An Observational View of Relationships Between Moisture Aggregation, Cloud, and Radiative Heating Profiles

Lebsock, Matthew; L’Ecuyer, Tristan; Pincus, Robert

doi:10.1007/s10712-017-9443-1

Cited by 12 publications

(9 citation statements)

References 36 publications

(58 reference statements)

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“…If spatial variations in water vapor do not substantially modify spatial variations in clear-sky radiative fluxes, then uniform net radiation implies near-uniform net CRE. Indeed, spatial variations in column water vapor within the warm pool region rarely exceed 10% of the large-scale average column water vapor (Lebsock et al, 2017). For humidity profiles typical of the warm pool, a 10% increase in free tropospheric relative humidity reduces clear-sky outgoing LW radiation by about 5 W/m 2 (Roca et al, 2012;Tobin et al, 2012).…”

Section: Review Of Hypothesismentioning

confidence: 99%

Is the Net Cloud Radiative Effect Constrained to be Uniform Over the Tropical Warm Pools?

Wall

Hartmann

Norris

2019

Geophysical Research Letters

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Global radiative‐convective equilibrium simulations are used to investigate the hypothesis that mutual interactions among cloud albedo, sea surface temperature gradients, and atmospheric circulation constrain the net cloud radiative effect (CRE) to be similar in convective and nonconvective regions over the tropical warm pools. We perform an experiment in which convective clouds interact naturally with the ocean and atmosphere by forming over the warmest water and shading it and an experiment in which this interaction is removed by randomizing cloud shading of the ocean. Removing the cloud shading interaction enhances sea surface temperature gradients, lateral atmospheric heat transport, and large‐scale convective aggregation and produces convective clouds with much more negative net CRE. These findings support the hypothesis that feedbacks between sea surface temperature and convection are critical to obtaining similar net CRE in convective and nonconvective regions over the tropical warm pools.

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Section: Review Of Hypothesismentioning

confidence: 99%

Is the Net Cloud Radiative Effect Constrained to be Uniform Over the Tropical Warm Pools?

Wall

Hartmann

Norris

2019

Geophysical Research Letters

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“…2 Instrument overview 2.1 DAWN DAWN, a pulsed 2 µm coherent-detection Doppler wind lidar (DWL), was initially developed in the 2000s at NASA LaRC as an airborne instrument simulator to demonstrate technologies that would be required for a future space-borne Doppler wind lidar mission and to support airborne process studies and satellite Cal/Val activities. DAWN is one of several airborne DWLs operated by the international community, such as those described by Wang et al (2012), Witschas et al (2017), Bucci et al (2018), Lux et al (2018), Marksteiner et al (2018), Tucker et al (2018.…”

Section: Introductionmentioning

confidence: 99%

Airborne lidar observations of wind, water vapor, and aerosol profiles during the NASA Aeolus calibration and validation (Cal/Val) test flight campaign

et al. 2021

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Abstract. Lidars are uniquely capable of collecting high-precision and high spatiotemporal resolution observations that have been used for atmospheric process studies from the ground, aircraft, and space for many years. The Aeolus mission, the first space-borne Doppler wind lidar, was developed by the European Space Agency (ESA) and launched in August 2018. Its novel Atmospheric LAser Doppler INstrument (ALADIN) observes profiles of the component of the wind vector and aerosol/cloud optical properties along the instrument's line-of-sight (LOS) direction on a global scale. A total of two airborne lidar systems have been developed at NASA Langley Research Center in recent years that collect measurements in support of several NASA Earth Science Division focus areas. The coherent Doppler Aerosol WiNd (DAWN) lidar measures vertical profiles of LOS velocity along selected azimuth angles that are combined to derive profiles of horizontal wind speed and direction. The High Altitude Lidar Observatory (HALO) measures high resolution profiles of atmospheric water vapor (WV) and aerosol and cloud optical properties. Because there are limitations in terms of spatial and vertical detail and measurement precision that can be accomplished from space, airborne remote sensing observations like those from DAWN and HALO are required to fill these observational gaps and to calibrate and validate space-borne measurements. Over a 2-week period in April 2019, during their Aeolus Cal/Val Test Flight campaign, NASA conducted five research flights over the eastern Pacific Ocean with the DC-8 aircraft. The purpose was to demonstrate the following: (1) DAWN and HALO measurement capabilities across a range of atmospheric conditions, (2) Aeolus Cal/Val flight strategies and comparisons of DAWN and HALO measurements with Aeolus, to gain an initial perspective of Aeolus performance, and (3) ways in which atmospheric dynamic processes can be resolved and better understood through simultaneous observations of wind, WV, and aerosol profile observations, coupled with numerical model and other remote sensing observations. This paper provides a brief description of the DAWN and HALO instruments, discusses the synergistic observations collected across a wide range of atmospheric conditions sampled during the DC-8 flights, and gives a brief summary of the validation of DAWN, HALO, and Aeolus observations and comparisons.

