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Author(s):  
Keith A. Potts

Three significant changes have occurred in the winter climate in Europe recently: increased UK flooding; Iberian drought; and warmer temperatures north of the Alps. The literature links all three to a persistent, significant increase in sea level pressure over Southern Europe, the Mediterranean, Iberia and the Eastern Atlantic (SEMIEA) which changes the atmospheric circulation system: forcing cold fronts to the north away from Iberia; and creating a south westerly flow around the northern perimeter of the high-pressure region bringing warmer, moist air from the subtropical Atlantic to the UK and Europe which increases precipitation in the UK and raises the temperature in Europe. I use the Last Millennium Ensemble, MERRA-2 and Terra-NCEP data to demonstrate that the extreme, anthropogenic, West African aerosol Plume (WAP) which only exists from December to April perturbs the northern, regional Hadley Circulation creating the high pressure in the SEMIEA. I also show that the anthropogenic WAP has only existed in its extreme form in recent decades as the two major sources of the WAP aerosols: biomass burning; and gas flaring have both increased significantly since 1950 due to: a four-fold increase in population; and gas flaring rising from zero to 7.4 billion m3/annum and note that this time span coincides with the changes in the three elements of the winter climate of Europe. I also suggest that it may be possible to eliminate the WAP and return the winter climate of Europe to its natural state after the crucial first step of recognising the cause of the changes is taken.


2021 ◽  
Vol 17 (6) ◽  
pp. 2607-2632
Author(s):  
Christopher Garrison ◽  
Christopher Kilburn ◽  
David Smart ◽  
Stephen Edwards

Abstract. One of the largest climate forcing eruptions of the nineteenth century was, until recently, believed to have taken place at the Babuyan Claro volcano, in the Philippines, in 1831. However, a recent investigation found no reliable evidence of such an eruption, suggesting that the 1831 eruption must have taken place elsewhere. We here present our newly compiled dataset of reported observations of a blue, purple and green sun in August 1831, which we use to reconstruct the transport of a stratospheric aerosol plume from that eruption. The source of the aerosol plume is identified as the eruption of Ferdinandea, which took place about 50 km off the south-west coast of Sicily (37.1∘ N, 12.7∘ E), in July and August 1831. The modest magnitude of this eruption, assigned a volcanic explosivity index (VEI) of 3, has commonly caused it to be discounted or overlooked when identifying the likely source of the stratospheric sulfate aerosol in 1831. It is proposed, however, that convective instability in the troposphere contributed to aerosol reaching the stratosphere and that the aerosol load was enhanced by addition of a sedimentary sulfur component to the volcanic plume. Thus, one of the largest climate forcing volcanic eruptions of the nineteenth century would effectively have been hiding in plain sight, arguably “lowering the bar” for the types of eruptions capable of having a substantial climate forcing impact. Prior estimates of the mass of stratospheric sulfate aerosol responsible for the 1831 Greenland ice core sulfate deposition peaks which have assumed a source eruption at a low-latitude site will, therefore, have been overstated. The example presented in this paper serves as a useful reminder that VEI values were not intended to be reliably correlated with eruption sulfur yields unless supplemented with compositional analyses. It also underlines that eye-witness accounts of historical geophysical events should not be neglected as a source of valuable scientific data.


2021 ◽  
Author(s):  
Zhujun Li ◽  
David Painemal ◽  
Gregory Schuster ◽  
Marian Clayton ◽  
Richard Ferrare ◽  
...  

