Measurements of the aerosol and ice crystal populations in tropical stratospheric cumulonimbus anvils

Knollenberg, Robert G.; Dascher, A. J.; Huffman, Donald R.

doi:10.1029/gl009i006p00613

Cited by 40 publications

(25 citation statements)

References 2 publications

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“…The amount of supercooled water there peaked at only about 10% adiabatic water, in contrast to the peak of 50% in west Texas (Rosenfeld and Woodley 2000) to the record measurement of nearly 100% adiabatic water in Argentina (this study), respectively. Cloud-physics jet aircraft have been used also to make measurements in thunderstorm anvils (Knollenberg et al 1982;Smith et al 1994;Lawson et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina

Rosenfeld

Woodley²,

Krauss³

et al. 2006

Journal of Applied Meteorology and Climatology

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Documentation during January and February 2000 of the structure of severe convective storms in Mendoza, Argentina, with a cloud-physics jet aircraft penetrating the major feeder clouds from cloud base to the Ϫ45°C isotherm level is reported. Complementary radar, satellite, and radiosonde measurements are incorporated into the study. The main research goal was the description of the microphysical evolution of the convective feeders of the hailstorms from cloud base to the anvil in an attempt to gain insights into the microphysical evolution of the clouds that are associated with the high frequency of large hail in the region. The aircraft penetrated preferentially the tops of young growing elements, which were typically the major feeders to severe hailstorms, producing hail that is large (Ͼ3 cm) in size. Cloud bases typically were at 6°-14°C, with typical base updrafts of 4-7 m s Ϫ1 . The cloud updrafts increased with height, exceeding 25 m s Ϫ1 at heights Ն7 km and, on occasion, 40 m s Ϫ1 at heights Ͼ8 km. Thermal buoyancies of 5°-8°C were measured in the convective towers at heights of 8-10 km. The vertical wind shear was weak below 6 km but increased strongly above that level as the west winds cleared the Andes barrier, which averages 6.1 km to the west of Mendoza. The clouds had very little coalescence and contained no detectable precipitation-sized particles Ͼ100 m at temperatures ϾϪ15°C. Nearly adiabatic cloud water with most cloud water still not converted into precipitation-sized hydrometeors (Ͼ100 m in diameter) was found in cloud filaments within the strongest updrafts up to the level of homogeneous freezing, reaching 4 g m Ϫ3 at Ϫ38°C in one cloud before vanishing abruptly at colder temperatures. Graupel Ͼ1 mm appeared at the tops of growing new towers at temperatures ϽϪ27°C, in agreement with radar first-echo heights of about 8 km.

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Section: Introductionmentioning

confidence: 99%

Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina

Rosenfeld

Woodley²,

Krauss³

et al. 2006

Journal of Applied Meteorology and Climatology

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“…Those measurements, made during the summer over Colorado, Wyoming and Minnesota, showed that the largest size of crystals was between 10 and 30 mm with concentrations as high as 1000 L (1 . In 1980, Knollenberg et al (1982) flew an optical array probe and a new single particle light scattering probe (Knollenberg, 1976) with a size range from approximately 2 to 50 mm on the NASA U-2 high-altitude aircraft over Panama, the first airborne cirrus measurements to be made in the tropics. All of the measurements were made in anvil cirrus with the highest number concentrations in the size range 10 and 50 mm, but the mass was mostly in crystals between 40 and 50 mm.…”

Section: Introductionmentioning

confidence: 99%

Properties of small cirrus ice crystals from commercial aircraft measurements and implications for flight operations

Beswick

Baumgardner

Gallagher

et al. 2015

Tellus B: Chemical and Physical Meteorology

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A B S T R A C T Measurements of cloud ice crystal size distributions have been made by a backscatter cloud probe (BCP) mounted on five commercial airliners flying international routes that cross five continents. Bulk cloud parameters were also derived from the size distributions. As of 31 December 2014, a total of 4399 flights had accumulated data from 665 hours in more than 19 000 cirrus clouds larger than 5 km in length. The BCP measures the equivalent optical diameter (EOD) of individual crystals in the 5Á90 mm range from which size distributions are derived and recorded every 4 seconds. The cirrus cloud property database, an ongoing development stemming from these measurements, registers the total crystal number and mass concentration, effective and median volume diameters and extinction coefficients derived from the size distribution. This information is accompanied by the environmental temperature, pressure, aircraft position, date and time of each sample. The seasonal variations of the cirrus cloud properties measured from 2012 to 2014 are determined for six geographic regions in the tropics and extratropics. Number concentrations range from a few per litre for thin cirrus to several hundreds of thousands for heavy cirrus. Temperatures range from 205 to 250 K and effective radii from 12 to 20 mm. A comparison of the regional and seasonal number and mass size distributions, and the bulk microphysical properties derived from them, demonstrates that cirrus properties cannot be easily parameterised by temperature or by latitude. The seasonal changes in the size distributions from the extratropical Atlantic and Eurasian air routes are distinctly different, showing shifts from monomodal to bi-modal spectra out of phase with one another. This phase difference may be linked to the timing of deep convection and cold fronts that lead to the cirrus formation. Likewise, the size spectra of cirrus over the tropical Atlantic and Eastern Brazil differ from each other although they were measured in adjoining regions. The cirrus crystals in the maritime continental tropical region over Malaysia form tri-modal spectra that are not found in any of the other regions measured by the IAGOS aircraft so far, a feature that is possibly linked to biomass burning or dust. Frequent measurements of ice crystal concentrations greater than 1)10 5 L (1 , often accompanied by anomalously warm temperature and erratic airspeed readings, suggest that aircraft often experience conditions that affect their sensors. This new instrument, if used operationally, has the potential of providing real-time and valuable information to assist in flight operations as well as providing real-time information for along-track nowcasting.

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“…From this single measurement it is not possible to determine whether the smaller mode is the result of additional nucleation during the convective rise or of growth of the larger particles and evaporation of the smaller ones. Similar bimodality has appeared in some of the other observations as well [Knollenberg et al, 1982;Zhang et al, 1999], however, and we are presently undertaking a more thorough investigation of this aspect by means of modelling based on the meteorology.…”

Section: Resultsmentioning

confidence: 97%

Properties of high‐altitude tropical cirrus clouds determined from ACE FTS observations

Eremenko

Zasetsky

Boone

et al. 2005

Geophysical Research Letters

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[1] During tropical observations made in February and August of 2004, the Atmospheric Chemistry Experiment (ACE) FTIR instrument aboard the Canadian SciSat-1 satellite recorded several extinction spectra in the range of 700 -4400 cm À1 that exhibit strong signatures of cirrus clouds. We have analyzed these spectra in order to quantify the properties of these high-altitude cirrus clouds. This Letter reports the vertical profiles of the average ice density in the clouds and the particle size distributions. We also discuss the effect of particle shape on the retrieval results.

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Measurements of the aerosol and ice crystal populations in tropical stratospheric cumulonimbus anvils

Cited by 40 publications

References 2 publications

Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina

Aircraft Microphysical Documentation from Cloud Base to Anvils of Hailstorm Feeder Clouds in Argentina

Properties of small cirrus ice crystals from commercial aircraft measurements and implications for flight operations

Properties of high‐altitude tropical cirrus clouds determined from ACE FTS observations

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