Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder

Xinzhao Chu

Research Interests

My research goal is to explore unknowns in the atmosphere, space, and beyond. My group works to explore advanced spectroscopy principles and develop new lidar technologies to push detection limits and make new discoveries. By making measurements with unprecedented accuracy, resolution, and coverage, we study the fundamental physical and chemical processes that govern the structures and dynamics of the whole atmosphere, and advance the understanding of the universal processes in the Earth’s space-atmosphere interaction region and how they shape the atmospheres of Earth-like planets. In our quest to develop whole-atmosphere lidar and to explore the unmapped, we also aim to realize the full potential of lidar, making practical use of it to serve the world. 

Current Research

Lidar marathons in Antarctica and plasma-neutral atmosphere coupling

Discoveries of thermospheric neutral iron (Fe) layers (Chu et al., Geophys. Res. Lett., 2011), solar effects on Fe layer bottomside (Yu et al., J. Geophys. Res., 2012), persistent inertia-gravity waves (Chen et al., J. Geophys. Res., 2013), and super-exponential growth of thermal tide amplitude above 100 kilometers (Fong et al., J. Geophys. Res., 2014) by lidar observations in Antarctica are challenging our understanding of electrodynamics, neutral dynamics, chemistry, composition, and energetics in Earth’s geospace environment. CIRES students Zhibin Yu and Weichun Fong in the Chu research group are developing numerical models to study the mechanisms. We achieved initial success, having successfully modeled the thermospheric Fe layers after carefully considering the neutral-plasma coupling and the influences of polar electric field, vertical wind, and aurora activity (see figure). These science discoveries are motivating the atmosphere and space science community with a new initiative, Observatory for Atmosphere Space Interaction Studies (OASIS).

This also has been a year of setting records. The CIRES lidar team set a historic record for lidar observations: a continuous 174 hours of observations from Dec. 29, 2013, to Jan. 6, 2014, in Antarctica. CIRES student Cao Chen set new records, making continuous, sole-operator, 53- and 65-hour lidar observations in the harsh Antarctic winter. CIRES student John Smith and CIRES researcher Wentao Huang achieved lidar signal levels of 2,400 counts per shot at Boulder, Colorado. These long and very high-resolution data sets are invaluable in pushing the envelope of upper atmosphere sciences. Another unprecedented record: CIRES students in the Chu group have won prizes every year from 2009 to 2014 in the Coupling, Energetic, and Dynamics of Atmospheric Regions (CEDAR) Student Poster Competition— most recently Zhibin Yu in 2013 and Weichun Fong in 2014. CIRES researcher Xian Lu won a CEDAR grant as the principal investigator for the first time. Congratulations to these creative students and researchers!

Thermospheric iron (Fe) layers (top) discovered by lidar observations on May 28, 2011, at McMurdo, Antarctica (Chu et al., Geophys. Res. Lett., 2011) have been successfully modeled with a new thermospheric Fe/Fe+ model (middle and bottom) through the coupling between Fe+ and Fe layers in the polar geospace (Yu and Chu, J. Geophys. Res., 2014).

"Members" of the lidar team (from left to right: Cao Chen, Xinzhao Chu, and Jian Zhao) deployed in the summer of 2013–2014 at McMurdo, Antarctica.

CIRES Ph.D. students Cao Chen and Jian Zhao jump up at Arrival Heights Lidar Observatory near McMurdo, Antarctica, to celebrate an extremely successful summer season and Chen's qualification to winter-over in 2014.

