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Hung-I Lee (UCLA), Monsoon Onset and...

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Upcoming Seminar

Hung-I Lee (UCLA), Monsoon Onset and Precipitation Control by Mid-Latitude Waves in Modern and Glacial Climates

Wed, Apr 24, 2019

MS 7124

Monsoons are now increasingly considered seasonal and local migrations of the IntertropicalConvergence Zone (ITCZ). However, the East Asian and North American monsoonsextend well into the subtropics and midlatitudes and do not feature a well-defined crossequatorialflow, thus indicating that this well-adopted theory may be inadequate. Becauseof its importance to humanity, predicting monsoon onset remains a pressing goal of modernmeteorology. From a global space-time diagram of column water vapor (CWV) at 30Nlatitude from daily reanalysis data, we found two longitude-origin of atmospheric rivers(LOARs) that feature locally enhanced CWV and evolve from the Eastern Pacific/Atlanticbasins in the winter to the Western Pacific/Atlantic in the summer. East Asian SummerMonsoon (EASM) onset coincides with the time CWV in the Pacific LOAR first exceeds40 mm, which also typically occurs just before it makes landfall. LOARs exist in 39-year(1979-2017) daily climatological mean CWV, demonstrating the seasonal cycles of these featuresare quasi-stationary and potentially useful for monsoon onset prediction. EASM onsetis particularly predictable following El Niño Southern Oscillation (ENSO), consistently occurringone month after the LOAR crosses the dateline. Simplified GCM experiments anda semi-empirical theory reveal a plausible mechanism of LOAR formation, thus opening anew window into seasonal-scale prediction of subtropical monsoon extensions.The impotance of mid-latitude waves on monsoon precipitation distribution is also observedduring Last Glacial Maximum (LGM, 21ka) climate and leads to moistening of theLGM American Southwest. Here, we compare a synthesis of pollen proxies of precipitationduring Last Glacial Maximum (LGM, 21ka) over North America to constrain the PaleoclimateIntercomparison Model Project (PMIP3) ensemble. In model simulations that comparefavorably with proxy synthesis, we find a strong correlation between monsoon precipitationand meridional wind anomaly, suggesting the patterns are mainly governed by stationarywave forcing. The major perturbations of meridional wind anomaly under LGM consist of topographicforcing due to rising elevation from the Laurentide ice sheets and thermodynamicforcing due to alteration of the mean state from albedo change. Weak stationary waves andwesterlies are generated by models with favorable comparison to the proxy synthesis.

