A 2015 International Geomagnetic Reference Field (IGRF) candidate model based on <i>Swarm’s</i> experimental absolute magnetometer vector mode data

International audienceEach of the three satellites of the European Space Agency Swarm mission carries an absolute scalar magnetometer (ASM) that provides the nominal 1-Hz scalar data of the mission for both science and calibration purposes. These ASM instruments, however, also deliver autonomous 1-Hz experimental vector data. Here, we report on how ASM-only scalar and vector data from the Alpha and Bravo satellites between November 29, 2013 (a week after launch) and September 25, 2014 (for on-time delivery of the model on October 1, 2014) could be used to build a very valuable candidate model for the 2015.0 International Geomagnetic Reference Field (IGRF). A parent model was first computed, describing the geomagnetic field of internal origin up to degree and order 40 in a spherical harmonic representation and including a constant secular variation up to degree and order 8. This model was next simply forwarded to epoch 2015.0 and truncated at degree and order 13. The resulting ASM-only 2015.0 IGRF candidate model is compared to analogous models derived from the mission's nominal data and to the now-published final 2015.0 IGRF model. Differences among models mainly highlight uncertainties enhanced by the limited geographical distribution of the selected data set (essentially due to a lack of availability of data at high northern latitude satisfying nighttime conditions at the end of the time period considered). These appear to be comparable to differences classically observed among IGRF candidate models. These positive results led the ASM-only 2015.0 IGRF candidate model to contribute to the construction of the final 2015.0 IGRF model

International Geomagnetic Reference Field: the 12th generation

The 12th generation of the International Geomagnetic Reference Field (IGRF) was adopted in December 2014 by the Working Group V-MOD appointed by the International Association of Geomagnetism and Aeronomy (IAGA). It updates the previous IGRF generation with a definitive main field model for epoch 2010.0, a main field model for epoch 2015.0, and a linear annual predictive secular variation model for 2015.0-2020.0. Here, we present the equations defining the IGRF model, provide the spherical harmonic coefficients, and provide maps of the magnetic declination, inclination, and total intensity for epoch 2015.0 and their predicted rates of change for 2015.0-2020.0. We also update the magnetic pole positions and discuss briefly the latest changes and possible future trends of the Earth’s magnetic fiel

ASM status after 10 years of operation on-board the Swarm satellites

International audienceThe Absolute Scalar Magnetometers (ASM) on-board the ESA's Swarm satellites are helium-4 optically pumped magnetometers designed by CEA-Leti and developed in partnership with CNES. While the primary role of the ASM is to provide precise 1 Hz absolute scalar measurements for the vector calibration of VFM fluxgate, they are also able to deliver autonomously self-calibrated 1 Hz vector data or to provide high rate 250 Hz burst scalar data. In this presentation, we will first report on the current health status of these instruments and then review the specificities of the vector and the burst mode data provided by the ASM

The NanoMagSat magnetometry payload

International audienceTaking advantage from the lessons learnt on the Swarm's Absolute Scalar Magnetometers (ASM), a new generation of optically pumped helium scalar magnetometer also delivering calibrated vector measurements is currently being developed for the NanoMagSat satellites. A very significant miniaturization has been made possible for both the sensor head and the associated electronics, thanks to the replacement of the fiber laser by a laser diode and the definition of a new architecture to ensure the instrument's isotropy. These evolutions also imply modifying the signal detection scheme, thus leading to a completely revised design. Special emphasis will be put on the performance evolution opened by these changes. Given the results obtained by the ASMs flown on Swarm satellites respectively in vector and burst modes, this Miniaturized Absolute Magnetometer (MAM) will be operated to simultaneously deliver high accuracy vector measurements at a 1 Hz rate and high resolution scalar measurements at 2 kHz. In addition to the MAM, a High Frequency Magnetometer (HFM) delivering high-resolution (# 0,2 pT/Hz1/2 @ 1 Hz) vector data at a 2 kHz rate will be operated to support space weather related studies. It derives from a magnetometer developed at Leti for MagnetoEncephaloGraphy applications in shielded environments, which has been successfully adapted for operation in the Earth magnetic field. Finally, to allow in-orbit cross analyses of small scale structures - typically down to a few meters - magnetic measurements by both the MAM and the HFM will be synchronized with the plasma parameters delivered by the multi needle Langmuir probe (m-NLP) developed by the University of Oslo, which complements the NanoMagSat science payload. We will report here on the development status of these two MAM and HFM magnetometers and describe the results obtained so far, as well as the work still lying ahead

