Sciences and Exploration Directorate

Nimalan SWARNALINGAM

(RESEARCH ASSOCIATE)

Nimalan SWARNALINGAM's Contact Card & Information.
Email: nimalan.swarnalingam@nasa.gov
Phone: 301.286.0266
Org Code: 675
Address:
NASA/GSFC
Mail Code 675
Greenbelt, MD 20771
Employer: CATHOLIC UNIV OF AMERICA

Brief Bio


Dr. Nimalan Swarnalingam, a member of the Ionosphere-Thermosphere-Mesosphere (ITM) Laboratory at NASA Goddard Space Flight Center, has been using satellite and ground-based remote sensing techniques to study significant and complex phenomena in the atmosphere and ionosphere. Dr. Swarnalingam has extensive experience in employing radar techniques. He obtained his M.Phil at the University of Tromso in Norway and his Ph.D at the University of Western Ontario in Canada. In Canada, he focused on the complex phenomenon of polar mesosphere summer echoes (PMSEs). He successfully introduced smaller and less powerful but cost-effective all-sky meteor radar systems into PMSE observations. He conducted coordinated simultaneous radar observations using different systems with primary emphases on investigating the geographical and geomagnetic dependence of PMSEs in terms of calibrated backscattered signals, identifying terrestrial and extraterrestrial factors influencing PMSEs, and developing an aspect sensitivity model to study the radar scattering mechanism of PMSEs. When he joined NASA GSFC, he employed his modeling and experimental expertise to quantify and constrain the radar-observed influx of interplanetary dust particles into the Earth's atmosphere. He developed a radar sensitivity model and applied it to multiple high-sensitivity radar systems to analyze their capabilities and limitations in detecting small and micrometeors, entering with a range of physical and dynamic properties. He also developed a radar response function and determined the altitude distributions for the different radar systems in detecting small and micrometeors originating from different meteor populations.


Dr. Swarnalingam further focuses on the application of satellite-based remote sensing techniques; GNSS radio occultation (RO) and precise orbit determination (POD) limb sounding, to explore the state of global ionosphere under different conditions with primary emphasis on electron density, conductivity, and other key parameters in the F, E, and D regions of the ionosphere. He incorporates ground-based measurements from worldwide ionosondes and radars, as well as GNSS receivers to evaluate and validate new space-borne measurement techniques and mitigating uncertainty. Dr. Swarnalingam utilizes space-borne high-resolution spatial and temporal measurements of electron density to explore the fundamental phenomena and search for critical linkages between drivers and responses of the ionosphere for varying solar and geomagnetic conditions including geomagnetic storms. He uses large datasets from new measurements and associates them with widely utilized ionosphere and space weather operational models to assess and improve their nowcasting and forecasting capabilities. 

Education


Ph.D in Physics (Atmospheric Physics)

The University of Western Ontario, Canada.


M.Phil in Cosmic Geophysics and Plasma Physics

The University of Tromso, Norway.


B.Sc. Physics

The University of Jaffna, Sri Lanka.

Publications


Refereed

2023. "Improved models for estimating sporadic-E intensity from GNSS radio occultation measurements." Frontiers in Astronomy and Space Sciences 10 [10.3389/fspas.2023.1327979] [Journal Article/Letter]

2023. "Comparison of a Bottom-Up GNSS Radio Occultation Method to Measure D- and E-Region Electron Densities with Ionosondes and FIRI." Remote Sensing 15 (18): 4363 [10.3390/rs15184363] [Journal Article/Letter]

2023. "Optimal Estimation Inversion of Ionospheric Electron Density from GNSS-POD Limb Measurements: Part II-Validation and Comparison Using NmF2 and hmF2." Remote Sensing 15 (16): 4048 [10.3390/rs15164048] [Journal Article/Letter]

2023. "Optimal Estimation Inversion of Ionospheric Electron Density from GNSS-POD Limb Measurements: Part I-Algorithm and Morphology." Remote Sensing [https://doi.org/10.3390/rs15133245] [Journal Article/Letter]

2022. "A Statistical Analysis of Sporadic-E Characteristics Associated with GNSS Radio Occultation Phase and Amplitude Scintillations." Atmosphere 13 (12): 2098 [10.3390/atmos13122098] [Journal Article/Letter]

2022. "Interhemispheric Asymmetries in Ionospheric Electron Density Responses During Geomagnetic Storms: A Study Using Space‐Based and Ground‐Based GNSS and AMPERE Observations." Journal of Geophysical Research: Space Physics 127 (5): [10.1029/2021ja030247] [Journal Article/Letter]

2022. "Global GNSS-RO Electron Density in the Lower Ionosphere." Remote Sensing 14 (7): 1577 [10.3390/rs14071577] [Journal Article/Letter]

2020. "Comparison and evaluation of a bottom-up GPS-RO electron density retrieval for D and E regions using radar observations and models." Journal of Atmospheric and Solar-Terrestrial Physics 207 105333 [10.1016/j.jastp.2020.105333] [Journal Article/Letter]

2019. "Modeling the Altitude Distribution of Meteor Head Echoes Observed with HPLA Radars: Implications for the Radar Detectability of Meteoroid Populations." The Astronomical Journal 157 (5): 179 [10.3847/1538-3881/ab0ec6] [Journal Article/Letter]

