The Intriguing Structure of Stripes in GRACE Geopotential Models

Geopotential models derived from Gravity Recovery and Climate Experiment (GRACE) mission measurements are significantly obscured by the presence of a systematic artifact, known as longitudinal stripes. Based on our previous work (Peidou and Pagiatakis, 2020) we provide an in-depth analysis of the la...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Spiros Pagiatakis, Athina Peidou
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	GRACE stripes sub-Nyquist artifacts sampling artifacts aliasing disturbing potential Science Q
Acceso en línea:	https://doaj.org/article/ae53824bac1f498980102a38c9373dc8
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:ae53824bac1f498980102a38c9373dc8
record_format	dspace
spelling	oai:doaj.org-article:ae53824bac1f498980102a38c9373dc82021-11-11T18:54:42ZThe Intriguing Structure of Stripes in GRACE Geopotential Models10.3390/rs132143622072-4292https://doaj.org/article/ae53824bac1f498980102a38c9373dc82021-10-01T00:00:00Zhttps://www.mdpi.com/2072-4292/13/21/4362https://doaj.org/toc/2072-4292Geopotential models derived from Gravity Recovery and Climate Experiment (GRACE) mission measurements are significantly obscured by the presence of a systematic artifact, known as longitudinal stripes. Based on our previous work (Peidou and Pagiatakis, 2020) we provide an in-depth analysis of the latitudinal sampling characteristics of GRACE and we reveal the intriguing sampling mechanism that creates sub-Nyquist artifacts (stripes). Because the sub-Nyquist artifacts are poorly understood, we provide a simple simulation example to elucidate the mechanism of the sub-Nyquist artifact generation. Subsequently, we randomly select June 2009 daily GPS precise science orbits for GRACE-A to produce ground tracks to sample the low frequency disturbing potential (geoid) along the parallel of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ϕ</mi><mo>=</mo><msup><mrow><mn>10</mn></mrow><mo>°</mo></msup><mtext> </mtext><mi mathvariant="normal">N</mi></mrow></semantics></math></inline-formula>. The sampled geoid is then deinterlaced in space to produce a monthly data sequence whose detailed analysis shows that the sub-Nyquist artifacts (stripes) are produced from a critical sampling rate of the low degree gravitational field that is related to the ratio <i>m</i>/<i>n</i> of two mutually prime integers, where <i>m</i> is the number of days it takes to have a nearly repeat orbit and <i>n</i> is the number of complete orbits in one day. We perform extensive analyses of GRACE Level-2 data over a period of eight years to show the variability in the orbital characteristics that are directly linked to the orbit resonances (via integers <i>m</i> and <i>n</i>). It turns out that during short repeat cycle resonances the stripes are amplified. Finally, to minimize the presence of stripes in Level-2 data products, it is recommended that orbits of future missions should be designed to avoid the critical <i>m</i>/<i>n</i> ratios while appropriately monitoring and adjusting them during the mission. For completed missions, or missions that are already active, force modelling the latitudinal low frequency disturbing potential may be a viable and most preferred approach to filtering.Spiros PagiatakisAthina PeidouMDPI AGarticleGRACE stripessub-Nyquist artifactssampling artifactsaliasingdisturbing potentialScienceQENRemote Sensing, Vol 13, Iss 4362, p 4362 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	GRACE stripes sub-Nyquist artifacts sampling artifacts aliasing disturbing potential Science Q
spellingShingle	GRACE stripes sub-Nyquist artifacts sampling artifacts aliasing disturbing potential Science Q Spiros Pagiatakis Athina Peidou The Intriguing Structure of Stripes in GRACE Geopotential Models
description	Geopotential models derived from Gravity Recovery and Climate Experiment (GRACE) mission measurements are significantly obscured by the presence of a systematic artifact, known as longitudinal stripes. Based on our previous work (Peidou and Pagiatakis, 2020) we provide an in-depth analysis of the latitudinal sampling characteristics of GRACE and we reveal the intriguing sampling mechanism that creates sub-Nyquist artifacts (stripes). Because the sub-Nyquist artifacts are poorly understood, we provide a simple simulation example to elucidate the mechanism of the sub-Nyquist artifact generation. Subsequently, we randomly select June 2009 daily GPS precise science orbits for GRACE-A to produce ground tracks to sample the low frequency disturbing potential (geoid) along the parallel of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>ϕ</mi><mo>=</mo><msup><mrow><mn>10</mn></mrow><mo>°</mo></msup><mtext> </mtext><mi mathvariant="normal">N</mi></mrow></semantics></math></inline-formula>. The sampled geoid is then deinterlaced in space to produce a monthly data sequence whose detailed analysis shows that the sub-Nyquist artifacts (stripes) are produced from a critical sampling rate of the low degree gravitational field that is related to the ratio <i>m</i>/<i>n</i> of two mutually prime integers, where <i>m</i> is the number of days it takes to have a nearly repeat orbit and <i>n</i> is the number of complete orbits in one day. We perform extensive analyses of GRACE Level-2 data over a period of eight years to show the variability in the orbital characteristics that are directly linked to the orbit resonances (via integers <i>m</i> and <i>n</i>). It turns out that during short repeat cycle resonances the stripes are amplified. Finally, to minimize the presence of stripes in Level-2 data products, it is recommended that orbits of future missions should be designed to avoid the critical <i>m</i>/<i>n</i> ratios while appropriately monitoring and adjusting them during the mission. For completed missions, or missions that are already active, force modelling the latitudinal low frequency disturbing potential may be a viable and most preferred approach to filtering.
format	article
author	Spiros Pagiatakis Athina Peidou
author_facet	Spiros Pagiatakis Athina Peidou
author_sort	Spiros Pagiatakis
title	The Intriguing Structure of Stripes in GRACE Geopotential Models
title_short	The Intriguing Structure of Stripes in GRACE Geopotential Models
title_full	The Intriguing Structure of Stripes in GRACE Geopotential Models
title_fullStr	The Intriguing Structure of Stripes in GRACE Geopotential Models
title_full_unstemmed	The Intriguing Structure of Stripes in GRACE Geopotential Models
title_sort	intriguing structure of stripes in grace geopotential models
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/ae53824bac1f498980102a38c9373dc8
work_keys_str_mv	AT spirospagiatakis theintriguingstructureofstripesingracegeopotentialmodels AT athinapeidou theintriguingstructureofstripesingracegeopotentialmodels AT spirospagiatakis intriguingstructureofstripesingracegeopotentialmodels AT athinapeidou intriguingstructureofstripesingracegeopotentialmodels
_version_	1718431665859067904

The Intriguing Structure of Stripes in GRACE Geopotential Models

Ejemplares similares