Cigdem Akan	Postdoctoral Scholar	akanc [at] ucla.edu
Xin An	Postdoctoral Scholar	xinan [at] atmos.ucla.edu
Akio Arakawa	Distinguished Research Professor Emeritus	aar [at] atmos.ucla.edu	MSA 7141
Tersi Arias	Graduate Student	tersiarias [at] atmos.ucla.edu
Cody Ashe-McNalley	Systems Administrator / Programmer	cody [at] atmos.ucla.edu	MSA 7101
Roy Bakarn	Postdoctoral Scholar
Daniele Bianchi	Assistant Professor	dbianchi [at] atmos.ucla.edu	MSA 7949
Jacob Bortnik	Associate Professor	jbortnik [at] atmos.ucla.edu	MSA 7228
Nathaniel Brockway	Graduate Student	nwbrock [at] atmos.ucla.edu
Marcelo Chamecki	Associate Professor	chamecki [at] ucla.edu
Yi Chao	Adjunct Professor	ychao001 [at] gmail.com
Mickael D. Chekroun	Associate researcher	mchekroun [at] atmos.ucla.edu
Gang Chen	Associate Professor	gchenpu [at] atmos.ucla.edu	MSA 7149
Jie Rou Chen	Graduate Student	jchen [at] atmos.ucla.edu
Tomas Chor	Graduate Student	tomaschor [at] atmos.ucla.edu
Chris Collimore	Graduate Student	cccollimore [at] atmos.ucla.edu
Santo Fedele Colosimo	Postdoctoral Scholar	fedele [at] atmos.ucla.edu
Daniel Dauhajre	Graduate Student	ddauhajre [at] atmos.ucla.edu
Anthony DeAngelis	Postdoctoral Scholar	adeangelis [at] atmos.ucla.edu
Daphne Dizon	Administrative Specialist	djdizon [at] atmos.ucla.edu	MS 7127
Charles Dong	Research Professor	cdong [at] atmos.ucla.edu
Rob Eagle	Assistant Professor	robeagle [at] g.ucla.edu
Annmarie Eldering	Adjunct Assistant Professor	eldering [at] atmos.ucla.edu
Monica Fiello	Administrative Assistant
Robert Fovell	Professor Emeritus	fovell [at] atmos.ucla.edu	MSA 7162
Randall Friedl	Adjunct Professor
Rong Fu	Professor	rfu [at] atmos.ucla.edu	MSA 7173
Michael Ghil	Distinguished Research Professor	ghil [at] atmos.ucla.edu	MSA 7236
Geoff Girard	Chief Administrative Officer	girard [at] atmos.ucla.edu	MS 7133
David Gonzalez-Martinez	Graduate Student	dhgonzalez89 [at] ucla.edu
Matthew Grieco	Graduate Student	mgrieco [at] atmos.ucla.edu
Andreas Groth	Researcher	andreasgroth [at] atmos.ucla.edu	MS 7234
Yu Gu	Researcher	gu [at] atmos.ucla.edu	GE 2645
Jonathan Gula	Assistant Researcher
Katrina Hales	Staff Research Associate
Alex Hall	Professor/Vice Chair	alexhall [at] atmos.ucla.edu	MSA 7955
Larry Harding	Adjunct Professor	lharding [at] atmos.ucla.edu	SH 5853
Julia Hazel	Graduate Student	jhazel [at] atmos.ucla.edu
Spencer Hill	Postdoctoral Scholar	shill [at] gps.caltech.edu	Geology 4684
Dial Hoang	Graduate Student	dhoang [at] atmos.ucla.edu
Yue Huang	Graduate Student	yhuang [at] atmos.ucla.edu
Steve Hurlock	Assistant Researcher	steveh [at] atmos.ucla.edu	BH 9277A
Alex Jousse	Postdoctoral Scholar	jousse [at] atmos.ucla.edu
Heejeong Kim	Assistant Researcher	heekim [at] atmos.ucla.edu	MS 7115
Jinwon Kim	Researcher	jkim [at] atmos.ucla.edu	GE 2645
Jasper Kok	Associate Professor	jfkok [at] ucla.edu	MSA 7142
Dmitri Kondrashov	Researcher	dkondras [at] atmos.ucla.edu	MS 7232
Yi-Hung Kuo	Graduate Student	yhkuo [at] atmos.ucla.edu
Baird Langenbrunner	Researcher	baird [at] atmos.ucla.edu
Hung-I Lee	Graduate Student	hilee [at] atmos.ucla.edu
Anita Leinweber	Adjunct Assistant Professor	leinweber [at] igpp.ucla.edu	SH 5843
Sydnie Lemieux	Graduate Student	slemieux [at] atmos.ucla.edu
Grace Leon	Contract and Grants Manager	gleon [at] atmos.ucla.edu	MS 7127
Kara Leung	User Support & Systems Administrator	kleung [at] atmos.ucla.edu	MS 7101A
Jeffrey Lew	Lecturer	lew [at] atmos.ucla.edu	MSA 1963
Jinxing Li	Postdoctoral Scholar	jli [at] atmos.ucla.edu
Qinbin Li	Professor	qli [at] atmos.ucla.edu	MSA 7220
Wen Li	Assistant Researcher	moonli [at] atmos.ucla.edu	MS 7984
Kuo-Nan Liou	Distinguished Professor	knliou [at] atmos.ucla.edu	MSA 7163
