John Nelson’s map of tornado migration in the United States, showing the seasonal variations in tornado occurrence, is a master class in data visualization and design—in deciding on the right way to present geographic information. The map combines three styles—impressionistic choropleth, weighted mean centre movement diagram, and small multiple—to present month-by-month information all at once; in the accompanying text (also here), Nelson discusses some of the alternatives he could have chosen instead. And in a separate post he talks about how he made the map. [Esri]
The Climate Atlas of Canada’s interactive map shows the future impact of climate change in Canada. It shows what a number of different weather variables—temperature, number of very hot or very cold days, precipitation, growing season, and so forth—would be under two potential scenarios: one high-carbon, one low-carbon. There’s a lot of data hidden behind a lot of menus; the legends are hidden behind dialog boxes as well. [CBC News]
Winter isn’t quite done with us yet where I live. And with that in mind, here’s a neat animated map from the Washington Post that shows the total accumulated snowfall in the contiguous United States. The link includes 48-hour snowfall accumulation maps, satellite imagery, and a map showing which areas of the lower 48 have had more or less snowfall than Washington, D.C. I imagine these maps will have to be updated now.
Global sea level rise has been accelerating in recent decades, according to a new study based on 25 years of NASA and European satellite data. This acceleration has been driven mainly by increased ice melting in Greenland and Antarctica, and it has the potential to double the total sea level rise projected by 2100[. …]
The rate of sea level rise has risen from about 2.5 millimeters (0.1 inch) per year in the 1990s to about 3.4 millimeters (0.13 inches) per year today. These increases have been measured by satellite altimeters since 1992, including the TOPEX/Poseidon, Jason-1, Jason-2, and Jason-3 missions, which have been jointly managed by NASA, France’s Centre national d’etudes spatiales (CNES), the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), and the U.S. National Oceanic and Atmospheric Administration (NOAA). The maps on this page depict the changes in sea level observed by those satellites between 1992 and 2014.
Cape Town is running out of drinking water, a crisis dramatically depicted by NASA Earth Observatory maps that show the depletion of the city’s reservoirs. The animated gif above, for example, “shows how dramatically Theewaterskloof [Cape Town’s largest reservoir] has been depleted between January 2014 and January 2018. The extent of the reservoir is shown with blue; non-water areas have been masked with gray in order to make it easier to distinguish how the reservoir has changed. Theewaterskloof was near full capacity in 2014. During the preceding year, the weather station at Cape Town airport tallied 682 millimeters (27 inches) of rain (515 mm is normal), making it one of the wettest years in decades. However, rains faltered in 2015, with just 325 mm falling. The next year, with 221 mm, was even worse. In 2017, the station recorded just 157 mm of rain.”
The deep freeze is unevenly distributed. NASA Earth Observatory published this temperature anomaly map based on data from the MODIS instrument on NASA’s Terra satellite. A temperature anomaly map shows how much warmer or colder temperatures are versus the average—in this case, land surface temperatures from 26 December 2017 to 2 January 2018 are compared to the 2001-2010 average for the same period. While it’s awfully cold in Canada, and the central and eastern United States, it’s warmer than normal in the southwest. And if you look beyond the North American continent (which is something people should do more often), it’s generally warmer worldwide, particularly in Europe and Asia:
The highest and lowest ranked causes are highlighted when the chart loads. These represent the cumulative ranking across all years. Lightning, a natural cause, often floats to the top, but that’s only because on the human side, the vote is split between more than twenty options. Lightning doesn’t predominate in all states, though. In Alabama, the number one cause is pyromania. In Indiana, it’s brakeshoes. In Minnesota, it’s field burning. There are a couple of overall trends, too. Smoking is going down as a cause, and powerlines are going up.
NASA’s Goddard Space Flight Center produced this visualization, based on computer modelling and data from Earth observing satellites, tracking how hurricanes transport sea salt, dust, and smoke across the globe.
During the 2017 hurricane season, the storms are visible because of the sea salt that is captured by the storms. Strong winds at the surface lift the sea salt into the atmosphere and the particles are incorporated into the storm. Hurricane Irma is the first big storm that spawns off the coast of Africa. As the storm spins up, the Saharan dust is absorbed in cloud droplets and washed out of the storm as rain. This process happens with most of the storms, except for Hurricane Ophelia. Forming more northward than most storms, Ophelia traveled to the east picking up dust from the Sahara and smoke from large fires in Portugal. Retaining its tropical storm state farther northward than any system in the Atlantic, Ophelia carried the smoke and dust into Ireland and the UK.
NASA: “Satellites measured land and ocean life from space as early as the 1970s. But it wasn’t until the launch of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) in 1997 that the space agency began what is now a continuous, global view of both land and ocean life. A new animation captures the entirety of this 20-year record, made possible by multiple satellites, compressing a decades-long view of life on Earth into a captivating few minutes.” Here’s a video about it:
NASA’s Jet Propulsion Laboratory: “New maps of Greenland’s coastal seafloor and bedrock beneath its massive ice sheet show that two to four times as many coastal glaciers are at risk of accelerated melting as previously thought. Researchers at the University of California at Irvine (UCI), NASA and 30 other institutions have published the most comprehensive, accurate and high-resolution relief maps ever made of Greenland’s bedrock and coastal seafloor. Among the many data sources incorporated into the new maps are data from NASA’s Ocean Melting Greenland (OMG) campaign.”
There are many circumstances where the amount of data vastly exceeds the ability to process and analyze it—and computers can only do so much. Enter crowdsourcing. Steve Coast points to Digital Globe’s Tomnod project, which basically crowdsources satellite image analysis. In the case of the current project to map the presence of Weddell seals on the Antarctic Peninsula and the ice floes of the Weddell Sea, users are given an image tile and asked to indicate whether there are seals in the image. It’s harder than it looks, but it’s the kind of routine task that most people can do—many hands, light work and all that—and it helps researchers focus their attention where it needs focusing. (A similar campaign for the Ross Sea took place in 2016.)
Another ongoing campaign asks users to identify flooded and damaged infrastructure and trash heaps in post-Hurricane Maria Puerto Rico.
Using elevation data from stereo satellite observations, David Shean is mapping the retreat of some 1,200 mountain glaciers in the continental United States. “Until recently, glaciers in the United States have been measured in two ways: placing stakes in the snow, as federal scientists have done each year since 1957 at South Cascade Glacier in Washington state; or tracking glacier area using photographs from airplanes and satellites.” Shean’s method, which measures each glacier twice a year and uses automated software to track changes, seems to cover a lot more territory. [GIS and Science]
This NOAA article looks at three kinds of imagery provided by the GOES-16 geostationary weather satellite: GeoColor, the Geostationary Lightning Mapper (!), and full disk infrared imagery from the Advanced Baseline Imager. GOES-16 launched last November and is currently in the checkout phase before it replaces GOES-13 at 75° west latitude.