The NanoMagSat magnetometry payload

International audienceTaking advantage from the lessons learnt on the Swarm's Absolute Scalar Magnetometers (ASM), a new generation of optically pumped helium scalar magnetometer also delivering calibrated vector measurements is currently being developed for the NanoMagSat satellites. A very significant miniaturization has been made possible for both the sensor head and the associated electronics, thanks to the replacement of the fiber laser by a laser diode and the definition of a new architecture to ensure the instrument's isotropy. These evolutions also imply modifying the signal detection scheme, thus leading to a completely revised design. Special emphasis will be put on the performance evolution opened by these changes. Given the results obtained by the ASMs flown on Swarm satellites respectively in vector and burst modes, this Miniaturized Absolute Magnetometer (MAM) will be operated to simultaneously deliver high accuracy vector measurements at a 1 Hz rate and high resolution scalar measurements at 2 kHz. In addition to the MAM, a High Frequency Magnetometer (HFM) delivering high-resolution (# 0,2 pT/Hz1/2 @ 1 Hz) vector data at a 2 kHz rate will be operated to support space weather related studies. It derives from a magnetometer developed at Leti for MagnetoEncephaloGraphy applications in shielded environments, which has been successfully adapted for operation in the Earth magnetic field. Finally, to allow in-orbit cross analyses of small scale structures - typically down to a few meters - magnetic measurements by both the MAM and the HFM will be synchronized with the plasma parameters delivered by the multi needle Langmuir probe (m-NLP) developed by the University of Oslo, which complements the NanoMagSat science payload. We will report here on the development status of these two MAM and HFM magnetometers and describe the results obtained so far, as well as the work still lying ahead

A 4He vector zero-field optically pumped magnetometer operated in the Earth-field

International audienceLow intrinsic noise, high bandwidth and high accuracy vector magnetometers are key components for many ground or space geophysical applications. Here we report the design and the test of a 4He vector optically pumped magnetometer specifically dedicated to these needs. It is based on a parametric resonance magnetometer architecture operated in the Earth magnetic field with closed-loop compensation of the 3 components of the magnetic field. It provides offset-free vector measurements in a ±70 µT range with a DC to 1 kHz bandwidth. We demonstrate a vector sensitivity up to 130 fT/sqrt(Hz), which is about ten times better than the best available fluxgate magnetometers currently available for the same targeted applications

Swarm's Absolute Scalar Magnetometers Burst Mode Results

International audienceEach of the three Swarm satellites embarks an Absolute Scalar Magnetometer (ASM) to provide absolute scalar measurements of the magnetic field with high accuracy and stability. Nominal data acquisition of these ASMs is 1 Hz. But they can also run in a so-called "burst mode" and provide data at 250 Hz. During the commissioning phase of the mission, seven burst mode acquisition campaigns have been run simultaneously for all satellites, obtaining a total of ten days of burst-mode data. These campaigns allowed the identification of issues related to the operations of the piezo-electric motor and the heaters connected to the ASM, that do not impact the nominal 1 Hz scalar data. We analyze the burst mode data to identify high frequency geomagnetic signals, focusing the analysis in two regions: the low latitudes, where we seek signatures of ionospheric irregularities, and the high latitudes, to identify high frequency signals related to polar region currents. Since these campaigns have been conducted during the initial months of the mission, the three satellites where still close to each other, allowing to analyze the spatial coherency of the signals

Swarm's Absolute Scalar Magnetometers Burst Mode Results

International audienceEach of the three Swarm satellites embarks an Absolute Scalar Magnetometer (ASM) to provide absolute scalar measurements of the magnetic field with high accuracy and stability. Nominal data acquisition of these ASMs is 1 Hz. But they can also run in a so-called "burst mode" and provide data at 250 Hz. During the commissioning phase of the mission, seven burst mode acquisition campaigns have been run simultaneously for all satellites, obtaining a total of ten days of burst-mode data. These campaigns allowed the identification of issues related to the operations of the piezo-electric motor and the heaters connected to the ASM, that do not impact the nominal 1 Hz scalar data. We analyze the burst mode data to identify high frequency geomagnetic signals, focusing the analysis in two regions: the low latitudes, where we seek signatures of ionospheric irregularities, and the high latitudes, to identify high frequency signals related to polar region currents. Since these campaigns have been conducted during the initial months of the mission, the three satellites where still close to each other, allowing to analyze the spatial coherency of the signals