[NASA Earth Observatory] Airborne Nitrogen Dioxide Plummets Over China

NASA and European Space Agency (ESA) pollution monitoring satellites have detected significant decreases in nitrogen dioxide (NO₂) over China. There is evidence that the change is at least partly related to the economic slowdown following the outbreak of coronavirus.

自从疫情爆发后, 各个学术领域都在争相进行相关的研究. 不管这个学科和医学也没有关联, 这个事件都会与各个领域产生那么些关系, 带来那么些影响. 于是, 一下子疫情成了各个领域的热门研究话题. 短短两个月的时间, 针对本次事件的论文已经发表了数十篇, 而研究工作也依旧如火如荼地进行.

疫情相关文献

疫情之于建筑结构设计...
疫情之于人口流动地理分析...
疫情之于国际关系和公共政策...
疫情之于...
...

在这样一个即将被载入人类史册的特殊的历史性事件中, 学术研究者又怎会错过发表论文的良好时机, 毕竟平时发篇论文有多难...

但是, 可以肯定的是研究工作是必要的且永不止息的, 没有研究, 就没有认知理解, 没有认知理解, 就没有对策方案, 没有对策方案, 就没有进步. 不管是什么领域, 都可以综其为认识世界, 学习世界, 改造世界的探索.

新民周刊相关文章

新闻界的文章总是另外一种画风, 它以不同于学术论文的方式刺激着你的肾上腺和杏仁核.

“
冬将尽, 春已来...
庚子年, 一场大考...
”
它用文学的手段描述着这个世界, 表达着主流媒体的观点, 引导着大众的情感取向.

At the end of 2019, medical professionals in Wuhan, China, were treating dozens of pneumonia cases that had an unknown source. Days later, researchers confirmed the illnesses were caused by a new coronavirus (COVID-19). By January 23, 2020, Chinese authorities had shut down transportation going into and out of Wuhan, as well as local businesses, in order to reduce the spread of the disease. It was the first of several quarantines set up in the country and around the world.

• quarantine: 隔离

The maps on this page show concentrations of nitrogen dioxide, a noxious gas emitted by motor vehicles, power plants, and industrial facilities. The maps above show NO₂ values across China from January 1-20, 2020 (before the quarantine) and February 10-25 (during the quarantine). The data were collected by the Tropospheric Monitoring Instrument (TROPOMI) on ESA’s Sentinel-5 satellite. A related sensor, the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite, has been making similar measurements.

According to NASA scientists, the reduction in NO₂ pollution was first apparent near Wuhan, but eventually spread across the country. Millions of people have been quarantined in one of the largest such actions in human history. As of February 28, 2020, the virus had been detected in at least 56 countries.

“This is the first time I have seen such a dramatic drop-off over such a wide area for a specific event,” said Fei Liu, an air quality researcher at NASA’s Goddard Space Flight Center. Liu recalls seeing a drop in NO₂ over several countries during the economic recession that began in 2008, but the decrease was gradual. Scientists also observed a significant reduction around Beijing during the 2008 Olympics, but the effect was mostly localized around that city, and pollution levels rose again once the Olympics ended.

The drop in nitrogen dioxide in 2020 also coincided with Lunar New Year celebrations in China and much of Asia. Generally, businesses and factories close from the last week in January into early February to celebrate the festival. Past observations have shown that air pollution usually decreases during this period and then increases once the celebration is over.

“There is always this general slowdown around this time of the year,” said Barry Lefer, an air quality scientist at NASA. “Our long-term OMI data allows us to see if these amounts are abnormal and why.” Launched in 2004, OMI has been collecting global data on NO₂and various air pollutants for more than 15 years.

The maps above show NO₂ values over three periods in 2020: January 1-20 (before Lunar New Year), January 28-February 9 (around New Year celebrations), and February 10-25 (after the event). The 2020 values are compared to the same periods in 2019 for reference. Lefer noted that the overall values in 2020 were lower than 2019 due to new environmental regulations that China has enforced over the past few years.

While the Lunar New Year may have played a role in the recent dropoff, researchers believe the decrease is more than a holiday effect or weather-related variation. In a preliminary analysis, NASA researchers compared NO₂ values detected by OMI in 2020 with the average amounts detected at this time of year from 2005-2019. In 2020, NO₂values in eastern and central China were significantly lower (from 10 to 30 percent lower) than what is normally observed for this time period.

Additionally, Liu and colleagues have not seen a rebound in NO₂ after the holiday. “This year, the reduction rate is more significant than in past years and it has lasted longer,” she said. “I am not surprised because many cities nationwide have taken measures to minimize spread of the virus.”

• rebound: 回升, 反弹

总结:
这篇文章就是从环境的角度去分析疫情控制前后NO₂的排放量的变化, 以此描述隔离产生的环境上的影响, 以及空间上的分布. 类似的空间可视化结果也可以从交通的角度去获得人口流动对比.

原文