Archive for January, 2018

Climate Monday: Keeling Curve Animation from NOAA

January 29th, 2018

While Dr. Wilson is away on leave this semester, I am going through 15 weeks of “Climate Monday”, in which every week I get the opportunity to highlight one graphic or animation or data tool that shows something interesting about climate (and weather). I’m also using these tools to share a little climate science. Last week I highlighted a weather animation tool, so this week is fully in the realm of climate with NOAA’s animated Keeling Curve (also on youtube).

map of mauna loa observatory

The Scripps carbon dioxide program, including the Mauna Loa Observatory. (Image Credit: Scripps Institution of Oceanography)

Humans have decades of direct observations of carbon dioxide concentration in the atmosphere. The longest continuous record dates back to March 1958, when C. David Keeling started analyzing air at the Mauna Loa observatory in Hawai’i. Mauna Loa is a good place to make such measurements because Hawai’i is isolated from major industrial regions like the Midwest of the USA, the Ruhr Valley in Germany, and the Pearl River Delta in China. There is relatively little regional pollution (although there is some from cities like Hilo and Kona, and from nearby islands like Oahu and Mau’i). The composition of the air in Hawai’i is a better reflection of the Earth’s average atmosphere than measuring, say, at LAX or O’Hare.  Atmospheric measurements have been made up on Mauna Loa ever since.

The Mauna Loa Observatory (Image Credit: Theo Stein, NOAA)

The resulting data is the Keeling Curve, which is plotted below. The “sawtooth” pattern of the red line is the seasonal cycle of winter and summer in the Northern Hemisphere.  In summer, plants take up carbon dioxide during photosynthesis, reducing carbon dioxide concentration. In winter, photosynthesis slows or stops throughout much of the Northern Hemisphere, and carbon dioxide can accumulate in the atmosphere. So carbon dioxide is always a bit higher in winter than it is the following summer. The black line has the seasonal cycle removed, so it shows the year-to-year changes in carbon dioxide. It also shows the increase from under 320 ppm in the 1950s to over 400 ppm today.

This is all really cool to seem but there is much more to our record of carbon dioxide than just Mauna Loa.  NOAA has put together an animation that shows all of the dozens of other sites around the global that record carbon dioxide concentration and how that record has changed through time. It also puts that record in the context of paleoclimate. Seeing the whole animation, you can detect all of the nuance in the global carbon dioxide record.  For instance, the Northern Hemisphere has a much stronger seasonal cycle than the Southern Hemisphere since it has substantially more land plants at mid and high latitudes.  Other locales are even more variable, like many in the continental USA closer to major industrial centers. The South Pole generally lags a little behind the Northern Hemisphere, in part because it takes awhile for carbon dioxide emissions to mix throughout the whole atmosphere.

 

Climate Monday: Weather Animations by Cameron Beccario

January 22nd, 2018

While Dr. Wilson is on leave and taking a hiatus from his acclaimed “Fossil of the Week” series, the Department of Geology decided to fill the void with something completely different: Climate Monday. For 15 weeks in the Spring 2018 semester, I am going to highlight one animation, graphic, or online tool that helps visualize some aspect of the climate system. Some are about weather, some about climate. Most are about the atmosphere, but the ocean comes into play as well.

I want to start with a bang, so first up is my favorite weather animation: Cameron Beccario’s “Earth”. A screenshot below is from just after  New Years’, when a nor’easter was blasting the northeast USA and cold Arctic air was surging southward over the Midwest.  (Wooster, OH is in the middle of the little green circle.) This is a beautiful image on its own. The swirling convergence of wind around the nor’easter turns red to indicate the high wind speeds. The easterly Trade Winds blowing off Africa are clearly defined. Two additional winter storms can be seen by the clustered wind streamers and red coloring in the North Atlantic and North Pacific Oceans, although neither is as tight and powerful as the East Coast blizzard.

Screenshot of wind animation for 5 January 2018, from Cameron Beccario’s weather animation tool. Redder colors indicate stronger wind and the streamers indicate wind direction.

But that’s just a glimpse at what this tool can do.  Besides staring at colorful wind patterns and watching cyclones churn, users can pan around the entire Earth, zoom in and out, change the color variable to temperature, humidity, or cloud density, even aerosols or ocean currents.  You can toy around with different projections, examine different levels of the atmosphere, and even go back in time.

