Advanced Baseline Imager Cloud-Top Trajectories and Properties of Electrified Snowfall Flash Initiation

2021 ◽  
Author(s):  
Sebastian S. Harkema ◽  
Emily B. Berndt ◽  
John R. Mecikalski ◽  
Alana Cordak
Keyword(s):  
Water Vapor ◽  
Feature Tracking ◽  
Lead Time ◽  
Environmental Changes ◽  
Detection Algorithm ◽  
Ice Crystal ◽  
Air Masses ◽  
Cloud Characteristics ◽  
Fundamental Understanding ◽  
Upper Level

AbstractUsing gridded and interpolated Derived Motion Winds from the Advanced Baseline Imager (ABI), a Lagrangian cloud-feature tracking technique was developed to create, and document trajectories associated with electrified snowfall and changes in cloud characteristics leading up to the initiation of lightning, respectively. This study implemented the thundersnow detection algorithm and defined thundersnow initiation (TSI) as the first group in a flash detected by the Geostationary Lightning Mapper when snow was occurring. Ten ABI channels and four multispectral (e.g., red-green-blue–RGB) composites were analyzed to investigate characteristics that lead up to TSI for 16,644 thundersnow (TSSN) flashes. From the 10.3 μm channel, TSI trajectories were associated with a median decrease of 12.2 K in brightness temperature (TB) one hour prior to TSI. Decreases in the reflectance component of the 3.9 μm channel indicated that TSI trajectories were associated with ice crystal collisions and/or particle settling at cloud top. The Nighttime Microphysics, Day Cloud Phase Distinction, Differential Water Vapor, and Airmass RGBs were examined to evaluate the microphysical and environmental changes prior to TSI. For daytime TSI trajectories, the predominant colors associated with the Day Cloud Phase Distinction RGB transitioned from cyan to yellow/green, physically representing cloud growth and glaciation at cloud top. Gold/orange hues in the Differential Water Vapor RGB indicated that some trajectories were associated with dry upper-level air masses prior to TSI. The analysis of ABI characteristics prior to TSI, and subsequently relating those characteristics to physical processes, inherently increases the fundamental understanding and ability to forecast TSI; thus, providing additional lead-time into changes in surface conditions (i.e., snowfall rates).

scholarly journals Upper Tropospheric Water Vapor Transport from Indian to Sahelian Regions

Atmosphere ◽  
2018 ◽  
Vol 9 (10) ◽  
pp. 403 ◽  
Author(s):  
Abdoulaye Sy ◽  
Bouya Diop ◽  
Joël Van Baelen ◽  
Christophe Duroure ◽  
Yahya Gour ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Monsoon ◽  
Water Vapor Transport ◽  
Substantial Part ◽  
Monsoon Region ◽  
Direct Role ◽  
Air Masses ◽  
Upper Troposphere ◽  
Tropical Easterly Jet

We present a study of upper tropospheric westward transport of air masses coming from the Indian monsoon zone over the period 1998–2008. The objective is to characterize upper tropospheric transport of water vapor from the Indian to Sahelian regions, and to improve the understanding of the dynamical mechanisms that govern water vapor variations in West Africa and the interconnections between India and the Sahel, focusing on the direct role of the Indian monsoon region on Sahel tropospheric water vapor and precipitation. The calculations of forward trajectories with LACYTRAJ (LACY TRAJectory code) and humidity fluxes show that a substantial part (40 to 70% at 300 hPa) of trajectories coming from the upper troposphere of the monsoon region crossed the Sahelian region in a few days (3–14 days), and water vapor fluxes connecting these two regions are established when the Indian monsoon begins at latitudes higher than 15° N in its south–north migration. The intensity and orientation of water vapor fluxes are related to the tropical easterly jet, but they are from the east above the high convection zones. Between 1998 and 2008, these fluxes between the 500–300 hPa pressure levels are associated with precipitation in Sahel only if they are from the east and with an intensity exceeding 8 kg·(m·s)−1.

scholarly journals A water vapor modulated aerosol impact on ice crystal size

2017 ◽  
Author(s):  
Bin Zhao ◽  
Kuo-Nan Liou ◽  
Yu Gu ◽  
Jonathan H. Jiang ◽  
Qinbin Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Radiative Forcing ◽  
Deep Convection ◽  
Significant Negative Correlation ◽  
Formation Mechanisms ◽  
Strong Positive Correlation ◽  
Ice Crystal ◽  
Ice Clouds ◽  
Dry Conditions ◽  
The Impact