Honors and Awards

  • Faculty Early Career Development (CAREER) Award, National Science Foundation
  • Director, Consortium Technology Center for the Consortium of Resonance and Rayleigh Lidars, National Science Foundation

View Publications

  • Jiao J; Chu X; Jin H; Wang Z; Xun Y; Du L; Zheng H; Wu F; Xu J; Yuan W. (Sep 2022). First Lidar Profiling of Meteoric Ca; +; Ion Transport From ?80 to 300km in the Midlatitude Nighttime Ionosphere. Geophysical Research Letters , 49(18). 10.1029/2022gl100537
  • Wu F; Chu X; Du L; Jiao J; Zheng H; Xun Y; Feng W; Plane JMC; Yang G. (Aug 2022). First Simultaneous Lidar Observations of Thermosphere?Ionosphere Sporadic Ni and Na (TISNi and TISNa) Layers (?105120km) Over Beijing (40.42N, 116.02E). Geophysical Research Letters , 49(16). 10.1029/2022gl100397
  • Chu X; Gardner CS; Li X; Ying?Tsen Lin C. (Jul 2022). Vertical Transport of Sensible Heat and Meteoric Na by the Complete Temporal Spectrum of Gravity Waves in the MLT Above McMurdo (77.84?S, 166.67?E), Antarctica. Journal of Geophysical Research: Atmospheres. 10.1029/2021jd035728
  • Jandreau J; Chu X. (Dec 2021). Comparison of Three Methodologies for Removal of Random?Noise?Induced Biases From Second?Order Statistical Parameters of Lidar and Radar Measurements. Earth and Space Science. 10.1029/2021ea002073
  • Chu X; Chen Y; Cullens CY; Yu Z; Xu Z; Zhang S-R; Huang W; Jandreau J; Immel TJ; Richmond AD. (Jun 2021). Mid-Latitude Thermosphere-Ionosphere Na (TINa) Layers Observed With High-Sensitivity Na Doppler Lidar Over Boulder (40.13 degrees N, 105.24 degrees W). Geophysical Research Letters , 48(11). 10.1029/2021gl093729
  • Emmert JT; Drob DP; Picone JM; Siskind DE; Jones M; Mlynczak MG; Bernath PF; Chu X; Doornbos E; Funke B. (Mar 2021). NRLMSIS 2.0: A Whole-Atmosphere Empirical Model of Temperature and Neutral Species Densities. Earth and Space Science , 8(3). 10.1029/2020EA001321
  • Chu X; Nishimura Y; Xu Z; Yu Z; Plane JMC; Gardner CS; Ogawa Y. (Oct 2020). First Simultaneous Lidar Observations of Thermosphere-Ionosphere Fe and Na (TIFe and TINa) Layers at McMurdo (77.84 degrees S, 166.67 degrees E), Antarctica With Concurrent Measurements of Aurora Activity, Enhanced Ionization Layers, and Converging Electric Field. Geophysical Research Letters , 47(20). 10.1029/2020GL090181
  • Gardner CS; Chu X. (Sep 2020). Eliminating photon noise biases in the computation of second-order statistics of lidar temperature, wind, and species measurements. Applied Optics , 59(27), 8259-8271. 10.1364/AO.400375
  • Wu H; Lu X; Lu G; Chu X; Wang W; Yu Z; Kilcommons LM; Knipp DJ; Wang B; Nishimura Y. (Sep 2020). Importance of Regional-Scale Auroral Precipitation and Electrical Field Variability to the Storm-Time Thermospheric Temperature Enhancement and Inversion Layer (TTEIL) in the Antarctic E Region. Journal of Geophysical Research: Space Physics , 125(9). 10.1029/2020JA028224
  • Li Z; Chu X; Harvey VL; Jandreau J; Lu X; Yu Z; Zhao J; Fong W. (Aug 2020). First Lidar Observations of Quasi-Biennial Oscillation-Induced Interannual Variations of Gravity Wave Potential Energy Density at McMurdo via a Modulation of the Antarctic Polar Vortex. Journal of Geophysical Research: Atmospheres , 125(16). 10.1029/2020JD032866
