Cooperative Institute for Research in Environmental Sciences

Xinzhao Chu

Xinzhao Chu

Dr. Chu explores advanced spectroscopy principles, develops new lidar technologies, and studies the fundamental physical and chemical processes that govern the structure and dynamics of the whole atmosphere. She is a Fellow of CIRES that is funded by CU and NOAA, and an Associate Professor in the Department of Aerospace Engineering Sciences. She teaches graduate classes of spectroscopy and lidar remote sensing, and undergraduate classes ASEN 3300 "Electronics and Communications" and ASEN 3113 "Thermodynamics and Heat Transfer".

Xinzhao Chu and her research group focus on both lidar technology development and atmospheric/space science study. The technology development involves atomic, molecular and laser spectroscopy, lidar technology and instrument development, and cluster remote sensing technology applications including observational campaigns from the North Pole to the South Pole. The science study is currently focused on the polar mesospheric and stratospheric clouds, thermal structure and dynamics in the stratosphere, mesosphere and lower thermosphere in both polar and equatorial regions with observations, data analysis, and modeling. One of the goals is to send a resonance lidar into space to study the global middle atmosphere dynamics.


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.


  • 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

  • Chen, C, XZ Chu, J Zhao, BR Roberts, ZB Yu, WC Fong, X Lu and JA Smith (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). J. Geophys. Res-.Space Version: 1 121 (2) 1483-1502, issn: 2169-9380, ids: DH7VN, doi: 10.1002/2015JA022127
  • Tsuda, TT, X Chu, T Nakamura, MK Ejiri, TD Kawahara, AS Yukimatu and K Hosokawa (2015), A thermospheric Na layer event observed up to 140km over Syowa Station (69.0 degrees S, 39.6 degrees E) in Antarctica. Geophys. Res. Lett. Version: 1 42 (10) 3647-3653, issn: 0094-8276, ids: CL0KJ, doi: 10.1002/2015GL064101
  • Lu, X, XZ Chu, WC Fong, C Chen, ZB Yu, BR Roberts and AJ McDonald (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). J. Geophys. Res-Atmos. Version: 1 120 (7) 2719-2737, issn: 2169-897X, ids: CG6LY, doi: 10.1002/2014JD022751
  • Huang, WT, XZ Chu, CS Gardner, JD Carrillo-Sanchez, WH Feng, JMC Plane and D Nesvorny (2015), Measurements of the vertical fluxes of atomic Fe and Na at the mesopause: Implications for the velocity of cosmic dust entering the atmosphere. Geophys. Res. Lett. Version: 1 42 (1) 169-175, issn: 0094-8276, ids: CA6PE, doi: 10.1002/2014GL062390
  • Fong, W. C., X. Z. Chu, X. Lu, C. Chen, T. J. Fuller‐Rowell, M. Codrescu, and A. D. Richmond (2015), Lidar and CTIPe model studies of the fast amplitude growth with altitude of the diurnal temperature. Geophys. Res. Lett. Version: 1 42 (3) 697-704, issn: 0094-8276, ids: CD8OT, doi: 10.1002/2014GL062784
  • Smith, JA and XZ Chu (2015), High-efficiency receiver architecture for resonance-fluorescence and Doppler lidars. Appl. Optics Version: 1 54 (11) 3173-3184, issn: 1559-128X, ids: CG4FP, doi: 10.1364/AO.54.003173
  • Abari, CF, XZ Chu, RM Hardesty and J Mann (2015), A reconfigurable all-fiber polarization-diversity coherent Doppler lidar: principles and numerical simulations. Appl. Optics Version: 1 54 (30) 8999-9009, issn: 1559-128X, ids: CU1VZ, doi: 10.1364/AO.54.008999
  • Lu, X, C Chen, WT Huang, JA Smith, XZ Chu, T Yuan, PD Pautet, MJ Taylor, J Gong and CY Cullens (2015), A coordinated study of 1 h mesoscale gravity waves propagating from Logan to Boulder with CRRL Na Doppler lidars and temperature mapper. J. Geophys. Res.-Atmos. Version: 1 120 (19) , issn: 2169-897X, ids: CX1CC, doi: 10.1002/2015JD023604
