Heating Rates in Tropical Anvils

Ackerman, Thomas P.; Liou, Kuo‐Nan; Valero, Francisco; Pfister, Leonhard

doi:10.1175/1520-0469(1988)045<1606:hrita>2.0.co;2

Cited by 233 publications

(185 citation statements)

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“…This is consistent with ®ndings from other model comparisons for optically thin clouds (King and Harshvardhan, 1986). Similar to cirrus cases (Ackerman et al, 1988), any errors in the scattering properties of individual particles is dwarfed by the uncertainty in the assumed IWP values of contrails. The tropospheric aerosol slightly enhances the planetary albedo and the absorption properties, reducing both the SW and LW contrail forcing.…”

Section: Resultssupporting

confidence: 90%

“…5 shows the contrail induced volumetric heat source given by the change in divergence of the sum of the solar and infrared radiation¯uxes (Loiu, 1986, Ackerman et al, 1988. In the reference case, the 200 m deep contrail layer gets heated at a rate of 17 K/day for 100% contrail cover at about equal fractions by LW and SW¯ux changes, while the stratosphere above the contrail gets cooled and the troposphere below the contrail layer gets heated mainly in the LW range at a rate of order 0.3 K/day.…”

Section: Resultsmentioning

confidence: 99%

“…For increasing IWP values, the emissivity approaches one and``saturates'' (approaches a constant) quickly when the particles are small while the albedo is still much smaller than one (Stephens and Webster, 1981). Use of spheres instead of more realistic ice particle shapes may overestimate the absorption by ice particles but only to a minor degree in the infrared regime (Ackerman et al, 1988;Fu et al, 1998).…”

Section: Forcing By a Layer Of Contrail Cirrusmentioning

confidence: 99%

“…The radiative properties of cirrus clouds have been investigated in several studies (Ackerman et al, 1988;Rockel et al, 1991;Ebert and Curry, 1992;Fu and Liou, 1993). However, contrails di er from cirrus clouds in having relatively small vertical depth and occur mainly at temperatures below a threshold of order A40°C (Schumann, 1996).…”

Section: Introductionmentioning

confidence: 99%

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Radiative forcing by contrails

Meerkötter¹,

Schumann²,

et al. 1999

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Abstract. A parametric study of the instantaneous radiative impact of contrails is presented using three di erent radiative transfer models for a series of model atmospheres and cloud parameters. Contrails are treated as geometrically and optically thin plane parallel homogeneous cirrus layers in a static atmosphere. The ice water content is varied as a function of ambient temperature. The model atmospheres include tropical, mid-latitude, and subarctic summer and winter atmospheres. Optically thin contrails cause a positive net forcing at top of the atmosphere. At the surface the radiative forcing is negative during daytime. The forcing increases with the optical depth and the amount of contrail cover. At the top of the atmosphere, a mean contrail cover of 0.1% with average optical depth of 0.2 to 0.5 causes about 0.01 to 0.03 Wm A2 daily mean instantaneous radiative forcing. Contrails cool the surface during the day and heat the surface during the night, and hence reduce the daily temperature amplitude. The net e ect depends strongly on the daily variation of contrail cloud cover. The indirect radiative forcing due to particle changes in natural cirrus clouds may be of the same magnitude as the direct one due to additional cover.

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Section: Resultssupporting

confidence: 90%

Section: Resultsmentioning

confidence: 99%

Section: Forcing By a Layer Of Contrail Cirrusmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Radiative forcing by contrails

Meerkötter¹,

Schumann²,

et al. 1999

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“…coverage and optical thickness) as well as by sun zenith angle, surface albedo and temperature (Meerkötter et al, 1999). Concerning heating rates or radiative forcing the optical thickness of cirrus clouds is the key factor (Ackerman et al, 1988;Schumann et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Retrieval of cirrus cloud optical thickness and top altitude from geostationary remote sensing

2014

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Abstract.A novel approach for the detection of cirrus clouds and the retrieval of optical thickness and top altitude based on the measurements of the Spinning Enhanced Visible and Infrared Imager (SEVIRI) aboard the geostationary Meteosat Second Generation (MSG) satellite is presented. Trained with 8000000 co-incident measurements of the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission the new "cirrus optical properties derived from CALIOP and SEVIRI algorithm during day and night" (COCS) algorithm utilizes a backpropagation neural network to provide accurate measurements of cirrus optical depth τ at λ = 532 nm and top altitude z every 15 min covering almost one-third of the Earth's atmosphere. The retrieved values are validated with independent measurements of CALIOP and the optical thickness derived by an airborne high spectral resolution lidar.

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Impact of large‐scale dynamics on the microphysical properties of midlatitude cirrus

et al. 2014

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In situ microphysical observations of midlatitude cirrus collected during the Department of Energy Small Particles in Cirrus (SPARTICUS) field campaign are combined with an atmospheric state classification for the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site to understand statistical relationships between cirrus microphysics and the large‐scale meteorology. The atmospheric state classification is informed about the large‐scale meteorology and state of cloudiness at the ARM SGP site by combining ECMWF ERA‐Interim reanalysis data with 14 years of continuous observations from the millimeter‐wavelength cloud radar. Almost half of the cirrus cloud occurrences in the vicinity of the ARM SGP site during SPARTICUS can be explained by three distinct synoptic conditions, namely, upper level ridges, midlatitude cyclones with frontal systems, and subtropical flows. Probability density functions (PDFs) of cirrus microphysical properties such as particle size distributions (PSDs), ice number concentrations, and ice water content (IWC) are examined and exhibit striking differences among the different synoptic regimes. Generally, narrower PSDs with lower IWC but higher ice number concentrations are found in cirrus sampled in upper level ridges, whereas cirrus sampled in subtropical flows, fronts, and aged anvils show broader PSDs with considerably lower ice number concentrations but higher IWC. Despite striking contrasts in the cirrus microphysics for different large‐scale environments, the PDFs of vertical velocity are not different, suggesting that vertical velocity PDFs are a poor predictor for explaining the microphysical variability in cirrus. Instead, cirrus microphysical contrasts may be driven by differences in ice supersaturations or aerosols.

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Heating Rates in Tropical Anvils

Cited by 233 publications

References 0 publications

Radiative forcing by contrails

Radiative forcing by contrails

Retrieval of cirrus cloud optical thickness and top altitude from geostationary remote sensing

Impact of large‐scale dynamics on the microphysical properties of midlatitude cirrus

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