  • Li X; Wang Z; Du L; Liu X; Wang X; Chen C; Meng X; Li H; Zhuang Q; Deng W. (Mar 2020). Shipborne MAX-DOAS Observations of Tropospheric Trace Gases over a Coastal City and the Yellow Sea near Qingdao, China. Journal of Atmospheric and Oceanic Technology , 37(3), 365-380. 10.1175/jtech-d-18-0179.1
  • Yu, ZB; Chu, XZ; Lu, X; Chen, C. (Jan 2020). DYNAMIC DRIVERS OF TIFE DIURNAL CYCLE IN ANTARCTICA. 29TH INTERNATIONAL LASER RADAR CONFERENCE (ILRC 29) , 237. 10.1051/epjconf/202023704002
  • Lu X; Wu H; Chu X; Oberheide J; Mlynczak MG; Russell JM. (Nov 2019). Quasi-Biennial Oscillation of Short-Period Planetary Waves and Polar Night Jet in Winter Antarctica Observed in SABER and MERRA-2 and Mechanism Study With a Quasi-Geostrophic Model. Geophysical Research Letters , 46(22), 13526-13534. 10.1029/2019GL084759
  • Camporeale, E; Chu, X; Agapitov, OV; Bortnik, J. (Mar 2019). On the Generation of Probabilistic Forecasts From Deterministic Models. SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS , 17(3). 10.1029/2018SW002026
  • Vadas, SL, J Zhao, XZ Chu and E Becker. (Sep 2018). The Excitation of Secondary Gravity Waves From Local Body Forces: Theory and Observation. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 123(17). 10.1029/2017jd027970
  • Dawkins, ECM, A Feofilov, L Rezac, AA Kutepov, D Janches, J Hoffner, X Chu, X Lu, MG Mlynczak and J Russell. (Sep 2018). Validation of SABER v2.0 Operational Temperature Data With Ground-Based Lidars in the Mesosphere-Lower Thermosphere Region (75-105km). JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 123(17). 10.1029/2018JD028742
  • Chu, XZ, J Zhao, X Lu, VL Harvey, RM Jones, E Becker, C Chen, WC Fong, ZB Yu, BR Roberts and A Dornbrack. (Aug 2018). Lidar Observations of Stratospheric Gravity Waves From 2011 to 2015 at McMurdo (77.84 degrees S, 166.69 degrees E), Antarctica: 2. Potential Energy Densities, Lognormal Distributions, and Seasonal Variations. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 123(15). 10.1029/2017JD027386
  • Becker E; Vadas SL. (Mar 2018). Secondary Gravity Waves in the Winter Mesosphere: Results From a High-Resolution Global Circulation Model. Journal of Geophysical Research: Atmospheres , 123(5), 2605-2627. 10.1002/2017JD027460
  • Lu, X, XZ Chu, C Chen, V Nguyen and AK Smith. (Oct 2017). First Observations of Short-Period Eastward Propagating Planetary Waves From the Stratosphere to the Lower Thermosphere (110 km) in Winter Antarctica. GEOPHYSICAL RESEARCH LETTERS , 44(20). 10.1002/2017GL075641
  • Shim, JS, L Rastatter, M Kuznetsova, D Bilitza, M Codrescu, AJ Coster, BA Emery, M Fedrizzi, M Forster, TJ Fuller-Rowell, LC Gardner, L Goncharenko, J Huba, SE McDonald, AJ Mannucci, AA Namgaladze, X Pi, BE Prokhorov, AJ Ridley, L Scherliess, RW Schunk, JJ Sojka and L Zhu. (Oct 2017). CEDAR-GEM Challenge for Systematic Assessment of Ionosphere/Thermosphere Models in Predicting TEC During the 2006 December Storm Event. SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS , 15(10). 10.1002/2017SW001649
  • Chu X; Marsh DR. (Sep 2017). Preface to special issue: Layered Phenomena in the Mesopause Region. Journal of Atmospheric and Solar: Terrestrial Physics , 162, 1-2. 10.1016/j.jastp.2017.08.032
  • Lu, X, XZ Chu, HY Li, C Chen, JA Smith and SL Vadas. (Sep 2017). Statistical characterization of high-to-medium frequency mesoscale gravity waves by lidar-measured vertical winds and temperatures in the MLT. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 162. 10.1016/j.jastp.2016.10.009
