CLUSTER–STAFF search coil magnetometer calibration – comparisons with FGM

Abstract. The main part of the Cluster Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment consists of triaxial search coils allowing the measurements of the three magnetic components of the waves from 0.1 Hz up to 4 kHz. Two sets of data are produced, one by a module to filter and transmit the corresponding waveform up to either 10 or 180 Hz (STAFF-SC), and the second by the onboard Spectrum Analyser (STAFF-SA) to compute the elements of the spectral matrix for five components of the waves, 3 × B and 2 × E (from the EFW experiment), in the frequency range 8 Hz to 4 kHz. In order to understand the way the output signals of the search coils are calibrated, the transfer functions of the different parts of the instrument are described as well as the way to transform telemetry data into physical units across various coordinate systems from the spinning sensors to a fixed and known frame. The instrument sensitivity is discussed. Cross-calibration inside STAFF (SC and SA) is presented. Results of cross-calibration between the STAFF search coils and the Cluster Fluxgate Magnetometer (FGM) data are discussed. It is shown that these cross-calibrations lead to an agreement between both data sets at low frequency within a 2% error. By means of statistics done over 10 yr, it is shown that the functionalities and characteristics of both instruments have not changed during this period.

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CLUSTER STAFF search coils magnetometer calibration – comparisons with FGM

Geoscientific Instrumentation Methods and Data Systems Discussions ◽

10.5194/gid-3-679-2013 ◽

2013 ◽

Vol 3 (2) ◽

pp. 679-751

Author(s):

P. Robert ◽

N. Cornilleau-Wehrlin ◽

R. Piberne ◽

Y. de Conchy ◽

C. Lacombe ◽

...

Keyword(s):

Transfer Functions ◽

Low Frequency ◽

Temporal Analysis ◽

Data Sets ◽

Spectral Matrix ◽

Magnetic Components ◽

Spatio Temporal ◽

Cross Calibration ◽

The Waves ◽

The Way

Abstract. The main part of Cluster Spatio Temporal Analysis of Field Fluctuations (STAFF) experiment consists of triaxial search coils allowing the measurements of the three magnetic components of the waves from 0.1 Hz up to 4 kHz. Two sets of data are produced, one by a module to filter and transmit the corresponding waveform up to either 10 or 180 Hz (STAFF-SC) and the second by an onboard Spectrum Analyser (STAFF-SA) to compute the elements of the spectral matrix for five components of the waves, 3 × B and 2 × E (from EFW experiment) in the frequency range 8 Hz to 4 kHz. In order to understand the way the output signal of the search coils are calibrated, the transfer functions of the different parts of the instrument are described as well as the way to transform telemetry data into physical units, across various coordinate systems from the spinning sensors to a fixed and known frame. The instrument sensitivity is discussed. Cross-calibration inside STAFF (SC and SA) is presented. Results of cross-calibration between the STAFF search coils and the Cluster Flux Gate Magnetometer (FGM) data are discussed. It is shown that these cross-calibrations lead to an agreement between both data sets at low frequency within a 2% error. By means of statistics done over 10 yr, it is shown that the functionalities and characteristics of both instruments have not changed during this period.

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Historical drought patterns over Canada and their teleconnections with large-scale climate signals

Hydrology and Earth System Sciences ◽

10.5194/hess-22-3105-2018 ◽

2018 ◽

Vol 22 (6) ◽

pp. 3105-3124 ◽

Cited By ~ 24

Author(s):

Zilefac Elvis Asong ◽

Howard Simon Wheater ◽

Barrie Bonsal ◽

Saman Razavi ◽

Sopan Kurkute

Keyword(s):

Large Scale ◽

Southern Oscillation ◽

Low Frequency ◽

Kendall Test ◽

Wavelet Coherence ◽

Climate Indices ◽

Data Sets ◽

Canadian Prairies ◽

Agriculture Industry ◽

Spatio Temporal

Abstract. Drought is a recurring extreme climate event and among the most costly natural disasters in the world. This is particularly true over Canada, where drought is both a frequent and damaging phenomenon with impacts on regional water resources, agriculture, industry, aquatic ecosystems, and health. However, nationwide drought assessments are currently lacking and impacted by limited ground-based observations. This study provides a comprehensive analysis of historical droughts over the whole of Canada, including the role of large-scale teleconnections. Drought events are characterized by the Standardized Precipitation Evapotranspiration Index (SPEI) over various temporal scales (1, 3, 6, and 12 consecutive months, 6 months from April to September, and 12 months from October to September) applied to different gridded monthly data sets for the period 1950–2013. The Mann–Kendall test, rotated empirical orthogonal function, continuous wavelet transform, and wavelet coherence analyses are used, respectively, to investigate the trend, spatio-temporal patterns, periodicity, and teleconnectivity of drought events. Results indicate that southern (northern) parts of the country experienced significant trends towards drier (wetter) conditions although substantial variability exists. Two spatially well-defined regions with different temporal evolution of droughts were identified – the Canadian Prairies and northern central Canada. The analyses also revealed the presence of a dominant periodicity of between 8 and 32 months in the Prairie region and between 8 and 40 months in the northern central region. These cycles of low-frequency variability are found to be associated principally with the Pacific–North American (PNA) and Multivariate El Niño/Southern Oscillation Index (MEI) relative to other considered large-scale climate indices. This study is the first of its kind to identify dominant periodicities in drought variability over the whole of Canada in terms of when the drought events occur, their duration, and how often they occur.

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Spatio-temporal analysis of stimuli-modulated spontaneous low frequency oscillations

Chinese Science Bulletin ◽

10.1007/s11434-007-0219-8 ◽

2007 ◽

Vol 52 (11) ◽

pp. 1475-1483 ◽

Cited By ~ 8

Author(s):

Ming Li ◽

YaDong Liu ◽

DeWen Hu ◽

YuCheng Wang ◽

FaYi Liu ◽

...

