GAS: Generic Atmosphere Solutions for radar measurements
Lead Research Organisation:
University of Glasgow
Department Name: School of Geographical & Earth Sciences
Abstract
Land surface deformation is a major worldwide hazard that can result from natural processes such as landslides, earthquakes, and volcanoes, or from anthropogenic processes including extraction of groundwater, oil and coal. Repeat-pass Interferometric Synthetic Aperture Radar (InSAR) has been widely used to map land surface deformation in the past two decades (Massonnet and Feigl, 1998). However, change in the atmosphere (especially tropospheric water vapour) is one of the major sources of uncertainty in determining surface deformation using InSAR, and correcting for such errors is key to the detection of subtle deformation signals. The PI has considerable experience in InSAR atmospheric correction models. Indeed, the PI has been at the forefront of InSAR atmospheric correction by developing five models to reduce water vapour effects on InSAR measurements using remotely-sensed water vapour data (e.g. Global Positioning System(GPS), NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and ESA Medium Resolution Imaging Spectrometer (MERIS)): Each model is capable of improving the accuracy of InSAR derived deformation signals from 10 mm before correction to 5 mm after correction (e.g. Li et al., 2009, Li et al., 2006c, Li et al., 2006b, Li et al., 2006a, Li et al., 2005). The PI is determined to capitalize on it in this research. The objectives of this proposed research are as follows: (i) to develop atmospheric model based correction technique(s) to make our correction models globally applicable; (ii) to demonstrate the ease of application of the atmospheric model based correction technique(s) under any possible scenario: (a) with a single InSAR pair, or (b) with multiple InSAR pairs; (iii) to develop atmospheric estimation techniques in InSAR time series analysis so that deformation signals can be extracted without any assumption on deformation models or any requirement on atmosphere data. This is desirable for users who are not able to access any atmospheric model. Methodology: All the above-mentioned correction models are inherently limited by data availability, e.g. the lack of a dense GPS network (for GPS-based model) and the sensitivity to the presence of clouds (for MODIS and MERIS). The Unified Model developed by the UK MET Office provides high spatial resolution (e.g. 1 km) estimates of tropospheric path delays with a global coverage, 24 hours a day in all weather, which is highly desirable for InSAR atmospheric correction, and will be investigated for the correction of atmospheric effects on a single-pair and/or multi-pairs of SAR interferograms in this research. A prior deformation model and/or some spatial/temporal filtering techniques are commonly assumed in most of current InSAR time series techniques to separate deformation signals from atmospheric effects, which is evidently not optimal. Based on three key physical features of atmospheric signals identified by previous studies, an iteration process is proposed to estimate atmospheric signals from multiple InSAR pairs and then to extract deformation signals without any assumption of deformation models and any requirement on atmosphere data.
People |
ORCID iD |
Zhenhong Li (Principal Investigator) |
Publications
Albino F
(2020)
Automated Methods for Detecting Volcanic Deformation Using Sentinel-1 InSAR Time Series Illustrated by the 2017-2018 Unrest at Agung, Indonesia
in Journal of Geophysical Research: Solid Earth
Chen M
(2016)
Imaging Land Subsidence Induced by Groundwater Extraction in Beijing (China) Using Satellite Radar Interferometry
in Remote Sensing
Elliott J
(2010)
Extension on the Tibetan plateau: recent normal faulting measured by InSAR and body wave seismology Extension on the Tibetan plateau
in Geophysical Journal International
Elliott J
(2012)
Slip in the 2010-2011 Canterbury earthquakes, New Zealand
in Journal of Geophysical Research: Solid Earth
Feng W
(2013)
The 2011 MW 6.8 Burma earthquake: fault constraints provided by multiple SAR techniques
in Geophysical Journal International
Fielding E
(2013)
Kinematic fault slip evolution source models of the 2008 M7.9 Wenchuan earthquake in China from SAR interferometry, GPS and teleseismic analysis and implications for Longmen Shan tectonics
