the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 27 Jun 2022
Biomass Burning and Gas Flares create the extreme West African Aerosol Plume Which Perturbs the Hadley Circulation and thereby Changes Europe’s Winter Climate
Abstract. 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.
Status: closed
-
RC1: 'Comment on egusphere-2022-383', Anonymous Referee #1, 06 Oct 2022
Review of manuscript "Biomass Burning and Gas Flares create the extreme West African
Aerosol Plume which perturbs the Hadley Circulation and thereby changes Europe's
winter climate"This manuscript explores a hypothesis identified in the study that anthropogenic
influence from increased biomass burning and gas flaring in West Africa has perturbed
winter European climate via circulation changes associated with the frequency of
continental high pressure blocking of North Atlantic weather systems.The analysis identifies a specific seasonal aerosol plume that emerges each year
in West Africa from December through to April, and introduces a terminology
"the West African aerosol plume", within a proposed categorisation of 8
"continental-scale aerosol plumes" in existence in the present-day atmosphere.The manuscript'a Abstract acknowledges the analysis is to-some-extent preliminary
identifying the presnted information as "a first step" in relation to a specific
tele-connection between the central Africa pollution and winter climate in Europe.However, whilst the topic is interesting, and has the potential to progress to a
pubishable analysis, several parts of the current manuscript are poorly worded
and present too certain a narrative in relation to the magnitude and causality
within the results presented: a set of individual trend analysis of different
observational datasets.Also, the climate influences from anthropogenic aerosol are well-known, whilst
the manuscript seems to present the analysis as establishing something new.In its current state, the particular advance presented in this manuscript is not
sufficiently explained. Whilst there is a moderate referencing of other related studies
such as the Fawole et al. (2016b) analysis to establish signatures of gas-flaring within
AERONET aerosol optical properties, the manuscript in its current form does not yet
inform the reader of the specifics of the findings in relation to the relatively recent
progression in understanding from being able to isolate the role that gas flaring
black carbon and sulphate aerosol plays alongside desert dust and other aerosol
types/sources within the West African aerosol plume.Overall, the manuscript reads like a report that has not yet been worked-up sufficiently
to be at a publishable-level analysis, and requires further work to set out and establish
a particular advance it represents within the current scientific literature on at least
one of the two topics it addresses: the West African aerosol plume (and/or associated
radiative effects), and/or its influence on European climate.A general area of improvement also is in the scientific writing style, where the precision
and specific language used needs to reflect the multiple influences that combine both
from the aerosol plume and its climate affects. Too often the current wording sometimes
seems to indicate a unique causality of effect, via "creating" a system or effect.The title for example refers to the West African Aerosol Plume, and whilst the definition
presented in the manuscript is clear this terminology refers to a particular season,
the reader cannot be expected to appreciate that within the title itself.The climate influences the manuscript points to are currently presented only in the
frame of correlations, and whilst that does not necessarily preclude the manuscript
from being publishable, the narrative of the manuscript presents the correlations
as indicative of a causal relationship.Although previous studies have indeed identified a strong signature of gas flaring aerosol
(Fawole et al., 2016), this study explores only trends in total aerosol optical depth,
then dependent on that previous finding, rather than this being a result established
by this manuscript. So the title should not present that as the topic of this paper.A revised title should reflect at least some of the broader context for the research,
and set out the main finding it addresses (rather than a simple causality and specifics
of the datasets it analyses or methods it applies).When re-drafting the manuscript the author needs to ensure the narrative conveys
the broader influences on the North Atlantic and European climate, with currently
almost no recognition of the primary role of greenhouse gas changes and more general
anthropogenic aerosol influences (see e.g. Booth et al., 2012).A potential future re-working of this manuscript could address trends in multi-wavelength
aerosol optical properties, aligned to the AERONET analysis from Fawole et al. (2016),
but the current analysis seems to assume 100% of the AOD comes from these sources.I would advise the author also to present the analysis within established metrics for
the effect he identifies is perturbed by this regional aerosol system, primarily
the index for the mode of climate variability known as the North Atlantic Oscillation
(e.g. Stephenson et al., 2006).The Introduction needs also to be refer to some of the extensive literature exploring
changes in blocking frequency and European winter climate (e.g. Shabbar et al., 2001;
Buehler et al., 2011; Breton et al., 2022). The manuscript would be strengthened also
by explaining the role of gas flaring pollution, see for example he review paper by
Fawole et al. (2016a), and references therein.I realise the author will be disappointed in this rejection and re-submission finding,
but the manuscript has promise in identifying the specifc tele-connections between
the under-appreciated gas flaring sources and European climate.
