scholarly journals Changes in satellite retrievals of atmospheric composition over eastern China during the 2020 COVID-19 lockdowns

2021 ◽  
Vol 21 (24) ◽  
pp. 18333-18350
Author(s):  
Robert D. Field ◽  
Jonathan E. Hickman ◽  
Igor V. Geogdzhayev ◽  
Kostas Tsigaridis ◽  
Susanne E. Bauer
Keyword(s):  
Southern China ◽  
Eastern China ◽  
Atmospheric Composition ◽  
Fire Season ◽  
Ozone Monitoring Instrument ◽  
Active Fire ◽  
Background Period ◽  
Satellite Retrievals ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Future Work

Abstract. We examined daily level-3 satellite retrievals of Atmospheric Infrared Sounder (AIRS) CO, Ozone Monitoring Instrument (OMI) SO2 and NO2, and Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) over eastern China to understand how COVID-19 lockdowns affected atmospheric composition. Changes in 2020 were strongly dependent on the choice of background period since 2005 and whether trends in atmospheric composition were accounted for. Over central east China during the 23 January–8 April lockdown window, CO in 2020 was between 3 % and 12 % lower than average depending on the background period. The 2020 CO was not consistently less than expected from trends beginning between 2005 and 2016 and ending in 2019 but was 3 %–4 % lower than the background mean during the 2017–2019 period when CO changes had flattened. Similarly for AOD, 2020 was between 14 % and 30 % lower than averages beginning in 2005 and 14 %–17 % lower compared to different background means beginning in 2016. NO2 in 2020 was between 30 % and 43 % lower than the mean over different background periods and between 17 % and 33 % lower than what would be expected for trends beginning later than 2011. Relative to the 2016–2019 period when NO2 had flattened, 2020 was 30 %–33 % lower. Over southern China, 2020 NO2 was between 23 % and 27 % lower than different background means beginning in 2013, the beginning of a period of persistently lower NO2. CO over southern China was significantly higher in 2020 than what would be expected, which we suggest was partly because of an active fire season in neighboring countries. Over central east and southern China, 2020 SO2 was higher than expected, but this depended strongly on how daily regional values were calculated from individual retrievals and reflects background values approaching the retrieval detection limit. Future work over China, or other regions, needs to take into account the sensitivity of differences in 2020 to different background periods and trends in order to separate the effects of COVID-19 on air quality from previously occurring changes or from variability in other sources.

scholarly journals Changes in satellite retrievals of atmospheric composition over eastern China during the 2020 COVID-19 lockdowns

2020 ◽  
Author(s):  
Robert D. Field ◽  
Jonathan E. Hickman ◽  
Igor V. Geogdzhayev ◽  
Kostas Tsigaridis ◽  
Susanne E. Bauer
Keyword(s):  
Southern China ◽  
Eastern China ◽  
Atmospheric Composition ◽  
Fire Season ◽  
Active Fire ◽  
Modis Aod ◽  
Satellite Retrievals ◽  
Level 3 ◽  
Recent Trends ◽  
Future Work

Abstract. We examined daily Level-3 satellite retrievals of AIRS CO, OMI SO2 and NO2, and MODIS AOD over eastern China to understand how COVID-19 lockdowns affected atmospheric composition, taking into account trends that have occurred since 2005. Over central east China during the January 23–April 8 lockdown window, CO in 2020 was 12 % lower than the 2005–2019 mean, but only 2 % lower than what would be expected given the decreasing CO trend over that period. Similarly for AOD, 2020 was 30 % lower than the 2011–2019 mean, but not distinct from what would be expected from the trend. NO2 in 2020 was 43 % lower than the 2011–2019 mean, but only 17 % lower than what would be expected given the trend over that period. Over southern China, 2020 NO2 was not significantly different from anticipated, and CO and AOD were significantly higher that what would be expected, which we suggest was partly because of an active fire season in neighbouring countries. Over east central and southern China, SO2 was higher than expected, but the magnitude depended strongly on how daily regional values were calculated from individual retrievals. Future work over China, or other regions, needs to take these trends into account in order to separate the effects of COVID-19 on air quality from recent trends, or from variability in other sources.

scholarly journals Characterization of wildfire NO<sub>x</sub> emissions using MODIS fire radiative power and OMI tropospheric NO<sub>2</sub> columns

2011 ◽  
Vol 11 (12) ◽  
pp. 5839-5851 ◽  
Author(s):  
A. K. Mebust ◽  
A. R. Russell ◽  
R. C. Hudman ◽  
L. C. Valin ◽  
R. C. Cohen
Keyword(s):  
Ozone Monitoring Instrument ◽  
Fire Emissions ◽  
Active Fire ◽  
Radiative Power ◽  
Flaming Combustion ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Current Emission ◽  
Fire Radiative Power

