Assimilation of thermospheric measurements for ionosphere‐thermosphere state estimation

Miladinovich, D.; Datta‐Barua, Seebany; Bust, G. S.; Makela, J. J.

doi:10.1002/2016rs006098

Cited by 7 publications

(39 citation statements)

References 32 publications

(48 reference statements)

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“…For this reason tracer trajectories appear to cross the LCS ridges. In addition, using data assimilation drifts from methods such as Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE; Miladinovich et al, 2016) and Super Dual Auroral Radar Network (SuperDARN; Ruohoniemi et al, 1989) could provide data-driven plasma drifts that could be used as the inputs to ITALCS in the future.…”

Section: Discussionmentioning

confidence: 99%

Horseshoes in the High‐Latitude Ionosphere

et al. 2018

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In the high‐latitude ionosphere, predicting transport of polar cap patches is important because of their impact on radio communications and navigation systems. Lagrangian coherent structures (LCSs) are barriers to transport in nonlinear time‐varying flow fields, found by computing the local maximum finite‐time Lyapunov exponent (FTLE). We propose that LCSs are barriers governing patch formation. In this work, we compute and visualize the LCSs in high‐latitude ionospheric convection by computing the FTLE field with the Ionosphere‐Thermosphere Algorithm for Lagrangian Coherent Structures (ITALCS). The Weimer 2005 high‐latitude electric potential model and the 12th‐generation International Geomagnetic Reference Field (IGRF‐12) are used to generate the trueE→×trueB→ drift field at each gridpoint in the ionosphere. The trueE→×trueB→ drifts are used as the input to ITALCS. Time‐varying structures are detected in two‐dimensional ionospheric drifts at high latitudes based on locally maximum forward time FTLE values for both geomagnetically stormy and quiet periods. Typically, the dominant structure is shaped like the letter “U,” or a “horseshoe,” oriented with the curved portion of the “U” on the dayside around local noon. The LCSs during the geomagnetically stormy period have more complex topology and shift equatorward compared to the LCSs during quiet times. Analysis of a polar cap patch observed on 17 March 2015 with the Multi‐Instrument Data Analysis System indicates that a necessary condition for its formation and transport is that storm enhanced density exist poleward of the LCS.

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Section: Discussionmentioning

confidence: 99%

Horseshoes in the High‐Latitude Ionosphere

et al. 2018

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“…The correction to the field‐parallel drift δv || in Equation 2 is estimated as due strictly to projections of the horizontal geographic meridional and zonal components of the neutral wind δu N and δu E , respectively, onto the field‐aligned direction. Each is fit to its own power series basis functions (Miladinovich et al, 2016), for example, δu N as shown below:

δ v_{false| false|} = δ u_{false| false|} = δ u_{N} \overset{n}{true} \cdot \overset{b}{true} + δ u_{E} \overset{e}{true} \cdot \overset{b}{true}

δ u_{N} false(r, θ, ϕ false) = true \sum_{k = 0}^{k_{m a x}} true \sum_{l = 0}^{l_{m a x}} true \sum_{p = 0}^{p_{m a x}} x_{k l p} {()(, \frac{r}{R_{e}})}^{k} {false(θ - θ_{0} false)}^{l} {false(ϕ - ϕ_{0} false)}^{p}

where

\overset{n}{true}

is a unit vector pointing toward geographic north,

\overset{e}{true}

geographic east, and

\overset{b}{true}

along the field line. We assume that there is negligible vertical wind motion.…”

Section: Overview Of the Empire Algorithmmentioning

confidence: 99%

“…The correction to the field-parallel drift 𝛿v || in Equation 2 is estimated as due strictly to projections of the horizontal geographic meridional and zonal components of the neutral wind 𝛿u N and 𝛿u E , respectively, onto the field-aligned direction. Each is fit to its own power series basis functions (Miladinovich et al, 2016), for example, 𝛿u N as shown below:…”

