Importance Profiles for Water Vapor

Mapes, Brian E.; Chandra, Arunchandra S.; Kuang, Zhiming; Zuidema, Paquita

doi:10.1007/s10712-017-9427-1

Cited by 15 publications

(31 citation statements)

References 33 publications

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“…Many examples of drier atmospheres coexisting with more isolated convection are documented within shallow-to-deep transition studies (Feng et al 2014;Ruppert and Johnson 2015), as well as with linearly organized convection such as squall lines (Takemi and Satomura 2000;Mapes et al 2017;Schiro and Neelin 2017). A correspondence between stronger cold pools and drier mid-tropospheres has not yet been robustly identified in observations, but is consistent with published emphases (see also Takemi et al 2004).…”

Section: Cold Pools From Deep Tropical Convectionsupporting

confidence: 60%

“…This is also evident in space-based cloud radar observations of cumulus congestus/cumulonimbus occurring underneath upper-level stratiform cloud (e.g., Riley et al 2011). The moisture distribution is influenced more by layer-lifting and less by surface-based buoyancy (see, e.g., in this issue, Mapes et al (2017), dating back to at least Houze and Betts (1981), so that it cannot be argued that cold pools are important for redistributing moisture.…”

Section: Cold Pools From Deep Tropical Convectionmentioning

confidence: 91%

“…That higher clouds are associated with stronger cold pools may reflect a correlation between downdraft width and clouds that are wider as a result of organization, discouraging environmental dilution of the downdraft air (Schlemmer and Hohenegger 2014; Schiro and . The red half-circles in panels a, c correspond to the cold pool arriving at Gan island $ 3 h later Neelin 2017; Mapes et al 2017). The low-altitude origin discounts contributions to the convective downdrafts (treated separately from stratiform precipitation) by the melting or sublimation of ice particles (Srivastava 1987).…”

Section: Cold Pools From Deep Tropical Convectionmentioning

confidence: 99%

“…The distribution of moisture near cloud base remains poorly known, along with the vertical structure of cold pools. This is unlikely to be solved soon via remote sensing (see, e.g., Mapes et al 2017;Zhang et al 2017), with what is possibly the best passive remote sensing technique, using spectral infrared (Blumberg et al 2015) still primarily limited to clear skies. Differential absorption and Raman lidars can profile moisture but are obstructed by cloud, although extrapolation from points nearby could provide insight, and in combination with Doppler wind lidar might be able to resolve moist updrafts.…”

Section: Thermodynamic Secondary Initiation Processesmentioning

confidence: 99%

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A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

et al. 2017

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Pools of air cooled by partial rain evaporation span up to several hundreds of kilometers in nature and typically last less than 1 day, ultimately losing their identity to the large-scale flow. These fundamentally differ in character from the radiatively-driven dry pools defining convective aggregation. Advancement in remote sensing and in computer capabilities has promoted exploration of how precipitation-induced cold pool processes modify the convective spectrum and life cycle. This contribution surveys current understanding of such cold pools over the tropical and subtropical oceans. In shallow convection with low rain rates, the cold pools moisten, preserving the near-surface equivalent potential temperature or increasing it if the surface moisture fluxes cannot ventilate beyond the new surface layer; both conditions indicate downdraft origin air from within the boundary layer. When rain rates exceed $ 2 mm h À1 , convective-scale downdrafts can bring down drier air of lower equivalent potential temperature from above the boundary layer. The resulting density currents facilitate the lifting of locally thermodynamically favorable air and can impose an arc-shaped mesoscale cloud organization. This organization allows clouds capable of reaching 4-5 km within otherwise dry environments. These are more commonly observed in the northern hemisphere trade wind regime, where the flow to the intertropical 123Surv Geophys (2017) 38:1283-1305 https://doi.org/10.1007/s10712-017-9447-x convergence zone is unimpeded by the equator. Their near-surface air properties share much with those shown from cold pools sampled in the equatorial Indian Ocean. Cold pools are most effective at influencing the mesoscale organization when the atmosphere is moist in the lower free troposphere and dry above, suggesting an optimal range of water vapor paths. Outstanding questions on the relationship between cold pools, their accompanying moisture distribution and cloud cover are detailed further. Near-surface water vapor rings are documented in one model inside but near the cold pool edge; these are not consistent with observations, but do improve with smaller horizontal grid spacings.