  • Chen, C and XZ Chu. (Sep 2017). Two-dimensional Morlet wavelet transform and its application to wave recognition methodology of automatically extracting two-dimensional wave packets from lidar observations in Antarctica. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 162. 10.1016/j.jastp.2016.10.016
  • Chu, XZ and ZB Yu. (Jun 2017). Formation mechanisms of neutral Fe layers in the thermosphere at Antarctica studied with a thermosphere-ionosphere Fe/Fe+ (TIFe) model. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS , 122(6). 10.1002/2016JA023773
  • Zhao, J, XZ Chu, C Chen, X Lu, WC Fong, ZB Yu, RM Jones, BR Roberts and A Dornbrack. (May 2017). Lidar observations of stratospheric gravity waves from 2011 to 2015 at McMurdo (77.84 degrees S, 166.69 degrees E), Antarctica: 1. Vertical wavelengths, periods, and frequency and vertical wave number spectra. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 122(10). 10.1002/2016JD026368
  • Ningombam, SS, S Kathiravan, PS Parihar, EJL Larson, S Mohanan, D Angchuk, S Jorphel, KE Rangarajan and K Prabhu. (Apr 2017). Astronomical site survey report on dust measurement, wind profile, optical turbulence, and their correlation with seeing over IAO-Hanle. EXPERIMENTAL ASTRONOMY , 43(2). 10.1007/s10686-017-9525-6
  • Smith, JA and XZ Chu. (Feb 2016). Investigation of a field-widened Mach-Zehnder receiver to extend Fe Doppler lidar wind measurements from the thermosphere to the ground. APPLIED OPTICS , 55(6). 10.1364/AO.55.001366
  • Chen, C, XZ Chu, J Zhao, BR Roberts, ZB Yu, WC Fong, X Lu and JA Smith. (Feb 2016). Lidar observations of persistent gravity waves with periods of 3-10h in the Antarctic middle and upper atmosphere at McMurdo (77.83 degrees S, 166.67 degrees E). JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS , 121(2). 10.1002/2015JA022127
  • Abari, CF, XZ Chu, RM Hardesty and J Mann. (Oct 2015). A reconfigurable all-fiber polarization-diversity coherent Doppler lidar: principles and numerical simulations. APPLIED OPTICS , 54(30). 10.1364/AO.54.008999
  • Lu, X, C Chen, WT Huang, JA Smith, XZ Chu, T Yuan, PD Pautet, MJ Taylor, JE Gong and CY Cullens. (Oct 2015). A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 120(19). 10.1002/2015JD023604
  • Gao, Q, XZ Chu, XH Xue, XK Dou, TD Chen and JS Chen. (Oct 2015). Lidar observations of thermospheric Na layers up to 170km with a descending tidal phase at Lijiang (26.7 degrees N, 100.0 degrees E), China. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS , 120(10). 10.1002/2015JA021808
  • Tsuda, TT, X Chu, T Nakamura, MK Ejiri, TD Kawahara, AS Yukimatu and K Hosokawa. (May 2015). A thermospheric Na layer event observed up to 140km over Syowa Station (69.0 degrees S, 39.6 degrees E) in Antarctica. GEOPHYSICAL RESEARCH LETTERS , 42(10). 10.1002/2015GL064101
  • Lu, X, XZ Chu, WC Fong, C Chen, ZB Yu, BR Roberts and AJ McDonald. (Apr 2015). Vertical evolution of potential energy density and vertical wave number spectrum of Antarctic gravity waves from 35 to 105km at McMurdo (77.8 degrees S, 166.7 degrees E). JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 120(7). 10.1002/2014JD022751