Abstract. We use observations of fire radiative power (FRP) from the Moderate Resolution Imaging Spectroradiometer~(MODIS) and tropospheric NO2 column measurements from the Ozone Monitoring Instrument (OMI) to derive NO2 wildfire emission coefficients (g MJ−1) for three land types over California and Nevada. Retrieved emission coefficients were 0.279±0.077, 0.342±0.053, and 0.696±0.088 g MJ−1 NO2 for forest, grass and shrub fuels, respectively. These emission coefficients reproduce ratios of emissions with fuel type reported previously using independent methods. However, the magnitude of these coefficients is lower than prior estimates. While it is possible that a negative bias in the OMI NO2 retrieval over regions of active fire emissions is partly responsible, comparison with several other studies of fire emissions using satellite platforms indicates that current emission factors may overestimate the contributions of flaming combustion and underestimate the contributions of smoldering combustion to total fire emissions. Our results indicate that satellite data can provide an extensive characterization of the variability in fire NOx emissions; 67 % of the variability in emissions in this region can be accounted for using an FRP-based parameterization.

scholarly journals Indonesian fire activity and smoke pollution in 2015 show persistent nonlinear sensitivity to El Niño-induced drought

2016 ◽  
Vol 113 (33) ◽  
pp. 9204-9209 ◽  
Author(s):  
Robert D. Field ◽  
Guido R. van der Werf ◽  
Thierry Fanin ◽  
Eric J. Fetzer ◽  
Ryan Fuller ◽  
...  
Keyword(s):  
El Niño ◽  
El Nino ◽  
Fire Season ◽  
Ozone Monitoring Instrument ◽  
Earth Observing System ◽  
Active Fire ◽  
Fire Environment ◽  
Dry Conditions ◽  
Smoke Pollution ◽  
Moderate Resolution

The 2015 fire season and related smoke pollution in Indonesia was more severe than the major 2006 episode, making it the most severe season observed by the NASA Earth Observing System satellites that go back to the early 2000s, namely active fire detections from the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS), MODIS aerosol optical depth, Terra Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO), Aqua Atmospheric Infrared Sounder (AIRS) CO, Aura Ozone Monitoring Instrument (OMI) aerosol index, and Aura Microwave Limb Sounder (MLS) CO. The MLS CO in the upper troposphere showed a plume of pollution stretching from East Africa to the western Pacific Ocean that persisted for 2 mo. Longer-term records of airport visibility in Sumatra and Kalimantan show that 2015 ranked after 1997 and alongside 1991 and 1994 as among the worst episodes on record. Analysis of yearly dry season rainfall from the Tropical Rainfall Measurement Mission (TRMM) and rain gauges shows that, due to the continued use of fire to clear and prepare land on degraded peat, the Indonesian fire environment continues to have nonlinear sensitivity to dry conditions during prolonged periods with less than 4 mm/d of precipitation, and this sensitivity appears to have increased over Kalimantan. Without significant reforms in land use and the adoption of early warning triggers tied to precipitation forecasts, these intense fire episodes will reoccur during future droughts, usually associated with El Niño events.

scholarly journals An evaluation of the ability of the Ozone Monitoring Instrument (OMI) to observe boundary layer ozone pollution across China: application to 2005–2017 ozone trends

2019 ◽  
Vol 19 (9) ◽  
pp. 6551-6560 ◽  
Author(s):  
Lu Shen ◽  
Daniel J. Jacob ◽  
Xiong Liu ◽  
Guanyu Huang ◽  
Ke Li ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Tropospheric Ozone ◽  
Southern China ◽  
Surface Ozone ◽  
Eastern China ◽  
Ozone Pollution ◽  
Ozone Monitoring Instrument ◽  
Monitoring Instrument ◽  
Ozone Monitoring ◽  
Boundary Layer Ozone