Abstract. The interactions between aerosols and ice clouds represent one of the largest uncertainties in global radiative forcing from pre-industrial time to the present. In particular, the impact of aerosols on ice crystal effective radius (Rei), which is a key parameter determining ice clouds' net radiative effect, is highly uncertain due to limited and conflicting observational evidence. Here we investigate the effects of aerosols on Rei under different meteorological conditions using 9-year satellite observations. We find that the responses of Rei to aerosol loadings are modulated by water vapor amount in conjunction with several other meteorological parameters. While there is a significant negative correlation between Rei and aerosol loading in moist conditions, consistent with the Twomey effect for liquid clouds, a strong positive correlation between the two occurs in dry conditions. Simulations based on a cloud parcel model suggest that water vapor modulates the relative importance of different ice nucleation modes, leading to the opposite aerosol impacts between moist and dry conditions. When ice clouds are decomposed into those generated from deep convection and formed in-situ, the water vapor modulation remains in effect for both ice cloud types, although the sensitivities of Rei to aerosols differ noticeably between them due to distinct formation mechanisms. The water vapor modulation can largely explain the difference in the responses of Rei to aerosol loadings in various seasons. A proper representation of the water vapor modulation is essential for an accurate estimate of aerosol-cloud radiative forcing produced by ice clouds.

scholarly journals Relationships between Low-Level Jet and Low Visibility Associated with Precipitation, Air Pollution, and Fog in Tianjin

Atmosphere ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1197
Author(s):  
Tingting Ju ◽  
Bingui Wu ◽  
Zhaoyu Wang ◽  
Jingle Liu ◽  
Dehua Chen ◽  
...  
Keyword(s):  
Air Pollution ◽  
Water Vapor ◽  
Air Masses ◽  
Low Level ◽  
Vapor Channel ◽  
Low Visibility ◽  
Low Level Jet ◽  
Industrial Regions ◽  
Statistical Results ◽  
Pm2.5 Concentration

In this study, relationships between low-level jet (LLJ) and low visibility associated with precipitation, air pollution, and fog in Tianjin are investigated based on observational data from January to December, 2016. Statistical results show 55% of precipitation is accompanied by LLJ, and two causes responsible for the relatively high percentage are presented. The result of case analysis shows that some southwesterly LLJs are favorable for the formation of precipitation by transporting water vapor when the water vapor channel from the South China Sea or Bengal Bay to Bohai Rim region is established. Statistical results show 55% of pollution episodes (PEs) are accompanied by LLJs. When pollutions are observed in the southern industrial regions, nocturnal southwesterly LLJ, which can carry polluted air masses from polluted regions to Tianjin and induce turbulent mixing, can enhance surface PM2.5 concentration and is favorable for the formation of surface pollution at night. Nocturnal northerly or southeasterly LLJ leads to clear air masses mixing with polluted air masses and is favorable for increasing visibility. Contributions of southwesterly LLJs to the formation of fog and precipitation are similar, which both rely on establishing the water vapor channel despite occurrence heights of LLJs being different.

scholarly journals Multilayer Cloud Detection with the MODIS Near-Infrared Water Vapor Absorption Band

