Ice crystal number concentration from lidar, cloud radar and radar wind profiler measurements

Bühl, Johannes; Seifert, Patric; Radenz, Martin; Baars, Holger; Ansmann, Albert

doi:10.5194/amt-12-6601-2019

Cited by 22 publications

(32 citation statements)

References 42 publications

(51 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This cloud case deserves a detailed discussion of the entire life cycle. A dust-infused baroclinic storm (a synoptic-scale dynamics driven storm) (Fromm et al, 2016;Caffrey et al, 2018) associated with vigorous convective motions within cloud towers was responsible for the uplift of large amounts of dust into the upper troposphere over the Sahara, observed with lidar later on over Cyprus. According to Fig.…”

Section: The 17 March 2015 Case Study: Long-lasting Cirrus Evolution mentioning

confidence: 99%

“…5.2, case study 2, 17 March 2015). The event started with the generation of a dust-infused baroclinic storm (DIBS) (Fromm et al, 2016;Caffrey et al, 2018) that was associated with strong cloud convection over desert areas of northern Africa followed by the evolution of rather large anvil cirrus shield (of more than 15 000 km 2 ) and cirrus uncinus fields that extended from the eastern Mediterranean to central Asia (more than 3500 km). The storm lifted large amounts of Saharan dust into the upper troposphere and thus created favorable conditions for a strong contribution of heterogeneous ice nucleation to ice production and apparently to an extension of cirrus lifetime.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study

et al. 2019

Self Cite

View full text Add to dashboard Cite

Abstract. For the first time, a closure study of the relationship between the ice-nucleating particle concentration (INP; INPC) and ice crystal number concentration (ICNC) in altocumulus and cirrus layers, solely based on ground-based active remote sensing, is presented. Such aerosol–cloud closure experiments are required (a) to better understand aerosol–cloud interaction in the case of mixed-phase clouds, (b) to explore to what extent heterogeneous ice nucleation can contribute to cirrus formation, which is usually controlled by homogeneous freezing, and (c) to check the usefulness of available INPC parameterization schemes, applied to lidar profiles of aerosol optical and microphysical properties up to the tropopause level. The INPC–ICNC closure studies were conducted in Cyprus (Limassol and Nicosia) during a 6-week field campaign in March–April 2015 and during the 17-month CyCARE (Cyprus Clouds Aerosol and Rain Experiment) campaign. The focus was on altocumulus and cirrus layers which developed in pronounced Saharan dust layers at heights from 5 to 11 km. As a highlight, a long-lasting cirrus event was studied which was linked to the development of a very strong dust-infused baroclinic storm (DIBS) over Algeria. The DIBS was associated with strong convective cloud development and lifted large amounts of Saharan dust into the upper troposphere, where the dust influenced the evolution of an unusually large anvil cirrus shield and the subsequent transformation into an cirrus uncinus cloud system extending from the eastern Mediterranean to central Asia, and thus over more than 3500 km. Cloud top temperatures of the three discussed closure study cases ranged from −20 to −57 ∘C. The INPC was estimated from polarization/Raman lidar observations in combination with published INPC parameterization schemes, whereas the ICNC was retrieved from combined Doppler lidar, aerosol lidar, and cloud radar observations of the terminal velocity of falling ice crystals, radar reflectivity, and lidar backscatter in combination with the modeling of backscattering at the 532 and 8.5 mm wavelengths. A good-to-acceptable agreement between INPC (observed before and after the occurrence of the cloud layer under investigation) and ICNC values was found in the discussed three proof-of-concept closure experiments. In these case studies, INPC and ICNC values matched within an order of magnitude (i.e., within the uncertainty ranges of the INPC and ICNC estimates), and they ranged from 0.1 to 10 L−1 in the altocumulus layers and 1 to 50 L−1 in the cirrus layers observed between 8 and 11 km height. The successful closure experiments corroborate the important role of heterogeneous ice nucleation in atmospheric ice formation processes when mineral dust is present. The observed long-lasting cirrus event could be fully explained by the presence of dust, i.e., without the need for homogeneous ice nucleation processes.

show abstract

Section: The 17 March 2015 Case Study: Long-lasting Cirrus Evolution mentioning

confidence: 99%

mentioning

confidence: 99%

Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…DACAPO-PESO belongs to a series of long-term ACI-related field studies performed with the mobile LACROS station. Before that, we deployed LACROS for the 17-month field campaign CyCARE (Cyprus Clouds, Aerosol and Rain Experiment) at Limassol, Cyprus (October 2016 to March 2018) (Bühl et al, 2019;Ansmann et al, 2019), in the highly polluted and dusty eastern Mediterranean. All these campaigns are aimed at the central question: how do aerosol particles influence the evolution and microphysical properties of liquid-water, mixed-phase, and ice clouds and precipitation in different meteorological regimes and at contrasting levels of anthropogenic and natural aerosol concentrations?…”