  • Smith, JA and XZ Chu. (Apr 2015). High-efficiency receiver architecture for resonance-fluorescence and Doppler lidars. APPLIED OPTICS , 54(11). 10.1364/AO.54.003173
  • Fong, WC, XZ Chu, X Lu, C Chen, TJ Fuller-Rowell, M Codrescu and AD Richmond. (Feb 2015). Lidar and CTIPe model studies of the fast amplitude growth with altitude of the diurnal temperature "tides" in the Antarctic winter lower thermosphere and dependence on geomagnetic activity. GEOPHYSICAL RESEARCH LETTERS , 42(3). 10.1002/2014GL062784
  • Huang, WT, XZ Chu, CS Gardner, JD Carrillo-Sanchez, WH Feng, JMC Plane and D Nesvorny. (Jan 2015). Measurements of the vertical fluxes of atomic Fe and Na at the mesopause: Implications for the velocity of cosmic dust entering the atmosphere. GEOPHYSICAL RESEARCH LETTERS , 42(1). 10.1002/2014GL062390
  • Fong, WC, X Lu, XZ Chu, TJ Fuller-Rowell, ZB Yu, BR Roberts, C Chen, CS Gardner and AJ McDonald. (Mar 2014). Winter temperature tides from 30 to 110 km at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica: Lidar observations and comparisons with WAM. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 119(6). 10.1002/2013JD020784
  • Friedman, JS, XZ Chu, CGM Brum and X Lu. (Nov 2013). Observation of a thermospheric descending layer of neutral K over Arecibo. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 104. 10.1016/j.jastp.2013.03.002
  • Lu, X, XZ Chu, T Fuller-Rowell, LR Chang, WC Fong and ZB Yu. (Sep 2013). Eastward propagating planetary waves with periods of 1-5 days in the winter Antarctic stratosphere as revealed by MERRA and lidar. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 118(17). 10.1002/jgrd.50717
  • Huang, WT, XZ Chu, CS Gardner, ZJ Wang, WC Fong, JA Smith and BR Roberts. (Aug 2013). Simultaneous, common-volume lidar observations and theoretical studies of correlations among Fe/Na layers and temperatures in the mesosphere and lower thermosphere at Boulder Table Mountain (40 degrees N, 105 degrees W), Colorado. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 118(15). 10.1002/jgrd.50670
  • Chen, C, XZ Chu, AJ McDonald, SL Vadas, ZB Yu, WC Fong and X Lu. (Apr 2013). Inertia-gravity waves in Antarctica: A case study using simultaneous lidar and radar measurements at McMurdo/Scott Base (77.8 degrees S, 166.7 degrees E). JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 118(7). 10.1002/jgrd.50318
  • Yu, ZB, XZ Chu, WT Huang, WC Fong and BR Roberts. (Nov 2012). Diurnal variations of the Fe layer in the mesosphere and lower thermosphere: Four season variability and solar effects on the layer bottomside at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 117. 10.1029/2012JD018079
  • Tan, B, XZ Chu, HL Liu, C Yamashita and JM Russell. (May 2012). Zonal-mean global teleconnection from 15 to 110 km derived from SABER and WACCM. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 117. 10.1029/2011JD016750
  • Friedman, JS, D Maldonado-Nieves, I Gonzalez, J Lautenbach, XZ Chu, JA Smith and WT Huang. (May 2012). High spectral resolution test and calibration of an ultra-narrowband Faraday anomalous dispersion optical filter for use in daytime mesospheric resonance Doppler lidar. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 80. 10.1016/j.jastp.2012.01.017
  • Chu, XZ, ZB Yu, CS Gardner, C Chen and WC Fong. (Dec 2011). Lidar observations of neutral Fe layers and fast gravity waves in the thermosphere (110-155 km) at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. GEOPHYSICAL RESEARCH LETTERS , 38. 10.1029/2011GL050016
