scholarly journals Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment

2020 ◽  
Author(s):  
Anonymous
Keyword(s):  
Cloud Microphysics ◽  
Polluted Environment ◽  
Warm Cloud

scholarly journals Ground-based retrieval of continental and marine warm cloud microphysics

2011 ◽  
Vol 4 (12) ◽  
pp. 2749-2765 ◽  
Author(s):  
G. Martucci ◽  
C. D. O'Dowd
Keyword(s):  
Remote Sensing ◽  
Cloud Condensation Nuclei ◽  
Microwave Radiometer ◽  
Cloud Microphysics ◽  
Effective Radius ◽  
Research Station ◽  
Marine Stratocumulus ◽  
Adiabatic Conditions ◽  
Warm Cloud ◽  
Marine Air

Abstract. A technique for retrieving warm cloud microphysics using synergistic ground based remote sensing instruments is presented. The SYRSOC (SYnergistic Remote Sensing Of Cloud) technique utilises a Ka-band Doppler cloud RADAR, a LIDAR (or ceilometer) and a multichannel microwave radiometer. SYRSOC retrieves the main microphysical parameters such as cloud droplet number concentration (CDNC), droplets effective radius (reff), cloud liquid water content (LWC), and the departure from adiabatic conditions within the cloud. Two retrievals are presented for continental and marine stratocumulus advected over the Mace Head Atmospheric Research Station. Whilst the continental case exhibited high CDCN (N = 382 cm−3; 10th-to-90th percentile [9.4–842.4] cm−3) and small mean effective radius (reff = 4.3; 10th-to-90th percentile [2.9–6.5] μm), the marine case showed low CDNC and large mean effective radius (N = 25 cm−3, 10th-to-90th percentile [1.5–69] cm−3; reff = 28.4 μm, 10th-to-90th percentile [11.2–42.7] μm) as expected since continental air at this location is typically more polluted than marine air. The mean LWC was comparable for the two cases (continental: 0.19 g m−3; marine: 0.16 g m−3) but the 10th–90th percentile range was wider in marine air (continental: 0.11–0.22 g m−3; marine: 0.01–0.38 g m−3). The calculated algorithm uncertainty for the continental and marine case for each variable was, respectively, σN = 161.58 cm−3 and 12.2 cm−3, σreff = 0.86 μm and 5.6 μm, σLWC = 0.03 g m−3 and 0.04 g m−3. The retrieved CDNC are compared to the cloud condensation nuclei concentrations and the best agreement is achieved for a supersaturation of 0.1% in the continental case and between 0.1%–0.75% for the marine stratocumulus. The retrieved reff at the top of the clouds are compared to the MODIS satellite reff: 7 μm (MODIS) vs. 6.2 μm (SYRSOC) and 16.3 μm (MODIS) vs. 17 μm (SYRSOC) for continental and marine cases, respectively. The combined analysis of the CDNC and the reff, for the marine case shows that the drizzle modifies the droplet size distribution and reff especially if compared to reffMOD. The study of the cloud subadiabaticity and the LWC shows the general sub-adiabatic character of both clouds with more pronounced departure from adiabatic conditions in the continental case than in the marine.

scholarly journals Cloud-top microphysics evolution in the Gamma phase space from a modeling perspective

2018 ◽  
Author(s):  
Lianet Hernández Pardo ◽  
Luiz Augusto Toledo Machado ◽  
Micael Amore Cecchini
Keyword(s):  
Life Cycle ◽  
Phase Space ◽  
Driving Forces ◽  
Cloud Droplet ◽  
Cloud Microphysics ◽  
Effective Diameter ◽  
Gamma Phase ◽  
Wet Season ◽  
Warm Cloud ◽  
Aerosol Number Concentration

