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Dennis L. Hartmann – One of the best experts on this subject based on the ideXlab platform.
A Lagrangian perspective on tropical Anvil cloud lifecycle in present and future climate, 2020Co-Authors: Blaž Gasparini, Casey J Wall, Dennis L. Hartmann, Philip J. Rasch, Marina DuetschAbstract:
The evolution of tropical Anvil Clouds from their origin in deep convective cores to their slow decay determines the climatic effects of Clouds in tropical convective regions. Despite the relevance…
Tropical Anvil Clouds: Radiative Driving Towards a Preferred StateJournal of Geophysical Research: Atmospheres, 2020Co-Authors: Adam B. Sokol, Dennis L. HartmannAbstract:
The evolution of Anvil Clouds detrained from deep convective systems has important implications for the tropical energy balance and is thought to be shaped by radiative heating. We use combined rad…
Supporting data for Sokol and Hartmann (2020), Tropical Anvil Clouds: Radiative Driving Towards a Preferred State, 2020Co-Authors: Adam B. Sokol, Dennis L. HartmannAbstract:
This dataset enables the reproduction of figures and statistics in the paper “Tropical Anvil Clouds: Radiative Driving Towards a Preferred State” by Adam B Sokol and Dennis L Hartmann (2020).
Robert A Houze – One of the best experts on this subject based on the ideXlab platform.
in monsoon regions, 2016Co-Authors: Jasmine Cetrone, Robert A HouzeAbstract:
Anvil Clouds of tropical mesoscale convective system
Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models, 2013Co-Authors: Robert A HouzeAbstract:
We examined cloud radar data in monsoon climates, using cloud radars at Darwin in the Australian monsoon, on a ship in the Bay of Bengal in the South Asian monsoon, and at Niamey in the West African monsoon. We followed on with a more in-depth study of the continental MCSs over West Africa. We investigated whether the West African Anvil Clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the observed Anvil Clouds to Anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model at high resolution using six different ice-phase microphysical schemes. We carried out further simulations with a cloud-resolving model forced by sounding network budgets over the Niamey region and over the northern Australian region. We have devoted some of the effort of this project to examining how well satellite data can determine the global breadth of the Anvil cloud measurements obtained at the ARM ground sites. We next considered whether satellite data could be objectively analyzed to so that their large global measurement sets can be systematically related to the ARM measurements. Further differences were detailed between the land and ocean MCS Anvilmore » Clouds by examining the interior structure of the Anvils with the satellite-detected the Cloudsat Cloud Profiling Radar (CPR). The satellite survey of Anvil Clouds in the Indo-Pacific region was continued to determine the role of MCSs in producing the cloud pattern associated with the MJO.« less
Comparison of Simulated and Observed Continental Tropical Anvil Clouds and Their Radiative Heating ProfilesJournal of the Atmospheric Sciences, 2012Co-Authors: Scott Powell, Robert A Houze, Anil Kumar, Sally A. McfarlaneAbstract:
AbstractVertically pointing millimeter-wavelength radar observations of Anvil Clouds extending from mesoscale convective systems (MCSs) that pass over an Atmospheric Radiation Measurement Program (ARM) field site in Niamey, Niger, are compared to Anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model using six different microphysical schemes. The radar data provide the statistical distribution of the radar reflectivity values as a function of height and Anvil thickness. These statistics are compared to the statistics of the modeled Anvil cloud reflectivity at all altitudes. Requiring the model to be statistically accurate at all altitudes is a stringent test of the model performance. The typical vertical profile of radiative heating in the Anvil Clouds is computed from the radar observations. Variability of Anvil structures from the different microphysical schemes provides an estimate of the inherent uncertainty in Anvil radiative heating profiles. All schemes underestima…
Andrew J Heymsfield – One of the best experts on this subject based on the ideXlab platform.
