i.e., ocean). Water cycle processes that occur near or over the ocean affect its salinity, as you will learn in the following sections. The transition from fresh to salty water often occurs in estuaries. Daily tides (i.e., regular rise and fall of the sea's surface) are a major influence on many of the dynamic environments of estuaries. Most fish and shellfish eaten in the U.S. complete at least part of their life cycles in estuaries. Estuaries also filter out sediments and pollutants from rivers and streams before they flow into the oceans, providing cleaner waters for marine life.

Question 1: The ocean covers over 70% of Earth's surface, so why do most water cycle diagrams (like the one here) have so much land in them?

Challenge

In this activity you will investigate the following research challenge...

Why does water salinity (i.e., dissolved salt concentration) vary from place to place? How might salinity variations impact organisms (e.g., humans)?

Explore the Data

Analyze the evidence below to determine how and why salinity varies over 30 days for one station located closer to a river source (Galveston, TX or Dover, DE) and another station located closer to the ocean (Prince William Sound, AK or Narragansett Bay, RI). Chose the two stations you'd like to examine, just make sure one is labeled as a "Near-River Example" and the other is a "Near-Ocean Example." Together these stations will help you better understand conditions at the near and far ends of estuaries. There is also one video to watch and two concept maps to examine. Together, these resources will show the connections between salinity, the water cycle, ocean circulation and climate. They will also help you understand why NASA launched the Aquarius satellite instrument in 2011 to continuously monitor global ocean surface salinity.

When you're done investigating each dataset, continue to the last section.

Near-River Example: Galveston TX over Past 30 Days (Station #8770613)

The plot above has the past 30 days of salinity, predicted tide, water and air temperature data for a station off of Galveston, Texas. Use the pull-down menu at right to switch among the four data sets.

While investigating these time-series data sets, you should focus on:

  • The overall RANGE of the data (i.e., difference between the highest and lowest values).
  • TRENDS in the data (i.e., general direction of change over time).
  • Any CORRELATIONS between data sets (i.e., similar trends in two or more of the data sets).
  • Near-River Example: Dover DE over Past 30 Days (Station #8537121)

    The plot above has the past 30 days of salinity, predicted tide, water and air temperature data for a station off of Dover, Delaware. Use the pull-down menu at right to switch among the four data sets.

    While investigating these time-series data sets, you should focus on:

  • The overall RANGE of the data (i.e., difference between the highest and lowest values).
  • TRENDS in the data (i.e., general direction of change over time).
  • Any CORRELATIONS between data sets (i.e., similar trends in two or more of the data sets).
  • Near-Ocean Example: Prince William Sound AK over Past 30 Days (Station #9454050)

    The plot above has the past 30 days of salinity, predicted tide, water and air temperature data for a station in Narragansett Bay, Rhode Island. Use the pull-down menu at right to switch among the four data sets.

    While investigating these time-series data sets, you should focus on:

  • The overall RANGE of the data (i.e., difference between the highest and lowest values).
  • TRENDS in the data (i.e., general direction of change over time).
  • Any CORRELATIONS between data sets (i.e., similar trends in two or more of the data sets).
  • Near-Ocean Example: Narragansett Bay RI over Past 30 Days (Station #8452660)

    The plot above has the past 30 days of salinity, predicted tide, water and air temperature data for a station in Prince William Sound, Alaska. Use the pull-down menu at right to switch among the four data sets.

    While investigating these time-series data sets, you should focus on:

  • The overall RANGE of the data (i.e., difference between the highest and lowest values).
  • TRENDS in the data (i.e., general direction of change over time).
  • Any CORRELATIONS between data sets (i,e., similar trends in two or more of the data sets).
  • One Year of NASA Aquarius Ocean Surface Salinity Data

    The Aquarius instrument is designed to measure global sea surface salinity. It is important to understand salinity, the amount of dissolved salts in water, because it will lead us to better understanding of the water cycle and can lead to improved climate models. This visualization celebrates over a year of successful Aquarius observations.

    Sea surface salinity is shown at various locations around the globe highlighting the following:
    - The Atlantic Ocean is generally much more salty than the Pacific
    - Low salinity waters in the Eastern Equatorial Pacific are transported westward
    - High influxes of fresh water from the Amazon River basin can be clearly seen
    - Low salinity waters are transported by the Labrador current to the south
    - High influxes of fresh water from the Ganges River basin can be seen keeping the Eastern Indian Ocean lower salinity than the Western Indian Ocean.

