The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
A E Dessler - One of the best experts on this subject based on the ideXlab platform.
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analysis of cirrus in the tropical tropopause layer from calipso and mls data a water perspective
Journal of Geophysical Research, 2012Co-Authors: Tao Wang, A E DesslerAbstract:[1] Two mechanisms are thought to be primarily responsible for the formation of cirrus in the Tropical Tropopause Layer (TTL): detrainment from deep Convective anvils and in situ initiation. By analyzing water vapor (H2O) measurements from the Aura Microwave Limb Sounder (MLS) and ice water content (IWC) measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we identify TTL cirrus that contain too much ice to have been formed in situ—and therefore must be of Convective origin. Analyzing 3 years of CALIPSO measurements (2008–2010), we found three maxima in the occurrence of Convective cirrus: equatorial Africa, the tropical western Pacific, and South America. Over the entire tropics, we found that Convective cirrus occur more frequently during boreal winter-spring and less frequently during boreal summer-fall. The Convective fractions of cirrus also increase until the cold point tropopause is reached in most seasons—implying higher probabilities of cirrus around the tropopause being of Convective origin. Averaged over 3 years, we find that at least ∼30% of cirrus in the TTL are definitely of Convective origin.
Tao Wang - One of the best experts on this subject based on the ideXlab platform.
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more frequent showers and thunderstorm days under a warming climate evidence observed over northern eurasia from 1966 to 2000
Climate Dynamics, 2017Co-Authors: Eric J Fetzer, Sun Wong, Bjorn Lambrigtsen, Tao Wang, Luke Chen, Van DangAbstract:This study uses 3-hourly synoptic observations at 547 stations to examine changes in Convective and non-Convective precipitation days and their associations with surface air temperature and specific humidity over Northern Eurasia. We found that Convective days (showers and those associated with thunder and lightning) have become more frequent possibly at the expense of non-Convective ones for all seasons during the study period of 1966–2000. The mean trends for Convective day fraction (total Convective precipitation events divided by all precipitation events for each season) are very similar among all four seasons at around 0.61–0.76% per year averaged over the study region. The temperature and humidity associated with Convective events are on average 2.4–5.6 °C and 0.4–0.9 g/kg higher than those of non-Convective events, respectively. This study suggests that surface warming and moistening lead to increased tropospheric static instability, contributing to the observed trends.
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analysis of cirrus in the tropical tropopause layer from calipso and mls data a water perspective
Journal of Geophysical Research, 2012Co-Authors: Tao Wang, A E DesslerAbstract:[1] Two mechanisms are thought to be primarily responsible for the formation of cirrus in the Tropical Tropopause Layer (TTL): detrainment from deep Convective anvils and in situ initiation. By analyzing water vapor (H2O) measurements from the Aura Microwave Limb Sounder (MLS) and ice water content (IWC) measurements from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), we identify TTL cirrus that contain too much ice to have been formed in situ—and therefore must be of Convective origin. Analyzing 3 years of CALIPSO measurements (2008–2010), we found three maxima in the occurrence of Convective cirrus: equatorial Africa, the tropical western Pacific, and South America. Over the entire tropics, we found that Convective cirrus occur more frequently during boreal winter-spring and less frequently during boreal summer-fall. The Convective fractions of cirrus also increase until the cold point tropopause is reached in most seasons—implying higher probabilities of cirrus around the tropopause being of Convective origin. Averaged over 3 years, we find that at least ∼30% of cirrus in the TTL are definitely of Convective origin.
Yukari N. Takayabu - One of the best experts on this subject based on the ideXlab platform.
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Convective cloud top vertical velocity estimated from geostationary satellite rapid scan measurements
Geophysical Research Letters, 2016Co-Authors: Atsushi Hamada, Yukari N. TakayabuAbstract:We demonstrate that the rate of development of cumulus clouds, as inferred from the so-called geostationary satellite “rapid-scan” measurements, is a good proxy for Convective cloud top vertical velocity related to deep Convective clouds. Convective cloud top vertical velocity is estimated from the decreasing rate of infrared brightness temperature observed by the Multi-functional Transport SATellite-1R (MTSAT-1R) over the ocean south of Japan during boreal summer. The frequency distribution of the estimated Convective cloud top vertical velocity at each height is shown to distribute lognormally, and it is consistent with the statistical characteristics of direct measurements acquired in previous studies.
