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AGU期刊一周Research Spotlight
AGU发布最新Editor's Highlight和国外工作学习机会(Jan 4~Jan 10, 2020)
时间:2020年01月10日 15:05来源: 点击数:

Microphysics and Positive Lightning in Hokuriku Winter Clouds

The microphysics of the frequent, and frequently positive, lightning of Hokuriku winter clouds was investigated by systematic, in situ observation of individual precipitation particle type and charge.

SOURCE: Journal of Geophysical Research: Atmospheres

Model of cloud development, charge evolution, and cloud-to-ground lightning initiation in Hokuriku winter clouds. The main charging mechanism is riming electrification, in which collisions between graupel particles and ice crystals leave them oppositely charged, with the polarity of the separated charge dependent on temperature. Mid-level, negatively charged graupel particles in the mature stage are the main source of negative lightning. Positively charged ice crystals, blown out of the upper level of mature stage clouds by wind shear and then descending, may be the main source of positive lightning. Credit: Takahashi et al. [2019], Figure 10

The winter storm clouds of the Hokuriku region of Japan, though relatively shallow, are famous not only for producing prodigious amounts of snow, but also for producing high frequencies of lightning. An unusually high proportion is positive lightning, that is, lightning that has an electric charge opposite of the more common negative lightning.

Takahashi et al. [2019] present a comprehensive and detailed analysis of balloon-borne and ground-based observations of these storms, attributing microphysical parameters in the thunderclouds to lightning types and origins. The authors found that the space charge increases with the number concentrations of graupel particles and ice crystals, indicating riming electrification. The charge structures of the different stages of the cloud life cycle were also obtained.

In addition, they found enormous numbers of small ice particles which appear to have been ejected from the graupel particle surface in inter-particle collisions. The small particles generated by this new ice multiplication mechanism could contribute substantially to seeding the development of the large numbers of ice crystals which support the high electrification of these clouds.

The results of this manuscript shed substantial light on the relationship between the distribution of hydrometeor particles and charge structure.

Citation: Takahashi, T., Sugimoto, S., Kawano, T., & Suzuki, K. [2019]. Microphysical structure and lightning initiation in Hokuriku winter clouds. Journal of Geophysical Research: Atmospheres, 124. https://doi.org/10.1029/2018JD030227

—Minghua Zhang, Editor in Chief, JGR: Atmospheres

AGU发布最新国外工作学习机会:

1.Postdoc - Terrestrial Biogeochemical Modeling

Oak Ridge, Tennessee

competitive salary, full benefits, paid relocation, paid vacation, on-site fitness / wellness center

The Environmental Sciences Division at Oak Ridge National Laboratory is seeking a postdoc with expertise in terrestrial biogeochemical modeling.

https://findajob.agu.org/job/8011879/postdoc-terrestrial-biogeochemical-modeling/

2.PhD students - Remote Sensing

Valencia (Provincia), Comunidad Valenciana (ES)

We are seeking for highly motivated PhD students, starting in fall semester in the year 2020.

The new students will have an option to pursue a Ph.D. degree in Remote Sensing at the University of Valencia, and will have the opportunity to participate in the GenT-sponsored project on improving regional-scale projections of climate variability and change through data-informed decision making.

https://findajob.agu.org/job/8011878/phd-students-remote-sensing/

3.Postdoctoral Research Position Working at the Forefront of Plant Growth Predictive Modelling

University of Adelaide

AUD$97,577 per annum plus an employer contribution of up to 17% superannuation may apply

The researcher will develop predictive models for the viticulture sector to optimise resource consumption (including water, chemical and energy).

https://findajob.agu.org/job/8011864/postdoctoral-research-position-working-at-the-forefront-of-plant-growth-predictive-modelling/?LinkSource=PremiumListing

4.USDA-ARS Postdoctoral Associate (Agricultural Engineer/Hydrologist/Soil Scientist)

East Wareham, Massachusetts

$69,016 to $89,726 per year

USDA -Agricultural Research Service, Pasture Systems and Watershed Management Unit

USDA-ARS is seeking a postdoctoral research associate to conduct research on water quality and drainage management in agriculture.

https://findajob.agu.org/job/8011861/usda-ars-postdoctoral-associate-agricultural-engineer-hydrologist-soil-scientist-/?LinkSource=PremiumListing

5.Doctoral Researchers in Atmospheric Physics

Kuehlungsborn/Germany

Leibniz-Institut of Atmospheric Physics

The IAP focusses its research in the middle atmosphere and offers 7 maily experimental PhD positions, covering lidar, radar and in situ.

https://findajob.agu.org/job/8011857/doctoral-researchers-in-atmospheric-physics/

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