2010 ◽  
Vol 49 (11) ◽  
pp. 2315-2333 ◽  
Author(s):  
Galina Wind ◽  
Steven Platnick ◽  
Michael D. King ◽  
Paul A. Hubanks ◽  
Michael J. Pavolonis ◽  
...  
Keyword(s):  
Water Vapor ◽  
Near Infrared ◽  
Single Layer ◽  
Precipitable Water ◽  
Detection Algorithm ◽  
Cloud Detection ◽  
Water Vapor Absorption ◽  
Cloud Properties ◽  
Cloud Models ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract Data Collection 5 processing for the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Earth Observing System (EOS) Terra and Aqua spacecraft includes an algorithm for detecting multilayered clouds in daytime. The main objective of this algorithm is to detect multilayered cloud scenes, specifically optically thin ice cloud overlying a lower-level water cloud, that present difficulties for retrieving cloud effective radius using single-layer plane-parallel cloud models. The algorithm uses the MODIS 0.94-μm water vapor band along with CO2 bands to obtain two above-cloud precipitable water retrievals, the difference of which, in conjunction with additional tests, provides a map of where multilayered clouds might potentially exist. The presence of a multilayered cloud results in a large difference in retrievals of above-cloud properties between the CO2 and the 0.94-μm methods. In this paper the MODIS multilayered cloud algorithm is described, results of using the algorithm over example scenes are shown, and global statistics for multilayered clouds as observed by MODIS are discussed. A theoretical study of the algorithm behavior for simulated multilayered clouds is also given. Results are compared to two other comparable passive imager methods. A set of standard cloudy atmospheric profiles developed during the course of this investigation is also presented. The results lead to the conclusion that the MODIS multilayer cloud detection algorithm has some skill in identifying multilayered clouds with different thermodynamic phases.

scholarly journals Water vapor increase in the lower stratosphere of the Northern Hemisphere due to the Asian monsoon anticyclone observed during the TACTS/ESMVal campaigns

2018 ◽  
Vol 18 (4) ◽  
pp. 2973-2983 ◽  
Author(s):  
Christian Rolf ◽  
Bärbel Vogel ◽  
Peter Hoor ◽  
Armin Afchine ◽  
Gebhard Günther ◽  
...  
Keyword(s):  
Water Vapor ◽  
Northern Hemisphere ◽  
Asian Monsoon ◽  
Eastern China ◽  
Potential Temperature ◽  
Monsoon Region ◽  
Asian Monsoon Region ◽  
Air Mass ◽  
Air Masses ◽  
The Impact

Abstract. The impact of air masses originating in Asia and influenced by the Asian monsoon anticyclone on the Northern Hemisphere stratosphere is investigated based on in situ measurements. A statistically significant increase in water vapor (H2O) of about 0.5 ppmv (11 %) and methane (CH4) of up to 20 ppbv (1.2 %) in the extratropical stratosphere above a potential temperature of 380 K was detected between August and September 2012 during the HALO aircraft missions Transport and Composition in the UT/LMS (TACTS) and Earth System Model Validation (ESMVal). We investigate the origin of the increased water vapor and methane using the three-dimensional Chemical Lagrangian Model of the Stratosphere (CLaMS). We assign the source of the moist air masses in the Asian region (northern and southern India, eastern China, southeast Asia, and the tropical Pacific) based on tracers of air mass origin used in CLaMS. The water vapor increase is correlated with an increase of the simulated Asian monsoon air mass contribution from about 10 % in August to about 20 % in September, which corresponds to a doubling of the influence from the Asian monsoon region. Additionally, back trajectories starting at the aircraft flight paths are used to differentiate transport from the Asian monsoon anticyclone and other source regions by calculating the Lagrangian cold point (LCP). The geographic location of the LCPs, which indicates the region where the set point of water vapor mixing ratio along these trajectories occurs, can be predominantly attributed to the Asian monsoon region.

scholarly journals Rapid Cyclogenesis from a Mesoscale Frontal Wave on an Atmospheric River: Impacts on Forecast Skill and Predictability during Atmospheric River Landfall

2019 ◽  
Vol 20 (9) ◽  
pp. 1779-1794 ◽  
Author(s):  
Andrew C. Martin ◽  
F. Martin Ralph ◽  
Anna Wilson ◽  
Laurel DeHaan ◽  
Brian Kawzenuk
Keyword(s):  
Water Vapor ◽  
Lead Time ◽  
Forecast Skill ◽  
Vapor Transport ◽  
Lead Times ◽  
Forecast Uncertainty ◽  
Water Vapor Flux ◽  
Vapor Flux ◽  
Frontal Wave ◽  
Atmospheric River

