scholarly journals Comments on “Impacts of long-range transport of aerosols on marine boundary layer clouds in the Eastern North Atlantic” by Wang et al.

2020 ◽  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Long Range Transport ◽  
Boundary Layer Clouds ◽  
Range Transport ◽  
Eastern North Atlantic

scholarly journals Impacts of long-range transport of aerosols on marine-boundary-layer clouds in the eastern North Atlantic

2020 ◽  
Vol 20 (23) ◽  
pp. 14741-14755
Author(s):  
Yuan Wang ◽  
Xiaojian Zheng ◽  
Xiquan Dong ◽  
Baike Xi ◽  
Peng Wu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Long Range Transport ◽  
Vertical Profiles ◽  
Remote Region ◽  
Cloud Properties ◽  
Range Transport ◽  
Eastern North Atlantic

Abstract. Vertical profiles of aerosols are inadequately observed and poorly represented in climate models, contributing to the current large uncertainty associated with aerosol–cloud interactions. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign near the Azores islands provided ample observations of vertical distributions of aerosol and cloud properties. Here we utilize the in situ aircraft measurements from the ACE-ENA and ground-based remote-sensing data along with an aerosol-aware Weather Research and Forecast (WRF) model to characterize the aerosols due to long-range transport over a remote region and to assess their possible influence on marine-boundary-layer (MBL) clouds. The vertical profiles of aerosol and cloud properties measured via aircraft during the ACE-ENA campaign provide detailed information revealing the physical contact between transported aerosols and MBL clouds. The European Centre for Medium-Range Weather Forecasts Copernicus Atmosphere Monitoring Service (ECMWF-CAMS) aerosol reanalysis data can reproduce the key features of aerosol vertical profiles in the remote region. The cloud-resolving WRF sensitivity experiments with distinctive aerosol profiles suggest that the transported aerosols and MBL cloud interactions (ACIs) require not only aerosol plumes to get close to the marine-boundary-layer top but also large cloud top height variations. Based on those criteria, the observations show that the occurrence of ACIs involving the transport of aerosol over the eastern North Atlantic (ENA) is about 62 % in summer. For the case with noticeable long-range-transport aerosol effects on MBL clouds, the susceptibilities of droplet effective radius and liquid water content are −0.11 and +0.14, respectively. When varying by a similar magnitude, aerosols originating from the boundary layer exert larger microphysical influence on MBL clouds than those entrained from the free troposphere.

scholarly journals Impacts of Long-range Transport of Aerosols on Marine Boundary Layer Clouds in the Eastern North Atlantic

2020 ◽  
Author(s):  
Yuan Wang ◽  
Xiaojian Zheng ◽  
Xiquan Dong ◽  
Baike Xi ◽  
Peng Wu ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Long Range Transport ◽  
Vertical Profiles ◽  
Remote Region ◽  
Cloud Properties ◽  
Range Transport ◽  
Eastern North Atlantic

Abstract. Vertical profiles of aerosols are inadequately observed and poorly represented in climate models, contributing to the current large uncertainty associated with aerosol-cloud interactions. The DOE ARM Aerosol and Cloud Experiments in the Eastern North Atlantic (ACE-ENA) aircraft field campaign near the Azores islands provided ample accurate observations of vertical distributions of aerosol and cloud properties. Here we utilize the in situ aircraft measurements from the ACE-ENA and ground-based remote sensing data along with an aerosol-aware Weather Research and Forecast (WRF) model to characterize the aerosols due to long-range transport over a remote region and to assess their possible influence on marine boundary-layer (MBL) clouds. The vertical profiles of aerosol and cloud properties measured via aircraft during the ACE-ENA campaign provide detailed information revealing the physical contact between transported aerosols and MBL clouds. The ECMWF-CAMS aerosol reanalysis data can reproduce the key features of aerosol vertical profiles in the remote region. The cloud-resolving WRF sensitivity experiments with distinctive aerosol profiles suggest that the transported aerosols and MBL cloud interactions (ACI) require not only low-altitude aerosol preferably getting close to the marine boundary layer top, but also large cloud top height variations. Based on those criteria, the observations show the occurrence of ACI involving the transport of aerosol over the Eastern North Atlantic is about 62 % in summer. For the case with noticeable long-range transport aerosol effect on MBL cloud, the susceptibilities of droplet effective radius and liquid water content are −0.11 and +0.14, respectively. When varying on the similar magnitude, aerosols originating from the boundary layer exert larger microphysical influence on MBL clouds than those entrained from free troposphere.