References
----------Booth et al. (2012),
Aerosols implicated as a prime driver of twientieth-century North Atlantic
climate variability, Nature, vol. 484, https://doi.org/10.1038/nature10946Breton et al. (2022),
Seasonal circulation regimes in the North Atlantic: Towards a new seasonality
International Journal of Climatology, https://doi.org/10.1002/joc.7565Buehler et al. (2011)
The relationship of winter season North Atlantic blocking frequencies to
extreme cold or dry spells in the ERA-40
Tellus A (Dynamic Meteorology and Oceanography),
https://doi.org/10.1111/j.1600-0870.2010.00492.xFawole et al. (2016a),
Gas flaring and resultant air pollution: A review focusing on black carbon
Environmental Pollution, vol. 216, 182-197, http://dx.doi.org/10.1016/j.envpol.2016.05.075.Fawole et al. (2016b),
Detection of a gas flaring signature in the AERONET optical properties of aerosols at
a tropical station in West Africa
J. Geophys. Res. Atmos., 121, 14,513–14,524, https://doi.org/10.1002/2016JD025584.Shabbar et al. (2001)
The relationship between the wintertime North Atlantic Oscillation and blocking
episodes in the North Atlantic,
International Journal of Climatology, https://doi.org/10.1002/joc.612Stephenson et al. (2006),
North Atlantic Oscillation response to transient greenhouse gas forcing
and the impact on European winter climate: a CMIP2 multi-model assessment
Climate Dynamics, 27, 401–420 https://doi.org/10.1007/s00382-006-0140-xCitation: https://doi.org/10.5194/egusphere-2022-383-RC1 -
RC2: 'Comment on egusphere-2022-383', Anonymous Referee #2, 17 Nov 2022
Biomass Burning and Gas Flares create the extreme West African Aerosol Plume Which Perturbs the Hadley Circulation and thereby Changes Europe’s Winter Climate
Topic of this paper it self is interesting as in the future there will be interesting emerging aerosol patterns in Africa. This paper concentrates on Biomass burning aerosols on western part of Africa and their influences on European winter climate.
General comments:
While the topic is relevant and interesting, the author interpred causality from only correlation from different datasets. Example, one can include climate model analysis where individual aerosols sources and their effect are studied separately. Author does not presents any evolution of different aerosol species but assumes that observed trend is anthropogenic and not an example dust from sahara. Author should include also relevant previus studies and link these to new narrative of region aerosols and emergin aerosol patterns. The topic it self is relevant but this draft need much more detalied analysis to be accepted as scientific publication
Citation: https://doi.org/10.5194/egusphere-2022-383-RC2 - AC1: 'Comment on egusphere-2022-383', Keith Potts, 02 Jan 2023
Status: closed
-
RC1: 'Comment on egusphere-2022-383', Anonymous Referee #1, 06 Oct 2022
Review of manuscript "Biomass Burning and Gas Flares create the extreme West African
Aerosol Plume which perturbs the Hadley Circulation and thereby changes Europe's
winter climate"This manuscript explores a hypothesis identified in the study that anthropogenic
influence from increased biomass burning and gas flaring in West Africa has perturbed
winter European climate via circulation changes associated with the frequency of
continental high pressure blocking of North Atlantic weather systems.The analysis identifies a specific seasonal aerosol plume that emerges each year
in West Africa from December through to April, and introduces a terminology
"the West African aerosol plume", within a proposed categorisation of 8
"continental-scale aerosol plumes" in existence in the present-day atmosphere.The manuscript'a Abstract acknowledges the analysis is to-some-extent preliminary
identifying the presnted information as "a first step" in relation to a specific
tele-connection between the central Africa pollution and winter climate in Europe.However, whilst the topic is interesting, and has the potential to progress to a
pubishable analysis, several parts of the current manuscript are poorly worded
and present too certain a narrative in relation to the magnitude and causality
within the results presented: a set of individual trend analysis of different
observational datasets.Also, the climate influences from anthropogenic aerosol are well-known, whilst
the manuscript seems to present the analysis as establishing something new.In its current state, the particular advance presented in this manuscript is not
sufficiently explained. Whilst there is a moderate referencing of other related studies
such as the Fawole et al. (2016b) analysis to establish signatures of gas-flaring within
AERONET aerosol optical properties, the manuscript in its current form does not yet
inform the reader of the specifics of the findings in relation to the relatively recent
progression in understanding from being able to isolate the role that gas flaring
black carbon and sulphate aerosol plays alongside desert dust and other aerosol
types/sources within the West African aerosol plume.Overall, the manuscript reads like a report that has not yet been worked-up sufficiently
to be at a publishable-level analysis, and requires further work to set out and establish
a particular advance it represents within the current scientific literature on at least
one of the two topics it addresses: the West African aerosol plume (and/or associated
radiative effects), and/or its influence on European climate.A general area of improvement also is in the scientific writing style, where the precision
and specific language used needs to reflect the multiple influences that combine both