in Geophysical Journal International
Guo-Hong Z
(2011)
The coseismic InSAR measurements of 2008 Yutian earthquake and its inversion for source parameters
in CHINESE JOURNAL OF GEOPHYSICS-CHINESE EDITION
Hammond W
(2012)
Contemporary uplift of the Sierra Nevada, western United States, from GPS and InSAR measurements
in Geology
Jolivet R
(2014)
Improving InSAR geodesy using Global Atmospheric Models
in Journal of Geophysical Research: Solid Earth
Description | A Switzerland-based InSAR company (sarmap sa) incorporated the MERIS atmospheric correction model developed by the PI into their commercial InSAR package (i.e. SARscape) in 2010. Based on the outcomes of the GAS project, we developed the Iterative Tropospheric Decomposition (ITD) model in 2016 to separate stratified and turbulent signals from tropospheric total delays, and generate high spatial resolution zenith total delay and/or precipitable water vapour maps to be used for correcting InSAR measurements and other applications. This research was published in Journal of Geophysical Research (doi:10.1002/2016JD025753). |
Exploitation Route | A new correction model based on Numerical Weather Model for radar measurements is being developed at Newcastle, which is funded by NERC through the LICS project (NE/K010794/1). samap as has expressed their interests in it. The correction models and time series techniques developed in the GAS project have been released to three research groups and two government departments. |
Sectors | Digital/Communication/Information Technologies (including Software),Education,Environment,Other |
URL | http://www.sarmap.ch/pdf/SARscapeTechnical.pdf |
Description | A Switzerland-based InSAR company (sarmap sa) incorporated the MERIS atmospheric correction model developed by the PI into their commercial InSAR package (i.e. SARscape) in 2010. The MODIS/MERIS-based InSAR correction models have been used in several research organisations including JPL and COMET partners. |
First Year Of Impact | 2009 |
Sector | Digital/Communication/Information Technologies (including Software),Education,Environment,Other |
Impact Types | Cultural,Economic |
Description | Radar training course for a delegation from China Academy of Space Technology (CAST) |
Geographic Reach | Asia |
Policy Influence Type | Influenced training of practitioners or researchers |
Impact | In the CAST Radar Training Course, we have demonstrated how to best collect observations with radar satellites (e.g. Sentinel-1A/1B, TanDEM-X) and provided some suggestions to the observational plan of Chinese Gaofen-3 satellite. |
Description | Ground Based Synthetic Aperture Radar (GB-SAR) |
Amount | £152,100 (GBP) |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 11/2014 |
End | 03/2016 |
Description | Increasing Resilience to Natural Hazards In Earthquake-prone regions in China (IRNHiC) |
Amount | £122,641 (GBP) |
Organisation | Natural Environment Research Council |
Sector | Public |
Country | United Kingdom |
Start | 01/2016 |
End | 01/2019 |
Description | NERC NCEO Small Grant: Assessing the performances of Terrestrial Imaging Systems for Topographic Mapping |
Amount | £57,158 (GBP) |
Organisation | National Centre for Earth Observation |
Sector | Academic/University |
Country | United Kingdom |
Start | 11/2013 |
End | 03/2014 |
Description | RApID: Resilient Application of Intelligent Disaster management |
Amount | £14,000 (GBP) |
Organisation | Satellite Applications Catapult |
Sector | Charity/Non Profit |
Country | United Kingdom |
Start | 12/2014 |
End | 03/2015 |
Title | ITD model: Generation of real-time mode high-resolution water vapor fields from GPS observations |
Description | We have developed the Iterative Tropospheric Decomposition (ITD) model to separate stratified and turbulent signals from tropospheric total delays, and generate high spatial resolution zenith total delay and/or precipitable water vapour maps to be used for correcting InSAR measurements and other applications. This research has been published in Journal of Geophysical Research (doi:10.1002/2016JD025753). |
Type Of Material | Improvements to research infrastructure |
Year Produced | 2017 |
Provided To Others? | Yes |
Impact | The InSAR atmospheric correction model, incorporating continuous and global tropospheric delay datasets (e.g. numerical weather models), being developed by LiCS is based on this research. |