  • Gao, Q, XZ Chu, XH Xue, XK Dou, TD Chen and JS Chen (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. J. Geophys. Res-.Space Version: 1 120 (10) 9213-9220, issn: 2169-9380, ids: CY0ZI, doi: 10.1002/2015JA021808
  • Fong, W., X. Lu, X. Chu, T. J. Fuller-Rowell, Z. Yu, B. R. Roberts, C. Chen, C. S. Gardner, and A. J. McDonald (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. J. Geophys. Res-Atmos. Version: 1 119 (6) 2846-2863, issn: 2169-897X, ids: AH3SV, doi: 10.1002/2013JD020784
  • Huang, WT, XZ Chu, CS Gardner, ZJ Wang, WC Fong, JA Smith and BR Roberts (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. J. Geophys. Res-Atmos. Version: 1 118 (15) 8748-8759, issn: 2169-897X, ids: 213DA, doi: 10.1002/jgrd.50670
  • Lu, X., X. Z. Chu, T. Fuller-Rowell, L. R. Chang, W. C. Fong, and Z. B. Yu (2013), Eastward propagating planetary waves with periods of 1-5 days in the winter Antarctic stratosphere as revealed by MERRA and lidar. J. Geophys. Res-Atmos. Version: 1 118 (17) 9565-9578, issn: 2169-897X, ids: 232JH, doi: 10.1002/jgrd.50717
  • Friedman, JS, XZ Chu, CGM Brum and X Lu (2013), Observation of a thermospheric descending layer of neutral K over Arecibo. J. Atmos. Sol.-Terr. Phys. Version: 1 104 253-259, issn: 1364-6826, ids: 255IH, doi: 10.1016/j.jastp.2013.03.002
  • Chen, C, XZ Chu, AJ McDonald, SL Vadas, ZB Yu, WC Fong and X Lu (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). J. Geophys. Res-Atmos. Version: 1 118 (7) 2794-2808, issn: 2169-897X, ids: 153QT, doi: 10.1002/jgrd.50318
  • Friedman, JS, D Maldonado-Nieves, I Gonzalez, J Lautenbach, XZ Chu, JA Smith and WT Huang (2012), High spectral resolution test and calibration of an ultra-narrowband Faraday anomalous dispersion optical filter for use in daytime mesospheric resonance Doppler lidar. J. Atmos. Sol.-Terr. Phys. Version: 1 80 187-194, issn: 1364-6826, ids: 953SR, doi: 10.1016/j.jastp.2012.01.017
  • Yu, ZB, XZ Chu, WT Huang, WC Fong and BR Roberts (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. J. Geophys. Res-Atmos. Version: 1 117 , issn: 2169-897X, ids: 043RF, doi: 10.1029/2012JD018079
  • Tan, B, XZ Chu, HL Liu, C Yamashita and JM Russell (2012), Zonal-mean global teleconnection from 15 to 110 km derived from SABER and WACCM. J. Geophys. Res-Atmos. Version: 1 117 , issn: 2169-897X, ids: 945GC, doi: 10.1029/2011JD016750
  • Chu, XZ, ZB Yu, CS Gardner, C Chen and WC Fong (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. Geophys. Res. Lett. Version: 1 38 , issn: 0094-8276, ids: 864TA, doi: 10.1029/2011GL050016
  • Gardner, CS, XZ Chu, PJ Espy, JMC Plane, DR Marsh and D Janches (2011), Seasonal variations of the mesospheric Fe layer at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). J. Geophys. Res-Atmos. Version: 1 116 , issn: 2169-897X, ids: 710OC, doi: 10.1029/2010JD014655
  • Chu, XZ, WT Huang, WC Fong, ZB Yu, ZJ Wang, JA Smith and CS Gardner (2011), First lidar observations of polar mesospheric clouds and Fe temperatures at McMurdo (77.8 degrees S, 166.7 degrees E), Antarctica. Geophys. Res. Lett. Version: 1 38 , issn: 0094-8276, ids: 813LQ, doi: 10.1029/2011GL048373
  • Yamashita, C, HL Liu and XZ Chu (2010), Gravity wave variations during the 2009 stratospheric sudden warming as revealed by ECMWF-T799 and observations. Geophys. Res. Lett. Version: 1 37 , issn: 0094-8276, ids: 683ML, doi: 10.1029/2010GL045437
  • Wang, ZJ, ZS Liu, LP Liu, SH Wu, BY Liu, ZG Li and XZ Chu (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. Appl. Optics Version: 1 49 (36) 6960-6978, issn: 1559-128X, ids: 697FZ, doi: 10.1364/AO.49.006960, PubMed ID: 21173831