scholarly journals Long-range transport of ozone and related pollutants over the North Atlantic in spring and summer

2004 ◽  
Vol 4 (4) ◽  
pp. 4407-4454 ◽  
Author(s):  
S. A. Penkett ◽  
M. J. Evans ◽  
C. E. Reeves ◽  
K. S. Law ◽  
P. S. Monks ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Long Range Transport ◽  
Ozone Concentrations ◽  
The North ◽  
Range Transport ◽  
The North Atlantic ◽  
The Uk

Abstract. This paper presents strong experimental evidence for a major perturbation in ozone concentrations over large parts of the North Atlantic Ocean from the surface to 8 km associated with continental pollutants. The evidence was gathered in the course of 7 flights by the UK Meteorological Office C-130 aircraft based on the Azores, and 4 ferry flights between the UK to the Azores in spring and summer 1997 as a component of the NERC-funded ACSOE project. The total latitude range covered was approximately 55°N–25°N, and the longitude range was approximately 0° to 40°W. Many profiles were made between the sea surface and altitudes up to 9 km to survey the composition of the marine atmosphere. The C-130 aircraft was comprehensively equipped to measure many chemical and physical parameters along with standard meteorological instrumentation. Thus it was able to measure ozone and speciated NOy, along with tracers including water vapour, carbon monoxide and condensation nuclei, in near real time. The overall "picture" of the troposphere over large parts of the North Atlantic is of layers of pollution from the continents of different ages interspersed with layers of air uplifted from the marine boundary layer. The lowest ozone concentrations were recorded in the marine boundary layer where there is evidence for extensive ozone destruction in summer. Flights were made to penetrate the outflow of hurricane Erica, to determine the southerly extent of polluted air in summer, to examine the impact of frontal systems on the composition of remote marine air, and to trace long-range pollution from the west coast of the USA interspersed with air with a stratospheric origin. In one of the spring flights it is possible that a plume of polluted air with high ozone and NOy, and with an origin in southeast Asia, was intercepted off the coast of Portugal. The concentrations of NOx, in this plume were sufficient for ozone formation to be continuing along its track from west to east. The instrument to measure NOy almost certainly was only measuring the sum of organic nitrates (mostly in the form of PAN) plus NOx. The high correlation between NOy and ozone under these conditions strongly suggests a non-stratospheric source for most of the ozone encountered over large parts of the atmosphere upwind of Europe. There was a marked seasonal variation in the NOy with about twice as much present in the spring flights than in the summer flights. The overall ozone levels in both spring and summer were somewhat similar although the highest ozone concentration encountered (~100 ppbv) was observed in summer in some polluted layers in mid Atlantic with an origin in the boundary layer over the southeastern USA. The bulk of the pollutants, ozone, CO, and NOy, were in the free troposphere at altitudes between 3 and 8 km. The only instances of pollution at lower levels were in the form of ship plumes, which were encountered several times. The data therefore strongly support the need for more in-situ aircraft experiments to quantify and understand the phenomenon of long-range transport of pollution from continent to continent. Observations at ground-based stations are inadequate for this purpose and satellite data is incomplete both in terms of its altitude detail and in the extent of chemical speciation, particularly for ascertaining whether chemical production and destruction processes for ozone are occurring.

scholarly journals Long-range transported North American wildfire aerosols observed in marine boundary layer of eastern North Atlantic

2020 ◽  
Vol 139 ◽  
pp. 105680 ◽  
Author(s):  
Guangjie Zheng ◽  
Arthur J. Sedlacek ◽  
Allison C. Aiken ◽  
Yan Feng ◽  
Thomas B. Watson ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
North Atlantic ◽  
North American ◽  
Marine Boundary Layer ◽  
Eastern North Atlantic