Abstract. We assess the CALIPSO Version 4.2 (V4) aerosol typing and assigned lidar ratios over ocean using aerosol optical depth (AOD) retrievals from the Synergized Optical Depth of Aerosols (SODA) algorithm and retrieved columnar lidar ratio estimated by combining SODA AOD and CALIPSO attenuated backscatter (CALIPSO-SODA). Six aerosol types – clean marine, dusty marine, dust, polluted continental/smoke, polluted dust, and elevated smoke – are characterized using CALIPSO-SODA over ocean and the results are compared against the prescribed V4 lidar ratios, when only one aerosol type is present in the atmospheric column. For samples detected at 5-km or 20-km spatial resolutions and having AOD > 0.05, the CALIPSO-SODA lidar ratios are significantly different between different aerosol types, and are consistent with the type-specific values assigned in V4 to within 10 sr (except for polluted continental/smoke). This implies that the CALIPSO classification scheme generally categorizes aerosols correctly. We find remarkable daytime/nighttime regional agreement for clean marine aerosol over the open ocean (CALIPSO-SODA = 20–25 sr, V4 = 23 sr), elevated smoke over the southeast Atlantic (CALIPSO-SODA = 65–75 sr, V4 = 70 sr), and dust over the subtropical Atlantic adjacent to the African continent (CALIPSO-SODA = 40–50 sr, V4 = 44 sr). In contrast, daytime polluted continental/smoke lidar ratio is more than 20 sr smaller than the constant V4 vaue for that type, attributed in part to the challenge of classifying tenuous aerosol with low signal-to-noise ratio. Dust over most of the Atlantic Ocean features CALIPSO-SODA lidar ratios less than 40 sr, possibly suggesting the presence of dust mixed with marine aerosols or lidar ratio values that depend on source and evolution of the aerosol plume. The new dusty marine type introduced in V4 features similar magnitudes and spatial distribution as its clean marine counterpart with lidar ratio differences of less than 3 sr, and nearly identical values over the open ocean, implying that some modification of the classification scheme for the marine subtypes is warranted.


Author(s):  
Keith A. Potts

Three significant changes have occurred in the winter climate in Europe recently: increased UK flooding; Iberian drought; and warmer temperatures north of the Alps. The literature links all three to a persistent, significant increase in sea level pressure over Southern Europe, the Medi-terranean, Iberia and the Eastern Atlantic (SEMIEA) which changes the atmospheric circulation system: forcing cold fronts to the north away from Iberia; and creating a south westerly flow around the northern perimeter of the high-pressure region bringing warmer, moist air from the subtropical Atlantic to the UK and Europe which increases precipitation in the UK and raises the temperature in Europe. I use the Last Millennium Ensemble, MERRA-2 and Terra-NCEP data to demonstrate that the extreme, anthropogenic, West African aerosol Plume (WAP) which only exists from December to April perturbs the northern, regional Hadley Circulation creating the high pressure in the SEMIEA. I also show that the anthropogenic WAP has only existed in its extreme form in recent decades as the two major sources of the WAP aerosols: biomass burning; and gas flaring have both increased significantly since 1950 due to: a four-fold increase in population; and gas flaring rising from zero to 7.4 billion m3/annum and note that this time span coincides with the changes in the three elements of the winter climate of Europe. I also suggest that it may be possible to eliminate the WAP and return the winter climate of Europe to its natural state after the crucial first step of recognising the cause of the changes is taken.


Author(s):  
Keith A. Potts

Europe’s winter climate has experienced three significant changes recently: increased UK flooding; Iberian drought; and warmer temperatures north of the Alps. The literature links all three to a persistent, significant increase in sea level pressure over the Mediterranean and Iberia which changes the atmospheric circulation system by: forcing cold fronts north away from Iberia; and creating a south westerly flow around the high-pressure region bringing warmer, moist air from the subtropical Atlantic to Europe which increases UK precipitation and European temperatures. Here I show, using modelled, reanalysis and measured data, that: the extreme, anthropogenic, West African aerosol Plume (WAP) which exists from late December to early April perturbs the northern, regional Hadley Circulation creating the high-pressure region; and that the WAP has only existed in its extreme form in recent decades as the major sources of the aerosols: biomass burning; and gas flaring have both increased significantly since 1950 due to: a four-fold increase in population (United Nations); and gas flaring rising from zero to 7.4 billion m3/annum (Global Gas Flaring Reduction Partnership). I also suggest that the WAP can be eliminated and Europe’s winter climate returned to its natural state after the crucial first step of recognising the cause of the changes is taken.