Denise Lopez	Administrative Specialist	dlopez [at] atmos.ucla.edu	MS 7127
Larry Lyons	Distinguished Professor	larry [at] atmos.ucla.edu	MSA 7138
Qianli Ma	Postdoctoral Scholar	qianlima [at] atmos.ucla.edu
Raleigh Martin	Postdoctoral Scholar	raleighm [at] atmos.ucla.edu	BH 9258
Cristian Martinez-Villalobos	Postdoctoral Scholar	cmartinezvil [at] atmos.ucla.edu
Matthew McKinney	Graduate Student	mmckinney [at] atmos.ucla.edu
Diana McWilliams	Administrative Specialist	dmcw [at] atmos.ucla.edu	MSA 7983
Jim McWilliams	Louis B. Slichter Professor of Earth Sciences	jcm [at] atmos.ucla.edu	MSA 7983
C. Roberto Mechoso	Distinguished Professor	mechoso [at] atmos.ucla.edu	MSA 7173
Joyce E. Meyerson	Staff Research Associate
Jonathan Mitchell	Associate Professor	mitch [at] atmos.ucla.edu	GE 4684
Jeroen Molemaker	Associate researcher	nmolem [at] atmos.ucla.edu
Jordyn Moscoso	Graduate Student	jmoscoso [at] atmos.ucla.edu
James Murakami	Staff Meteorologist	tenki [at] atmos.ucla.edu	MS 7101
Timothy Myers	Postdoctoral Scholar	tamyers [at] atmos.ucla.edu
J. David Neelin	Professor	neelin [at] atmos.ucla.edu	MSA 7969
Yukitoshi Nishimura	Assistant Researcher	toshi [at] atmos.ucla.edu	MS 7115
Jesse Norris	Project Scientist	jessenorris [at] ucla.edu	MS 7235
Paul Northrop	Assistant Development Engineer
S. C. (Steve) Ou	Researcher	ssou [at] atmos.ucla.edu	GE 2645
Suzanne Paulson	Professor	paulson [at] atmos.ucla.edu	MSA 7157
Kimberly Perez	Student Affairs Officer	kperez [at] atmos.ucla.edu	MS 7127
Ole Peters	Assistant Researcher	ole [at] santafe.edu
Olga Pikelnaya	Researcher	olga [at] atmos.ucla.edu
Victor Pinto	Graduate Student	vpinto [at] ucla.edu
Xin Qu	Assistant Researcher	xinqu [at] atmos.ucla.edu
Dilhara Ranasinghe	Graduate Student	dilharar [at] atmos.ucla.edu	BH 9277
Katharine Reich	Administrative Specialist
Lionel Renault	Assistant Researcher
Rigoberto Resendiz	Contract and Grants Manager	rigoberto.resendiz [at] stat.ucla.edu	MS 8125D
Pablo Saide	Assistant Professor	saide [at] atmos.ucla.edu	MSA 7234
Ulli Seibt	Associate Professor	ulli [at] atmos.ucla.edu	MSA 7975
Alexander Shchepetkin	Project Scientist	alex [at] atmos.ucla.edu
Yong Shi	Assistant Researcher	yongshi [at] atmos.ucla.edu
Aviv Solodoch	Graduate Student	asolodoch [at] atmos.ucla.edu
Andrew Stewart	Assistant Professor	astewart [at] atmos.ucla.edu	MSA 7162
Jochen Stutz	Professor / Chair	jochen [at] atmos.ucla.edu	MSA 7172
Hui Su	Adjunct Professor	Hui.Su [at] jpl.nasa.gov
Fengpeng Sun	Assistant Researcher	sun [at] atmos.ucla.edu	MS 7343
Wu Sun	Graduate Student	wu.sun [at] ucla.edu	MS 7221
Yoshihide Takano	Project Scientist	ytakano [at] atmos.ucla.edu	GE B691
Richard Thorne	Distinguished Professor	rmt [at] atmos.ucla.edu	MSA 7979
Tina Treude	Professor	ttreude [at] g.ucla.edu	SH 5859
Aradhna Tripati	Associate Professor	ripple [at] zephyr.ess.ucla.edu	GE 2659
Katie Tuite	Graduate Student	ktuite [at] atmos.ucla.edu
Richard Turco	Distinguished Professor Emeritus	turco [at] atmos.ucla.edu	MSA 7157
Francis Turney	Graduate Student	fturney [at] ucla.edu
Duane Waliser	Adjunct Professor	duane.waliser [at] jpl.nasa.gov	MSA 7969
Chih-Ping Wang	Associate researcher	cat [at] atmos.ucla.edu	MS 7115
Boyi Wang	Graduate Student	bywang [at] atmos.ucla.edu
Xiaoyan Xing	Assistant Researcher	xyxing [at] atmos.ucla.edu
Yongkang Xue	Professor	yxue [at] geog.ucla.edu	Bunche 1255
Chao Yue	Postdoctoral Scholar	yuechao [at] atmos.ucla.edu
Henry Zapata	User Support Specialist	henryz [at] atmos.ucla.edu	MS 7101
Eftyhia Zesta	Associate researcher	ezesta [at] atmos.ucla.edu	MS 7220
Ken Zhao	Graduate Student	kzhao [at] atmos.ucla.edu
Ying Zou	Postdoctoral Scholar	ying [at] atmos.ucla.edu

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