from the aerosol plume and its climate affects. Too often the current wording sometimes
seems to indicate a unique causality of effect, via "creating" a system or effect.The title for example refers to the West African Aerosol Plume, and whilst the definition
presented in the manuscript is clear this terminology refers to a particular season,
the reader cannot be expected to appreciate that within the title itself.The climate influences the manuscript points to are currently presented only in the
frame of correlations, and whilst that does not necessarily preclude the manuscript
from being publishable, the narrative of the manuscript presents the correlations
as indicative of a causal relationship.Although previous studies have indeed identified a strong signature of gas flaring aerosol
(Fawole et al., 2016), this study explores only trends in total aerosol optical depth,
then dependent on that previous finding, rather than this being a result established
by this manuscript. So the title should not present that as the topic of this paper.A revised title should reflect at least some of the broader context for the research,
and set out the main finding it addresses (rather than a simple causality and specifics
of the datasets it analyses or methods it applies).When re-drafting the manuscript the author needs to ensure the narrative conveys
the broader influences on the North Atlantic and European climate, with currently
almost no recognition of the primary role of greenhouse gas changes and more general
anthropogenic aerosol influences (see e.g. Booth et al., 2012).A potential future re-working of this manuscript could address trends in multi-wavelength
aerosol optical properties, aligned to the AERONET analysis from Fawole et al. (2016),
but the current analysis seems to assume 100% of the AOD comes from these sources.I would advise the author also to present the analysis within established metrics for
the effect he identifies is perturbed by this regional aerosol system, primarily
the index for the mode of climate variability known as the North Atlantic Oscillation
(e.g. Stephenson et al., 2006).The Introduction needs also to be refer to some of the extensive literature exploring
changes in blocking frequency and European winter climate (e.g. Shabbar et al., 2001;
Buehler et al., 2011; Breton et al., 2022). The manuscript would be strengthened also
by explaining the role of gas flaring pollution, see for example he review paper by
Fawole et al. (2016a), and references therein.I realise the author will be disappointed in this rejection and re-submission finding,
but the manuscript has promise in identifying the specifc tele-connections between
the under-appreciated gas flaring sources and European climate.
References
----------Booth et al. (2012),
Aerosols implicated as a prime driver of twientieth-century North Atlantic
climate variability, Nature, vol. 484, https://doi.org/10.1038/nature10946Breton et al. (2022),
Seasonal circulation regimes in the North Atlantic: Towards a new seasonality
International Journal of Climatology, https://doi.org/10.1002/joc.7565Buehler et al. (2011)
The relationship of winter season North Atlantic blocking frequencies to
extreme cold or dry spells in the ERA-40
Tellus A (Dynamic Meteorology and Oceanography),
https://doi.org/10.1111/j.1600-0870.2010.00492.xFawole et al. (2016a),
Gas flaring and resultant air pollution: A review focusing on black carbon
Environmental Pollution, vol. 216, 182-197, http://dx.doi.org/10.1016/j.envpol.2016.05.075.Fawole et al. (2016b),
Detection of a gas flaring signature in the AERONET optical properties of aerosols at
a tropical station in West Africa
J. Geophys. Res. Atmos., 121, 14,513–14,524, https://doi.org/10.1002/2016JD025584.Shabbar et al. (2001)
The relationship between the wintertime North Atlantic Oscillation and blocking
episodes in the North Atlantic,
International Journal of Climatology, https://doi.org/10.1002/joc.612Stephenson et al. (2006),
North Atlantic Oscillation response to transient greenhouse gas forcing
and the impact on European winter climate: a CMIP2 multi-model assessment
Climate Dynamics, 27, 401–420 https://doi.org/10.1007/s00382-006-0140-xCitation: https://doi.org/10.5194/egusphere-2022-383-RC1 -
RC2: 'Comment on egusphere-2022-383', Anonymous Referee #2, 17 Nov 2022
Biomass Burning and Gas Flares create the extreme West African Aerosol Plume Which Perturbs the Hadley Circulation and thereby Changes Europe’s Winter Climate
Topic of this paper it self is interesting as in the future there will be interesting emerging aerosol patterns in Africa. This paper concentrates on Biomass burning aerosols on western part of Africa and their influences on European winter climate.
General comments:
While the topic is relevant and interesting, the author interpred causality from only correlation from different datasets. Example, one can include climate model analysis where individual aerosols sources and their effect are studied separately. Author does not presents any evolution of different aerosol species but assumes that observed trend is anthropogenic and not an example dust from sahara. Author should include also relevant previus studies and link these to new narrative of region aerosols and emergin aerosol patterns. The topic it self is relevant but this draft need much more detalied analysis to be accepted as scientific publication
Citation: https://doi.org/10.5194/egusphere-2022-383-RC2 - AC1: 'Comment on egusphere-2022-383', Keith Potts, 02 Jan 2023
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