Marine Stratocumulus Cloud Clearing Episodes Observed during FIRE

Kloesel, Kevin A.

doi:10.1175/1520-0493(1992)120<0565:mscceo>2.0.co;2

Cited by 17 publications

(21 citation statements)

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“…Spirals S5 and S6 (latitude 39.5°) were conducted at the leading edge of the cloud‐clearing event and exhibited inversion profiles similar to those measured outside of plume influence (S1–S4). Thus, the evolution of the plume is consistent with a continental perturbation at high latitudes and redevelopment of the boundary layer as the air mass is advected southward over the ocean [ Kloesel , ]. This mechanism would suggest a BOA impact on lower latitude clouds in Figure given that this area had been impacted by a plume the previous day and filled with clouds overnight (see Movie S1).…”

Section: Resultsmentioning

confidence: 70%

“…Given the observation of enhanced BOA above cloud, it leads to the question of the extent to which BOA also impacts the marine boundary layer and, subsequently, marine stratocumulus. As demonstrated by Kloesel [], cloud‐clearing events may develop when dry continental air displaces the marine boundary layer. As the airmass is advected downwind over the ocean, the marine inversion redevelops and, given time, may refill with clouds.…”

Section: Resultsmentioning

confidence: 99%

“…Given the presence of BOA above cloud both within and outside of plume‐impacted airspace, we question the extent to which the area of the dry plume in satellite data represents the general area of impact by continental BOA. From back trajectory analysis of the N10 event (see Movie S1), it is likely that a significant fraction of the plume is continental in nature; however, the Twin Otter did not measure aerosol near the plume's western boundary which may have cleared solely due to subsidence [ Kloesel , ]. We suspect, however, that such plume events could carry BOA over a wide region of the marine atmosphere.…”

Section: Resultsmentioning

confidence: 99%

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Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

et al. 2014

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During the 2011 Eastern Pacific Emitted Aerosol Cloud Experiment (E‐PEACE) and 2013 Nucleation in California Experiment (NiCE) field campaigns, a predominantly organic aerosol (> 85% by mass) was observed in the free troposphere over marine stratocumulus off the coast of California. These particles originated from a densely forested region in the Northwestern United States. The organic mass spectrum resolved by positive matrix factorization is consistent with the mass spectra of previously measured biogenic organic aerosol. Particulate organic mass exhibits a latitudinal gradient that corresponds to the geographical distribution of vegetation density and composition, with the highest concentration over regions impacted by densely populated monoterpene sources. Due to meteorological conditions during summer months, cloud‐clearing events transport aerosol from the Northwestern United States into the free troposphere above marine stratocumulus. Based on the variation of meteorological variables with altitude, dry air containing enhanced biogenic organic aerosol is shown to entrain into the marine boundary layer. Fresh impacts on cloud water composition are observed north of San Francisco, CA which is consistent with fresh continental impacts on the marine atmosphere at higher latitudes. Continental aerosol size distributions are bimodal. Particles in the 100 nm mode are impacted by biogenic sources, while particles in the ∼ 30 nm mode may originate from fresh biogenic emissions. Continental aerosol in the 100 nm mode is cloud condensation nuclei active and may play a role in modulating marine stratocumulus microphysics.

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Section: Resultsmentioning

confidence: 70%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

et al. 2014

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“…Large clearings (.100 km in width) in the stratocumulus cloud deck capping the marine boundary layer are often found off the western coast of the United States (e.g., Kloesel 1992). The frequency, temporal persistence, and nature of how these clearings develop and evolve are unclear.…”

Section: Introductionmentioning

confidence: 99%

Stratocumulus Cloud Clearings and Notable Thermodynamic and Aerosol Contrasts across the Clear–Cloudy Interface

Crosbie

Wang

Sorooshian

et al. 2016

Journal of the Atmospheric Sciences

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Data from three research flights, conducted over water near the California coast, are used to investigate the boundary between stratocumulus cloud decks and clearings of different sizes. Large clearings exhibit a diurnal cycle with growth during the day and contraction overnight and a multiday life cycle that can include oscillations between growth and decay, whereas a small coastal clearing was observed to be locally confined with a subdiurnal lifetime. Subcloud aerosol characteristics are similar on both sides of the clear–cloudy boundary in the three cases, while meteorological properties exhibit subtle, yet important, gradients, implying that dynamics, and not microphysics, is the primary driver for the clearing characteristics. Transects, made at multiple levels across the cloud boundary during one flight, highlight the importance of microscale (~1 km) structure in thermodynamic properties near the cloud edge, suggesting that dynamic forcing at length scales comparable to the convective eddy scale may be influential to the larger-scale characteristics of the clearing. These results have implications for modeling and observational studies of marine boundary layer clouds, especially in relation to aerosol–cloud interactions and scales of variability responsible for the evolution of stratocumulus clearings.

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“…We provide the classical analysis of entrainment rates as a basis for further studies of the aerosol evolution and transport in the boundary layer. In comparing this climatology with that of more commonly studied stratocumulus off the coast of California [Kloesel, 1992], we note that the clouds over the eastern Pacific Ocean can cover an area 10-20 times larger for much of the northern summer. In comparison, the clouds over the Southern Ocean exist locally only for 12-24 hours.…”

Section: 638 Boers Et Al: Thermodynamic Structure and Entrainmentmentioning

confidence: 85%

Thermodynamic structure and entrainment of stratocumulus over the Southern Ocean

Boers¹,

Krummel²,

Siems³

et al. 1998

J. Geophys. Res.

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Marine Stratocumulus Cloud Clearing Episodes Observed during FIRE

Cited by 17 publications

References 0 publications

Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

Observations of continental biogenic impacts on marine aerosol and clouds off the coast of California

Stratocumulus Cloud Clearings and Notable Thermodynamic and Aerosol Contrasts across the Clear–Cloudy Interface

Thermodynamic structure and entrainment of stratocumulus over the Southern Ocean

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