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“…Here, we use CWV instead since the spatial variations of MSE in the tropics are mostly contributed from variations of CWV due to weaker temperature gradients there. The degree of CA is defined as below (Lebsock et al, 2017):…”

Section: Degree Of Camentioning

confidence: 99%

“…A mode of aggregation that is self-organized into humid clusters has long been recognized and studied as a radiative-convective instability in numerical simulations (Bretherton et al, 2005;Held & Hemler, 1993;Wing et al, 2017). Observations (observations here refer to CA of all cause, not necessarily convective self-aggregation in numerical simulations) have substantiated some characteristics of CA and its interaction with large-scale environment, including domain-mean moisture, cloudiness, radiation, and surface fluxes (Holloway et al, 2017;Lebsock et al, 2017;Tobin et al, 2012). CA is recently proposed as one of the key knowledge gaps because of its potential to modulate tropical climate sensitivity (Bony et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Convective Aggregation and the Amplification of Tropical Precipitation Extremes

Dai

Soden

2020

AGU Advances

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It is widely believed that precipitation extremes will increase in response to a warming climate, as inferred from both observations and numerical simulations. In the absence of changes in atmospheric circulations, extreme precipitation is expected to increase in already-moist regions along a thermodynamical Clausius-Clapeyron scaling. However, within the tropics, the sensitivities inferred from observations of interannual variability are roughly twice as large, implying an unknown contribution from atmospheric dynamics. In this paper, we use satellite observations and climate model simulations to investigate the relationship between convective aggregation and precipitation and the role that convective aggregation plays in amplifying the response of tropical precipitation extremes to interannual surface warming. We find that the occurrence of heavier precipitation coincides with a higher degree of convective aggregation. Extreme precipitation events and convective aggregation tend to increase during warm, El Niño events compared to colder, La Niña events. Although both the frequency and intensity of heavy to extreme precipitation can increase with increased aggregation during El Niño, the changes in frequency are more consistent among the observations and models than changes in intensity. In both the observations and models, increases in large-scale convective aggregation contribute to roughly one third of the increase in extreme precipitation frequency due to interannual warming by shifting moderate-to-heavy precipitation events to more extreme precipitation intensities. The linkages between convective aggregation and precipitation extremes considered here offer insights into their potential response to anthropogenic warming. Plain Language Summary As climate warms, one of the most prominent changes in the global water cycle is more common extreme rainfall events in the tropics. A mechanism that enhances the convection process and its related precipitation could increase the rate of occurrence and strength of these events rising with the temperature. Here, we investigate how a phenomenon known as convective aggregation contributes to more common tropical extreme rainfall events on a year-to-year basis. We find that heavier rainfall is closely tied to a more aggregated state of atmospheric water vapor. Both observations and models show that more extreme rainfall events and the aggregation of moisture occur during warm, El Niño events relative to colder, La Niña events. The enhanced aggregation process creates extra moisture in the already-moist regions leading to more common heavier precipitation events and less common lighter precipitation ones. As a result, the increase in convective aggregation amplifies the increase in extreme rainfall events related to year-to-year surface warming by roughly one third. Our findings provide new insight on projections of future rainfall extremes, which have strong implications for disaster risk management.

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An Observational View of Relationships Between Moisture Aggregation, Cloud, and Radiative Heating Profiles

Cited by 12 publications

References 36 publications

Is the Net Cloud Radiative Effect Constrained to be Uniform Over the Tropical Warm Pools?

Is the Net Cloud Radiative Effect Constrained to be Uniform Over the Tropical Warm Pools?

Airborne lidar observations of wind, water vapor, and aerosol profiles during the NASA Aeolus calibration and validation (Cal/Val) test flight campaign

Convective Aggregation and the Amplification of Tropical Precipitation Extremes

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