Abstract. Nadir-viewing satellite observations of tropospheric ozone in the UV have been shown to have some sensitivity to boundary layer ozone pollution episodes, but so far they have not yet been compared to surface ozone observations collected by large-scale monitoring networks. Here we use 2013–2017 surface ozone data from China's new Ministry of Ecology and Environment (MEE) network of ∼ 1000 sites, together with vertical profiles from ozonesondes and aircraft, to quantify the ability of tropospheric ozone retrievals from the Ozone Monitoring Instrument (OMI) and to detect boundary layer ozone pollution in China. We focus on summer when ozone pollution in China is most severe and when OMI has the strongest sensitivity. After subtracting the Pacific background, we find that the 2013–2017 mean OMI ozone enhancements over eastern China have strong spatial correlation with the corresponding multiyear means in the surface afternoon observations (R=0.73), and that OMI can estimate these multiyear means in summer afternoon surface ozone with a precision of 8 ppb. The OMI data show significantly higher values on observed surface ozone episode days (>82 ppb) than on non-episode days. Day-to-day correlations with surface ozone are much weaker due to OMI noise and are stronger for sites in southern China (<34∘ N; R=0.3–0.6) than in northern China (R=0.1–0.3) because of weaker retrieval sensitivity and larger upper tropospheric variability in the north. Ozonesonde data show that much of the variability of OMI ozone over southern China in summer is driven by the boundary layer. Comparison of 2005–2009 and 2013–2017 OMI data indicates that mean summer afternoon surface ozone in southern China (including urban and rural regions) has increased by 3.5±3.0 ppb over the 8-year period and that the number of episode days per summer has increased by 2.2±0.4 (as diagnosed by an extreme value model), generally consistent with the few long-term surface records. Ozone increases have been particularly large in the Yangtze River Delta and in the Hubei, Guangxi and Hainan provinces.

scholarly journals A Climatological Assessment of Intense Desert Dust Episodes over the Broader Mediterranean Basin Based on Satellite Data

2021 ◽  
Vol 13 (15) ◽  
pp. 2895
Author(s):  
Maria Gavrouzou ◽  
Nikolaos Hatzianastassiou ◽  
Antonis Gkikas ◽  
Christos J. Lolis ◽  
Nikolaos Mihalopoulos
Keyword(s):  
Mediterranean Basin ◽  
Eastern Mediterranean ◽  
Mean Value ◽  
Early Spring ◽  
Dust Aerosol ◽  
Ozone Monitoring Instrument ◽  
Central Mediterranean ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

A satellite algorithm able to identify Dust Aerosols (DA) is applied for a climatological investigation of Dust Aerosol Episodes (DAEs) over the greater Mediterranean Basin (MB), one of the most climatologically sensitive regions of the globe. The algorithm first distinguishes DA among other aerosol types (such as Sea Salt and Biomass Burning) by applying threshold values on key aerosol optical properties describing their loading, size and absorptivity, namely Aerosol Optical Depth (AOD), Aerosol Index (AI) and Ångström Exponent (α). The algorithm operates on a daily and 1° × 1° geographical cell basis over the 15-year period 2005–2019. Daily gridded spectral AOD data are taken from Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua Collection 6.1, and are used to calculate the α data, which are then introduced into the algorithm, while AI data are obtained by the Ozone Monitoring Instrument (OMI) -Aura- Near-UV aerosol product OMAERUV dataset. The algorithm determines the occurrence of Dust Aerosol Episode Days (DAEDs), whenever high loads of DA (higher than their climatological mean value plus two/four standard deviations for strong/extreme DAEDs) exist over extended areas (more than 30 pixels or 300,000 km2). The identified DAEDs are finally grouped into Dust Aerosol Episode Cases (DAECs), consisting of at least one DAED. According to the algorithm results, 166 (116 strong and 50 extreme) DAEDs occurred over the MB during the study period. DAEDs are observed mostly in spring (47%) and summer (38%), with strong DAEDs occurring primarily in spring and summer and extreme ones in spring. Decreasing, but not statistically significant, trends of the frequency, spatial extent and intensity of DAECs are revealed. Moreover, a total number of 98 DAECs was found, primarily in spring (46 DAECs) and secondarily in summer (36 DAECs). The seasonal distribution of the frequency of DAECs varies geographically, being highest in early spring over the eastern Mediterranean, in late spring over the central Mediterranean and in summer over the western MB.

scholarly journals Twenty-first century droughts have not increasingly exacerbated fire season severity in the Brazilian Amazon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
R. Libonati ◽  
J. M. C. Pereira ◽  
C. C. Da Camara ◽  
L. F. Peres ◽  
D. Oom ◽  
...  
Keyword(s):  
Forest Fires ◽  
Brazilian Amazon ◽  
First Century ◽  
Fire Season ◽  
Fire Intensity ◽  
Amazon Forest ◽  
Active Fire ◽  
Fire Activity ◽  
Twenty First Century ◽  
In Fire

