1. Ionospheric impact on Biomass ESA mission
Lucilla Alfonsi1, Gabriella Povero2, Luca Spogli1,3, Claudio Cesaroni1, Biagio Forte4, Cathryn N.Mitchell4, Robert Burston4, Sreeja Veettil5, Marcio Aquino5, Virginia Klausner6, Marcio Muella6, Michael Pezzopane1, Alessandra Giuntini1, Ingrid Hunstad1, Giorgiana De Franceschi1, Elvira Musicò1,13, Marco Pini2, La The Vinh7, Ta Hai Tung7, Asnawi Husin8, Sri Ekawati8, Charisma Victoria de la Cruz-Cayapan9 , Mardina Abdullah10, Noridawaty Mat Daud10 , Minh Le Huy11, Nicolas Floury12
[1] Istituto Nazionale di Geofisica e Vulcanologia, Italy
[2] Istituto Superiore Mario Boella, Italy
[3] SpacEarth Technology, Italy
[4] University of Bath, UK
[5] University of Nottingham, UK
[6] Universidade do Vale do Paraíba (UNIVAP), Brazil
[7] Hanoi University of Science and Technology, Vietnam
[8] National Institute of Aeronautics and Space (LAPAN), Indonesia
[9] National Mapping and Resource Information Authority (NAMRIA), The Philippines
[10] Universiti Kebangsaan Malaysia (UKM), Malaysia
[11] Institute of Geophysics, Vietnam Academy of Science and Technology, Vietnam
[12] European Space Agency
[13] “Sapienza” University of Rome, Italy

2. Outline Scientific context The IRIS & IBISCO projects Data and methods
Highlights of the scientific results
Remarks

3. Scientific context (1/2)
Ionospheric propagation effects cause significant distortions in the data of low-frequency synthetic aperture radar (SAR) systems, whose severity is increasing with decreasing system frequency.
Left:
Examples of ionospheric phase screens in L-band InSAR data observed by the ALOS PALSAR system in the Arctic (Alaska).
From:
Meyer, F. J. (2011). Performance requirements for ionospheric correction of low-frequency SAR data. IEEE transactions on geoscience and remote sensing, 49(10),
Right: The georeferenced result of the azimuth shifts over central Italy from InSAR data by ALOS Palsar system. A clear effect due to the electromagnetic waves propagation through the ionospheric plasma is seen on ± 1 m displacements.
From: Musicò et al., The Total Electron Content from InSAR and GNSS: a mid-latitude case study, IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, under revision, 2017.
Ionospheric effect visible in the 2 narrow streaks on bottom of the left picture, at high latitudes the effect is evident from the interferogram
Ionospheric effect visible in the azimuth shifts (along the flight direction), with related fake displacement as the most evident streaks in the right picture

4. Scientific context (2/2)
Biomass carries synthetic aperture radar (SAR) at P-band (435 MHz)
Imaging to determine the amount of biomass and carbon stored in forests
Planned to be launched around 2021 (5 years duration).
Single satellite in a near-polar, Sunsynchronous orbit at an altitude of 637– 666 km.
The ionosphere introduces two effects into the BIOMASS SAR imaging process:
Faraday Rotation
Scintillation
Both effects are determined by the Total Electron Content (TEC), and its fluctuations, along the propagation path of every pulse emitted by the SAR.
The calibration targets should be located as closest as possible to the magnetic equator, to minimize the effect of the Faraday rotation.
Scintillation is a big threat near the magnetic equator
Good knowledge of the local features of the equatorial and low latitudes ionosphere is of great help to choose the SAR calibration sites.
Credits: ESA
Quegan, S., et al. "Ionospheric mitigation schemes and their consequences for BIOMASS product quality." Eur. Space Agency, Paris, France (2012)

