author_facet Xia, P.
Cai, C.
Liu, Z.
Xia, P.
Cai, C.
Liu, Z.
author Xia, P.
Cai, C.
Liu, Z.
spellingShingle Xia, P.
Cai, C.
Liu, Z.
Annales Geophysicae
GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
Space and Planetary Science
Earth and Planetary Sciences (miscellaneous)
Atmospheric Science
Geology
Astronomy and Astrophysics
author_sort xia, p.
spelling Xia, P. Cai, C. Liu, Z. 1432-0576 Copernicus GmbH Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Geology Astronomy and Astrophysics http://dx.doi.org/10.5194/angeo-31-1805-2013 <jats:p>Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3. </jats:p> GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles Annales Geophysicae
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series Annales Geophysicae
source_id 49
title GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_unstemmed GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_full GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_fullStr GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_full_unstemmed GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_short GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_sort gnss troposphere tomography based on two-step reconstructions using gps observations and cosmic profiles
topic Space and Planetary Science
Earth and Planetary Sciences (miscellaneous)
Atmospheric Science
Geology
Astronomy and Astrophysics
url http://dx.doi.org/10.5194/angeo-31-1805-2013
publishDate 2013
physical 1805-1815
description <jats:p>Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3. </jats:p>
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author Xia, P., Cai, C., Liu, Z.
author_facet Xia, P., Cai, C., Liu, Z., Xia, P., Cai, C., Liu, Z.
author_sort xia, p.
container_issue 10
container_start_page 1805
container_title Annales Geophysicae
container_volume 31
description <jats:p>Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3. </jats:p>
doi_str_mv 10.5194/angeo-31-1805-2013
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spelling Xia, P. Cai, C. Liu, Z. 1432-0576 Copernicus GmbH Space and Planetary Science Earth and Planetary Sciences (miscellaneous) Atmospheric Science Geology Astronomy and Astrophysics http://dx.doi.org/10.5194/angeo-31-1805-2013 <jats:p>Abstract. Traditionally, balloon-based radiosonde soundings are used to study the spatial distribution of atmospheric water vapour. However, this approach cannot be frequently employed due to its high cost. In contrast, GPS tomography technique can obtain water vapour in a high temporal resolution. In the tomography technique, an iterative or non-iterative reconstruction algorithm is usually utilised to overcome rank deficiency of observation equations for water vapour inversion. However, the single iterative or non-iterative reconstruction algorithm has their limitations. For instance, the iterative reconstruction algorithm requires accurate initial values of water vapour while the non-iterative reconstruction algorithm needs proper constraint conditions. To overcome these drawbacks, we present a combined iterative and non-iterative reconstruction approach for the three-dimensional (3-D) water vapour inversion using GPS observations and COSMIC profiles. In this approach, the non-iterative reconstruction algorithm is first used to estimate water vapour density based on a priori water vapour information derived from COSMIC radio occultation data. The estimates are then employed as initial values in the iterative reconstruction algorithm. The largest advantage of this approach is that precise initial values of water vapour density that are essential in the iterative reconstruction algorithm can be obtained. This combined reconstruction algorithm (CRA) is evaluated using 10-day GPS observations in Hong Kong and COSMIC profiles. The test results indicate that the water vapor accuracy from CRA is 16 and 14% higher than that of iterative and non-iterative reconstruction approaches, respectively. In addition, the tomography results obtained from the CRA are further validated using radiosonde data. Results indicate that water vapour densities derived from the CRA agree with radiosonde results very well at altitudes above 2.5 km. The average RMS value of their differences above 2.5 km is 0.44 g m−3. </jats:p> GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles Annales Geophysicae
spellingShingle Xia, P., Cai, C., Liu, Z., Annales Geophysicae, GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles, Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Geology, Astronomy and Astrophysics
title GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_full GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_fullStr GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_full_unstemmed GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_short GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
title_sort gnss troposphere tomography based on two-step reconstructions using gps observations and cosmic profiles
title_unstemmed GNSS troposphere tomography based on two-step reconstructions using GPS observations and COSMIC profiles
topic Space and Planetary Science, Earth and Planetary Sciences (miscellaneous), Atmospheric Science, Geology, Astronomy and Astrophysics
url http://dx.doi.org/10.5194/angeo-31-1805-2013