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About Sage Lichtenwalner

Sage is a research programmer and outreach specialist at the Rutgers University Institute of Marine and Coastal Sciences.

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Tropical Storm Andrea clouds up the ocean

By on June 7, 2013 in Visualizations

False-color image from NOAA-18 at 4:36pm on June 7, 2013

This week, was the start of the 2013 Hurricane Season, and already forecasters have declared the first storm of the season. So with one week down, I’d say we’re on track to meet NOAA’s prediction of an active to extremely active season.

Tropical Storm Andrea started as a small storm system in the in the Gulf of Mexico earlier this week, and by Wednesday evening she had grown (barely) into a low level Tropical storm. Tropical Storm Andrea then made landfall in the Big Bend region of Florida, causing some minor coastal flooding and wind damage in the Tampa area, before heading up the eastern seaboard. For the most part, Andrea was primarily a major rain event, dampening the spirits of many who are anxious for summer to finally arrive.

Large storm systems are also a nuisance to satellite oceanographers, who generally need a clear view of the ocean to measure physical variables like sea surface temperature, or the amount of chlorophyll and sediment in the water.

The image above was generated using data collected by the AVHRR instrument on NOAA-18 as it flew over the area at 4:36pm. AVHRR does not collect data in the visible light range, so this false-color representation was created by converting data from the red and infrared channels on the satellite into an image resembling a true-color photo.

What is clear from this image, is that the sky is not so clear over the ocean. In fact, the only clear areas over water are off the coast of South Carolina and over the Great Lakes, which show up as dark blue. To an oceanographer then, this image doesn’t offer much to look at, but for a meteorologist, it’s a different story.

For more on the aftermath of Tropical Storm Andrea’s deluge, I encourage you to check out the New Jersey CoCoRaHS site tomorrow to see how much rain fell on the state.

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Next Generation Activity Development

By on May 15, 2013 in Educational Resources, Thoughts

NGSS Middle School performance expectations for Weather and Climate - page 58
If you’re a science educator, unless you’re a troglodyte (which let’s face it, every department has at least one of), you’ve probably been paying attention to the development of the Next Generation Science Standards or NGSS. The new standards are the culmination of years of work by scientists and educators across the country to rethink the way science is taught (and assessed) at the K-12 level, focusing on the depth of knowledge rather than breadth, while emphasizing an understanding of scientific practices rather than just core content.

Now, if you’re like me, you probably glanced at the draft versions a few times, but never really took the time to truly understand the new standards and the NRC Framework they are built upon. But now that the NGSS is out, for those of us dedicated to supporting K-12 educators with curriculum and professional development, the hard work really begins.

Last week, I had an opportunity to look through the standards alongside many other ocean educators at the National COSEE Network Meeting. Our goal was to figure out how the NGSS could be used to develop activities, or rather, how we need to adjust our activity development process to meet the goals of the new standards (and by extension, the districts and teachers who will follow them). Given how dense the NGSS is, and with only an hour to review and reflect on them, we didn’t get very far. However, I did take away a few key insights:

  • As they’re presented, the top of each page features the “performance expectations” for each topic or theme. These are the new standards, but in general, they are not content specific as many existing standards are.
  • The disciplinary core ideas, found in the middle orange box at the bottom of each page, are more akin to existing content-based standards. If you are going to develop an activity on a particular subject, identifying standards that include a given topic as a core idea might be a good place to start.
  • However an activity should be more than just an elicitation of content, and it’s important to understand how a core idea intersects with a given set of science and engineering practices, included in the blue box in the bottom left. These practices could be incorporated as the approach or methodology students use when carrying out an activity, again placing the emphasis of the activity on the practices of science rather than a hodgepodge of content.
  • To that end, I think the performance expectations are not necessarily the “content” that one might teach towards, but rather they should be used as the activity goal one can use to assess students’ scientific competency in a given area.
  • As the Appendix on Conceptual Shifts explains, the standards are “student performance expectations – NOT curriculum” meaning that the combinations of core ideas, practices and expectations provided should not be thought of as rigidly linked. That said, in these early days, as we think about developing new curriculum to meet these standards they are a good place to start.
  • Similarly, it seems that many districts may use the Topic Arrangement of the NGSS as the basis for structuring their curriculum, and will probably be looking for help at that level.

Personally, I’ve never really been a fan of standards. That is to say, I’ve always disliked how many educators and especially administrators simply use them as an exercise in bean counting.