2021 ◽  
Author(s):  
Christopher Garrison ◽  
Christopher Kilburn ◽  
David Smart ◽  
Stephen Edwards

Abstract. One of the largest climate forcing eruptions of the nineteenth century was, until recently, believed to have taken place at Babuyan Claro volcano, in the Philippines, in 1831. However, a recent investigation found no reliable evidence of such an eruption, suggesting that the 1831 eruption must have taken place elsewhere. A newly compiled dataset of reported observations of a blue, purple and green sun in August 1831 is here used to reconstruct the transport of a stratospheric aerosol plume from that eruption. The source of the aerosol plume is identified as the eruption of Ferdinandea, which took place about 50 km off the south-west coast of Sicily (lat. 37.1° N., long. 12.7° E.), in July and August 1831. The modest magnitude of this eruption, assigned a Volcanic Explosivity Index (VEI) of 3, has commonly caused it to be discounted or overlooked when identifying the likely source of the stratospheric sulphate aerosol in 1831. It is proposed, however, that convective instability in the troposphere contributed to aerosol reaching the stratosphere and that the aerosol load was enhanced by addition of a sedimentary sulphur component to the volcanic plume. One of the largest climate forcing volcanic eruptions of the nineteenth century would thus effectively have been hiding in plain sight, arguably ‘lowering the bar’ for the types of eruptions capable of having a substantial climate forcing impact. Prior estimates of the mass of stratospheric sulphate aerosol responsible for the 1831 Greenland ice-core sulphate deposition peaks which have assumed a source eruption at a low-latitude site will therefore have been overstated. The example presented in this paper serves as a useful reminder that VEI values were not intended to be reliably correlated with eruption sulphur yields unless supplemented with compositional analyses. It also underlines that eye-witness accounts of historical geophysical events should not be neglected as a source of valuable scientific data.


2021 ◽  
Author(s):  
Logan Marriott ◽  
Matthew Harper ◽  
Tongming Zhou ◽  
Chenlin Sun

Background Engineering controls are a necessity for minimising aerosol transmission of SARS-CoV-2, yet so far, little attention has been given to such interventions. High flow local extraction (HFLE) is a standard in other industries that deal with airborne contaminants. This study provides a quantitative evaluation of an HFLE concept feasible to implement in most real clinical settings. Method A unique combined experimental model of Laser sheet illumination videography paired with continuous nanoparticle counts was used to quantitatively assess the impact of HFLE in an operating theatre. Propylene Glycol was aerosolised via a customised physiological lung simulator and dispersion was measured in 3 dimensions. Cumulative probability heat maps were generated to describe aerosol behaviour. Continuous particle counts were made at 15 locations throughout the room to validate laser assessments. Results HFLE effectively reduced dispersion of simulated exhaled aerosols to undetectable levels. With the HFLE in operation and optimally positioned, the aerosol plume was tightly controlled. Particle counts remained at baseline when HFLE was active. HFLE becomes less effective with increasing distance from source. Plume behaviour in the absence of HFLE was highly variable and unpredictable. Conclusions This analysis demonstrates great potential for HFLE to have a significant impact in reducing aerosol transmission. Simple HFLE devices can be easily engineered and could be widely deployed without impacting on the safe delivery of care. Keywords: aerosol; high flow local extraction; aerosol-generating procedure; tracheal intubation; SARS-CoV-2; COVID-19; plume; personal protective equipment; engineering controls


2021 ◽  
Author(s):  
Keith Potts

<p>Volcanic aerosols over south east Asia have always been the trigger and sustaining cause of ENSO events. In recent decades this natural plume has been augmented by the anthropogenic plume which has intensified ENSO events especially in SON. Data from the Last Millennium Ensemble (13,872 months), and Large Ensemble (3,012 months) demonstrate this connection with three ENSO indices and aerosol data derived from the same datasets correlating at 1.00 (LME), 0.97 and 0.99 magnitude (segmented and averaged). ENSO events are the dominant mode of variability in the global climate responsible for Australian, Indian and Indonesian droughts, American floods and increased global temperatures. Understanding the mechanism which enables aerosols over SE Asia and only over SE Asia to create ENSO events is crucial to understanding the global climate. I show that the South East Asian aerosol Plume causes ENSO events by: reflecting/absorbing solar radiation which warms the upper troposphere; and reducing surface radiation which cools the surface under the plume. This inversion reduces convection in the region thereby suppressing the Walker Circulation and the Trade Winds which causes the SST to rise in the central Pacific Ocean and creates convection there. This further weakens/reverses the Walker Circulation driving the climate into an ENSO state which is maintained until the aerosols dissipate and the climate system relaxes into a non-ENSO state. Measured aerosol data from four NASA satellites, estimates of volcanic tephra from the Global Volcanism Program (GVP) for over 100 years and the NASA MERRA-2 reanalysis dataset all confirm this analysis.</p>


2021 ◽  
Author(s):  
Mariel Friberg ◽  
Dong Wu ◽  
James Carr ◽  
James Limbacher ◽  
Yufei Zou ◽  
...  