Abstract Mesoscale frontal waves have the potential to modify the hydrometeorological impacts of atmospheric rivers (ARs). The small scale and rapid growth of these waves pose significant forecast challenges. We examined a frontal wave that developed a secondary cyclone during the landfall of an extreme AR in Northern California. We document rapid changes in significant storm features including integrated vapor transport and precipitation and connect these to high forecast uncertainty at 1–4-days’ lead time. We also analyze the skill of the Global Ensemble Forecast System in predicting secondary cyclogenesis and relate secondary cyclogenesis prediction skill to forecasts of AR intensity, AR duration, and upslope water vapor flux in the orographic controlling layer. Leveraging a measure of reference accuracy designed for cyclogenesis, we found forecasts were only able to skillfully predict secondary cyclogenesis for lead times less than 36 h. Forecast skill in predicting the large-scale pressure pattern and integrated vapor transport was lost by 96-h lead time. For lead times longer than 36 h, the failure to predict secondary cyclogenesis led to significant uncertainty in forecast AR intensity and to long bias in AR forecast duration. Failure to forecast a warm front associated with the secondary cyclone at lead times less than 36 h caused large overprediction of upslope water vapor flux, an important indicator of orographic precipitation forcing. This study highlights the need to identify offshore mesoscale frontal waves in real time and to characterize the forecast uncertainty inherent in these events when creating hydrometeorological forecasts.

scholarly journals The South Carolina Flood of October 2015: Moisture Transport Analysis and the Role of Hurricane Joaquin

2017 ◽  
Vol 18 (11) ◽  
pp. 2973-2990 ◽  
Author(s):  
Christopher G. Marciano ◽  
Gary M. Lackmann
Keyword(s):  
South Carolina ◽  
Water Vapor ◽  
Moisture Transport ◽  
Heavy Precipitation ◽  
Water Vapor Content ◽  
Precipitation Event ◽  
The South ◽  
Flooding Event ◽  
Additional Water ◽  
Upper Level

Abstract Record-setting rainfall occurred over the state of South Carolina in early October 2015, with maximum accumulations exceeding 500 mm. During the heavy rainfall, Hurricane Joaquin was located offshore to the southeast of the flooding event. Prior research, storm summaries, satellite imagery, and media accounts suggest that Joaquin played a major role in the flooding, mostly through the provision of additional water vapor. Here, numerical simulations are utilized to elucidate Joaquin’s role in the flooding and to diagnose moisture transport mechanisms. The South Carolina precipitation event and the track of Hurricane Joaquin are reasonably represented by two control simulations, a 36-km simulation without nesting and another with 12- and 4-km nests added; the latter improves upon a negative intensity bias for Joaquin. A band of intense moisture transport into the flooding region is associated with a narrow, diabatically produced cyclonic lower-tropospheric potential vorticity (PV) maximum. Simulations in which Joaquin is removed exhibit a similar moisture transport mechanism and also produce a band of heavy precipitation, though the axis of heaviest precipitation shifts northward into North Carolina, and there is a modest reduction (~7%) in area-averaged rainfall. Removing Joaquin produces negligible changes in regional total water vapor content but diminished upper-tropospheric diabatic outflow. The diminished outflow allows greater eastward progression of an upper-level trough, consistent with the northward precipitation shift and with weaker forcing for ascent. Changes in the upper jet associated with Joaquin appear to exert a greater influence on the flooding event than Joaquin’s contribution to water vapor content.

scholarly journals Empirical Modeling of Layered Integrated Water Vapor Using Surface Mixing Ratio in Nigeria

2009 ◽  
Vol 48 (2) ◽  
pp. 369-380 ◽  
Author(s):  
B. Adeyemi
Keyword(s):  
Water Vapor ◽  
Empirical Modeling ◽  
Specific Humidity ◽  
Mixing Ratio ◽  
Coastal Station ◽  
Northern Regions ◽  
Surface Mixing ◽  
Kolmogorov Smirnov ◽  
The Difference ◽  
Upper Level

Abstract Using the available upper-air data for three stations in Nigeria (Lagos, a coastal station; Minna, an inland station; and Kano, a sub-Sahelian station), an intensive examination has been carried out on the linkage between surface mixing ratio rs and layered integrated water vapor W (g cm−2) over Nigeria. The goal was to identify the seasonal distribution of the parameter and to develop models that can best be used to estimate W from surface mixing ratio. To achieve these objectives, integrated water vapor at the low level (WL), midlevel (Wm), and upper level (Wu) and total column integrated water WT have been calculated using daily values of upper-air data spanning over a decade from the above three radiosonde stations. A relationship of the form W = αrs + β (where α and β are constants) has been established between W and rs using the analysis-of-variance (ANOVA) technique. Tests carried out on the models, using daily soundings made in 1990 for Lagos, 1983 for Minna, and 1991 for Kano, respectively, gave encouraging results as established by the use of Kolmogorov–Smirnov tests. Owing to the difference in the climatological patterns of precipitation among the different regions in Nigeria (i.e., southern, midland, and northern regions) as represented by the three stations, no single relationship was found to be suitable for the entire country of Nigeria. Earlier models, generally of the form W = αqb (where α and b are constants and q is specific humidity), were found to be less adequate over the stations.