Dimethyl sulfide: Less important than long-range transport as a source of sulfate to the remote tropical Pacific marine boundary layer

2014 ◽  
Vol 119 (14) ◽  
pp. 9142-9167 ◽  
Author(s):  
Rebecca M. C. Simpson ◽  
Steven G. Howell ◽  
Byron W. Blomquist ◽  
Antony D. Clarke ◽  
Barry J. Huebert
Keyword(s):  
Boundary Layer ◽  
Long Range ◽  
Dimethyl Sulfide ◽  
Marine Boundary Layer ◽  
Tropical Pacific ◽  
Long Range Transport ◽  
Range Transport

scholarly journals Observations of aerosol, cloud, turbulence, and radiation properties at the top of the marine boundary layer over the Eastern North Atlantic Ocean: The ACORES campaign

2020 ◽  
pp. 1-59
Author(s):  
Holger Siebert ◽  
Kai-Erik Szodry ◽  
Ulrike Egerer ◽  
Birgit Wehner ◽  
Silvia Henning ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Resolution ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
North Atlantic Ocean ◽  
Fine Scale ◽  
Boundary Layer Clouds ◽  
Radiation Properties ◽  
Eastern North Atlantic ◽  
Eastern North Atlantic Ocean

Capsule summary.Helicopter-borne observations with unprecedented high resolution provide new insights in the fine-scale structure of marine boundary layer clouds and aerosol stratification over the Eastern North Atlantic.

scholarly journals Mind-the-gap part I: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars

2020 ◽  
Author(s):  
Katia Lamer ◽  
Pavlos Kollias ◽  
Alessandro Battaglia ◽  
Simon Preval
Keyword(s):  
Boundary Layer ◽  
North Atlantic ◽  
Marine Boundary Layer ◽  
Radar Observations ◽  
Boundary Layer Clouds ◽  
Eastern North Atlantic

Abstract. Ground-based radar observations show that, in the eastern north Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities

scholarly journals Mind the gap – Part 1: Accurately locating warm marine boundary layer clouds and precipitation using spaceborne radars

2020 ◽  
Vol 13 (5) ◽  
pp. 2363-2379 ◽  
Author(s):  
Katia Lamer ◽  
Pavlos Kollias ◽  
Alessandro Battaglia ◽  
Simon Preval
Keyword(s):  
Boundary Layer ◽  
Cloud Cover ◽  
Marine Boundary Layer ◽  
Short Pulse ◽  
Pulse Mode ◽  
Cloud Base ◽  
Boundary Layer Clouds ◽  
Highly Sensitive ◽  
Eastern North Atlantic ◽  
Long Pulse

Abstract. Ground-based radar observations show that, over the eastern North Atlantic, 50 % of warm marine boundary layer (WMBL) hydrometeors occur below 1.2 km and have reflectivities of < −17 dBZ, thus making their detection from space susceptible to the extent of surface clutter and radar sensitivity. Surface clutter limits the ability of the CloudSat cloud profiling radar (CPR) to observe the true cloud base in ∼52 % of the cloudy columns it detects and true virga base in ∼80 %, meaning the CloudSat CPR often provides an incomplete view of even the clouds it does detect. Using forward simulations, we determine that a 250 m resolution radar would most accurately capture the boundaries of WMBL clouds and precipitation; that being said, because of sensitivity limitations, such a radar would suffer from cloud cover biases similar to those of the CloudSat CPR. Observations and forward simulations indicate that the CloudSat CPR fails to detect 29 %–43 % of the cloudy columns detected by ground-based sensors. Out of all configurations tested, the 7 dB more sensitive EarthCARE CPR performs best (only missing 9.0 % of cloudy columns) indicating that improving radar sensitivity is more important than decreasing the vertical extent of surface clutter for measuring cloud cover. However, because 50 % of WMBL systems are thinner than 400 m, they tend to be artificially stretched by long sensitive radar pulses, hence the EarthCARE CPR overestimation of cloud top height and hydrometeor fraction. Thus, it is recommended that the next generation of space-borne radars targeting WMBL science should operate interlaced pulse modes including both a highly sensitive long-pulse mode and a less sensitive but clutter-limiting short-pulse mode.

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