But I am excited about the new standards because they represent a fundamental shift in thinking away from content to how science is practiced in the real world. Hopefully, as ocean science educators we can be at the forefront of this shift, capitalizing on the opportunity to build innovative activities for students built on the compelling content and real world science that oceanographers can bring to the table.

The trick will be, can we really practice what we… well… practice?

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Blog Roundup #1 – Ocean Science and More

By on April 25, 2013 in Great Sites

If you follow this blog and my twitter feed, you can probably guess that I have a lot of interest in the fields of data visualization, education, ocean science and web development, and especially how those worlds intersect. Each of these subjects is incredibly diverse, which makes it difficult to stay on top of new developments that are of personal interest.

In the past, one would have subscribed to several broad-ranging magazines in the hope that a few relevant articles might appear each year. But in the Internet age of blogging, micro-reporting, social networking, and web sites dedicated to every niche imaginable, the resources for personal knowledge development are immense. This is both a blessing and a curse.

To help weed through the chaff, I hope to occasionally share some of my favorite web sites and blogs – provided in easily digestible chunks for the busy educator or scientist.

This first roundup includes five of my favorite ocean and climate science related sites. Here they are in no particular order.

1) Community Collaborative Rain, Hail & Snow Network Blog – CoCoRaHS is a nation-wide network of volunteer observers who measure precipitation around the country. The maps and data on their main site is awesome, but the community blog features short synopses of major precipitation events. Each post includes lots of neat maps, and is written in easily understandable language.

2) GLOBE Scientists’ Blog – The GLOBE project enables classrooms around the world to collect environmental data that is used by scientists in their research. Their Scientists’ blog highlights the cool science that students can be involved in, and often features suggested activities.

3) Marinexplore Blog – Marinexplore is a relatively new company that is trying to build a comprehensive data portal that allows users to peruse and download a large variety of ocean datasets. Their blog is primarily devoted to promoting feature updates, but occasionally it includes some neat data visualizations and stories showcasing the datasets available on the site and the kinds of research that can be accomplished with them.

4) RealClimate – RealClimate is perhaps one of the top environmental blogs on the internet (at least when considering blogs written by scientists), and is certainly one that scientists, the media and educators regularly follow for analysis on recent developments in climate science. While the site is dedicated to making climate science more accessible, many posts are arguably rather high-level. However, it’s a great place to go when you want to look beyond the headline and learn more about how data on a global scale is processed, interpolated and modeled to better understand climate processes.

5) NOAA News – The U.S. National Oceanic and Atmospheric Administration is tasked with monitoring and forecasting weather and climate around the globe (not to mention their impacts on fisheries and humans). As a result, following their news feed is a great way to stay informed on all the cool things that NOAA does. Whether it’s the launch of a new weather satellite, a recent report on the health of fish stocks, a new system for issuing storm warnings or a recent national climate analysis, there are plenty of cool things to learn about, courtesy of your local U.S. taxpayer.

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Streamflow and Conductance on the Delaware

By on April 22, 2013 in Visualizations

Conductance vs. Streamflow on the Delaware River at Trenton, NJ

Rivers play an important role in our ecosystem. They provide water for drinking and irrigation of crops, a habitat for fish and other organisms, and routes to easily transport goods. For these reasons and more, it is important to monitor the quality of river water, including its physical, chemical, and biological characteristics.

One often measured parameter is specific conductance. Conductance is a measurement of a substance’s ability to conduct electricity and is related to the amount of ions, like salt, that are dissolved in the water.

Where rivers meet the ocean, the salt typically comes from seawater flowing upstream into the river. How far upriver the saltwater can reach (often called the salt front or salt line) depends greatly on an estuary’s type and the current streamflow.

Further upstream, where the ocean doesn’t have as much influence, the amount of dissolved salts in river water is generally related to how much precipitation there has been. When rainfall is light, more water on land can evaporate before it reaches the river, which concentrates the amount of dissolved salts in the water that remains. When rainfall is heavy, water tends to flow more quickly into rivers and streams, with smaller concentrations of dissolved salts.