  • Chu, XZ, WT Huang, WC Fong, ZB Yu, ZJ Wang, JA Smith and CS Gardner. (Aug 2011). First lidar observations of polar mesospheric clouds and Fe temperatures at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. GEOPHYSICAL RESEARCH LETTERS , 38. 10.1029/2011GL048373
  • Gardner, CS, XZ Chu, PJ Espy, JMC Plane, DR Marsh and D Janches. (Jan 2011). Seasonal variations of the mesospheric Fe layer at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 116. 10.1029/2010JD014655
  • Wang, ZJ, ZS Liu, LP Liu, SH Wu, BY Liu, ZG Li and XZ Chu. (Dec 2010). Iodine-filter-based mobile Doppler lidar to make continuous and full-azimuth-scanned wind measurements: data acquisition and analysis system, data retrieval methods, and error analysis. APPLIED OPTICS , 49(36). 10.1364/AO.49.006960
  • Yamashita, C, HL Liu and XZ Chu. (Nov 2010). Gravity wave variations during the 2009 stratospheric sudden warming as revealed by ECMWF-T799 and observations. GEOPHYSICAL RESEARCH LETTERS , 37. 10.1029/2010GL045437
  • McDonald, AJ, B Tan and XZ Chu. (Oct 2010). Role of gravity waves in the spatial and temporal variability of stratospheric temperature measured by COSMIC/FORMOSAT-3 and Rayleigh lidar observations. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 115. 10.1029/2009JD013658
  • Xu, L, XO Hu, YQ Cheng, SY Guo, ZA Yan and XZ Chu. (Jul 2010). Simulation of echo-photon counts of a Sodium Doppler Lidar and retrievals of atmospheric parameters. CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION , 53(7). 10.3969/j.issn.0001-5733.2010.07.003
  • Yamashita, C, HL Liu and XZ Chu. (May 2010). Responses of mesosphere and lower thermosphere temperatures to gravity wave forcing during stratospheric sudden warming. GEOPHYSICAL RESEARCH LETTERS , 37. 10.1029/2009GL042351
  • Smith, JA, XZ Chu, WT Huang and B Tan. (Oct 2009). Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars. OPTICAL ENGINEERING , 48(10). 10.1117/1.3251080
  • Yamashita, C, XZ Chu, HL Liu, PJ Espy, GJ Nott and WT Huang. (Jun 2009). Stratospheric gravity wave characteristics and seasonal variations observed by lidar at the South Pole and Rothera, Antarctica. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 114. 10.1029/2008JD011472
  • Friedman, JS, XL Zhang, XZ Chu and JM Forbes. (Jun 2009). Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 114. 10.1029/2009JD011763
  • Huang, WT, XZ Chu, J Wiig, B Tan, C Yamashita, T Yuan, J Yue, SD Harrell, CY She, BP Williams, JS Friedman and RM Hardesty. (May 2009). Field demonstration of simultaneous wind and temperature measurements from 5 to 50 km with a Na double-edge magneto-optic filter in a multi-frequency Doppler lidar. OPTICS LETTERS , 34(10). 10.1364/OL.34.001552
  • Chu, XZ, C Yamashita, PJ Espy, GJ Nott, EJ Jensen, HL Liu, WT Huang and JP Thayer. (Mar 2009). Responses of polar mesospheric cloud brightness to stratospheric gravity waves at the South Pole and Rothera, Antarctica. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 71(4-Mar). 10.1016/j.jastp.2008.10.002
  • Huang, WT, XZ Chu, BP Williams, SD Harrell, J Wiig and CY She. (Jan 2009). Na double-edge magneto-optic filter for Na lidar profiling of wind and temperature in the lower atmosphere. OPTICS LETTERS , 34(2). 10.1364/OL.34.000199