Keyword(s):

Low Frequency ◽

Temporal Analysis ◽

Low Frequency Oscillations ◽

Spatio Temporal

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Spatio-Temporal Analysis and Uncertainty of Fractional Vegetation Cover Change over Northern China during 2001–2012 Based on Multiple Vegetation Data Sets

Remote Sensing ◽

10.3390/rs10040549 ◽

2018 ◽

Vol 10 (4) ◽

pp. 549 ◽

Cited By ~ 9

Author(s):

Linqing Yang ◽

Kun Jia ◽

Shunlin Liang ◽

Meng Liu ◽

Xiangqin Wei ◽

...

Keyword(s):

Vegetation Cover ◽

Northern China ◽

Temporal Analysis ◽

Data Sets ◽

Fractional Vegetation Cover ◽

Spatio Temporal ◽

Vegetation Cover Change

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Spatio-temporal analysis of spontaneous low frequency oscillations to single whisker stimulation in rat cerebral cortex

TENCON 2015 - 2015 IEEE Region 10 Conference ◽

10.1109/tencon.2015.7373082 ◽

2015 ◽

Author(s):

Guoliang Han ◽

Liangming Huang ◽

Ming Li ◽

Yadong Liu ◽

Lihua He ◽

...

Keyword(s):

Cerebral Cortex ◽

Low Frequency ◽

Temporal Analysis ◽

Rat Cerebral Cortex ◽

Low Frequency Oscillations ◽

Whisker Stimulation ◽

Spatio Temporal

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Polarisation and propagation of lion roars in the dusk side magnetosheath

Annales Geophysicae ◽

10.5194/angeo-19-1429-2001 ◽

2001 ◽

Vol 19 (10/12) ◽

pp. 1429-1438 ◽

Cited By ~ 20

Author(s):

M. Maksimovic ◽

C. C. Harvey ◽

O. Santolík ◽

C. Lacombe ◽

Y. de Conchy ◽

...

Keyword(s):

Magnetic Field ◽

Temporal Analysis ◽

Radiowave Propagation ◽

Spectral Matrix ◽

Radio Science ◽

Source Regions ◽

Field Fluctuations ◽

Whistler Mode Waves ◽

Spatio Temporal ◽

The Magnetic Field

Abstract. We present observations of "lion roars" obtained in the magnetosheath by the Spectrum Analyser (SA) of the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment aboard Cluster. STAFF-SA calculates, in near real time, the complete auto- and cross-spectral matrix derived from three magnetic and two electric components of the electromagnetic field at 27 frequencies in the range of 8 Hz to 4 kHz. This allows the study of the properties of whistler mode waves and more particularly, the properties of "lion roars", which are intense, short-duration, narrow-banded packets of whistler waves. Their presence is favoured by the magnetic field troughs associated with mirror mode structures. During two short periods of well-defined mirror modes, we study the depth δB/B of the magnetic troughs, and the direction of propagation of the lion roars. During the first period, close to the magnetopause, deep magnetic troughs pass the satellites. Lion roars are then observed to propagate simultaneously in two directions, roughly parallel and anti-parallel to the magnetic field: this probably indicates that during this period, the satellites were within the successive source regions of lion roars. For the second period, far from the magnetopause, the magnetic troughs are less deep. Lion roars are propagating in only one direction, roughly anti-parallel to the magnetic field, suggesting that the source regions are more distant and predominantly on one side of the satellites.Key words. Magnetospheric physics (magnetosheath; plasma waves and instabilities) Radio science (radiowave propagation)

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First results obtained by the Cluster STAFF experiment

Annales Geophysicae ◽

10.5194/angeo-21-437-2003 ◽

2003 ◽

Vol 21 (2) ◽

pp. 437-456 ◽

Cited By ~ 162

Author(s):

N. Cornilleau-Wehrlin ◽

G. Chanteur ◽

S. Perraut ◽

L. Rezeau ◽

P. Robert ◽

...

Keyword(s):

Electric Fields ◽

Electromagnetic Waves ◽

Temporal Analysis ◽

Equatorial Region ◽

Magnetic Fluctuations ◽

Vector Method ◽

Spectral Matrix ◽

Spectrum Analyser ◽

First Results ◽

The Waves

Abstract. The Spatio Temporal Analysis of Field Fluctuations (STAFF) experiment is one of the five experiments, which constitute the Cluster Wave Experiment Consortium (WEC). STAFF consists of a three-axis search coil magnetometer to measure magnetic fluctuations at frequencies up to 4 kHz, a waveform unit (up to either 10 Hz or 180 Hz) and a Spectrum Analyser (up to 4 kHz). The Spectrum Analyser combines the 3 magnetic components of the waves with the two electric components measured by the Electric Fields and Waves experiment (EFW) to calculate in real time the 5 × 5 Hermitian cross-spectral matrix at 27 frequencies distributed logarithmically in the frequency range 8 Hz to 4 kHz. The time resolution varies between 0.125 s and 4 s. The first results show the capabilities of the experiment, with examples in different regions of the magnetosphere-solar wind system that were encountered by Cluster at the beginning of its operational phase. First results obtained by the use of some of the tools that have been prepared specifically for the Cluster mission are described. The characterisation of the motion of the bow shock between successive crossings, using the reciprocal vector method, is given. The full characterisation of the waves analysed by the Spectrum Analyser, thanks to a dedicated program called PRASSADCO, is applied to some events; in particular a case of very confined electromagnetic waves in the vicinity of the equatorial region is presented and discussed.Key words. Magnetospheric physics (magnetopause, cusp and boundary layer) – Space plasma physics (waves and instabilities; shock waves)

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