The image above shows the relationship between river flow (discharge) and conductance over a 3+ year period on the Delaware River in Trenton, NJ. In general, the conductance is quite low, and well below accepted salt front cutoffs of ~400-1,000 micro-Siemens per centimeter, which correspond to chloride concentrations of 100-250 milligrams/liter. However, there is clearly an inverse relationship between conductance and discharge. When discharge is strong, water conductance is low, though it never gets below ~100 µS/cm. Likewise, when discharge is light, conductance is 2-3 times higher. While the salt concentration on the Delaware River near Trenton is generally low, it does depend on the streamflow.

Knowing the location of the salt front is important, especially on rivers where water is drawn for human consumption or irrigation, and for protecting riverine infrastructure like ships that corrode more easily in salty water. The Delaware River Basin Commission regularly monitors the salt front location in order to control its location by storing and releasing water in reservoirs upstream.

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RTD Activity Idea: Monitoring Streamflow

By on April 17, 2013 in Data Tips

Streamflow over the course of 2012 from the USGS streamgage in Trenton, NJ

The task of monitoring the nation’s numerous streams and rivers falls to the United States Geological Survey. The USGS maintains a large network of instruments that record streamflow, water height, temperature, conductivity, water quality and several additional environmental variables. One of the chief uses of this network is to monitor the occurrence of floods and droughts.

Thanks to USGS’s National Water Information System, this data is easily accessible for students to access and visualize, allowing them to investigate river conditions at nearby locations or from across the nation.

Real-time Data Project

Here is a quick activity students can use to investigate current streamflow conditions and compare them with historical norms.

  1. Go to the Current Streamflow Map on the USGS WaterWatch site and select a state.
  2. Click on a station and note whether it is currently above, at, or below normal conditions, as denoted by the color of the dot.
  3. Click on the station ID number. This will take to you the station’s summary page.
  4. In the pull-down list, select “Time-series: Daily data“
  5. The top of the page includes some basic information on the station, including its location, a photo of the station, and (for some stations) the upstream drainage area. Underneath this information is a box to customize the graphs appear on the page.
  6. Select “Graph w/ stats” as the output format and enter a date range you’d like to visualize. (Here’s an example that displays data from Trenton, NJ for all of 2012.)
  7. Find the graph for discharge or gage height and compare how the measurements (shown in blue) compare with the historical average (shown in yellow).
  8. If you choose a full year (i.e. from January 1st to December 31st) you can quickly get a good idea of the annual differences and seasonal cycle at a station. (For example, for the Trenton station above, the highest average streamflows are typically seen in March and April, while the lowest occur in the summer and early fall.)
  9. Now that you have the hang of it, you can create graphs for individual years to compare them with each other, or you can look up data around specific events you know of, like major rain storms or droughts.

Engaging Questions

Here are a few questions students can think about before they start their research.

  • What do you know about floods and droughts? What causes them? What impacts do they have on the environment, ecosystems and people?
  • How do you think scientists study river flow? (The two primary methods are gage height and streamflow.)

Suggested Research Questions

Here are several questions students can try to answer by looking at the data.

  1. For your selected station, how does the most recent measurement compare with the current streamflow status (i.e. percentile class) shown on the map?
  2. How long has the station be at that state?
  3. What times of year have the highest streamflow? Which times have the lowest?
  4. Were there any times during the year where the streamflow was exceptionally high or low? Do you have any idea what may have caused these observations?

Relevant References

The WaterWatch web site, also maintained by the USGS, aggregates data from the entire stream gage network into a great set of maps, highlighting the current streamflow, drought and flood conditions around the country. If students are interested in looking at current or past conditions across the nation as a whole, this is a great place to start.

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Streamflow on the Delaware

By on April 12, 2013 in Visualizations

A 1-year graph of river flow on the Delaware River at Trenton NJ

Scientists who study river streamflow do not have an easy job. Unlike many weather measurements like temperature, pressure or humidity that change with more predictable variation throughout the course of a year, streamflow is more closely correlated with major rain and snow events. These events occur sporadically throughout the year, often in large doses.

The graph above is a good example of this complexity. The data shown was measured from a stream gauge on the Delaware River in Trenton, New Jersey. The daily mean streamflow (also referred to as “discharge”) from the most recent year is plotted in red, ending April 11, 2013. The long-term average streamflow statistics are calculated from a 99-year data set collected between 1913 and 2011.

The mean daily streamflow includes many large peaks over the course of the year. These peaks correspond to major precipitation events that occurred in the upper Delaware river basin. On the other hand, the lines showing the long-term average streamflow change more gradually throughout the year, with the highest streamflows observed in the spring (especially this week), and lower streamflows in the summer and fall.

