Concentrations of NO2 in the atmosphere are highly variable in space and time: they typically vary by one order of magnitude within each day and quite substantially from one day to another because of the variations in emissions (for example the impacts of commuter traffic, weekdays and weekend days) as well as changes in the weather conditions. This is why, even if observations are available on a daily (currently available from satellites) or even hourly (ground-based observations) basis, it is necessary to acquire data for a substantial period of time in order to check that a statistically robust departure from normal conditions has emerged.
Cloud cover is a factor that needs to be taken into account as well.
This interferogram shows the ground displacement caused by last week’s earthquakes in southern California. Produced by NASA’s Jet Propulsion Laboratory, it’s based on synthetic aperture radar (SAR) images from JAXA’s ALOS-2 satellite taken both before (16 April 2018) and after (8 July 2019) the earthquakes. Each colour cycle represents 12 centimetres (4.8 inches) of ground displacement.
Europe is in the middle of a severe heat wave. The European Space Agency has released a map of land temperatures in Europe as of 26 June, produced from the Copernicus Sentinel-3 satellite’s temperature radiometer, “which measures energy radiating from Earth’s surface in nine spectral bands—the map therefore represents temperature of the land surface, not air temperature which is normally used in forecasts. The white areas in the image are where cloud obscured readings of land temperature and the light blue patches are either low temperatures at the top of cloud or snow-covered areas.”
The San Francisco Chronicle’s 2018 California Fire Tracker is an interactive map of ongoing and contained wildfires—notably, at this moment, the Camp and Woolsey fires. It includes fire perimeter and air quality data. (Note: it’s glitchy on desktop Safari.)
The Reference Elevation Model of Antarctica is a terrain map of nearly the entire continent at eight-metre resolution, assembled from observations from polar-orbiting satellites (mostly in 2015 and 2016). Version 1 covers 98 percent of Antarctica, and observations are ongoing. Notably, each grid point is timestamped, which will allow researchers to track changes over time (useful when your continent is melting). Raw data is available for download, as are map posters; the data is also available via web apps. [Geographical]
NASA Earth Observatory: “The map above depicts changes in water storage on Earth—on the surface, underground, and locked in ice and snow—between 2002 and 2016. Shades of green represent areas where freshwater levels have increased, while browns depict areas where they have been depleted. Data were collected by the GRACE mission, which precisely measured the distance between twin spacecraft as they responded to changes in Earth’s gravity field. In sensing the subtle movements of mass around the planet, the satellites could decipher monthly variations in terrestrial water storage.” The GRACE observations form the basis of a study published this month in Nature on changes in global fresh water availability. More at the JPL’s GRACE-FO project page. [Benjamin Hennig]
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:
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.
This BBC News article leads with a reasonably interesting geographic fact: that Mount Hope, on the Antarctic Peninsula, has been remeasured at 3,239 metres, making it the tallest mountain in territory claimed by the United Kingdom. (Its location is also claimed by Argentina and Chile.) But it’s really about the British Antarctic Survey, who are using stereographic satellite data to create more accurate maps of Antarctica’s mountains for pilots operating on the continent. BAS press release. [Kenneth Field]
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:
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.
NASA Earth Observatory: “Clouds may seem like distant, ephemeral features that have little to do with life on Earth. In fact, they affect everything from the viability of ecosystems, to how much carbon plants absorb, to the reproductive success of reptiles. So by mapping clouds, new research shows, scientists can indirectly map life.”