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Project Loon based augmentation for global ionospheric modeling over Southern Hemisphere

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ABSTRACT

Global ionospheric products of vertical total electron content (VTEC) derived from GNSS measurements may have low accuracy over oceans and southern latitudes where there are not rich observations. Project Loon provides a great opportunity to enhance the measurements over those areas. In this contribution, a simulation of Project Loon based augmentation for global ionospheric modeling is performed by using the international reference ionosphere (IRI) which could simulate VTEC measurements for the balloons. The performance of the enhanced method based on simulation of Project Loon is investigated by comparing with VTEC maps from Ionosphere Associate Analysis Centers (IAACs) as well as IGS final GIMs. The comparison indicates that there is a better consistency between the VTEC maps by the enhanced method and IGS final GIMs. Also, obvious improvements of RMS maps in GIMs for the middle latitudes and southern latitudes are enabled by the augmentation of Project Loon. Additionally, JASON data are used to validate the specific improvement of the VTEC maps. The results show that the performance of VTEC maps is improved slightly, especially in southern latitudes. It is possible that the VTEC maps could be improved significantly by using real GPS measurements from balloons of Project Loon in the near future.

No MeSH data available.


Map showing the average RMS values by the proposed solution based on Project Loon augmentation for the 30 day period from DOY 152–181, 2015.The scale of this map is 1 TECU to 0.1 TECU. This figure is drawn using Gnuplot V5.0 (http://gnuplot.sourceforge.net) with map data of the world from Natural Earth (http://www.naturalearthdata.com/downloads/).
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f3: Map showing the average RMS values by the proposed solution based on Project Loon augmentation for the 30 day period from DOY 152–181, 2015.The scale of this map is 1 TECU to 0.1 TECU. This figure is drawn using Gnuplot V5.0 (http://gnuplot.sourceforge.net) with map data of the world from Natural Earth (http://www.naturalearthdata.com/downloads/).

Mentions: The daily global ionospheric products for DOY 152–181 in 2015 are generated by using the GPS measurements of approximately 325 IGS stations. The modeling are performed through the original solution and proposed method based on Project Loon, respectively. RMS maps are generated along with global VTEC maps, which indicate the internal coincident precision of VTEC value at each grid in GIMs. The average of RMS maps by the two solutions for the 30 day period from DOY 152–181, 2015 are presented as shown in Figs 2 and 3 (unit: 0.1 TECU), respectively. The RMS presented in these two figures are calculated by the average of 30 values for each grid during the 30 day period. According to the RMS values presented in Figs 2 and 3, the precision of VTEC values over continents are much higher than those over the Pacific, Atlantic, and Indian Oceans, Africa and the polar region. Also, as depicted in Fig. 3, the average RMS map is apparently improved over the southern latitudes. In order to investigate the specific improvement, the globe is divided into 3 latitudinal bands, the Northern Band (32.5°~87.5°), the Middle Band (−32.5°~32.5°) and the Southern Band (−87.5°~–32.5°). The average of RMS values for the globe and the 3 bands are calculated individually and are shown in Table 1 (unit: 0.1 TECU). From the values in Table 1, the internal coincident precision of the VTEC map for the Northern Band is the highest among the 3 bands, followed by the Middle Band and the Southern Band. The average of RMS values shows a very slight improvement for Northern Band. Because the simulation of Project Loon in this study has no balloons in northern latitudes. In contrast, since Project Loon balloons providing additional GPS measurements over Southern Hemisphere, there are obviously improvements for the Middle Band and Southern Band, obtaining a 1.40% and 8.54% improvement, respectively. The internal coincident precision of the global VTEC maps is improved by approximately 3.97%. These results indicate that VTEC RMS maps are substantially improved through Project Loon based augmentation.


Project Loon based augmentation for global ionospheric modeling over Southern Hemisphere
Map showing the average RMS values by the proposed solution based on Project Loon augmentation for the 30 day period from DOY 152–181, 2015.The scale of this map is 1 TECU to 0.1 TECU. This figure is drawn using Gnuplot V5.0 (http://gnuplot.sourceforge.net) with map data of the world from Natural Earth (http://www.naturalearthdata.com/downloads/).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5382668&req=5

f3: Map showing the average RMS values by the proposed solution based on Project Loon augmentation for the 30 day period from DOY 152–181, 2015.The scale of this map is 1 TECU to 0.1 TECU. This figure is drawn using Gnuplot V5.0 (http://gnuplot.sourceforge.net) with map data of the world from Natural Earth (http://www.naturalearthdata.com/downloads/).
Mentions: The daily global ionospheric products for DOY 152–181 in 2015 are generated by using the GPS measurements of approximately 325 IGS stations. The modeling are performed through the original solution and proposed method based on Project Loon, respectively. RMS maps are generated along with global VTEC maps, which indicate the internal coincident precision of VTEC value at each grid in GIMs. The average of RMS maps by the two solutions for the 30 day period from DOY 152–181, 2015 are presented as shown in Figs 2 and 3 (unit: 0.1 TECU), respectively. The RMS presented in these two figures are calculated by the average of 30 values for each grid during the 30 day period. According to the RMS values presented in Figs 2 and 3, the precision of VTEC values over continents are much higher than those over the Pacific, Atlantic, and Indian Oceans, Africa and the polar region. Also, as depicted in Fig. 3, the average RMS map is apparently improved over the southern latitudes. In order to investigate the specific improvement, the globe is divided into 3 latitudinal bands, the Northern Band (32.5°~87.5°), the Middle Band (−32.5°~32.5°) and the Southern Band (−87.5°~–32.5°). The average of RMS values for the globe and the 3 bands are calculated individually and are shown in Table 1 (unit: 0.1 TECU). From the values in Table 1, the internal coincident precision of the VTEC map for the Northern Band is the highest among the 3 bands, followed by the Middle Band and the Southern Band. The average of RMS values shows a very slight improvement for Northern Band. Because the simulation of Project Loon in this study has no balloons in northern latitudes. In contrast, since Project Loon balloons providing additional GPS measurements over Southern Hemisphere, there are obviously improvements for the Middle Band and Southern Band, obtaining a 1.40% and 8.54% improvement, respectively. The internal coincident precision of the global VTEC maps is improved by approximately 3.97%. These results indicate that VTEC RMS maps are substantially improved through Project Loon based augmentation.

View Article: PubMed Central - PubMed

ABSTRACT

Global ionospheric products of vertical total electron content (VTEC) derived from GNSS measurements may have low accuracy over oceans and southern latitudes where there are not rich observations. Project Loon provides a great opportunity to enhance the measurements over those areas. In this contribution, a simulation of Project Loon based augmentation for global ionospheric modeling is performed by using the international reference ionosphere (IRI) which could simulate VTEC measurements for the balloons. The performance of the enhanced method based on simulation of Project Loon is investigated by comparing with VTEC maps from Ionosphere Associate Analysis Centers (IAACs) as well as IGS final GIMs. The comparison indicates that there is a better consistency between the VTEC maps by the enhanced method and IGS final GIMs. Also, obvious improvements of RMS maps in GIMs for the middle latitudes and southern latitudes are enabled by the augmentation of Project Loon. Additionally, JASON data are used to validate the specific improvement of the VTEC maps. The results show that the performance of VTEC maps is improved slightly, especially in southern latitudes. It is possible that the VTEC maps could be improved significantly by using real GPS measurements from balloons of Project Loon in the near future.

No MeSH data available.