    Transcript for this movie is available by clicking here.

    The range of time shown is December 2011 through December 2012.

    Salinity Matters: Water Cycle

    Salinity Matters: Water Cycle


    CLICK HERE TO ACCESS INTERACTIVE VERSION OF THE MAP SHOWN ABOVE.

    This concept map illustrates connections between the water cycle, salinity and climate. The map can be simplified by clicking the color blocks on/off the upper left of the map. Be sure to view the images, movies, and/or information linked to each of the concepts (i.e., by clicking on the icons).

    You should view the map elements in the following order:

  • Water Cycle (red);
  • Land processes (orange);
  • Land and Ocean processes (yellow);
  • Weather and Climate (green); and
  • Salinity (blue).
  • Interpretation Questions

    • Based on the "One Year of NASA Aquarius Data" video and your investigation of this map, how is the water cycle related to salinity and climate?

    Salinity Matters: Ocean Circulation

    Salinity Matters: Ocean Circulation


    CLICK HERE TO ACCESS INTERACTIVE VERSION OF THE MAP SHOWN ABOVE.

    This concept map illustrates connections between the sun's heat, salinity and ocean circulation. The map can be simplified by clicking the color blocks on/off the upper left of the map. Be sure to view the images, movies and/or information linked to each of the concepts (i.e., by clicking on the icons).

    You should view the map elements in the following order:

  • Ocean Heat (red);
  • Evaporation, Precipitation and Salinity (orange);
  • Temperature, Density and Ocean Circulation (yellow);
  • Climate (green); and
  • NASA Aquarius (blue).
  • Interpretation Questions

    • Based on your investigation of this map, how does salinity affect ocean circulation and the heat it transports?

    Salinity Matters: Ocean Circulation

    This concept map illustrates connections between the sun's heat, salinity and ocean circulation. The map can be simplified by clicking the color blocks on/off the upper left of the map. Be sure to view the images, movies and/or information linked to each of the concepts (i.e., by clicking on the icons). You should view the map elements in the following order: Ocean Heat (red); Evaporation, Precipitation and Salinity (orange); Temperature, Density and Ocean Circulation (yellow); Climate (green); and NASA Aquarius (blue).

    Interpretation Questions

    • Based on your investigation of this map, how does salinity affect ocean circulation and the heat it transports?

    Salinity Matters: Water Cycle Concept Map

    This concept map illustrates connections between the water cycle, salinity and climate. The map can be simplified by clicking the color blocks on/off the upper left of the map. Be sure to view the images, movies, and/or information linked to each of the concepts (i.e., by clicking on the icons).

    You should view the map elements in the following order:

    • Water Cycle (red);
    • Land processes (orange);
    • Land and Ocean processes (yellow);
    • Weather and Climate (green); and
    • Salinity (blue).

    Develop an Explanation

    Recall that the research challenge you are trying to address is:

    Why does water salinity (i.e., dissolved salt concentration) vary from place to place? How might salinity variations impact organisms (e.g., humans)?

    As you consider the data you just investigated, consider the following questions:

    1. How do salinity, water temperature, tides, and air temperature vary over time within estuaries?
    2. What are the differences between estuarine stations located closer to rivers versus closer to the ocean?
    3. Why is monitoring global ocean salinity helping us better understand the water cycle, ocean circulation, and climate?

    Assessment

    The goal of this investigation is to construct a written explanation of the observed phenomena seen in the data

    Additional Instructions

    Using the two time-series datasets that you investigated, compare and contrast the ranges of salinity, water temperature, and air temperature. Discuss why the range in salinity values of the near-ocean example is smaller than the near-river example. Also address why the range in air temperature values are generally greater than that of water temperature. Summarize the general trends in the data sets and identify which, if any, of the data sets are correlated. Hypothesize which environmental factors might be responsible for the correlations in your data. Based on the "One Year of NASA Aquarius Data" video and concept maps, summarize the relationships between the ocean salinity, the water cycle, ocean circulation and climate. Lastly, identify potential impacts of salinity variations on organisms from regional scales (i.e., estuaries) to global scales.

    About this Data Investigation