The Earth at Night, Updated

NASA Earth Observatory images by Joshua Stevens, using Suomi NPP VIIRS data from Miguel Román, NASA’s Goddard Space Flight Center.

NASA has released updated global maps of the Earth at night. The so-called “black marble” maps show where human activity lights up the darkness. NASA’s page highlights some of the differences between the 2016 and 2012 versions of the map with before/after interactive sliders. John Nelson has tried something different: overlaying the 2016 map on the 2012 map with a clipping mask shows newly illuminated parts of the globe as dark patches.

John M. Nelson, “A Changing Earth at Night,” 2017.

Mapping Arctic Warming

At All Over the Map, Betsy Mason posts 11 Ways to See How Climate Change Is Imperilling the Arctic, a collection of maps and infographics depicting several different indicators of global warming, including sea ice extent, atmospheric temperatures, growing season, polar bear populations, as well as projected shipping routes for an ice-free Arctic Ocean.

NASA Earth Observatory

Meanwhile, NASA Earth Observatory points—while it still can—to a study mapping the extent of existing and potential thermokarst (thawed permafrost) landscapes. On the Earth Observatory maps (see North America, above), “[t]he different colors reflect the types of landscapes—wetlands, lakes, hillslopes, etc.—where thermokarst is likely to be found today and where it is most likely to form in the future.”

Previously: Mapping Arctic Sea IceMapping the Thaw.

November Sea Ice


NASA Earth Observatory: “In November, the sea ice extent averaged 9.08 million square kilometers (3.52 million square miles)—the lowest November extent in the satellite record. The yellow line shows the median extent from 1981 to 2010, and gives an idea of how conditions this November strayed from the norm.” Also shows sea ice extent for previous years dating back to 1978. Hudson Bay was icebound in November not that long ago.

Previously: Mapping Arctic Sea Ice.

Mapping Arctic Sea Ice


Something’s going on in the Arctic. As the Washington Post reported last month, the Arctic Ocean was far, far warmer than normal—about 20 degrees Celsius higher than average. (Meanwhile, the air over Sibera is at record cold levels.) According to the Post, the higher temperatures are the result of record low amounts of thinning sea ice, as well as warm air being brought north by an increasingly errant jet stream.

NASA has been tracking sea ice levels and thickness by looking at the age of the ice in the sea ice cap. The video above shows “how Arctic sea ice has been growing and shrinking, spinning, melting in place, and drifting out of the Arctic for the past three decades. The age of the ice is represented in shades of blue-gray to white, with the brightest whites representing the oldest ice.”

The ESA reports that their CryoSat satellite “has found that the Arctic has one of the lowest volumes of sea ice of any November, matching record lows in 2011 and 2012.” The animated GIF below shows the change in November sea ice from 2011 to 2016, as observed by CryoSat.


Hurricane Matthew Map Roundup


Start with the National Hurricane Center, which has lots of different maps of Hurricane Matthew’s predicted path, weather warnings, rainfall potential and so forth. See also maps from Weather Underground.

Google’s Crisis Map includes evacuation resources—Red Cross shelters, evacuation routes, traffic data—in addition to storm track and precipitation information.

Matthew has already struck southwest Haiti; the Humanitarian OSM Team has put out a call for crisis mappers on the following projects: buildings in Nippes; road network in Grand’Anse and Sud.


Wind maps from Windytv and EarthWindMap visualize the wind patterns of Matthew and, further out in the Atlantic, Nicole.

Hurricane imagery from NOAA’s GOES East satellite. NASA Earth Observatory has imagery of Matthew’s path toward Florida.

[Dave Smith/Maps Mania/NASA Earth/NOAA Satellites]

Louisiana Flooding: NASA Animation of Accumulated Rainfall


NASA Earth Observatory: “Days of intense rainfall in August 2016 led to widespread flooding in southern Louisiana, as rivers swelled high above their banks and many crested at record-high levels. […] The animation above shows satellite-based measurements of the rainfall as it accumulated over the southern United States. Specifically, it shows rainfall totals every three hours over the span of 72 hours from August 12-14, 2016. These rainfall totals are regional, remotely sensed estimates, and local amounts can be significantly higher when measured from the ground.”

New Orleans Is Sinking


“New Orleans and surrounding areas continue to sink at highly variable rates due to a combination of natural geologic and human-induced processes,” according to the findings of a new study that maps the rate at which New Orleans is sinking.

The maps were created using data from NASA’s Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), which uses a technique known as interferometric synthetic aperture radar (InSAR). InSAR compares radar images of Earth’s surface over time to map surface deformation with centimeter-scale precision. It measures total surface elevation changes from all sources—human and natural, deep seated and shallow. Its data must be carefully interpreted to disentangle these phenomena, which operate at different time and space scales. UAVSAR’s spatial resolution makes it ideal for measuring subsidence in New Orleans, where human-produced subsidence can be large and is often localized.


Mapping Arctic Permafrost


NASA Earth Observatory: “The map above, based on data provided by the National Snow and Ice Data Center, shows the extent of Arctic permafrost. Any rock or soil remaining at or below 0 degrees Celsius (32 degrees Fahrenheit) for two or more years is considered permafrost.” The map differentiates between continuous, discontinuous, sporadic and isolated permafrost. [NASA Earth]

New Gravity Map of Mars


A new gravity map of Mars, based on data from three orbiting spacecraft, has been released. “Slight differences in Mars’ gravity changed the trajectory of the NASA spacecraft orbiting the planet, which altered the signal being sent from the spacecraft to the Deep Space Network. These small fluctuations in the orbital data were used to build a map of the Martian gravity field.”

Mars Gravity Map
NASA/GSFC/Scientific Visualization Studio

The data enables the crustal thickness of Mars to be determined to a resolution of approximately 120 kilometres. Here’s a short video explaining the significance:

Mapping Global Sea Surface Height

Credit: NASA/JPL Ocean Surface Topography Team.

Jason-3 is the latest earth observation satellite tasked with measuring global sea surface height; its data will be used in weather and climate research (e.g., El Niño, climate change). Launched on January 17, it’s now in its six-month checkout phase and has produced its first complete map, which corresponds well with the map produced by the still-operational Jason-2 satellite, so that’s a good sign. [via]

Seafloor Gravity Map

NASA Earth Observatory map by Joshua Stevens

The ocean floor is still very much terra incognita: only 5 to 15 percent of it has been mapped via bathymetry. But using military satellite measurements of the Earth’s shape and gravity field, a new map of the ocean floor has been created. “The result of their efforts is a global data set that tells where the ridges and valleys are by showing where the planet’s gravity field varies. […] Shades of orange and red represent areas where seafloor gravity is stronger (in milligals) than the global average, a phenomenon that mostly coincides with the location of underwater ridges, seamounts, and the edges of Earth’s tectonic plates. Shades of blue represent areas of lower gravity, corresponding largely with the deepest troughs in the ocean.”


Mapping Nitrogen Dioxide Pollution

A decade’s worth of data from the Ozone Monitoring Instrument aboard the Aura satellite reveals the change in global nitrogen dioxide (NO2) pollution from 2005 to 2014: down significantly in some areas, due to stricter emissions controls, but up sharply in others. More at NASA Earth Observatory.

Surface Temperatures Warmest Since 1880

According to analyses by NASA and NOAA scientists, 2015 was the warmest year on record, with average surface temperatures the highest they’ve been since 1880. The above video shows the long-term warming trend since 1880 as a five-year rolling average. The baseline average is from 1951 to 1980; orange colours are warmer than that average, blue colours cooler. (Credit: GSFC Scientific Visualization Studio.)