Tropical tropopause layer cirrus and its relation to tropopause

Tseng, Hsiu-Hui; Fu, Qiang

doi:10.1016/j.jqsrt.2016.05.029

Cited by 19 publications

(33 citation statements)

References 53 publications

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“…We used the CALIPSO level 2 version 3 5 km cloud and aerosol layer products. The clouds included in the aerosol layer product as so-called "stratospheric features" were considered here by separating clouds from aerosols following Tseng and Fu [25]. For cloud layers that the CALIPSO lidar could penetrate, we used cloud top and cloud base heights from CALIPSO.…”

Section: Cloud Radiative Effects In Tropicsmentioning

confidence: 99%

The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

Smith

Yang

2018

Atmosphere

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A single-column radiative-convective model (RCM) is a useful tool to investigate the physical processes that determine the tropical tropopause layer (TTL) temperature structures. Previous studies on the TTL using the RCMs, however, omitted the cloud radiative effects. In this study, we examine the impact of cloud radiative effects on the simulated TTL temperatures using an RCM. We derive the cloud radiative effects based on satellite observations, which show heating rates in the troposphere but cooling rates in the stratosphere. We find that the cloud radiative effect warms the TTL by as much as 2 K but cools the lower stratosphere by as much as −1.5 K, resulting in a thicker TTL. With (without) considering cloud radiative effects, we obtain a convection top of ≈167 hPa (≈150 hPa) with a temperature of ≈213 K (≈209 K), and a cold point at ≈87 hPa (≈94 hPa) with a temperature of ≈204 K (≈204 K). Therefore, the cloud radiative effects widen the TTL by both lowering the convection-top height and enhancing the cold-point height. We also examine the impact of TTL cirrus radiative effects on the RCM-simulated temperatures. We find that the TTL cirrus warms the TTL with a maximum temperature increase of ≈1.3 K near 110 hPa.

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Section: Cloud Radiative Effects In Tropicsmentioning

confidence: 99%

The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

Smith

Yang

2018

Atmosphere

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“…In this study, we use the CALIPSO level 2 version 3 5 km cloud and aerosol layer products, which have a vertical resolution of 30 m from the surface to 8.2 km and 60 m from 8.2 km to 20.2 km. The clouds included in the aerosol layer product as so‐called “stratospheric features” are considered here by separating clouds from aerosols following Tseng and Fu (). We only consider more reliable nighttime measurements because the detection of layers during the daytime has less signal‐to‐noise ratio for lidar due to solar background noise.…”

Section: Datamentioning

confidence: 99%

“…This layer is termed the tropical tropopause layer (TTL), which is from about 14.5 to 18.5 km (Alcala & Dessler, ; Folkins et al, ; Fu et al, ; Gettelman et al, ; Gettelman & Forster, ; Holton & Gettelman, ; Sherwood & Dessler, ). In this study, we define the TTL clouds as clouds with bases higher than 14.5 km (Tseng & Fu, ).…”

Section: Introductionmentioning

confidence: 99%

“…The TTL temperatures control the tropical lower stratospheric water vapor amount through the dehydration process (e.g., Brewer, ; Ding & Fu, ; Fueglistaler et al, ; Fueglistaler & Haynes, ), and thus, the temperature is a critical factor in influencing the TTL cloud formation by bringing air to saturation. By analyzing satellite data, recent studies have shown that annual variations of the TTL clouds and tropical tropopause temperatures are strongly inversely correlated both temporally and spatially (Fu, ; Tseng & Fu, ; Virts et al, ). On the other hand, the variability of the TTL temperature is largely caused by a complex combination of the stratospheric quasi‐biennial oscillation (QBO), tropospheric convective processes in the tropics, and the Brewer‐Dobson circulation (BDC) driven by midlatitude and subtropical atmospheric waves (e.g., Ding & Fu, ).…”

Section: Introductionmentioning

confidence: 99%

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Temperature Control of the Variability of Tropical Tropopause Layer Cirrus Clouds

Tseng

2017

JGR Atmospheres

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This study examines the temperature control of variability of tropical tropopause layer (TTL) cirrus clouds (i.e., clouds with bases higher than 14.5 km) by using 8 years (2006–2014) of observations from the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC). It is found that the temporal variability of vertical structure of TTL cirrus cloud fraction averaged between 15°N and 15°S can be well explained by the vertical temperature gradient below ~17.5 km but by the local temperature above for both seasonal and interannual time scales. It is also found that the TTL cirrus cloud fraction at a given altitude is best correlated with the temperature at a higher altitude and this vertical displacement increases with a decrease of the cirrus altitude. It is shown that the TTL cirrus cloud fractions at all altitudes are significantly correlated with tropical cold point tropopause (CPT) temperature. The plausible mechanisms that might be responsible for the observed relations between TTL cirrus fraction and temperature‐based variables are discussed, which include ice particle sediments, cooling associated with wave propagations, change of atmospheric stability, and vertical gradient of water vapor mixing ratio. We further examine the spatial covariability of TTL total cirrus cloud fraction and CPT temperature for the interannual time scale. It is found that the El Niño–Southern Oscillation and quasi‐biennial oscillation are the leading factors in controlling the spatial variability of the TTL cirrus clouds and temperatures.

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“…The launch of the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on-board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) has offered an unprecedented global representation of ice cloud occurrence and optical depth [19]. Many studies have leveraged CALIPSO's capability to characterize ice clouds, providing new insights into the global ice cloud observations [5,[20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Optically Very Thin Ice Clouds from Ground-Based ARM Raman Lidars

Balmes

2018

Atmosphere

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Optically very thin ice clouds from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and ground-based Raman lidars (RL) at the atmospheric radiation measurement (ARM) sites of the Southern Great Plains (SGP) and Tropical Western Pacific (TWP) are analyzed. The optically very thin ice clouds, with ice cloud column optical depths below 0.01, are about 23% of the transparent ice-cloudy profiles from the RL, compared to 4–7% from CALIPSO. The majority (66–76%) of optically very thin ice clouds from the RLs are found to be adjacent to ice clouds with ice cloud column optical depths greater than 0.01. The temporal structure of RL-observed optically very thin ice clouds indicates a clear sky–cloud continuum. Global cloudiness estimates from CALIPSO observations leveraged with high-sensitivity RL observations suggest that CALIPSO may underestimate the global cloud fraction when considering optically very thin ice clouds.

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Tropical tropopause layer cirrus and its relation to tropopause

Cited by 19 publications

References 53 publications

The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

The Impact of Cloud Radiative Effects on the Tropical Tropopause Layer Temperatures

Temperature Control of the Variability of Tropical Tropopause Layer Cirrus Clouds

An Investigation of Optically Very Thin Ice Clouds from Ground-Based ARM Raman Lidars

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