Join 3,436 readers in helping fund MetaFilter (Hide)


NASA Images Highlight U.S. Air Quality Improvement
June 27, 2014 1:11 PM   Subscribe

It appears that we're doing a bit better... "After ten years in orbit, the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite has been in orbit sufficiently long to show that people in major U.S. cities are breathing less nitrogen dioxide – a yellow-brown gas that can cause respiratory problems."
posted by HuronBob (20 comments total) 4 users marked this as a favorite

 
After ten years high in orbit, the Orbital Monitoring Gizmo (OMG) has finally been high long enough to show that lots of people in the US are breathing more and more nitrous oxide.
posted by hippybear at 1:25 PM on June 27 [1 favorite]


Cool images, but the scale bar only gives "low" to "high". The concentration information given in the text is:
Blue and green denote lower concentrations and orange and red denote higher concentrations, ranging from 1x1015 to 5x1015 molecules per square centimeter, respectively.
Is "molecules per square centimeter" a normal method of reporting units for remote sensing of atmospheric concentrations? I can't even imagine how they would arrive at that. Did they mean molecules per cubic centimeter?
posted by agentofselection at 1:26 PM on June 27


But seriously, I love how we finally have an army of instruments that can actually look at what the atmosphere is doing over a long period of time. It may be coming too late to gather data and do anything meaningful about the real problems we face, but it's amazing what we are learning these days. Science isn't over; in some ways it's scarcely begun.
posted by hippybear at 1:27 PM on June 27


I'm assuming that net nitrogen dioxide levels are still rising globally seeing how there are still an increasing number of ICEs and (as far as my quick Google search informed me) it is not converted into another compound in the atmosphere. Can someone please clarify this for me? Is the NO2 just spreading out?
posted by Don Don at 1:34 PM on June 27


After ten years high in orbit, the Orbital Monitoring Gizmo (OMG) has finally been high long enough to show that lots of people in the US are breathing more and more nitrous oxide.

Actually, it just felt like 10 years. It was more like 10 minutes.
posted by vibrotronica at 1:39 PM on June 27 [2 favorites]


Hey! What's that funny discoloration over Colorado?
posted by mondo dentro at 1:39 PM on June 27


I'm assuming that net nitrogen dioxide levels are still rising globally seeing how there are still an increasing number of ICEs and (as far as my quick Google search informed me) it is not converted into another compound in the atmosphere. Can someone please clarify this for me? Is the NO2 just spreading out?

Nitrogen dioxide is one of the components of automotive exhaust that is converted in to nitrogen gas by the catalytic converter on modern automobiles. Over the last 20 years, catalytic converter efficiency has increased dramatically, so the effect of more newer, cleaner burning ICE's, plus the retirement of older vehicles with less robust emission controls has more than offset the overall increase in numbers.
posted by dudemanlives at 1:43 PM on June 27 [4 favorites]


If you live in an area that has emissions testing, nitrogen dioxide is one of the components of NOx emissions. In fact the main component.
posted by dudemanlives at 1:45 PM on June 27


Is "molecules per square centimeter" a normal method of reporting units for remote sensing of atmospheric concentrations? I can't even imagine how they would arrive at that. Did they mean molecules per cubic centimeter?

No. The satellites work in 2D basically looking for signs of the pollutants. The main way is tuning your cameras for a specific wavelength (the emissive spectrum of what you're looking for) and then counting the photons. It's much more complicated than that since some things will have overlapping or extremely close peaks and modeling needs to account for this.
posted by Talez at 1:48 PM on June 27 [1 favorite]


However, our former jobs are breathing even worse air over there.
posted by srboisvert at 1:56 PM on June 27 [3 favorites]


Meanwhile, in China -- Beijing: From Hardship Post To Plum Assignment And Back Again (because the air quality is just that bad).
posted by filthy light thief at 1:57 PM on June 27


Oops, just realized the quote in my previous post had the superscript stripped out. Those numbers in-text were 1x10^15 to 5x10^15, of course.

The satellites work in 2D basically looking for signs of the pollutants.

I get that, but giving us raw numbers as reported from their sensor seems really uninformative. Why wouldn't they convert those into PPM or something more understandable? I don't want to have to start thinking about the thickness of the troposphere in order to understand the concentrations as reported. It seems like it would be pretty easy to calibrate their sensor's reports with ground or aircraft based air quality monitoring stations.
posted by agentofselection at 2:31 PM on June 27


I'm assuming that net nitrogen dioxide levels are still rising globally seeing how there are still an increasing number of ICEs and (as far as my quick Google search informed me) it is not converted into another compound in the atmosphere.

