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Research Areas
  • Atmosphere–Ionosphere Interactions
  • Remote–sensing techniques
  • Earth’s Upper Atmosphere
  • Coupling/Dynamics of different atmospheric regions
  • Mesospheric metallic layers
  • Sporadic–E and Intermediate layers
  • Space Weather Effects on the Ionosphere
  • Inter–planetary scintillations

Shikha Raizada

Dr. Raizada is a senior scientist at Arecibo Observatory (AO), and she focuses on mesosphere, thermosphere and ionospheric investigations using both radio and optical techniques. Her work is recognized internationally, and she is recipient of prestigious “Humboldt Fellowship” awarded by Germany to promote international collaborations. Also, she has been awarded senior visiting fellow at CIRES institute, University of Colorado, Boulder, in 2008. At AO, she has developed novel resonance lidar capabilities, which includes UV transmission of laser beam to monitor and investigate meteoric species like neutral calcium and its ion in the mesosphere and the lower thermosphere of the Earth’s atmosphere. In addition, she has experience with sodium resonance and Rayleigh lidar systems. She has authored more than 30 papers in peer–reviewed journals and has presented more than 100 papers in international conferences and meetings. She has served in NSF panels and reviewed proposals as well as papers for publications in several international journals.

Dr. Raizada research includes the study of Mesosphere and lower Thermosphere using resonance and Rayleigh lidars, Atmosphere–Ionosphere Interactions using resonance lidar and Incoherent Scatter Radar (ISR), and study of D–region to infer negative ions using ISR. Her research also covers meteor effects on the ionosphere using ISR and lidars, coupling between different regions of the Earth’s atmosphere, space weather studies using Inter–Planetary Scintillations, and irregularities in the ionosphere.

Dr. Raizada projects include the following projects:

  • PI on NSF (AGS–1241436) proposal, “New directions in optical–instrument driven aeronomy at Arecibo Observatory, Amount: $301,112).” This was a collaborative proposal between AO (S. Raizada) and PSU (Prof. J. D. Mathews) to upgrade an all–sky optical imager and one of the resonance lidars at AO. This work supported a post–doctoral fellow Dr. S. Sarkhel, who worked at AO under supervision of S. Raizada.

  • PI on NSF (CEDAR) proposal (Award number: AGS–1243063) titled, “Collaborative Research: CEDAR Correlative Study of Metal Atoms and Ion Concentrations Using Simultaneous and Common Volume Multi–lidar and Radar Measurements at Arecibo Amount: $192,134).”: This proposal strengthened collaborations between AO (S. Raizada) and Miami University, OH (Prof. Q. Zhou). The proposal focused on simultaneous resonance lidar observations in conjunction with Incoherent Scatter Radar. Awarded a supplement on the CEADR proposal for an amount $31,541 USD. This allowed funding of a visiting scientist, (Dr. J. Smith), who worked in supervision of Dr. S. Raizada to upgrade the lidar receivers.

  • PI on a National Science Foundation (CEDAR) Award entitled ‘An Observational and Theoretical Study of the Climatology of the Ca/Ca+ Layer in the MLT at Arecibo and its Relation to the Sporadic Micrometeor Flux, Amount: 289,079)’: This work led to the purchase of a Nd:YAG and a dye laser to perform simultaneous Ca and Ca+ lidar observations along with ISR. This work was done in collaboration with Dr. D. Janches, now at NASA.

Mentored several REU students from both local and U.S. universities. Mentored Postdocs.

Peer-reviewed publications


S. Raizada, J. Smith. J. Lautenbach, N. Aponte, P. Perillat, M. Sulzer, J. D. Mathews (2020), New lidar observations of Ca+ in the mesosphere and lower thermosphere over Arecibo. Geophysical Research Letters, 47, e2020GL087113.


X. Cai, T. Yuan, J. Eccles, S. Raizada, Investigation on the distinct nocturnal secondary sodium layer behavior above 95 km in winter and summer over Logan, UT (41.7° N, 112° W) and Arecibo Observatory, PR (18.3° N, 67° W), J. Geophys. Res., 10.1029/2019JA026746, 2019.


Plane J. M. C., W. Feng, J. C. G. Martin, M. Gerding, S. Raizada, A new model of meteoric calcium in the mesosphere and lower thermosphere, Atmos. Chem. Phys., 18, 14799–14811, 2018.


S. Raizada, C. G. M. Brum, J. D. Mathews, C. Gonzalez, and E. Franco, Characteristics of nighttime E–region over Arecibo: Dependence on Solar flux and geomagnetic variations, Advances in Space Research,doi: 10.1016/j.asr.2017.07.006, 2017.


Yue, X., Q. Zhou, F. Yi, J. Friedman, S. Raizada, and C. Tepley (2016), Simultaneous and common–volume lidar observations of K/Na layers and temperature at Arecibo Observatory (18°N, 67°W), J. Geophys. Res. Atmos.,121, 8038–8054, doi:10.1002/2015JD024494.


S. Raizada, C. M. Brum, C. A. Tepley, J. Lautenbach, J. S. Friedman, J. D. Mathews, F. T. Djuth, and C. Kerr (2015), First simultaneous measurements of Na and K thermospheric layers along with TILs from Arecibo, Geophys. Res. Lett., 42, doi:10.1002/2015GL066714.

S. Sarkhel, J. D. Mathews, S. Raizada, R Sekar, D. Chakrabarty, A. Guharay, Robert B. Kerr, Geetha Ramkumar, S. Sridharan, Qian Wu, Martin G. Mlynczak, and James M. Russell III (2015), A case study on occurrence of an unusual structure in the sodium layer over Gadanki, India. Earth, Planet & Space, doi:10.1186/s40623–015–0183–5.–015–0183–5

S. Raizada, C.A. Tepley. Q. Zhou, S. Sarkhel. J. D. Mathews, N. A, Aponte, I. Sekar, R. Kerr and E. Cabassa (2015), Dependence of mesospheric Na and Fe distributions on electron density at Arecibo, Earth, Planet and Space, 67:146, doi: 10.1186/s40623–015–0322–z.–015–0322–z


Yue., X., Q. Zhou, S. Raizada, C.A. Tepley, and J. F. Friedman, Relationship between mesospheric Na and Fe layers from simultaneous and common–volume lidar observations at Arecibo, J. Geophys. Res doi: 10.1002/jgrd.50148, 2013.


S. Sarkhel, S. Raizada, J. D. Mathews, S. Smith, C. A. Tepley, Francisco Rivera, S. A. Gonzalez, Identification of large scale billows–like structure in the neutral Na layer over Arecibo, , J. Geophys. Res., Vol. 117, A10301, doi:10.1029/2012JA017891, 2012.

S. Raizada, C. A. Tepley, B. P. Williams, R. Garcia, Summer to winter variability in mesospheric calcium ion distribution and its dependence on Sporadic E at Arecibo, J. Geophys. Res., Vol. 117, A02303, doi:10.1029/2011JA016953, 2012.