2017. "Radar Detectability Studies of Slow and Small Zodiacal Dust Cloud Particles. III. The Role of Sodium and the Head Echo Size on the Probability of Detection." The Astrophysical Journal 843 (1): 1 [10.3847/1538-4357/aa775c] [Journal Article/Letter]

2017. "Observation of Polar Mesosphere Summer Echoes Using the Northernmost MST Radar at Eureka (80N)." Journal of Atmospheric and Solar Terrestrial Physics [10.1016/j.jastp.2017.03.015] [Journal Article/Letter]

2015. "The Southern Argentina Agile MEteor Radar Orbital System (SAAMER-OS): An Initial Sporadic Meteoroid Orbital Survey in the Southern Sky." Astrophysical Journal 809 [10.1088/0004-637X/809/1/36] [Journal Article/Letter]

2015. "Radar detectability studies of slow and small Zodiacal Dust Cloud Particles: II. A study of three radars with different sensitivity." Astrophysical Journal 807 (13): [10.1088/0004-637X/807/1/13] [Journal Article/Letter]

2011. "Long-term aspect-sensitivity measurements of polar mesosphere summer echoes (PMSE) at Resolute Bay using a 51.5MHz VHF radar." Journal of Atmospheric and Solar-Terrestrial Physics 73 (9): 957-964 [10.1016/j.jastp.2010.09.032] [Journal Article/Letter]

2009. "Calibrated measurements of PMSE strengths at three different locations observed with SKiYMET radars and narrow beam VHF radars." Journal of Atmospheric and Solar-Terrestrial Physics 71 (17-18): 1807-1813 [10.1016/j.jastp.2009.06.014] [Journal Article/Letter]

2009. "Radar efficiency and the calculation of decade-long PMSE backscatter cross-section for the Resolute Bay VHF radar." Annales Geophysicae 27 (4): 1643-1656 [10.5194/angeo-27-1643-2009] [Journal Article/Letter]

2008. "Similarities and differences in polar mesosphere summer echoes observed in the Arctic and Antarctica." Annales Geophysicae 26 (9): 2795-2806 [10.5194/angeo-26-2795-2008] [Journal Article/Letter]

Talks, Presentations and Posters


Other

High-Resolution GNSS-Derived Ionosphere Electron Density Measurements: Insight into Global Ionosphere Variability Impacted by the Atmosphere and Magnetosphere

15, 2023

AGU Fall Meeting, San Francisco.


F2 peak observations from COSMIC/Spire GNSS-POD and ground-based measurements

15, 2022

AGU Fall Meeting, Chicago.


Hemisphere-asymmetric responses of the ionosphere to geomagnetic storms as observed by GNSS and AMPERE

13, 2021

AGU Fall Meeting, New Orleans.


GNSS-RO ionospheric electron density responses to geomagnetic storms induced by CMEs

May 9, 2021

International Radio Occultation Working Group Meeting


Evaluation of a new global electron density measurement technique for D- and E-region ionosphere using ground-based observations and models

15, 2020

AGU Fall Meeting, Dec 2020.


Modeling the Altitude Distribution of Meteor Head Echoes Observed with HPLA Radars: Implications for the Radar Detectability of Meteoroid Populations

2019

Meteoroids 2019, Bratislava, Slovakia.


Modeled and observed altitude distributions of the micrometeoroid influx in radar detection

2017

AGU Fall Meeting, New Orleans.


Constraining the detection of the meteoroid flux with the altitude distribution of meteor head echoes

2016

AGU Fall Meeting, San Francisco.


Does weak turbulence impact PMSEs’ absolute signal strengths closer to the North Pole? 

2015

AGU Fall Meeting, San Francisco.


Strength and Variability of Polar Mesosphere Summer Echoes inside the Northern Polar Cap

September 2015

12th International Workshop on Layered Phenomena in the Mesopause Region (LPMR), Boulder, Colorado.


Aspect Sensitivity study on PMSE using Resolute Bay and Eureka VHF radars

2010

Canadian Network for the Detection of Atmospheric Change Workshop


Polar Mesosphere Summer Echoes: Observations and Comparisons at Resolute Bay and Eureka using calibrated VHF radars

2009

Canadian Network for the Detection of Atmospheric Change Workshop


A Decade-long aspect-sensitivity study of polar mesosphere summer echoes at Resolute Bay

2009

The 12th International workshop on technical and scientific aspects of MST radar, London, Canada.


Observations and comparison of polar mesosphere summer echoes at multiple locations using commonly design radars in the northern hemisphere

2009

Division of Aeronomy and Space Physics Workshop, Calgary, Alberta, Canada.


Observations of Polar Mesosphere Summer Echoes in the Northern Magnetic Polar Cap Region with Two Calibrated MST Radars

2008

Committee on Space Research (COSPAR), Montreal, Canada.


Calibration and calculation of absolute backscatter cross-section using sky noise and calibrated noise source for Resolute Bay radar

2006

The 11th International workshop on technical and scientific aspects of MST radar, India.


A Decade of PMSE studies with the Resolute Bay VHF MST radar

2006

The 11th International workshop on technical and scientific aspects of MST radar, India.


Horizontal coverage of coherent radar echoes observed from Resolute Bay

2005

Division of Aeronomy and Space Physics Workshop - 2005, Edmonton, Alberta, Canada.


Polar Mesosphere Summer Echoes: Seasonal and interannual variability

2004

Division of Aeronomy and Space Physics Workshop, London, Ontario, Canada.