  • Smith, JA, XZ Chu, WT Huang, J Wiig and AT Brown. (Nov 2008). LabVIEW-based laser frequency stabilization system with phase-sensitive detection servo loop for Doppler LIDAR applications. OPTICAL ENGINEERING , 47(11). 10.1117/1.3013257
  • Friedman, JS and XZ Chu. (Jul 2007). Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35 degrees N, 66.75 degrees W): Seasonal variations. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 112(D14). 10.1029/2006jd008220
  • Chu, XZ, PJ Espy, GJ Nott, JC Diettrich and CS Gardner. (Oct 2006). Polar mesospheric clouds observed by an iron Boltzmann lidar at Rothera (67.5 degrees S, 68.0 degrees W), Antarctica from 2002 to 2005: Properties and implications. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 111(D20). 10.1029/2006JD007086
  • Diettrich, JC, GJ Nott, PJ Espy, XZ Chu and D Riggin. (Jan 2006). Statistics of sporadic iron layers and relation to atmospheric dynamics. JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS , 68(1). 10.1016/j.jastp.2005.08.008
  • Stevens, MH, RR Meier, XZ Chu, MT DeLand and JMC Plane. (Jul 2005). Antarctic mesospheric clouds formed from space shuttle exhaust. GEOPHYSICAL RESEARCH LETTERS , 32(13). 10.1029/2005GL023054
  • Gardner, CS, JMC Plane, WL Pan, T Vondrak, BJ Murray and XZ Chu. (May 2005). Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 110(D10). 10.1029/2004JD005670
  • Diettrich, JC, GJ Nott, PJ Espy, GR Swenson, X Chu, MJ Taylor, DM Riggin and DC Fritts. (May 2005). High frequency atmospheric gravity-wave properties using Fe-lidar and OH-imager observations. GEOPHYSICAL RESEARCH LETTERS , 32(9). 10.1029/2004GL021944
  • Zhao, Y, MJ Taylor and X Chu. (Feb 2005). Comparison of simultaneous Na lidar and mesospheric nightglow temperature measurements and the effects of tides on the emission layer heights. , 110(D9). 10.1029/2004JD005115
  • Franke SJ; Chu X; Liu AZ; Hocking WK. (Jan 2005). Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region above Maui, Hawaii. Journal of Geophysical Research: Atmospheres , 110(D9). 10.1029/2003JD004486
  • Franke, SJ, X Chu, AZ Liu and WK Hocking. (Jan 2005). "Comparison of meteor radar and Na Doppler lidar measurements of winds in the mesopause region above Maui, Hawaii. , 110(D9).
  • Chu, XZ, CS Gardner and SJ Franke. (Jan 2005). Nocturnal thermal structure of the mesosphere and lower thermosphere region at Maui, Hawaii (20.7 degrees N), and Starfire Optical Range, New Mexico (35 degrees N). JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 110(D9). 10.1029/2004JD004891
  • Plane, JMC, BJ Murray, XZ Chu and CS Gardner. (Apr 2004). Removal of meteoric iron on polar mesospheric clouds. SCIENCE , 304(5669). 10.1126/science.1093236
  • Chu, XZ, GJ Nott, PJ Espy, CS Gardner, JC Diettrich, MA Clilverd and MJ Jarvis. (Jan 2004). Lidar observations of polar mesospheric clouds at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). GEOPHYSICAL RESEARCH LETTERS , 31(2). 10.1029/2003GL018638
  • Chu, XZ, CS Gardner and RG Roble. (Mar 2003). Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds at the South Pole. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES , 108(D8). 10.1029/2002JD002524