<p>Wildfires have posed increasing risks to human health and loss of life and property. Observations of wildfire remain limited, particularly the plume variables such as injection height and wind velocity critical to assessing wildfire impacts. Lack of adequate spatiotemporal coverage and measurement accuracy hinder predictability and initialization needed by weather and chemical transport models. The new observations from the emerging stereo wind and aerosol imaging techniques with LEO-GEO and GEO-GEO satellites offer an unprecedented opportunity to study wildfire dynamics and evolution processes in great detail. The diurnal coverage of the GEO-GEO winds stereo products (Carr et al., 2020, 2019, 2018) and the daytime coverage (and detail) of GEO multi-angle aerosol products (Limbacher et al., 2021; In Prep) can capture and further our understanding of intense wildfire dynamics (e.g., pyroCb), planetary boundary layer (PBL) variations, and direction of aerosol loadings. Using two new satellite-based stereoscopic tracking algorithms, we compare stereo observations directly with the Coupled WRF-CMAQ simulations (Zou et al., 2019) to diagnose the modeled plume injection height and wind velocity, and aerosol properties (Friberg et al., 2021; In Prep). The validated LEO-GEO winds and height algorithm provides plume dynamics data with an accuracy of 200 m vertical resolution for plume height and 0.5 m/s for plume speed. Using these stereo algorithms, we can determine if fire plumes stay within or shoot above PBL, which plays a critical role in plume transport and air quality. From the GEO-based observations of dynamic wildfire aerosol loading dispersion, height, and winds, we can track wildfire development at a sub-hourly frequency and capture extreme and/or rare events such as pyroCb that often occur in a short period of time and are largely missed by LEO satellites.</p><p> </p><p><strong>References:</strong></p><p>Carr, J.L., Wu, D.L., Daniels, J., Friberg, M.D., Bresky, W., Madani, H. “GEO-GEO Stereo-Tracking of Atmospheric Motion Vectors (AMVs) from the Geostationary Ring,” Remote Sensing, 2020 https://doi.org/10.3390/rs12223779</p><p>Carr, J.L., D.L. Wu, R.E. Wolfe, H. Madani, G. Lin, B. Tan, “Joint 3D-Wind Retrievals with Stereoscopic Views from MODIS and GOES,” Remote Sensing, 2019, Satellite Winds Special Issue https://doi.org/10.3390/rs11182100</p><p>Carr, J.L., D.L. Wu, M.A. Kelly, and J. Gong, “MISR-GOES 3D Winds: Implications for Future LEO-GEO and LEO-LEO Winds,” Remote Sensing, 2018, MISR Special Issue. https://www.mdpi.com/2072-4292/10/12/1885</p><p>Limbacher, J. A., R. A. Kahn, and M. D. Friberg “A Multi-Angle Geostationary Aerosol Retrieval Algorithm,” 2021 [<strong>In Prep</strong>].</p><p>Zou, Y., O’Neill, S.M., Larkin, N.K., Alvarado, E.C., Solomon, R., Mass, C., Liu, Y., Odman, M.T., Shen, H. “Machine learning based integration of high-resolution wildfire smoke simulations and observations for regional health impact assessment. International Journal of Environmental Research and Public Health, 2019. https://doi.org/10.3390/ijerph16122137</p><p>Friberg, M.D., Wu, D.L., Carr, J.L., Limbacher, J. A., Zou<sup>, </sup>Y., O’Neill, S. “Diurnal Observations of Wildfires Boundary Layer Dynamics and Aerosol Plume Convection using Stereo-Imaging Techniques,” 2021 [<strong>In Prep</strong>].</p>


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