Section: Overview Of the Empire Algorithmmentioning

confidence: 99%

“…EMPIRE has been shown to estimate neutral winds and electric potential regionally during storm time events using the information provided by ionospheric plasma density (Datta‐Barua et al, 2009, 2011, 2013). More recently, it has been adapted to be able to ingest neutral wind measurements, that is, direct measurements of one of the ionospheric drivers, for estimating neutral winds (Miladinovich et al, 2016). While using measurements of plasma density alone only allows for estimation of field‐aligned neutral winds (given the EMPIRE continuity equation formulation), ingestion of neutral wind measurements from multiple look directions can in principle enable estimation of vector neutral winds.…”

Section: Introductionmentioning

confidence: 99%

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Assimilation of GNSS Measurements for Estimation of High‐Latitude Convection Processes

et al. 2020

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Geomagnetic storms produce significant electrodynamics at midlatitudes. Strong ion convection can affect thermospheric neutral wind motion. The converse is also true, such that both fields and winds can drive ionospheric plasma movement. This work adjusts a background modeled high‐latitude electrostatic potential to estimate the storm time electric field based on data‐derived plasma densities and measurements of neutral wind. Electron densities are derived from global navigation satellite system (GNSS) total electron content measurements using Ionospheric Data Assimilation Four‐Dimensional (IDA4D). These are input to Estimating Model Parameters from Ionospheric Reverse Engineering (EMPIRE) to estimate electric potential corrections to the background Weimer 2000 potential model. The EMPIRE basis functions for electric potential are spherical harmonics in dipole magnetic colatitude and longitude, enforced to be constant along a magnetic field line. For the 17 March 2015 storm, EMPIRE electric potential produces westward zonal ion drifts that more closely agree with incoherent scatter radar (ISR) measurements made at Millstone Hill than the background Weimer 2000 model alone, when electric potential and meridional neutral winds are both corrected. Additionally ingesting northward line‐of‐sight neutral wind measurements from a Fabry‐Perot interferometer at Millstone Hill makes little difference in the agreement between zonal ion drift predictions and measurements. Estimation of only electric potential reduces the agreement between the assimilated prediction of the field‐perpendicular zonal drifts and ISR measurements significantly.

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“…Understanding how energy and momentum are transferred through the generation, propagation, and dissipation of atmospheric waves over a wide range of spatial and temporal scales is one of key factors to understand the variability of the T/I system [20]. Connecting the dynamics of the neutral atmosphere and the ionosphere improves the modelling and forecasting capabilities (see, e.g., [13,19,20,24]. Observing gravity waves in the middle atmosphere at high spatial resolution will also contribute to improving global and regional climate projections and sub-seasonal weather forecasts (10-30 days) due to the downward coupling of these waves.…”

Section: Introductionmentioning

confidence: 99%

On the assembly and calibration of a spatial heterodyne interferometer for limb sounding of the middle atmosphere

et al. 2019

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Spatial heterodyne interferometers are an enabling technology to build highly miniaturized optical instruments for the observation of faint emissions in the atmosphere. They are particularly suited for the deployment on nano-or micro-satellite constellations. One application of the SHI technology is a middle atmosphere temperature sounder based on the measurement of relative intensities emitted by the O 2 atmospheric band system. Beside basic design considerations, aspects of the opto-mechanical design and assembly of a monolithic SHI for a space application are addressed. For the characterization of such an instrument, a light stimulus based on a Köhler illuminator is presented.

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Assimilation of thermospheric measurements for ionosphere‐thermosphere state estimation

Cited by 7 publications

References 32 publications

Horseshoes in the High‐Latitude Ionosphere

Horseshoes in the High‐Latitude Ionosphere

Assimilation of GNSS Measurements for Estimation of High‐Latitude Convection Processes

On the assembly and calibration of a spatial heterodyne interferometer for limb sounding of the middle atmosphere

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