Looking at this data, several interesting observations can be made.

  • In October 2012, Hurricane Sandy hit New Jersey causing extensive damage, however the observed streamflow during this time was not as high as some of the other events. As it turned out, most of the damage was caused by coastal flooding and high winds and not from flooding rivers.
  • Over the course of the winter, several large events were observed. These correspond to the major nor’easter’s that passed through the area, including the (strangely-named) winter storms Nemo and Saturn.
  • Last month was unseasonably cold and, while there was a nor’easter early in March, the month also ended up unseasonably dry. However, following today’s rainstorm, it is likely that the streamflow will rise to the more typical values expected during this time of year.

Ultimately, when studying rivers it’s important to remember that individual events will not always neatly line up with long-term averages, but over time, the trends should match.

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Observations and Forecasts of River Floods

By on April 9, 2013 in Data Sources

A map of the Advanced Hydrologic Prediction Service (AHPS) river forecasts

Every time it rains there is a potential for flooding to occur. This is especially true after major storms. It’s also common in the spring when snow melts at higher elevations, causing mountainous streams to surge. As water from rain storms and snow melt collects in larger rivers, it raises the water level. The greater the amount of water that enters a river, the higher the level can become, and the greater the risk of a major flood event.

Each year, it is estimated that on average 133 lives are lost and over $4 billion in damages to homes, businesses, bridges and other infrastructure occurs due to inland flooding from rivers. (Coastal flooding from storm surge causes even more damage.) To help save lives and minimize damage, the National Weather Service regularly forecasts the potential for inland flooding around the country. The National Weather Services’ Advanced Hydrologic Prediction Service (AHPS) analyzes data from over 5,000 stream gauges (many of which are operated by the USGS), and combines that data with numerical models to issue daily as well as long-range forecasts of the potential for flooding to occur.

The main page of the AHPS website displays a map of all of the active stream gages in the country. Each point is colored based on the current water level. Oranges and reds signify rivers with high water levels where flooding may be occurring, while greens indicate rivers that are currently at normal levels.

The AHPS forecast map (see above) displays a subset of stations where forecasts are available. On this map, dots are colored based on the potential for flooding to occur during the next 48 hours. You can click on each point to see a graph of the river’s water level over the last 2 days, as well as the forecasted level over the next two days. Lines on each graph show the water levels where, based on past observations, minor or major flooding is likely to occur and cause damage. These graphs are updated regularly. During a major storm event, you will often see the forecast lines change over time as new data comes in and more accurate predictions can be made.

A graph of river height observations and forecast predictions on the Souris River in North Dakota.

Educator Tip: The AHPS river forecast website provides great way to introduce students to flood monitoring and forecasting. Students can investigate the real-time conditions at rivers in their local area or across the country to see where floods might occur. The national maps of real-time and forecasted flooding provides a great overview of conditions across the country, and students can easily compare these maps with weather radar data to investigate the correlation of rainfall with potential flooding.

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USGS WaterWatch

By on April 2, 2013 in Data Sources

USGS WaterWatch Web SiteIt’s April. And while the cold temperatures here in New Jersey make it feel like spring hasn’t quite yet arrived, the flowers are starting to poke through the ground, reminding us that spring is coming, and with it, a steady stream of springtime showers should be on their way.

Of course, when rain falls on land, much of it ends up in rivers and streams. And thanks to a network of over 3,000 stream gages monitored by the U.S. Geological Survey, we can easily study how precipitation, including rain and snow, impacts local streams, rivers and estuaries.

All of this data is available on USGS’s WaterWatch web site, which features several easy to use maps, providing a great  way to introduce streamflow data to students and the public, while showcasing how it can be used to monitor floods and droughts – critical issues related to human health, safety and well-being.

Here are a few great places to start.

Current Streamflow Map: This map displays the real-time conditions from all of the streamflow stations across the country.  Some stations measure streamflow discharge or flow rate, while other stations measure gage height, that is, how high the water level is. A few stations even measure other things like temperature, pH and dissolved oxygen. From this map, you can select an individual station to view in detail, access raw data or create custom graphs.  

On the map, each station is represented as a colored dot, whose color is based on how the current streamflow or gage height compares with past records.  Reds designate those stations that are below average while blues are above average, and green dots represent those stations that are in line with historical norms. You can also view historical streamflow maps.

