According to new research from the National Institute of Standards and Technology (NIST) In the Los Angeles and Washington DC/Baltimore areas, carbon dioxide (CO2) is expected to rise in April 2020 as roads are emptied and economic activity has slowed due to the COVID-19 pandemic.2) emissions fell by about 33 percent compared to previous years. On the other hand, the new research method used to measure emissions reductions may have a longer-term impact.

Geophysical Research Letters’da yayınlanan According to a new study, carbon dioxide emissions in Los Angeles fell 33% in April 2020 compared to previous years as roads are empty due to the COVID-19 pandemic and economic activity has slowed. In the Washington, DC / Baltimore area, carbon dioxide or CO2 It was concluded that emissions fell 34% over the same period.

The work was led by scientists at NASA’s Jet Propulsion Laboratory (JPL), the National Institute of Standards and Technology (NIST), and the University of Notre Dame.

What Kind of Method Was Followed in Emission Measurement?

While emissions reductions are significant, the method scientists use to measure them may have a longer-term impact.

In both locations, scientists are primarily concerned with airborne CO2 They installed sensor networks on rooftops and towers to monitor its concentration. They used data from these sensor networks to estimate the reduction in emissions.

This may seem like an obvious way of estimating emissions, but usually no such estimation method is followed. Most cities estimate their emissions by calculating the effects of activities that cause emissions, such as the number of vehicle kilometers traveled or the square meters of buildings heated and cooled. These are called “bottom-up” methods because they are mostly based on ground-based activities.

This new study, CO2 It illustrates methods based on “top-down” measurement of concentration. So in air, it can produce reliable emission estimates. Scientists have had the opportunity to test these methods when emissions suddenly drop due to COVID-19.

“This was a totally unexpected experiment and one that we didn’t want to do again,” says lead author and JPL data scientist Vineet Yadav. “However, our results show that we were able to detect the onset of emission reductions within a few days.” he adds.

For several years, scientists have2 was developing top-down methods to measure its emissions. “This study demonstrates that the technology is mature enough to produce reliable results and can be included as a research method,” says NIST scientist and co-author Kimberly Mueller. This will provide cities with an important new tool in their efforts to reduce emissions.

Top-down estimates are difficult to come by because CO2 in the air above cities2 ‘nin most are not from local emissions. Most are naturally there, and some spread outside the city limits and come with the wind. The trick is CO in the air above the city2Find out how much of it is produced locally.

What are the Advantages of the New Research Method?

“My doctoral advisor used to describe the atmosphere as a big cup of coffee,” Mueller says. says. After mixing the cream into the coffee, it becomes impossible to detect where you added the cream.

To detect atmospheric coffee, the scientists used data on wind speed, direction and other factors. This allowed them to estimate where in a city the emissions originated and how large.

Although difficult to achieve, top-down measurements have many advantages. First, they can provide relatively quick feedback on whether emissions reduction efforts are working. For example, if a city changes its traffic patterns or increases public transport, top-down estimates can provide data on whether these efforts have actually led to emissions reductions.

In addition, a recent study co-authored with Mueller showed that US cities often underestimate their emissions when using bottom-up methods only. Another recent study showed that combining bottom-up methods with top-down methods improves accuracy. (Both studies were partially funded by NIST.)

“Accurate measurements are key to any strategy for managing greenhouse gas emissions,” says James Whetstone, leader of NIST’s greenhouse gas measurements group and co-author of the study. This seems to be the only way to know if you’re moving towards goals.

NIST, NASA, and other research partners are using sensor networks in the Los Angeles and Washington, DC/Baltimore area to develop and test top-down methods as a way to obtain more accurate emission estimates. This research project focuses in part on cities because cities are the world’s CO22 accounts for a large and growing share of its emissions.

Emission reductions of 33% and 34% in the Los Angeles and DC/Baltimore region represent reductions from the average April emissions of the previous two years. The researchers used three different methods to detect the change in emissions based on atmospheric measurements, all of which detected the simultaneous decrease.

“These independent statistical tests on different pieces of the puzzle yielded consistent results,” says University of Notre Dame computational scientist (Statistician) and co-author Subhomoy Ghosh. This seems to be a result that ensures the reliability of the findings.

Also, the methods appear to work well at both locations despite very different environmental conditions. In Los Angeles, relatively fresh air comes from the Pacific. DC and Baltimore regularly receive emissions from cities and power plants in the west. Also in DC and Baltimore, emission patterns show that plants are turning green again and airborne CO2 The effects of the spring that it started to draw should be taken into account. Los Angeles experiences less seasonal effects in uptake by plants. “These methods were robust enough to work in very different environments,” Mueller said. says. The fact that the methods worked in both places makes it clear that the results were no coincidence.


Writer: Nil GÜREL

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