Combining In Situ and Satellite Observations to Understand the Vertical Structure of Tropical Anvil Cloud Microphysical Properties During the TC4 Experiment.Earth and space science (Hoboken N.J.), 2020Co-Authors: Qing Yue, Andrew J Heymsfield, Kuo-nan Liou, Jonathan H. Jiang, Arushi SinhaAbstract:
Tropical Anvil Clouds have a profound impact on Earth’s weather and climate. Their role in Earth’s energy balance and hydrologic cycle is heavily modulated by the vertical structure of the microphysical properties for various hydrometeors in these Clouds and their dependence on the ambient environmental conditions. Accurate representations of the variability and covariability of such vertical structures are key to both the satellite remote sensing of cloud and precipitation and numerical modeling of weather and climate, which remain a challenge. This study presents a new method to combine vertically resolved observations from Cloudsat radar reflectivity and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation cloud masks with probability distributions of cloud microphysical properties and the ambient atmospheric conditions from detailed in situ measurements on tropical Anvils sampled during the National Aeronautics and Space Administration TC4 (Tropical Composition, Cloud and Climate Coupling) mission. We focus on the microphysical properties of the vertical distribution of ice water content, particle size distributions, and effective sizes for different hydrometeors, including ice particles and supercooled liquid droplets. Results from this method are compared with those from in situ data alone and various Cloudsat/Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation cloud retrievals. The sampling limitation of the field experiment and algorithm limitations in the current retrievals is highlighted, especially for the liquid cloud particles, while a generally good agreement with ice cloud microphysical properties is seen from different methods. While the method presented in this study is applied to tropical Anvil Clouds observed during TC4, it can be readily employed to study a broad range of ice Clouds sampled by various field campaigns.
vertical structures of Anvil Clouds of tropical mesoscale convective systems observed by CloudsatJournal of the Atmospheric Sciences, 2011Co-Authors: Jian Yuan, Robert A Houze, Andrew J HeymsfieldAbstract:
AbstractA global study of the vertical structures of the Clouds of tropical mesoscale convective systems (MCSs) has been carried out with data from the Cloudsat Cloud Profiling Radar. Tropical MCSs are found to be dominated by cloud-top heights greater than 10 km. Secondary cloud layers sometimes occur in MCSs, but outside their primary raining cores. The secondary layers have tops at 6–8 and 1–3 km. High-topped Clouds extend outward from raining cores of MCSs to form Anvil Clouds. Closest to the raining cores, the Anvils tend to have broader distributions of reflectivity at all levels, with the modal values at higher reflectivity in their lower levels. Portions of Anvil Clouds far away from the raining core are thin and have narrow frequency distributions of reflectivity at all levels with overall weaker values. This difference likely reflects ice particle fallout and therefore cloud age. Reflectivity histograms of MCS Anvil Clouds vary little across the tropics, except that (i) in continental MCS Anvils…
Evidence of nitric acid uptake in warm cirrus Anvil Clouds during the NASA TC4 campaignJournal of Geophysical Research, 2010Co-Authors: Eric Scheuer, Andrew J Heymsfield, Jack E. Dibb, Cynthia H. Twohy, David C. Rogers, Aaron BansemerAbstract:
 Uptake of HNO3 onto cirrus ice may play an important role in tropospheric NOx cycling. Discrepancies between modeled and in situ measurements of gas-phase HNO3 in the troposphere suggest that redistribution and removal mechanisms by cirrus ice have been poorly constrained. Limited in situ measurements have provided somewhat differing results and are not fully compatible with theory developed from laboratory studies. We present new airborne measurements of HNO3 in cirrus Clouds from Anvil outflow made during the Tropical Composition, Cloud, and Climate Coupling Experiment (TC4). Upper tropospheric (>9 km) measurements made during three flights while repeatedly traversing the same cloud region revealed depletions of gas-phase HNO3 in regions characterized by higher ice water content and surface area. We hypothesize that adsorption of HNO3 onto cirrus ice surfaces could explain this. Using measurements of cirrus ice surface area density and some assumptions about background mixing ratios of gas-phase HNO3, we estimate molecular coverages of HNO3 on cirrus ice surface in the tropical upper troposphere during the TC4 racetracks to be about 1 × 1013 molecules cm−2. This likely reflects an upper limit because potential dilution by recently convected, scavenged air is ignored. Also presented is an observation of considerably enhanced gas-phase HNO3 at the base of a cirrus Anvil suggesting vertical redistribution of HNO3 by sedimenting cirrus particles and subsequent particle sublimation and HNO3 evaporation. The impact of released HNO3, however, appears to be restricted to a very thin layer just below the cloud.