The data behind these animations are from a variety of sources.  Cameron Beccario has integrated the National Oceanic and Atmospheric Administration’s (NOAA) Global Forecasting System (GFS), version 5 of NASA’s Goddard Earth Observing System (GEOS-5), various other datasets from the US and EU agencies, as well as a few non-profits. Underlying most of these monitoring systems are a combination satellites, surface observations, and atmospheric models. These are the same tools used for weather prediction and analysis, so although it’s not a research tool, Beccario’s animations have high-qaulity data behind them, and they’re the best animations of atmospheric and oceanic data I’ve seen.

For a little more fun, here’s a glimpse at the aerosols.  More specifically, this is the dust concentration from the same day: 5 January 2018.  I focused this on the widespread dust coming off the Sahara Desert. Some of those dust particles can end up as far away as Florida and Texas.

Screenshot of dust concentration on 5 January 2018 from Cameron Beccario’s weather animation tool. The tanner the color, the more dust.

Sometimes zooming in on a feature can be fun.  Here’s an example of the Gulf Stream, a warm water current along the western boundary of the North Atlantic Ocean that hugs the east coast of the USA from Florida to Cape Hatteras.  It’s because of this current that the Atlantic Coast of southern Florida often have warmer water than the Gulf Coast in winter. Beach-goers be aware!

Sea surface temperatures and ocean currents on 5 Jan 2018 from Cameron Beccario’s weather animation tool. Red is hot; blue is near freezing.

Weather Sensationalism: Boston is colder than Mars

January 4th, 2018

Today, CNN and several other news outlets are reporting that “Boston and part of New Hampshire will be colder than Mars” this weekend. At first glance, this sounds incredible.  It’s going to be really cold this weekend! Indeed, on Saturday, the coldest day forecasted, Boston is expected to see a low of -7°F (The Weather Channel), -4°F (AccuWeather), or -2°F (Weather Underground)… so yes, this is cold.

CNN headline from January 4, 2018 declaring that “Parts of the East Coast will be colder than Mars”.

But there are two things misleading with the statement “Boston will be colder than Mars”. First, the statement makes you think about this cold snap is a big extreme. The thing is, Boston can get colder. Last year on February 14, the low was -9°F, and on February 9, 1934, Boston had its record low of -18°F (NOAA).  Normally, the coldest temperature of the year in Boston is about 2°F (ibid.). So this isn’t unprecedented, even though it’s rare.  It’s an extreme, but nothing to put down in the history books.

The second misleading part is the comparison to Mars.  Yes, Mars is roughly 1.5 times farther away from the Sun than we are, and it has almost no atmosphere, so it on average much colder than Earth. In fact, the average temperature on Mars is about -81°F, whereas Earth is about 57°F (NASA Mars Facts). But wait! -81°F is much colder than Boston has ever been.  So what gives?  The numbers CNN are using come from the Rover Environment Monitoring Station (REMS), which was deployed in Gale Crater along with the Curiosity Rover. If you go to the REMS page and use the arrows on the big weather widget to go back to December 31 (Earth time), you’ll find a temperature of -19°C, or -2°F, as the maximum at Gale Crater. That’s warmer than (or as warm as) Boston is expected to be this weekend.

But this is a bad comparison because they compared the low temperature in Boston to the high temperature on Mars. Compare to the low temperature in the Gale Crater instead, and you have -79°C to contend with, or -110°F. So based on the lows, Mars is still colder than Boston.

Air temperature reported by the REMS instruments aboard the Curiosity Rover in Gale Crater, Mars on December 31, 2017 (Sol 1921).

However, there are two other things that make this comparison misleading. First, they are comparing Boston, at 42°N on Earth to the Gale Crater on Mars, at 5.4°S (REMS).  They are comparing a mid-latitude location in winter on Earth to a location near the Equator of Mars. The Equator of Mars is relatively warmer than the mid-latitudes of its winter hemisphere.

Second, Boston in winter is often colder than Gale Crater. Mars has very little atmosphere and no ocean, so daily and seasonal temperature swings at the surface are much greater than on Earth.  In summer, Gale Crater can exceed 32°F. In fact, if you look back to when Curiosity first landed on Mars, it recorded a high temperature of 37°F on Sol 10. (See that lower graph on the REMS page.) The average high temperature in Boston in January is only 36°F (NOAA).  So being “colder than Mars”, at least based on CNN’s loose phrasing, is not particularly strange.

With all that said, it will be cold in Boston this weekend after the blizzard, so bundle up, New Englanders!