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diurnal variations in tropical oceanic cumulus convection during toga coare
Journal of the Atmospheric Sciences, 1997Co-Authors: Chunghsiung Sui, Yukari N. Takayabu, K M Lau, D A ShortAbstract:Diurnal variations in atmospheric convection, dynamic/thermodynamic fields, and heat/moisture budgets over the equatorial Pacific warm pool region are analyzed based on data collected from different observation platforms during the Intensive Observation Period of the Tropical Ocean Global Atmosphere Coupled Ocean‐Atmosphere Response Experiment (TOGA COARE). Results reveal that the diurnal variations in rainfall/convection over the TOGA COARE region can be classified into three distinct stages: warm morning cumulus, afternoon Convective showers, and nocturnal Convective systems. Afternoon rainfall comes mostly from Convective cells, but the nocturnal rainfall is derived from deeper Convective cells and large areas of stratiform clouds. Results further show that afternoon Convective showers are more evident in the large-scale undisturbed periods when the diurnal SST cycle is strong, but the nocturnal Convective systems and morning cumulus are more enhanced in the disturbed periods when more moisture is available. The primary cause of the nocturnal rainfall maximum is suggested to be associated with more (less) available precipitable water in the night (day) due to the diurnal radiative cooling/heating cycle and the resultant change in tropospheric relative humidity.
D A Short - One of the best experts on this subject based on the ideXlab platform.
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diurnal variations in tropical oceanic cumulus convection during toga coare
Journal of the Atmospheric Sciences, 1997Co-Authors: Chunghsiung Sui, Yukari N. Takayabu, K M Lau, D A ShortAbstract:Diurnal variations in atmospheric convection, dynamic/thermodynamic fields, and heat/moisture budgets over the equatorial Pacific warm pool region are analyzed based on data collected from different observation platforms during the Intensive Observation Period of the Tropical Ocean Global Atmosphere Coupled Ocean‐Atmosphere Response Experiment (TOGA COARE). Results reveal that the diurnal variations in rainfall/convection over the TOGA COARE region can be classified into three distinct stages: warm morning cumulus, afternoon Convective showers, and nocturnal Convective systems. Afternoon rainfall comes mostly from Convective cells, but the nocturnal rainfall is derived from deeper Convective cells and large areas of stratiform clouds. Results further show that afternoon Convective showers are more evident in the large-scale undisturbed periods when the diurnal SST cycle is strong, but the nocturnal Convective systems and morning cumulus are more enhanced in the disturbed periods when more moisture is available. The primary cause of the nocturnal rainfall maximum is suggested to be associated with more (less) available precipitable water in the night (day) due to the diurnal radiative cooling/heating cycle and the resultant change in tropospheric relative humidity.
Thomas B Ryerson - One of the best experts on this subject based on the ideXlab platform.
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Convective transport of water vapor into the lower stratosphere observed during double tropopause events
Journal of Geophysical Research, 2014Co-Authors: Cameron R Homeyer, Laura L Pan, Samuel W Dorsi, L M Avallone, A J Weinheimer, Anthony S Obrien, J P Digangi, Mark A Zondlo, Thomas B RyersonAbstract:We present in situ observations of Convectively injected water vapor in the lower stratosphere from instruments aboard two aircraft operated during the Deep Convective Clouds and Chemistry experiment. Water vapor mixing ratios in the injected air are observed to be 60–225 ppmv at altitudes 1–2 km above the tropopause (350–370 K potential temperature), well above observed background mixing ratios of 5–10 ppmv in the lower stratosphere. Radar observations of the responsible Convective systems show deep overshooting at altitudes up to 4 km above the lapse rate tropopause and above the flight ceilings of the aircraft. Backward trajectories from the in situ observations show that Convectively injected water vapor is observed from three distinct types of systems: isolated convection, a Convective line, and a leading line-trailing stratiform mesoscale Convective system. Significant transport of additional tropospheric or boundary layer trace gases is observed only for the leading line-trailing stratiform case. In addition, all observations of Convective injection are found to occur within large-scale double-tropopause events from poleward Rossby wave breaking. Based on this relationship, we present a hypothesis on the role of the large-scale lower stratosphere during Convective overshooting. In particular, the reduced lower stratosphere stability associated with double-tropopause environments may facilitate deeper levels of overshooting and Convective injection.
