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.
The U.S. National Library of Medicine’s TOXNET, an interactive map that tracked pollution, chemical exposure, toxicology and other data, was shut down last month. The move has been criticized in the context of the Trump administration’s rollback of environmental protections, but the NLM insists that the decision was theirs. The data mapped by TOXNET is available from other sources, but, and this is the point, not as easily or centrally accessible. [The Hill, Newsweek]
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]
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:
Earlier this year, we shared the first results of this effort with pollution levels throughout the city of Oakland.
We’re just beginning to understand what’s possible with this hyper-local information and today, we’re starting to share some of our findings for the three California regions we’ve mapped: the San Francisco Bay Area, Los Angeles, and California’s Central Valley (the Street View cars drove 100,000 miles, over the course of 4,000 hours to collect this data!) Scientists and air quality specialists can use this information to assist local organizations, governments, and regulators in identifying opportunities to achieve greater air quality improvements and solutions.
The Atlas for the End of the World collects a series of world maps that measure our planet’s environmental well-being. More specifically, they examine the amount of protected area in our planet’s biological hotspots, especially relative to the UN Convention on Biological Diversity’s 2020 conservation targets. Created by landscape architects, the accompanying text (by project lead Richard J. Weller) tends toward the abstruse and verbose, but the maps themselves are quite interesting. (I note that they make extensive use of the Goode homolosine projection, which is refreshing.) [Geo Lounge]
President Trump’s budget proposes eliminating the EPA’s Great Lakes Restoration Initiative. That fact is no doubt what’s behind two publications posting maps earlier this month, only a couple of days apart, showing the environmental stresses on the Great Lakes basin.
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]
Vox’s lead exposure risk map takes a nationwide look at a crisis some might have thought was limited to Flint, Michigan. “The areas where kids are at highest risk of lead exposure—an estimate calculated using government data about the surroundings—are scattered all across the country.” Lead exposure data is hard to come by, so exposure risk is calculated based on Washington State’s methodology, which uses age of housing and poverty as risk factors. [Mapbox]
The European Space Agency has released a map showing the northern hemisphere’s biomass — specifically, its growing stock volume (GSV), which is the amount of wood per hectare in cubic metres. The map is based on radar images taken by the now-defunct Envisat satellite between October 2009 and February 2011.
Today NASA released a set of vegetation maps based on data from the Suomi NPP satellite. Flickr photoset, YouTube video. The maps depict a year’s worth of changes in vegetation. “High values of Normalized Difference Vegetation Index, or NDVI, represent dense green functioning vegetation and low NDVI values represent sparse green vegetation or vegetation under stress from limiting conditions, such as drought.” Image credit: NASA/NOAA.