AbstractBiomass burning in the Brazilian Amazon is modulated by climate factors, such as droughts, and by human factors, such as deforestation, and land management activities. The increase in forest fires during drought years has led to the hypothesis that fire activity decoupled from deforestation during the twenty-first century. However, assessment of the hypothesis relied on an incorrect active fire dataset, which led to an underestimation of the decreasing trend in fire activity and to an inflated rank for year 2015 in terms of active fire counts. The recent correction of that database warrants a reassessment of the relationships between deforestation and fire. Contrasting with earlier findings, we show that the exacerbating effect of drought on fire season severity did not increase from 2003 to 2015 and that the record-breaking dry conditions of 2015 had the least impact on fire season of all twenty-first century severe droughts. Overall, our results for the same period used in the study that originated the fire-deforestation decoupling hypothesis (2003–2015) show that decoupling was clearly weaker than initially proposed. Extension of the study period up to 2019, and novel analysis of trends in fire types and fire intensity strengthened this conclusion. Therefore, the role of deforestation as a driver of fire activity in the region should not be underestimated and must be taken into account when implementing measures to protect the Amazon forest.

Detection of Russian Fires Using MOPITT and MODIS Data

2005 ◽  
Vol 277-279 ◽  
pp. 816-823
Author(s):  
Sang Hee Lee ◽  
Gi Hyuk Choi ◽  
Hyo Suk Lim ◽  
Joo Hee Lee ◽  
Kwon Ho Lee ◽  
...  
Keyword(s):  
East Asia ◽  
Forest Fires ◽  
Eastern China ◽  
Northeast Asia ◽  
Smoke Aerosol ◽  
Modis Data ◽  
Smoke Pollution ◽  
Moderate Resolution ◽  
Large Fires ◽  
Moderate Resolution Imaging Spectroradiometer

The great fires were detected through the Moderate Resolution Imaging Spectroradiometer (MODIS) observations over Northeast Asia. The large amount of smoke produced near Lake Baikal was transported to East Asia using high Aerosol Optical Thickness (AOT) as seen through the satellite images. The smoke pollution from the Russian forest fires would sometimes reach Korea through Mongolia and eastern China. In May 2003, a number of large fires blazed through eastern Russian, producing a thick, widespread pall of smoke over much of East Asia. This study focuses on the identification of the carbon monoxide (CO) for MOPITT released from MOPITT primarily into East Asia during the Russian Fires. In the wake of the fires, the 700hPa MOPITT retrieved CO concentrations which reached up to 250ppbv. Smoke aerosol retrieval using a separation technique was also applied to the MODIS data observed in 14-22 May 2003. Large AOT, 2.0 ~ 5.0, was observed over Korea on 20 May 2003 due to the influence of the long range transport of smoke aerosol plume from the Russian Fires.

scholarly journals Extreme levels of Canadian wildfire smoke in the stratosphere over central Europe on 21–22 August 2017

2018 ◽  
Vol 18 (16) ◽  
pp. 11831-11845 ◽  
Author(s):  
Albert Ansmann ◽  
Holger Baars ◽  
Alexandra Chudnovsky ◽  
Ina Mattis ◽  
Igor Veselovskii ◽  
...  
Keyword(s):  
Central Europe ◽  
Volcanic Eruptions ◽  
Light Extinction ◽  
Ozone Monitoring Instrument ◽  
Wildfire Smoke ◽  
The North ◽  
Radiative Power ◽  
Peak Mass ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. Light extinction coefficients of 500 Mm−1, about 20 times higher than after the Pinatubo volcanic eruptions in 1991, were observed by European Aerosol Research Lidar Network (EARLINET) lidars in the stratosphere over central Europe on 21–22 August 2017. Pronounced smoke layers with a 1–2 km vertical extent were found 2–5 km above the local tropopause. Optically dense layers of Canadian wildfire smoke reached central Europe 10 days after their injection into the upper troposphere and lower stratosphere which was caused by rather strong pyrocumulonimbus activity over western Canada. The smoke-related aerosol optical thickness (AOT) identified by lidar was close to 1.0 at 532 nm over Leipzig during the noon hours on 22 August 2017. Smoke particles were found throughout the free troposphere (AOT of 0.3) and in the pronounced 2 km thick stratospheric smoke layer at an altitude of 14–16 km (AOT of 0.6). The lidar observations indicated peak mass concentrations of 70–100 µg m−3 in the stratosphere. In addition to the lidar profiles, we analyzed Moderate Resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) over Canada, and the distribution of MODIS AOT and Ozone Monitoring Instrument (OMI) aerosol index across the North Atlantic. These instruments showed a similar pattern and a clear link between the western Canadian fires and the aerosol load over Europe. In this paper, we also present Aerosol Robotic Network (AERONET) sun photometer observations, compare photometer and lidar-derived AOT, and discuss an obvious bias (the smoke AOT is too low) in the photometer observations. Finally, we compare the strength of this record-breaking smoke event (in terms of the particle extinction coefficient and AOT) with major and moderate volcanic events observed over the northern midlatitudes.

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