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Section: Cold Pools From Deep Tropical Convectionsupporting

confidence: 60%

Section: Cold Pools From Deep Tropical Convectionmentioning

confidence: 91%

Section: Cold Pools From Deep Tropical Convectionmentioning

confidence: 99%

Section: Thermodynamic Secondary Initiation Processesmentioning

confidence: 99%

See 2 more Smart Citations

A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

et al. 2017

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“…While we have had little success in reducing the range of estimated climate sensitivity, we have greatly improved our knowledge of the processes involved. Fundamental mechanisms behind longwave feedbacks due to deep tropical clouds are better understood (Hartmann and Larson 2002), although questions remain about the importance of mesoscale organizing processes (Wing et al 2017;Wing and Emanuel 2014;Mauritsen and Stevens 2015;Mapes et al 2017). Shallow clouds are mediated more by atmospheric circulation than by microphysical processes.…”

Section: Introductionmentioning

confidence: 99%

Emerging Technologies and Synergies for Airborne and Space-Based Measurements of Water Vapor Profiles

Nehrir

Kiemle²,

Lebsock

et al. 2017

Surv Geophys

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A deeper understanding of how clouds will respond to a warming climate is one of the outstanding challenges in climate science. Uncertainties in the response of clouds, and particularly shallow clouds, have been identified as the dominant source of the discrepancy in model estimates of equilibrium climate sensitivity. As the community gains a deeper understanding of the many processes involved, there is a growing appreciation of the critical role played by fluctuations in water vapor and the coupling of water vapor and atmospheric circulations. Reduction of uncertainties in cloud-climate feedbacks and convection initiation as well as improved understanding of processes governing these effects will result from profiling of water vapor in the lower troposphere with improved accuracy and vertical resolution compared to existing airborne and space-based measurements. This paper highlights new technologies and improved measurement approaches for measuring lower tropospheric water vapor and their expected added value to current observations. Those include differential absorption lidar and radar, microwave occultation between lowEarth orbiters, and hyperspectral microwave remote sensing. Each methodology is briefly

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Congestus modes in circulating equilibria of the tropical atmosphere in a two‐column model

Nuijens

Emanuel

2018

Quart J Royal Meteoro Soc

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A two‐column radiative–convective equilibrium (RCE) model is used to study the depth of convection that develops in the subsiding branch of a Walker‐like overturning circulation. The model numerically solves for two‐dimensional non‐rotating hydrostatic flow, which is damped by momentum diffusion in the boundary layer and model interior, and by convective momentum transport. Convection, clouds and radiative transfer are parametrized, and the convection scheme does not include explicit freezing or melting. While integrating the model towards local RCE, the level of neutral buoyancy (LNB) fluctuates between mid‐ and high levels. Evaporation of detrained moisture at the LNB locally cools the environment, so that the final RCE state has a stable layer at mid‐levels (550 hPa ≈ 50–100 hPa below 0 °C), which is unrelated to melting of ice. Preferred detrainment at mid‐ and high levels leaves the middle‐to‐upper troposphere relatively dry. A circulation is introduced by incrementally lowering the sea‐surface temperature in one column, which collapses convection: first to a congestus mode with tops near 550 hPa, below the dry layer created in RCE; then to congestus with tops near 650 hPa; and finally to shallow cumulus with tops near 850 hPa. Critical to stabilizing congestus near 650 hPa is large radiative cooling near moist cumulus tops under a dry upper atmosphere. This congestus mode is very sensitive, and only develops when horizontal temperature gradients created by evaporative and radiative cooling can persist against the work of gravity waves. This only happens in runs with ample momentum diffusion, which are those with convective momentum transport or large domains. Compared to the shallow mode, the congestus mode produces a deep moist layer and more precipitation. This reduces radiative cooling in the cloud layer and enhances stability near the cloud base, which weakens the circulation, and leads to less precipitation over the warm ocean.

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Importance Profiles for Water Vapor

Cited by 15 publications

References 33 publications

A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

A Survey of Precipitation-Induced Atmospheric Cold Pools over Oceans and Their Interactions with the Larger-Scale Environment

Emerging Technologies and Synergies for Airborne and Space-Based Measurements of Water Vapor Profiles

Congestus modes in circulating equilibria of the tropical atmosphere in a two‐column model

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