scholarly journals Two types of quasi-liquid layers on ice crystals are formed kinetically

2016 ◽  
Vol 113 (7) ◽  
pp. 1749-1753 ◽  
Author(s):  
Harutoshi Asakawa ◽  
Gen Sazaki ◽  
Ken Nagashima ◽  
Shunichi Nakatsubo ◽  
Yoshinori Furukawa
Keyword(s):  
Water Vapor ◽  
Vapor Pressure ◽  
Water Vapor Pressure ◽  
Thin Layers ◽  
Ice Crystals ◽  
Ice Crystal ◽  
Crystal Surfaces ◽  
Fixed Temperature ◽  
Elementary Steps ◽  
Ice Surfaces

Surfaces of ice are covered with thin liquid water layers, called quasi-liquid layers (QLLs), even below their melting point (0 °C), which govern a wide variety of phenomena in nature. We recently found that two types of QLL phases appear that exhibit different morphologies (droplets and thin layers) [Sazaki G. et al. (2012) Proc Natl Acad Sci USA 109(4):1052−1055]. However, revealing the thermodynamic stabilities of QLLs remains a longstanding elusive problem. Here we show that both types of QLLs are metastable phases that appear only if the water vapor pressure is higher than a certain critical supersaturation. We directly visualized the QLLs on ice crystal surfaces by advanced optical microscopy, which can detect 0.37-nm-thick elementary steps on ice crystal surfaces. At a certain fixed temperature, as the water vapor pressure decreased, thin-layer QLLs first disappeared, and then droplet QLLs vanished next, although elementary steps of ice crystals were still growing. These results clearly demonstrate that both types of QLLs are kinetically formed, not by the melting of ice surfaces, but by the deposition of supersaturated water vapor on ice surfaces. To our knowledge, this is the first experimental evidence that supersaturation of water vapor plays a crucially important role in the formation of QLLs.

scholarly journals Middle Holocene rapid environmental changes and human adaptation in Greece

2016 ◽  
Vol 85 (2) ◽  
pp. 227-244 ◽  
Author(s):  
Laurent Lespez ◽  
Arthur Glais ◽  
José-Antonio Lopez-Saez ◽  
Yann Le Drezen ◽  
Zoï Tsirtsoni ◽  
...  
Keyword(s):  
Climate Change ◽  
Environmental Changes ◽  
Eastern Mediterranean ◽  
Late Neolithic ◽  
Air Masses ◽  
The Balkans ◽  
Middle Holocene ◽  
Dramatic Decline ◽  
Societal Changes ◽  
Climate Transition

Numerous researchers discuss of the collapse of civilizations in response to abrupt climate change in the Mediterranean region. The period between 6500 and 5000 cal yr BP is one of the least studied episodes of rapid climate change at the end of the Late Neolithic. This period is characterized by a dramatic decline in settlement and a cultural break in the Balkans. High-resolution paleoenvironmental proxy data obtained in the Lower Angitis Valley enables an examination of the societal responses to rapid climatic change in Greece. Development of a lasting fluvio-lacustrine environment followed by enhanced fluvial activity is evident from 6000 cal yr BP. Paleoecological data show a succession of dry events at 5800–5700, 5450 and 5000–4900 cal yr BP. These events correspond to incursion of cold air masses to the eastern Mediterranean, confirming the climatic instability of the middle Holocene climate transition. Two periods with farming and pastural activities (6300–5600 and 5100–4700 cal BP) are evident. The intervening period is marked by environmental changes, but the continuous occurrence of anthropogenic taxa suggests the persistence of human activities despite the absence of archaeological evidence. The environmental factors alone were not sufficient to trigger the observed societal changes.

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