Abstract. This research employs the recently introduced Gamma phase space to study the evolution of warm cloud microphysics, to evaluate different microphysics parameterizations and to propose an adjustment to bulk schemes for an improved description of cloud droplet size distributions (DSDs). A bin parameterization is employed to describe the main features of observed cloud-top DSD paths in the Gamma phase space. The modeled DSD evolution during the warm cloud life cycle is compared to the results obtained from HALO airplane measurements during the ACRIDICON-CHUVA campaign in the Amazon dry-to-wet season transition. The comparison shows an agreement between the observed and simulated trajectories in the Gamma phase space, providing a suitable qualitative representation of the DSD evolution. The degree of similarity between the trajectories is defined by the conditions of the environment, such as the aerosol number concentration, which modify the DSD evolution through modulation of its driving forces. The modeled DSD properties were also projected in the Nd − Deff space to obtain further insights into their life cycle. Two different bulk microphysics parameterizations were evaluated regarding the evolution of the DSD and using the bin scheme as a reference. The results show the weakness of bulk schemes in representing trajectories in the Gamma phase space; thus, a new closure is proposed for better comparisons to the reference. The new closure resulted in an improvement in the representation of the DSD evolution, cloud droplet effective diameter and rain mixing ratio.

scholarly journals Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment

2021 ◽  
Vol 21 (6) ◽  
pp. 4487-4502
Author(s):  
Ying-Chieh Chen ◽  
Sheng-Hsiang Wang ◽  
Qilong Min ◽  
Sarah Lu ◽  
Pay-Liam Lin ◽  
...  
Keyword(s):  
Size Distribution ◽  
Indirect Effects ◽  
Cloud Microphysics ◽  
Cloud Water ◽  
Aerosol Indirect Effects ◽  
Low Level ◽  
Warm Cloud ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Northern Taiwan

Abstract. Climate is critically affected by aerosols, which alter cloud lifecycles and precipitation distribution through radiative and microphysical effects. In this study, aerosol and cloud property datasets from MODIS (Moderate Resolution Imaging Spectroradiometer), onboard the Aqua satellite, and surface observations, including aerosol concentrations, raindrop size distribution, and meteorological parameters, were used to statistically quantify the effects of aerosols on low-level warm-cloud microphysics and drizzle over northern Taiwan during multiple fall seasons (from 15 October to 30 November of 2005–2017). Our results indicated that northwestern Taiwan, which has several densely populated cities, is dominated by low-level clouds (e.g., warm, thin, and broken clouds) during the fall season. The observed effects of aerosols on warm clouds indicated aerosol indirect effects (i.e., increased aerosol loading caused a decrease in cloud effective radius (CER)), an increase in cloud optical thickness, an increase in cloud fraction, and a decrease in cloud-top temperature under a fixed cloud water path. Quantitatively, aerosol–cloud interactions (ACI=-∂ln⁡CER∂ln⁡α|CWP, changes in CER relative to changes in aerosol amounts) were 0.07 for our research domain and varied between 0.09 and 0.06 in the surrounding remote (i.e., ocean) and polluted (i.e., land) areas, respectively, indicating aerosol indirect effects were stronger in the remote area. From the raindrop size distribution analysis, high aerosol loading resulted in a decreased frequency of drizzle events, redistribution of cloud water to more numerous and smaller droplets, and reduced collision–coalescence rates. However, during light rain (≤1 mm h−1), high aerosol concentrations drove raindrops towards smaller droplet sizes and increased the appearance of drizzle drops. This study used long-term surface and satellite data to determine aerosol variations in northern Taiwan, effects on clouds and precipitation, and observational strategies for future research on aerosol–cloud–precipitation interactions.

scholarly journals Aerosol impacts on warm-cloud microphysics and drizzle in a moderately polluted environment

2020 ◽  
Author(s):  
Ying-Chieh Chen ◽  
Sheng-Hsiang Wang ◽  
Qilong Min ◽  
Sarah Lu ◽  
Pay-Liam Lin ◽  
...  
Keyword(s):  
Size Distribution ◽  
Indirect Effects ◽  
Cloud Microphysics ◽  
Cloud Water ◽  
Aerosol Indirect Effects ◽  
Low Level ◽  
Warm Cloud ◽  
Raindrop Size Distribution ◽  
Raindrop Size ◽  
Northern Taiwan

