Thin Liquid Water Clouds: Their Importance and Our Challenge

Turner, David D.; Vogelmann, Andrew M.; Austin, R. T.; Barnard, James C.; Cady‐Pereira, Karen; Chiu, J. Christine; Clough, S. A.; Flynn, Connor; Khaiyer, Mandana M.; Liljegren, J. C.; Johnson, Karen; Lin, Bing; Long, Charles; Marshak, Alexander; Matrosov, Sergey Y.; McFarlane, Sally A.; Miller, Mark A.; Min, Qilong; Minnis, Patrick; O'Hirok, W.; Wang, Zhien; Wiscombe, W. J.

doi:10.1175/bams-88-2-177

Cited by 209 publications

(197 citation statements)

References 52 publications

Supporting

Mentioning

193

Contrasting

Unclassified

Order By: Relevance

“…Direct comparisons against in situ and surface-based microwave observations have yielded promising results for limited cases [Greenwald et al, 1993;Cober et al, 1996;Prigent et al, 1997;Offiler et al, 1998]; however, aircraft measurements have sample size and representativeness issues, as well as being relatively rare and costly; whereas observations from surface-based microwave radiometers can exhibit significant systematic errors [Turner et al, 2007].…”

Section: Introductionmentioning

confidence: 99%

“…For example, cloud LWP uncertainties constitute one of the largest error sources in simulating the Earth's radiation budget [L'Ecuyer and Stephens, 2003]. The sensitivity of top-of-atmosphere (TOA) and surface radiative fluxes to LWP is highest for thin water clouds (LWP < 0.05 kgm À2 ), thus placing an unusually high demand on LWP accuracy [Sengupta et al, 2003;Turner et al, 2007]. In satellite remote sensing of cloud droplet number concentration, LWP uncertainties are one of the dominant retrieval errors [Bennartz, 2007].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluating specific error characteristics of microwave‐derived cloud liquid water products

Greenwald

L’Ecuyer

Christopher

2007

Geophysical Research Letters

View full text Add to dashboard Cite

Methods are presented for assessing minimum errors and cloud inhomogeneity effects in cloud liquid water path (LWP) products derived from passive microwave satellite measurements. Using coincident visible/infrared satellite data, errors are isolated by identifying certain cloud conditions within the microwave sensor's field of view. Analysis of 3 weeks of global pixel‐level LWP data revealed that 70% of the systematic errors occurred between −0.011 and +0.025 kgm−2, with the mean random error being 0.013 kgm−2. For overcast clouds these systematic errors translate to a mean lower‐bound relative error of about +23%. A significant correlation of these products with near‐surface wind speed was also shown. The LWP products were found to depend on cloud fraction as well, suggesting the influence of beam filling errors. This approach shows promise in characterizing the minimum errors in LWP products needed for climate and remote sensing studies as well as future data assimilation applications.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluating specific error characteristics of microwave‐derived cloud liquid water products

Greenwald

L’Ecuyer

Christopher

2007

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…Since those clouds are relatively optically thin, their radiative impact is very sensitive to their vertically integrated liquid water content (i.e. the LWP) (Turner et al, 2007). The cloud deck off the coast of Africa, approximately at Namibia and Angola serves as an example of marine-boundary-layer clouds that consist mainly of water.…”

Section: Diurnal Cyclementioning

confidence: 99%

Characteristics of cloud liquid water path from SEVIRI onboard the Meteosat Second Generation 2 satellite for several cloud types

et al. 2014

View full text Add to dashboard Cite

Abstract. In this study the temporal and spatial characteristics of the liquid water path (LWP) of low, middle and high level clouds are analysed using space-based observations from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) instrument onboard the Meteosat Second Generation 2 (MSG 2) satellite. Both geophysical quantities are part of the CLAAS (CLoud property dAtAset using SEVIRI) data set and are generated by EUMETSAT's Satellite Application Facility on Climate Monitoring (CM SAF). In this article we focus on the statistical properties of LWP, retrieved during daylight conditions, associated with individual cloud types. We analysed the intrinsic variability of LWP, that is, the variability in only cloudy regions and the variations driven by cloud amount. The relative amplitude of the intrinsic diurnal cycle exceeded the cloud amount driven amplitude in our analysed cases. Our results reveal that each cloud type possesses a characteristic intrinsic LWP distribution. These frequency distributions are constant with time in the entire SE-VIRI field of view, but vary for smaller regions like Central Europe. Generally the average LWP is higher over land than over sea; in the case of low clouds this amounts to 15-27 % in 2009. The variance of the frequency distributions is enhanced as well. Also, the average diurnal cycle of LWP is related to cloud type with the most pronounced relative diurnal variations being detected for low and middle level clouds. Maps of the relative amplitude and the local time of maximum LWP show the variation throughout the SEVIRI field of view.

show abstract

“…It is based on the observations performed with multi-wavelength (355, 532 and 1064 nm) Raman lidars, a Ka-band cloud Doppler radar and a microwave radiometer operative at CIAO (CNR-IMAA Atmospheric Observatory), located in Potenza, Southern Italy (40.60N, 15.72E, 760 m above sea level) and on the study of thin warm clouds. These clouds are low or midlevel super-cooled clouds characterized by a liquid water path (LWP) less than about 100 gm -2 [2]. Thin warm clouds are often optically thin, i.e they allow the Raman lidar to measure the backscattered signal through the entire cloud structure and above, enabling the cloud top detection.…”

Section: Introductionmentioning

confidence: 99%

Study of Droplet Activation in Thin Clouds Using Ground-Based Raman Lidar and Ancillary Remote Sensors

Rosoldi

Madonna

Claramunt

et al. 2016

EPJ Web of Conferences

View full text Add to dashboard Cite

A methodology for the study of cloud droplet activation based on the measurements performed with ground-based multi-wavelength Raman lidars and ancillary remote sensors collected at CNR-IMAA observatory, Potenza, South Italy, is presented. The study is focused on the observation of thin warm clouds. Thin clouds are often also optically thin: this allows the cloud top detection and the full profiling of cloud layers using ground-based Raman lidar. Moreover, broken clouds are inspected to take advantage of their discontinuous structure in order to study the variability of optical properties and water vapor content in the transition from cloudy regions to cloudless regions close to the cloud boundaries. A statistical study of this variability leads to identify threshold values for the optical properties, enabling the discrimination between clouds and cloudless regions. These values can be used to evaluate and improve parameterizations of droplet activation within numerical models. A statistical study of the co-located Doppler radar moments allows to retrieve droplet size and vertical velocities close to the cloud base. First evidences of a correlation between droplet vertical velocities measured at the cloud base and the aerosol effective radius observed in the cloud-free regions of the broken clouds are found.

show abstract

Thin Liquid Water Clouds: Their Importance and Our Challenge

Abstract: Many clouds important to the Earth's energy balance contain small amounts of liquid water, yet despite many improvements, large differences in retrievals of their liquid water amount and particle size still must be resolved.

Cited by 209 publications

References 52 publications

Evaluating specific error characteristics of microwave‐derived cloud liquid water products

Evaluating specific error characteristics of microwave‐derived cloud liquid water products

Characteristics of cloud liquid water path from SEVIRI onboard the Meteosat Second Generation 2 satellite for several cloud types

Study of Droplet Activation in Thin Clouds Using Ground-Based Raman Lidar and Ancillary Remote Sensors

Contact Info

Product

Resources

About