  • McDonald, AJ, B Tan and XZ Chu (2010), Role of gravity waves in the spatial and temporal variability of stratospheric temperature measured by COSMIC/FORMOSAT-3 and Rayleigh lidar observations. J. Geophys. Res-Atmos. Version: 1 115 , issn: 2169-897X, ids: 666BU, doi: 10.1029/2009JD013658
  • Yamashita, C, HL Liu and XZ Chu (2010), Responses of mesosphere and lower thermosphere temperatures to gravity wave forcing during stratospheric sudden warming. Geophys. Res. Lett. Version: 1 37 , issn: 0094-8276, ids: 593RM, doi: 10.1029/2009GL042351
  • Xu, L, XO Hu, YQ Cheng, SY Guo, ZA Yan and XZ Chu (2010), Simulation of echo-photon counts of a Sodium Doppler Lidar and retrievals of atmospheric parameters. Chinese J. Geophys.-Chinese Ed. Version: 1 53 (7) 1520-1528, issn: 0001-5733, ids: 632NK, doi: 10.3969/j.issn.0001-5733.2010.07.003
  • Smith, JA, XZ Chu, WT Huang and B Tan (2009), Applications of spectral analysis and filter design in laser frequency locking for Na Doppler lidars. Opt. Eng. Version: 1 48 (10) , issn: 0091-3286, ids: 519DW, doi: 10.1117/1.3251080
  • 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 (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. Opt. Lett. Version: 1 34 (10) 1552-1554, issn: 0146-9592, ids: 458YB, PubMed ID: 19448818
  • Friedman, JS, XL Zhang, XZ Chu and JM Forbes (2009), Longitude variations of the solar semidiurnal tides in the mesosphere and lower thermosphere at low latitudes observed from ground and space. J. Geophys. Res-Atmos. Version: 1 114 , issn: 2169-897X, ids: 458FU, doi: 10.1029/2009JD011763
  • Yamashita, C, XZ Chu, HL Liu, PJ Espy, GJ Nott and WT Huang (2009), Stratospheric gravity wave characteristics and seasonal variations observed by lidar at the South Pole and Rothera, Antarctica. J. Geophys. Res-Atmos. Version: 1 114 , issn: 2169-897X, ids: 460KP, doi: 10.1029/2008JD011472
  • Smith, JA, XZ Chu, WT Huang, J Wiig and AT Brown (2008), LabVIEW-based laser frequency stabilization system with phase-sensitive detection servo loop for Doppler LIDAR applications. Opt. Eng. Version: 1 47 (11) , issn: 0091-3286, ids: 377RH, doi: 10.1117/1.3013257
  • Friedman, JS and XZ Chu (2007), Nocturnal temperature structure in the mesopause region over the Arecibo Observatory (18.35 degrees N, 66.75 degrees W): Seasonal variations. J. Geophys. Res-Atmos. Version: 1 112 (D14) , issn: 0148-0227, ids: 198AM, doi: 10.1029/2006JD008220
  • Chu, XZ, PJ Espy, GJ Nott, JC Diettrich and CS Gardner (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. J. Geophys. Res-Atmos. Version: 1 111 (D20) , issn: 2169-897X, ids: 103DP, doi: 10.1029/2006JD007086
  • Stevens, MH, RR Meier, XZ Chu, MT DeLand and JMC Plane (2005), Antarctic mesospheric clouds formed from space shuttle exhaust. Geophys. Res. Lett. Version: 1 32 (13) , Art. No. L13810, issn: 0094-8276, ids: 947JL, doi: 10.1029/2005GL023054
  • Gardner, CS, JMC Plane, WL Pan, T Vondrak, BJ Murray and XZ Chu (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. J. Geophys. Res-Atmos. Version: 1 110 (D10) , Art. No. D10302, issn: 0148-0227, ids: 932WK, doi: 10.1029/2004JD005670
  • Chu, XZ, CS Gardner and SJ Franke (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). J. Geophys. Res-Atmos. Version: 1 110 (D9) , Art. No. D09S03, issn: 0148-0227, ids: 892YD, doi: 10.1029/2004JD004891
  • Diettrich, JC, GJ Nott, PJ Espy, GR Swenson, X Chu, MJ Taylor, DM Riggin and DC Fritts (2005), High frequency atmospheric gravity-wave properties using Fe-lidar and OH-imager observations. Geophys. Res. Lett. Version: 1 32 (9) , Art. No. L09801, issn: 0094-8276, ids: 926TF, doi: 10.1029/2004GL021944
  • Chu, XZ, GJ Nott, PJ Espy, CS Gardner, JC Diettrich, MA Clilverd and MJ Jarvis (2004), Lidar observations of polar mesospheric clouds at Rothera, Antarctica (67.5 degrees S, 68.0 degrees W). Geophys. Res. Lett. Version: 1 31 (2) , Art. No. L02114, issn: 0094-8276, ids: 772WV, doi: 10.1029/2003GL018638