5. ALCANTARA INITIATIVE: INTERNATIONAL R&D STUDIES
The IRIS & IBISCO projects
ALCANTARA INITIATIVE: INTERNATIONAL R&D STUDIES
Characterisation of the ionospheric environment at low latitudes, application to Biomass external calibration sites
IRIS - Ionospheric Research for Biomass in South America
Contractor: Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italy), Study Responsible: Lucilla Alfonsi
Partners: University of Bath (UoB, UK), University of Nottingham (UoN, UK)
External Partners: Instituto Nacional de Pesquisas Espaciais (INPE, Brazil), University of Vale do Paraiba (UNIVAP, Brazil)
IBisCo - Ionospheric environment characterization for Biomass Calibration over South East Asia
Contractor: Istituto Superiore Mario Boella (ISMB, Italy), Study Responsible: Gabriella Povero
Partners: University of Bath (UoB, UK), Istituto Nazionale di Geofisica e Vulcanologia (INGV, Italy)
External Partners: Hanoi University of Science and Technology (HUST, Vietnam), National Institute of Aeronautics and Space (LAPAN, Indonesia)
This is the reason why at the end of 2015 ESA launched a call to fund studies of the upper atmosphere within an Alcantara initiative of the Space Agency’s General Studies Programme ( to support BIOMASS operations. The two projects named IRIS (Ionospheric Research for Biomass in South America) and IBISCO (Ionospheric environment characterization for Biomass Calibration over South East Asia) were among the successful proposals. IRIS and IBISCO released an in-depth climatological description of South-East Asia (SEA) as well as Brazilian Equatorial Ionospheric Anomaly (EIA) to support BIOMASS operations. The main objective of this paper is to report the principal findings of the two projects, highlighting the original approach adopted to assess the regional characteristics of the TEC, TEC gradients and scintillations around 06 AM and 06 PM, times of the BIOMASS orbital passes.

6. The methodology The network of GNSS receivers* West SEA East SEA
Climatology (1 year) of the ionosphere in the two quietest days of each month in the considered period over South East ASIA (SEA) and Brazil
Special focus is given to the times of the foreseen Biomass orbital passes, i.e. 06 AM and 06 PM
Variation of TEC (including its spatial and temporal variation) and amplitude scintillations (S4)
The sensitivity of TEC and TEC gradients mapping has been tested to assess the actual reliability of the method
More in the projects’ study (case events and climatology from ionosonde data, TIDs detection), not shown here
The network of GNSS receivers*
West SEA
East SEA
March 2015 to
February 2016
Dip equator
Considered period mar-feb 2016 (IBISCO)
2015 IRIS
West-East at 115°E (IBISCO)
Year 2015
EIA
Crest
115°E
Pins: geodetic receivers
(1 Hz – TEC measurement)
Circles: scintillation receivers
(50 Hz – S4 and TEC measurement)
*from partners + additional providers

7. Highlights of the scientific results

8. TEC spatial gradients (E-W): daily variation
06AM LT
06PM LT
06AM LT
06PM LT
West SEA
Brazilian EIA crest
06AM LT
06PM LT
East SEA
24 days to represent all the year round TEC gradients daily variation
TEC gradients are given as absolute values
Brazilian dip equator

9. TEC spatial gradients (N-S): monthly variation over SEA
06AM LT
Dip equator
06PM LT

10. TEC spatial gradients (N-S): monthly variation over Brazilian southern crest
06AM LT
Dip equator
at -9°N
06PM LT

11. Scintillation occurrence (S4>0.1, 0.25, 0.7): monthly variation
06AM LT
06PM LT
East SEA
West SEA

12. Scintillation occurrence (S4>0.1, 0.25): monthly variation
06AM LT
06PM LT
Brazil crest
Brazil dip-equator

13. Remarks
The climatological picture of the low-latitude ionosphere in SEA and Brazil has been customized to provide the information needed for the Biomass mission operational purposes.
The information derived from the two studies is considered by ESA a valuable contribution to the regional characterization of the ionospheric impact on remote sensing.
A reliable assessment of the ionospheric scenario, even during quiet times, must rely on data driven representation.
Our statistical analysis of the TEC gradients and of scintillations reveals:
An important distinction between the meridional TEC variation and the zonal variation;
A clear definition of the role of EIA crests in hosting the ionospheric irregularities;
Peculiar characteristics of the low-latitude ionosphere at the Biomass orbital passes (06 AM, 06 PM).

14. Thank you!