URL | http://onlinelibrary.wiley.com/doi/10.1002/2016JD025753/full |
Description | Success in Chinese radar mission: First interferograms from Gaofen-3 |
Organisation | China Academy of Space Technology |
Country | China |
Sector | Private |
PI Contribution | The main contributions of the Newcastle team were their expertise on radar interferometric processing and satellite orbit determination. |
Collaborator Contribution | The CAST team collected all the Gaofen-3 radar images requested by the Newcastle team and provided the datasets to the latter. The former also provided their expertise on radar missions and SAR processing. |
Impact | The collaboration between Professor Zhenhong Li's team at Newcastle University and the China Academy of Space Technology (CAST) generated interferograms using Chinese Gaofen-3 (GF-3) imagery for the first time in March 2017. These were also the first interferograms from Chinese SAR missions. CAST sent a delegation with 10 members to Newcastle for a radar training course in Jan 2018. |
Start Year | 2016 |
Title | MERIS-based InSAR water vapour correction model |
Description | MERIS-based InSAR atmospheric correction model developed by Prof Zhenhong Li was licensed to Switzerland-based InSAR company (sarmap sa) in 2009 and the correction model was incorporated into the sarmap's commercial InSAR package (i.e. SARscape) in 2010. |
IP Reference | |
Protection | Copyrighted (e.g. software) |
Year Protection Granted | 2010 |
Licensed | Yes |
Impact | The InSAR correction model has been widely used in the InSAR community. |
Title | GNSS-based InSAR Atmospheric Correction Model |
Description | We have developed the Iterative Tropospheric Decomposition (ITD) model to separate stratified and turbulent signals from tropospheric total delays, and generate high spatial resolution zenith total delay and/or precipitable water vapour maps to be used for correcting InSAR measurements and other applications. This research has been published in Journal of Geophysical Research (doi:10.1002/2016JD025753). |
Type Of Technology | Software |
Year Produced | 2016 |
Impact | A web-based toolbox is being developed, in which ITD is employed to generate high-resolution water vapour or tropospheric delay maps for InSAR correction. This toolbox will be open for the public. |
Title | Generic Atmospheric Correction Online Service for InSAR (GACOS) |
Description | GACOS utilises the Iterative Tropospheric Decomposition (ITD) model (Yu et al., 2017) to separate stratified and turbulent signals from tropospheric total delays, and generate high spatial resolution zenith total delay maps to be used for correcting InSAR measurements and other applications. GACOS has the following key features: (i) globally available; (ii) operational in a near real time mode; (iii) easy to implement; and (iv) users to be informed how the model performs and whether the correction is recommended. |
Type Of Technology | Webtool/Application |
Year Produced | 2017 |
Impact | GACOS was launched in the ESA FRINGE workshop in Helsinki, Finland on 6 June 2017, and has been widely used for correcting atmospheric effects on SAR intereferograms in the InSAR community - over 100k correction maps have been freely generated up to 28 Feb 2018. |
Title | Generic Atmospheric Correction Online Service for InSAR (GACOS) |
Description | GACOS was released in the FRINGE workshop in June 2017 and has been promoted in a series of workshops and conferences in the past 12 months. A paper introducing GACOS was published in JGR in 2018: Yu, C., Z. Li, N. T. Penna, and P. Crippa (2018), Generic atmospheric correction model for Interferometric Synthetic Aperture Radar observations, Journal of Geophysical Research: Solid Earth, 123(10), 9202-9222, doi:10.1029/2017JB015305. |
Type Of Technology | Webtool/Application |
Year Produced | 2018 |
Impact | GACOS has become a standard tool for atmospheric correction in the InSAR community. It has generated over 150k correction maps for InSAR users/researchers for free up to now. |
Title | Generic Atmospheric Correction Online Service for InSAR (GACOS, Version 1.5) |
