Rapidly Evolving Cirrus Clouds Modulated by Convectively Generated Gravity Waves

Prasad, Abhnil Amtesh; Sherwood, Steven C.; Reeder, Michael J.; Lane, Todd P.

doi:10.1029/2019jd030538

Cited by 7 publications

(6 citation statements)

References 79 publications

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“…The convectively driven latent heating also dictates the circulation pattern with a large updraft fed by the surface inflow, and detraining ICs between 12‐ and 15‐km elevation (Figures b, a, and b). The large initial heating is a vigorous source of gravity waves (Bretherton, ; Prasad et al, ), which significantly perturb the instantaneous wind fields while not influencing the mean winds.…”

Section: Resultsmentioning

confidence: 99%

What Drives the Life Cycle of Tropical Anvil Clouds?

Gasparini

Blossey

Hartmann

et al. 2019

J Adv Model Earth Syst

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The net radiative effects of tropical clouds are determined by the evolution of thick, freshly detrained anvil clouds into thin anvil clouds. Thick anvil clouds reduce Earth's energy balance and cool the climate, while thin anvil clouds warm the climate. To determine role of these clouds in climate change we need to understand how interactions of their microphysical and macrophysical properties control their radiative properties. We explore anvil cloud evolution using a cloud‐resolving model in three‐simulation setups of increasing complexity to disentangle the impacts of the various components of diabatic heating and their interaction with cloud‐scale motions. The first phase of evolution and rapid cloud spreading is dominated by latent heating within convective updrafts. After the convective detrainment stops, most of the spreading and thinning of the anvil cloud is driven by cloud radiative processes and latent heating. The combination of radiative cooling at cloud top, latent cooling due to sublimation at cloud base, latent heating due to deposition and radiative heating in between leads to a sandwich‐like, cooling‐heating‐cooling structure. The heating sandwich promotes the development of two within‐anvil convective layers and a double cell circulation, dominated by strong outflow at 12‐km altitude with inflow above and below. Our study reveals how small‐scale processes including convective, microphysical processes, latent and radiative heating interact within the anvil cloud system. The absence or a different representation of only one component results in a significantly different cloud evolution with large impacts on cloud radiative effects.

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Section: Resultsmentioning

confidence: 99%

What Drives the Life Cycle of Tropical Anvil Clouds?

Gasparini

Blossey

Hartmann

et al. 2019

J Adv Model Earth Syst

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“…However, there are still some discrepancies in N i between the McFarlane_D experiment and the observations in the upper troposphere. The discrepancies can be caused by a lack of sub‐grid scale fluctuations induced by other gravity waves (Kärcher et al., 2019; Plougonven & Zhang, 2014; Prasad et al., 2019) or by bias in simulated aerosol properties (Shan et al., 2021; Shi & Liu, 2019; Wu et al., 2020; Yu et al., 2019) and deficiency in ice nucleation parameterizations (Shi & Liu, 2016). The abnormal simulated high‐ N i values in the lower stratosphere are all sporadic cases and have little effect on cloud bulk properties and climate forcing.…”

Section: Resultsmentioning

confidence: 99%

Orographic Cirrus and Its Radiative Forcing in NCAR CAM6

et al. 2023

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Cirrus clouds, covering over 30% of the Earth's surface, play an essential role in climate (Liou, 1986). Composed of ice crystals, they can reflect solar radiation with a cooling effect, absorb and reemit longwave radiation with a warming effect, and therefore strongly influence the Earth's radiative budgets. The net radiative effect of cirrus clouds and their feedback on global warming is still uncertain (Ceppi et al., 2017;Stephens, 2005;Wetherald & Manabe, 1988). Current global climate models (GCMs) produce a large spread in cirrus feedback, ranging from weakly negative to strongly positive feedback (−0.13-1.24 W m −2 K −1 ) (Ceppi et al., 2017).Vertical velocity is a critical factor in triggering the formation of ice crystals in cirrus clouds. A larger vertical velocity can generate a stronger adiabatic cooling, decrease the parcel's temperature, increase the relative humidity with respect to ice, activate more aerosols, and thus form more ice crystals (Kärcher & Lohmann, 2002). Previous studies show that, when vertical velocity increases from 10 to 100 cm s −1 , the number of newly-formed ice particles increases by more than one order of magnitude (Kärcher & Lohmann, 2002). The vertical velocity on smaller scales is more important to the nucleation of ice crystals in cirrus clouds than the synoptic-scale vertical velocity (Mace et al., 2001;Quante & Starr, 2002). In the lower stratosphere and upper troposphere, mesoscale gravity waves are ubiquitous and usually generate strong disturbances (

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“…Theoretically, low values of LWCF imply a lesser amount of clouds in the atmosphere. Near the top of the atmosphere, high‐level cirrus clouds can still modulate LWCF (Prasad et al., 2019; Storelvmo & Herger, 2014; M. Wang et al., 2020). LWCF values from AIRS over Chiba from May 2017 to March 2020 show seasonal variations, as shown in Figure 12a.…”

Section: Resultsmentioning

confidence: 99%

Observations of Nighttime Clouds Over Chiba, Japan, Using Digital Cameras and Satellite Images

2021

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Nighttime cloud cover (CC) is analyzed from the data observed for 34 months over Chiba, Japan, using continuously operated digital cameras. The normal camera works in the visible region, providing quantitative and temporal changes of nighttime CC. The second camera captures sky images without the near‐infrared cut filter, and by applying the thresholding method, we obtain information on the temporal changes of thin (pixel values between 72 and 115) and thick (>115) clouds. Comparing the CC from the visible camera with cloud fraction from Atmospheric Infrared Sounder (AIRS) shows that long‐term data from the camera are valuable for correcting the underestimation of the cloud fraction product from AIRS for low‐level clouds. Furthermore, a comparison between the near‐ground temperature and CC results in estimating the seasonal changes of feedback effects of upward thermal radiation from the ground. The current results reveal that thick clouds contribute to longwave cloud forcing (LWCF) below 100 Wm−2, while thin clouds with CC below 30% contribute to LWCF below 10.2 Wm−2.

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Rapidly Evolving Cirrus Clouds Modulated by Convectively Generated Gravity Waves

Cited by 7 publications

References 79 publications

What Drives the Life Cycle of Tropical Anvil Clouds?

What Drives the Life Cycle of Tropical Anvil Clouds?

Orographic Cirrus and Its Radiative Forcing in NCAR CAM6

Observations of Nighttime Clouds Over Chiba, Japan, Using Digital Cameras and Satellite Images

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