  • Plane, JMC, BJ Murray, XZ Chu and CS Gardner (2004), Removal of meteoric iron on polar mesospheric clouds. Science Version: 1 304 (5669) 426-428, issn: 0036-8075, ids: 812NE, doi: 10.1126/science.1093236
  • Chu, XZ, CS Gardner and RG Roble (2003), Lidar studies of interannual, seasonal, and diurnal variations of polar mesospheric clouds at the South Pole. J. Geophys. Res-Atmos. Version: 1 108 (D8) , Art. No. 8447, issn: 0148-0227, ids: 665GK, doi: 10.1029/2002JD002524
  • Chu, XZ, WL Pan, GC Papen, CS Gardner and JA Gelbwachs (2002), Fe Boltzmann temperature lidar: design, error analysis, and initial results at the North and South Poles. Appl. Optics Version: 1 41 (21) 4400-4410, issn: 0003-6935, ids: 575WU, doi: 10.1364/AO.41.004400
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu, MC Kelley, C Kruschwitz and TJ Kane (2002), Observations of persistent Leonid meteor trails - 3. The "Glowworm''. J. Geophys. Res.-Space Phys. Version: 1 107 (A8) , Art. No. 1159, issn: 0148-0227, ids: 611HB, doi: 10.1029/2001JA000223
  • Drummond, JD, BW Grime, CS Gardner, AZ Liu, XZ Chu and TJ Kane (2001), Observations of persistent Leonid meteor trails 1. Advection of the "diamond ring". J. Geophys. Res.-Space Phys. Version: 1 106 (A10) 21517-21524, issn: 0148-0227, ids: 475XG, doi: 10.1029/2000JA000173
  • Gardner, CS, GC Papen, XZ Chu and WL Pan (2001), First lidar observations of middle atmosphere temperatures, Fe densities, and polar mesospheric clouds over the North and South poles. Geophys. Res. Lett. Version: 1 28 (7) 1199-1202, issn: 0094-8276, ids: 415GZ, doi: 10.1029/2000GL012622
  • Chu, XZ, CS Gardner and G Papen (2001), Lidar observations of polar mesospheric clouds at South Pole: Seasonal variations. Geophys. Res. Lett. Version: 1 28 (7) 1203-1206, issn: 0094-8276, ids: 415GZ, doi: 10.1029/2000GL012524
  • Chu, XZ, CS Gardner and G Papen (2001), Lidar observations of polar mesospheric clouds at South Pole: Diurnal variations. Geophys. Res. Lett. Version: 1 28 (10) 1937-1940, issn: 0094-8276, ids: 431EB, doi: 10.1029/2000GL012525
  • Chu, XZ, WL Pan, G Papen, CS Gardner, G Swenson and P Jenniskens (2000), Characteristics of Fe ablation trails observed during the 1998 Leonid meteor shower. Geophys. Res. Lett. Version: 1 27 (13) 1807-1810, issn: 0094-8276, ids: 331LY, doi: 10.1029/1999GL010756
  • Chu, XZ, AZ Liu, G Papen, CS Gardner, M Kelley, J Drummond and R Fugate (2000), Lidar observations of elevated temperatures in bright chemiluminescent meteor trails during the 1998 Leonid shower. Geophys. Res. Lett. Version: 1 27 (13) 1815-1818, issn: 0094-8276, ids: 331LY, doi: 10.1029/2000GL000080
  • Razvi, MAN, XZ Chu, R Alheit, G Werth and R Blumel (1998), Fractional frequency collective parametric resonances of an ion cloud in a Paul trap. Phys. Rev. A Version: 1 58 (1) R34-R37, issn: 1050-2947, ids: ZZ998, doi: 10.1103/PhysRevA.58.R34
  • Chu, XZ, M Holzki, R Alheit and G Werth (1998), Observation of high-order motional resonances of an ion cloud in a Paul trap. Int. J. Mass Spectrom. Version: 1 173 (2-Jan) 107-112, issn: 1387-3806, ids: ZC763, doi: 10.1016/S0168-1176(97)00262-0
  • Alheit, R, XZ Chu, M Hoefer, M Holzki, G Werth and R Blumel (1997), Nonlinear collective oscillations of an ion cloud in a Paul trap. Phys. Rev. A Version: 1 56 (5) 4023-4031, issn: 1050-2947, ids: YF529, doi: 10.1103/PhysRevA.56.4023
  • Chu, XZ, SQ Liu and TQ Dong (1996), Experimental study of AC Zeeman effect in Rb-87 atomic frequency standard. Acta Phys. Sin.-Overseas Ed. Version: 1 5 (6) 423-430, issn: 1004-423X, ids: VA201