Drought Map: This map highlights which areas of the country have below normal streamflow conditions, typically due to long periods of time with limited rainfall or, in mountainous areas, low levels of wintertime snowpack. Below normal streamflow is generally a good indicator of whether a drought exists, though precipitation, ground water and reservoir levels are also taken into account when declaring an official drought. (See for example, New Jersey’s Drought Information Site.)

Flood Map: Sometimes, you can have too much of a good thing. This map shows those stations stations that are currently reporting conditions drastically higher than their historically normal levels. This can often happen after severe storms with large amounts of precipitation (which is especially true after tropical storms and hurricanes), but it is also common in the spring when mountain snowpack melts. And of course, some rivers are susceptible to a springtime a double whammy.

Personally, I’ve always wondered if a more appropriate phrase for this time of year might be “April flowers bring May showers,” but to make that case, I need to dig through this data some more.

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Riding the Waves of the Seasonal Roller-Coaster

By on March 29, 2013 in Visualizations

Average monthly wave heights at NDBC Buoy 44025

It is often said in Pennsylvania that March comes in like a lion and goes out like a lamb. And while this March felt more like a ride on an Arctic roller-coaster that wouldn’t end, the good news is that, based on past years, we should soon be on the downward slope towards more calmer weather.

In the Mid-Atlantic, the winter months usually bring with them strong storms and high winds, like the nor’easter we saw earlier this month. In the ocean, strong winds lead to larger significant wave heights, as can be seen in the graph above that depicts the average monthly wave heights off the coast of New Jersey over the course of a year.

This graph was created using 8 years of significant wave height data from NDBC Buoy 44025, which is a little more than 40 miles from the New Jersey coast. Each line represents a particular percentile level, indicating the percentage of measurements that fall below the indicated level. The 50% percentile level is commonly called the median average value. For each month, half of the measured data over the course of the 8 years fell above the median value while the other half fell below.

This graph shows a distinct difference between the seasons. The median wave height in December, January and February is around 4.5 feet, while in the summer months of June, July and August, the average is closer to 3 feet. While the median value is higher in winter months than summer ones, the change is even larger for the 80th percentile line. For that, we can thank those large winter storm events that turn the ocean into one rough ride.

Thankfully, spring will soon give way to summer, and if the past averages hold true, the summer months of this roller-coaster should include calmer waters.

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Coastal Population Report

By on March 26, 2013 in Educational Resources
infographic2

Credit: NOAA

In ocean education, it’s often a challenge to convey how humans and the ocean are connected. One good place to start is where people live. By highlighting how many people live at or near the coast, the potential impact the ocean and humans have on each other becomes significant, and a stronger case for relevance can be made.

NOAA and the U.S. Census recently released the National Coastal Population Report which analyzes population trends in coastal counties over the past 40 years, and includes forecasts for 2020.

In 2010, 39% of the U.S. population lived in coastal “shoreline” counties, comprising less than 10% of the land area of the continental United States. Over half of the U.S. population (52%) lives in counties whose watersheds drain directly to the cost, comprising 20% of the U.S.

The full report features a number of additional tables and graphs. Here are a few of my favorite highlights:

  • Population growth in shoreline counties is slower than the national average (39% vs. 52%). Apparently, the deserts of Arizona and Texas and the woods of North Carolina have had more appeal in recent years than the coast. (The low cost of housing in these areas compared with the high cost on the coast is most likely to blame.)
  • Shoreline counties have slightly higher percentages of people with Bachelor’s degrees and higher, as well as households making over $75,000, than inland counties.
  • New Jersey has the 4th highest number of seasonal housing units in shoreline counties, following Florida (no suprise there), Michigan (thanks to the Great Lakes) and New York.
  • However, Maine has the highest percentage of seasonal housing units, followed by the Carolinas and Minnesota.
  • New Jersey ranks 4th in population and 5th in population density when only shoreline counties are taken into account. This reflects the fact that while most of NJ is coastal, other states like Illinois, Pennsylvania, and Massachusetts (which have lower overall densities) have populations concentrated in their coastal towns.

If you’re an educator, this report might be a useful starting point for fostering discussions on the relation between humans and the ocean. Overall, the report is quite accessible with a good variety of clear graphs and maps. It also eschews lengthly analyses, leaving the interpretation to the reader, while providing some helpful highlights in the sidebars.

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