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Observational constraints on the shape...

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Upcoming Seminar

Observational constraints on the shape and size of desert dust: implications for global aerosol models and remote sensing retrievals

Wed, May 12, 2021

270 Seminar

Speaker: Yue Huang

Institution: UCLA

Abstract:

Desert dust is the dominant aerosol type by mass in the atmosphere. Dust impacts on various aspects of the Earth system depend sensitively on its shape and size. However, global aerosol models and remote sensing retrievals struggle to correctly account for dust shape and size for a few reasons. These issues include that (i) models and retrieval algorithms lack a consistent and accurate quantification of dust shape, (ii) models and retrievals substantially underestimate the abundance of coarse dust in the atmosphere relative to measurements, and (iii) measurements of size distributions are also problematic because they are based on different diameter types that do not account for realistic dust shapes.

To address the three issues, I first compile dozens of in situ observations of dust shape across the globe to obtain a globally representative constraint on the probability distributions describing dust shape. I show that models and retrieval algorithms substantially underestimate dust asphericity by a factor of ~3–5. As aspherical dust deposits less quickly from the atmosphere, this underestimated dust asphericity causes models to underestimate dust lifetime by ~20%. I then use this shape constraint to correct a compilation of measurements of the size distributions of emitted dust that neglected this substantial dust asphericity. I find that accounting for asphericity yields a substantially coarser emitted dust size distribution and that, consequently, current parameterizations underestimate coarse dust emission by more than a factor of ∼2.

These findings have several key implications. First, our results highlight the importance of standardized diameter conversions. A lack of such standardization can generate substantial biases, for instance in the measurements of size distributions. Second, our findings that models and retrievals underestimate both dust asphericity and coarse dust emission help explain why models underestimate the abundance of coarse dust in the atmosphere. Furthermore, our simple observational constraints on dust shape and size are being implemented into global aerosol models.This work could ultimately help narrow the large uncertainties on dust impacts.

Blanca Alvarez	Graduate Student	balvarez [at] atmos.ucla.edu
Tersi Arias	Graduate Student	tersiarias [at] atmos.ucla.edu
Alex Arnold	Graduate Student
Catherine Banach		cbanach [at] atmos.ucla.edu
Marco Sandoval Belmar	Graduate Student	marcsandovalb [at] atmos.ucla.edu
Nathaniel Brockway	Graduate Student	nwbrock [at] atmos.ucla.edu
Zhijiong Cao	Graduate Student	czj9763 [at] g.ucla.edu
Santiago Giraldo Cardenas	Graduate Student	santigiraldoc [at] atmos.ucla.edu
Daniel Clements	Graduate Student	dclements [at] atmos.ucla.edu
Jackson Darke	Graduate Student	jdarke40 [at] atmos.ucla.edu
Xiuyuan Ding	Graduate Student	dingxy [at] atmos.ucla.edu
Todd Emmenegger	Graduate Student	temmen [at] atmos.ucla.edu
Alyson Fritzmann		afritzmann [at] ucla.edu
Bowen Ge		gebowen [at] ucla.edu
Sara Graves		saragraves [at] ucla.edu
Paige Hoel	Graduate Student	paigehoel [at] atmos.ucla.edu
Calvin Howes	Graduate Student	calvinhowes [at] atmos.ucla.edu
Yue Huang	Graduate Student	yhuang [at] atmos.ucla.edu
Sarah Johnson	Graduate Student	sjohnson [at] atmos.ucla.edu
Ning Kang		nkang20 [at] atmos.ucla.edu
Yi-Hung Kuo	Graduate Student	yhkuo [at] atmos.ucla.edu
Danny Leung	Graduate Student	dannymleung [at] g.ucla.edu
Jiawen Li	Graduate Student	jiawen0110 [at] atmos.ucla.edu
Bessie Liu	Graduate Student	bessieliu [at] ucla.edu
Weiming Ma	Graduate Student	mawei [at] atmos.ucla.edu
Donglai Ma	Graduate Student	dma96 [at] atmos.ucla.edu
Gavin Madakumbura	Graduate Student	gavindayanga [at] atmos.ucla.edu
Daniel McCoy	Graduate Student	demccoy [at] atmos.ucla.edu
Matthew McKinney	Graduate Student	mmckinney [at] atmos.ucla.edu
Jordyn Moscoso	Graduate Student	jmoscoso [at] atmos.ucla.edu
Zoe Pierrat	Graduate Student	zpierra [at] atmos.ucla.edu
Mingxin Qu	Graduate Student	mingxin23 [at] atmos.ucla.edu
De'Marcus Robinson	Graduate Student	demarcu1.robinson [at] atmos.ucla.edu
Rodrigo Rodakoviski	Graduate Student	rodakoviski [at] atmos.ucla.edu
Jiaqi Shen	Graduate Student	jqshen [at] ucla.edu
Zhan Shi		zhanshi1997 [at] gmail.com
Clara Si	Graduate Student	csi [at] atmos.cula.edu
Dominique Stumbaugh		NSTUMBAUGH07 [at] GMAIL.COM
Katie Tuite	Graduate Student	ktuite [at] atmos.ucla.edu
Francis Turney	Graduate Student	fturney [at] ucla.edu
Sarah Worden	Graduate Student
Kyongwon (Kevin) Yoo	Graduate Student	kyongwonyoo93 [at] atmos.ucla.edu
Ken Zhao	Graduate Student	kzhao [at] atmos.ucla.edu
Zewen Zheng	Graduate Student	zewenzheng [at] atmos.ucla.edu
Kuilin Zhu		kuilin [at] g.ucla.edu

67°

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