Abstract. Climate is critically affected by aerosols, which can alter cloud lifecycles and precipitation distribution through radiative and microphysical effects. In this study, aerosol and cloud properties datasets from MODIS onboard Aqua satellite and surface observations, including aerosol concentrations, raindrop size distribution, and meteorological parameters, were used to statistically quantify the effects of aerosols on low-level warm cloud microphysics and drizzle over northern Taiwan during fall seasons (from October 15 to November 30 of 2005–2017). Results indicated that clouds in northwestern Taiwan, which with active human activity is dominated by low-level clouds (e.g. warm, thin, and broken clouds). The observed effects of aerosols on warm clouds indicated aerosol indirect effects; increasing aerosol loading caused a decrease in cloud effective radius (CER), an increase in cloud optical thickness, an increase in cloud fraction, and a decrease in cloud top temperature under a fixed cloud water path. A quantitative value of aerosol–cloud interactions (ACI = (δ ln⁡ CER)/(δ  ln⁡ α), changes in CER depend on changes in aerosols) were calculated to be 0.07 for our research domain. ACI values varied between 0.09 and 0.06 in surrounding clean and heavily polluted areas, respectively, which indicated that aerosol indirect effects were more sensitive in the clean area. Analysis of raindrop size distribution observations during high aerosol loading resulted in a decreased frequency of drizzle events, redistributed cloud water to more numerous and smaller droplets, and reduced collision–coalescence rates. However, in the scenario of light precipitation (≤ 1 mm h−1), high aerosol concentrations drive raindrops towards smaller droplet sizes and increase the appearance of drizzle drops. This study used long-term surface and satellite data to determine aerosol variations in northern Taiwan, effects on the clouds and precipitations, and applications to observational strategy planning for future research on aerosol–cloud–precipitation interactions.

scholarly journals Ground-based retrieval of continental and marine warm cloud microphysics

2011 ◽  
Vol 4 (4) ◽  
pp. 4825-4865 ◽  
Author(s):  
G. Martucci ◽  
C. D. O'Dowd
Keyword(s):  
Remote Sensing ◽  
Cloud Condensation Nuclei ◽  
Microwave Radiometer ◽  
Cloud Microphysics ◽  
Effective Radius ◽  
Research Station ◽  
Marine Stratocumulus ◽  
Adiabatic Conditions ◽  
Warm Cloud ◽  
Marine Air

Abstract. A technique for retrieving warm cloud microphysics using synergistic ground based remote sensing instruments is presented. The SYRSOC (SYnergistic Remote Sensing Of Cloud) technique utilises a Ka-band Doppler cloud RADAR, a LIDAR-ceilometer and a multichannel microwave radiometer. SYRSOC retrieves the main microphysical parameters such as cloud droplet number concentration (CDNC), droplets effective radius (reff), cloud liquid water content (LWC), and the departure from adiabatic conditions within the cloud. Two retrievals are presented for continental and marine stratocumulus formed over the Mace Head Atmospheric Research Station. Whilst the continental case exhibited high CDCN (N = 382 cm−3; 10th-to-90th percentile [9.4–842.4] cm−3) and small mean effective radius (reff = 4.3; 10th-to-90th percentile [2.9–6.5] μm), the marine case exhibited low CDNC and large mean effective radius (N = 25 cm−3, 10th-to-90th percentile [1.5–69] cm−3; reff = 25.6 μm, 10th-to-90th percentile [11.2–42.7] μm) as expected since the continental air at this location is typically more polluted than marine air. The large reff of the marine case was determined by the contribution of drizzle drops (large radii and few occurrences) and in fact the modal radius was reffMOD = 12 μm (smaller radius and large occurrences). The mean LWC was comparable for the two cases (continental: 0.19 g m−3; marine: 0.16 g m–3) but the 10th–90th percentile range was wider in marine air (continental: 0.11–0.22 g m−3; marine: 0.01–0.38 g m−3). The calculated algorithm uncertainty for the continental and marine case for each variable was, respectively, σN=141.34 cm−3 and 11.5 cm−3, σreff=0.8 μm and 3.2 μm, σLWC = 0.03 g m−3 and 0.03 g m−3. The retrieved CDNC are compared to the cloud condensation nuclei concentrations and the best agreement is achieved for a super-saturation of 0.1 % in the continental case and between 0.1 %–0.75 % for the marine stratocumulus. The retrieved reff at the top of the clouds are compared to the MODIS satellite reff: 7 μm (MODIS) vs 6.2 μm (SYRSOC) and 16.3 μm (MODIS) vs. 17 μm (SYRSOC) for continental and marine cases, respectively. The combined analysis of the CDNC and the reff, for the marine case shows that the drizzle modifies the droplet size distribution and reff especially if compared to reffMOD. The study of the cloud subadiabaticity and the LWC shows the general sub-adiabatic character of both clouds with more pronounced departure from adiabatic conditions in the continental case due to the shallower cloud depth and more significant mixing with dry tropospheric air.

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