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu, MC Kelley, C Kruschwitz and TJ Kane. (Aug 2002). Observations of persistent Leonid meteor trails - 3. The "Glowworm''. JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS , 107(A8). 10.1029/2001JA000223
  • Chu, XZ, WL Pan, GC Papen, CS Gardner and JA Gelbwachs. (Jul 2002). Fe Boltzmann temperature lidar: design, error analysis, and initial results at the North and South Poles. APPLIED OPTICS , 41(21). 10.1364/AO.41.004400
  • Kruschwitz, CA, MC Kelley, CS Gardner, G Swenson, AZ Liu, X Chu, JD Drummond, BW Grime, WT Armstrong, JMC Plane and P Jenniskens. (Oct 2001). Observations of persistent Leonid meteor trails 2. Photometry and numerical modeling. , 106(A10). 10.1029/2000JA000174
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu and TJ Kane. (Oct 2001). Observations of persistent Leonid meteor trails 1. Advection of the "diamond ring". JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS , 106(A10). 10.1029/2000JA000173
  • Chu, XZ, CS Gardner and G Papen. (May 2001). Lidar observations of polar mesospheric clouds at South Pole: Diurnal variations. GEOPHYSICAL RESEARCH LETTERS , 28(10). 10.1029/2000GL012525
  • Gardner, CS, GC Papen, XZ Chu and WL Pan. (Apr 2001). First lidar observations of middle atmosphere temperatures, Fe densities, and polar mesospheric clouds over the North and South poles. GEOPHYSICAL RESEARCH LETTERS , 28(7). 10.1029/2000GL012622
  • Chu, XZ, CS Gardner and G Papen. (Apr 2001). Lidar observations of polar mesospheric clouds at South Pole: Seasonal variations. GEOPHYSICAL RESEARCH LETTERS , 28(7). 10.1029/2000GL012524
  • Kelley, MC, C Gardner, J Drummond, T Armstrong, A Liu, X Chu, G Papen, C Kruschwitz, P Loughmiller, B Grime and J Engelman. (Jul 2000). First observations of long-lived meteor trains with resonance lidar and other optical instruments. , 27(13). 10.1029/1999GL011175
  • Chu, XZ, WL Pan, G Papen, CS Gardner, G Swenson and P Jenniskens. (Jul 2000). Characteristics of Fe ablation trails observed during the 1998 Leonid meteor shower. GEOPHYSICAL RESEARCH LETTERS , 27(13). 10.1029/1999GL010756
  • Chu, XZ, AZ Liu, G Papen, CS Gardner, M Kelley, J Drummond and R Fugate. (Jul 2000). Lidar observations of elevated temperatures in bright chemiluminescent meteor trails during the 1998 Leonid shower. GEOPHYSICAL RESEARCH LETTERS , 27(13). 10.1029/2000GL000080
  • Razvi, MAN, XZ Chu, R Alheit, G Werth and R Blumel. (Jul 1998). Fractional frequency collective parametric resonances of an ion cloud in a Paul trap. PHYSICAL REVIEW A , 58(1). 10.1103/PhysRevA.58.R34
  • Chu, XZ, M Holzki, R Alheit and G Werth. (Jan 1998). Observation of high-order motional resonances of an ion cloud in a Paul trap. INTERNATIONAL JOURNAL OF MASS SPECTROMETRY , 173(2-Jan). 10.1016/S0168-1176(97)00262-0
  • Alheit, R, XZ Chu, M Hoefer, M Holzki, G Werth and R Blumel. (Nov 1997). Nonlinear collective oscillations of an ion cloud in a Paul trap. PHYSICAL REVIEW A , 56(5). 10.1103/PhysRevA.56.4023
  • Alt W; Block M; Schmidt V; Nakamura T; Seibert P; Chu X; Werth G. (Oct 1997). Shifts of the 3D-4P transitions in different isotopes of positive calcium ions. Journal of Physics B: Atomic, Molecular and Optical Physics , 30(20), L677-L681. 10.1088/0953-4075/30/20/001
  • Chu, XZ, SQ Liu and TQ Dong. (Jun 1996). Experimental study of AC Zeeman effect in Rb-87 atomic frequency standard. ACTA PHYSICA SINICA-OVERSEAS EDITION , 5(6).