Description | GACOS utilises the Iterative Tropospheric Decomposition (ITD) model (Yu et al., 2017) to separate stratified and turbulent signals from tropospheric total delays, and generate high spatial resolution zenith total delay maps to be used for correcting InSAR measurements and other applications. GACOS was upgraded to Version 1.5 in February 2020 with the following two new functions: (i) API available to order GACOS products in an automatic way; and (ii) indicators available to inform the users how the model performs and whether the correction is recommended. |
Type Of Technology | Webtool/Application |
Year Produced | 2019 |
Impact | GACOS has generated great impacts in the InSAR community with over 40k jobs received from ~2500 identical researchers across the world (up to December 2019) |
URL | http://ceg-research.ncl.ac.uk/v2/gacos/ |
Description | InSAR Meteorology Workshop in Miami |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | The InSAR Meteorology Workshop was funded by NASA, bringing together Meteorologists, Geodesists & InSAR engineers, and explore potential applications of the InSAR technique for Meteorology. It was expected that the workshop would serve as a resourceful atmospheric science program for ESA's Sentinel-1 and upcoming NASA-ISRO SAR (NISAR) mission, eventually paving a successful path for establishment of InSAR Meteorology field. |
Year(s) Of Engagement Activity | 2018 |
URL | https://insarmeteorologymiami2018.org |
Description | Land subsidence in Beijing |
Form Of Engagement Activity | A press release, press conference or response to a media enquiry/interview |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Media (as a channel to the public) |
Results and Impact | We employed Small Baseline InSAR technique to process ENVISAT ASAR and TerraSAR-X stripmap images collected from 2003 to 2011 and observed a maximum subsidence in the eastern part of Beijing with a rate greater than 100 mm/year; We also found some relationships between land subsidence and different conditioning and triggering factors (e.g., groundwater levels, soft soil thickness and active faults). This research finding has attracted attention of a wide range of prestigious international media (e.g., The Guardian, The Telegraph, Huffington Post, Forbes, BBC and Xinhua News), and is ranked in the top 5% of all research outputs ever tracked by Altmetric, a system that tracks the online attention for a specific piece of research (See: https://mdpi.altmetric.com/details/8441790#score). This contribution is also selected as TOP 10 published articles in 2016 by MDPI (http://blog.mdpi.com/2017/02/20/mdpi-altmetrics-top-10-published-articles-in-2016). Based on the research finding and an interview with Prof Zhenhong Li, Xinhua News Agency produced an internal report on land subsidence hazards in China for Central Chinese Government |
Year(s) Of Engagement Activity | 2016 |
URL | https://www.theguardian.com/world/2016/jun/24/beijing-has-fallen-chinas-capital-sinking-by-11cm-a-ye... |
Description | Mr Jiang Sunan, Minister Counsellor of Science and Technology Section, Chinese Embassy visited Professor Li's Imaging Geodesy Team (14 Mar 2017) |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Policymakers/politicians |
Results and Impact | Mr Jiang Sunan, Minister Counsellor of Science and Technology Section, Chinese Embassy and his colleague visited Professor Zhenhong Li's Imaging Geodesy Team at Newcastle University on 14 Mar 2017. Professor Li introduced his main research topics including satellite geodesy, remote sensing and their applications to geohazards (e.g. earthquakes, landslides and city subsidence), infrastructure stability and precision agriculture. The direct outcome of this event was that Professor Zhenhong Li was invited to deliver presentations at the UK-China Science and Innovation Forum held in the Royal Society London on 6 December 2017 (http://www.ncl.ac.uk/engineering/news/item/professorshowcasesresearchattheroyalsociety.html). |
Year(s) Of Engagement Activity | 2017 |
Description | School talk (Southridge First School, Whitley Bay) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Local |
Primary Audience | Schools |
Results and Impact | Professor Zhenhong Li was invited to give a talk to 60 students in Southridge First School, Whitley Bay. He introduced satellites and their potential applications (e.g. earthquakes, volcanoes, flooding and agriculture), which sparked questions and discussion afterwards. It appeared that a couple of students decided to become a professor in the future! |
Year(s) Of Engagement Activity | 2017 |