This simply isn't true. There are a whole mess of complex photochemical reactions occurring with NO/NO2/NOx compounds in the troposphere. First, NO and NO2 are rapidly converted back and forth due to photodissociation in the presence of tropospheric ozone. The main way these compounds are removed from the atmosphere is by reaction to HNO3 and scouring by precipitation: in the presence of hydroxyl radicals and sunlight, NOx is converted to HNO3, which is water soluble and results in wet deposition when precipitation occurs. UW has a good set of slides covering the NOx/ozone reactions here.

However, if the NOx compounds make it into the upper troposphere, NOx sticks around for a lot longer due to temperature-related changes in the rates of reaction. Further, NOx compounds can produce a great deal of tropospheric ozone through reaction with other hydrocarbon combustion byproducts and peroxyl radicals; while ozone is great in the stratosphere, it's poison in the troposphere due to its many harmful effects on human health (not to mention its exacerbating role in the NOx cycle).

One other thing that can happen to NOx compounds is that they can turn in to PAN (peroxyacetyl nitrate), or smog, when they interact with volatile organic compounds (due to photooxidation of hydrocarbons in the presence of NOx). PAN is not water-soluble and is not scavenged from the atmosphere by precipitation, and can be transported long distances before decomposing (temp-related on subsidence) to release NOx far away from the source of the emissions.

Nitrogen deposition is a huge deal for downwind ecosystems; we've been artificially fertilizing our northeastern forests with plant-usable N for decades, leading not only to some amount of acid rain (it isn't all from sulfur dioxide!) but also to some very strange stream chemistry dynamics and changing nutrient competition dynamics among native plant species. A lot of this work came out of the long-term ecological research station at Hubbard Brook, where they've been tracking ecosystem reactions to increased nitrogen deposition at a small-watershed scale for decades. Here's a neat blog post about the history of nitrogen research at Hubbard Brook - they touch on some of the issues, especially the weird interactions with stream calcium and the very mysterious missing N sink they've observed since emissions began to drop. Interesting stuff!
posted by dialetheia at 2:34 PM on June 27 [21 favorites]


After ten years in orbit, the Ozone Monitoring Instrument (OMI) on NASA's Aura satellite has been in orbit sufficiently long to show that people in major U.S. cities are breathing less nitrogen dioxide – a yellow-brown gas that can cause respiratory problems.? Umm we pretty much breathe that on a daily basis but this is life we are to blame and we need to make our world healthier as well.
posted by FrankNella at 3:21 PM on June 27


I get that, but giving us raw numbers as reported from their sensor seems really uninformative. Why wouldn't they convert those into PPM or something more understandable? I don't want to have to start thinking about the thickness of the troposphere in order to understand the concentrations as reported. It seems like it would be pretty easy to calibrate their sensor's reports with ground or aircraft based air quality monitoring stations.

Well it's hard to differentiate between surface nox and stratospheric nox. What shows up on the pictures doesn't 100% correlate to ground level. Plus the relative nature of the results is the real interest not absolute. We just want to know it's going down.
posted by Talez at 3:30 PM on June 27


"Courage, my friends; 'tis not too late to make a better world."
posted by KokuRyu at 3:34 PM on June 27 [1 favorite]


Why wouldn't they convert those into PPM or something more understandable? I don't want to have to start thinking about the thickness of the troposphere in order to understand the concentrations as reported. It seems like it would be pretty easy to calibrate their sensor's reports with ground or aircraft based air quality monitoring stations.

Without having read the papers, the simplest explanation is that the concentration as a function of height is not known, and that function of height probably is not uniform across the US, so calibration is not possible.
posted by Salvor Hardin at 3:52 PM on June 27


Okay, the concentration having an unpredictable variation by altitude makes sense, thanks.
posted by agentofselection at 4:10 PM on June 27


This seems like a pretty big deal. If I were running for President I'd be showing this to every citizen in the United States. Just look at what government can accomplish if you let it.
posted by SollosQ at 6:13 PM on June 27


Wow, dialetheia. Flagged as fantastic.
posted by clockzero at 9:02 PM on June 27


« Older For the first time, Primatologists have observed c...  |  220 images from Alien... Newer »


This thread has been archived and is closed to new comments