Section: Dacapo-peso and Lacrosmentioning

confidence: 99%

The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – case studies

et al. 2020

Self Cite

View full text Add to dashboard Cite

Abstract. In a companion article (Jimenez et al., 2020), we introduced a new lidar method to derive microphysical properties of liquid-water clouds (cloud extinction coefficient, droplet effective radius, liquid-water content, cloud droplet number concentration Nd) at a height of 50–100 m above the cloud base together with aerosol information (aerosol extinction coefficients, cloud condensation nuclei concentration NCCN) below the cloud layer so that detailed studies of the influence of given aerosol conditions on the evolution of liquid-water cloud layers with high temporal resolution solely based on lidar observations have become possible now. The novel cloud retrieval technique makes use of lidar observations of the volume linear depolarization ratio at two different receiver field of views (FOVs). In this article, Part 2, the new dual-FOV polarization lidar technique is applied to cloud measurements in pristine marine conditions at Punta Arenas in southern Chile. A multiwavelength polarization Raman lidar, upgraded by integrating a second polarization-sensitive channel to permit depolarization ratio observations at two FOVs, was used for these measurements at the southernmost tip of South America. Two case studies are presented to demonstrate the potential of the new lidar technique. Successful aerosol–cloud-interaction (ACI) studies based on measurements with the upgraded aerosol–cloud lidar in combination with a Doppler lidar of the vertical wind component could be carried out with 1 min temporal resolution at these pristine conditions. In a stratocumulus layer at the top of the convective boundary layer, we found values of Nd and NCCN (for 0.2 % water supersaturation) ranging from 15–100 and 75–200 cm−3, respectively, during updraft periods. The studies of the aerosol impact on cloud properties yielded ACI values close to 1. The impact of aerosol water uptake on the ACI studies was analyzed with the result that the highest ACI values were obtained when considering aerosol proxies (light-extinction coefficient αpar or NCCN) measured at heights about 500 m below the cloud base (and thus for dry aerosol conditions).

show abstract

“…The ICNC observed near cloud base was in the same order of magnitude as the ICNC retrieved from the remote sensing observations (red dots in Fig. 11) using the method described in Bühl et al (2019). The comparison between the observed ICNC of large ice particles (ICNC > 500 µm ) and the INP concentration at cloud top shows a discrepancy 295 between the observed INP concentration and ICNC during certain time periods (Fig.…”

Section: The Origin and Growth Of Ice Crystals In Cloud Top Generatinmentioning

confidence: 56%

“…The INP concentrations extrapolated to -21°C (cloud top, solid line) and to -25°C (convective overshooting, dashed line) are indicated by the black horizontal lines. The ICNC estimated from the radar observations are shown by the red dots using the procedure described inBühl et al (2019) (see also Section 2). No microphysical measurements were available within the gray shaded areas.…”

mentioning

confidence: 99%

Microphysical investigation of the seeder and feeder region of an Alpine mixed-phase cloud

Ramelli¹,

Henneberger²,

David³

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Abstract. The seeder-feeder mechanism has been observed to enhance orographic precipitation in previous studies. However, the microphysical processes active in the seeder and feeder region are still being understood. In this paper, we investigate the seeder and feeder region of a mixed-phase cloud passing over the Swiss Alps, focusing on (1) fallstreaks of enhanced radar reflectivity originating from cloud top generating cells (seeder region) and (2) a persistent low-level feeder cloud produced by the boundary layer circulation (feeder region). Observations were obtained from a multi-dimensional set of instruments including ground-based remote sensing instrumentation (Ka-band polarimetric cloud radar, microwave radiometer, wind profiler), in situ instrumentation on a tethered balloon system and ground-based aerosol and precipitation measurements. The cloud radar observations suggest that ice formation and growth was enhanced within cloud top generating cells, which is consistent with previous observational studies. However, uncertainties exist regarding the dominant ice formation mechanism within these cells. Here we propose different mechanisms that potentially enhance ice nucleation and growth in cloud top generating cells (convective overshooting, radiative cooling, droplet shattering) and attempt to estimate their potential contribution from an ice nucleating particle perspective. Once ice formation and growth within the seeder region exceeded a threshold value, the mixed-phase cloud became fully glaciated. Local flow effects on the lee side of the mountain barrier induced the formation of a persistent low-level feeder cloud over a small-scale topographic feature in the inner-Alpine valley. In situ measurements within the low-level feeder cloud observed the production of secondary ice particles likely due to the Hallett–Mossop process and ice particle fragmentation upon ice–ice collisions. Therefore, secondary ice production may have been partly responsible for the elevated ice crystal number concentrations that have been previously observed in feeder clouds at mountain-top observatories. Secondary ice production in feeder clouds can potentially enhance orographic precipitation.

show abstract

Ice crystal number concentration from lidar, cloud radar and radar wind profiler measurements

Cited by 22 publications

References 42 publications

Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study

Ice-nucleating particle versus ice crystal number concentrationin altocumulus and cirrus layers embedded in Saharan dust:a closure study

The dual-field-of-view polarization lidar technique: a new concept in monitoring aerosol effects in liquid-water clouds – case studies

Microphysical investigation of the seeder and feeder region of an Alpine mixed-phase cloud

Contact Info

Product

Resources

About