scholarly journals Volcanic SO<sub>2</sub> fluxes derived from satellite data: a survey using OMI, GOME-2, IASI and MODIS

2012 ◽  
Vol 12 (12) ◽  
pp. 31349-31412 ◽  
Author(s):  
N. Theys ◽  
R. Campion ◽  
L. Clarisse ◽  
H. Brenot ◽  
J. van Gent ◽  
...  
Keyword(s):  
Satellite Data ◽  
Large Scale ◽  
Volcanic Eruptions ◽  
Thermal Infrared ◽  
Primary Objective ◽  
High Spectral Resolution ◽  
Satellite Measurements ◽  
Spectral Ranges ◽  
Remote Sensing Methods ◽  
Satellite Instruments

Abstract. Sulphur dioxide (SO2) fluxes of active degassing volcanoes are routinely measured with ground-based equipment to characterize and monitor volcanic activity. SO2 of unmonitored volcanoes or from explosive volcanic eruptions, can be measured with satellites. However, remote-sensing methods based on absorption spectroscopy generally provide integrated amounts of already dispersed plumes of SO2 and satellite derived flux estimates are rarely reported. Here we review a number of different techniques to derive volcanic SO2 fluxes using satellite measurements of dispersed and large-scale plumes of SO2 and investigate the temporal evolution of the total emissions of SO2 for three very different volcanic events in 2011: Puyehue-Cordón Caulle (Chile), Nyamulagira (DR Congo) and Nabro (Eritrea). High spectral resolution satellite instruments operating both in the UV-visible (OMI/Aura and GOME-2/MetOp-A) and thermal infrared (IASI/MetOp-A) spectral ranges, and multispectral satellite instruments operating in the thermal infrared (MODIS/Terra-Aqua) are used. We show that satellite data can provide fluxes with a sampling of a day or less (few hours in the best case). Generally the flux results from the different methods are consistent, and we discuss the advantages and weaknesses of each technique. Although the primary objective of this study is the calculation of SO2 fluxes, it also enables to assess the consistency of the SO2 products from the different sensors used.

scholarly journals Volcanic SO<sub>2</sub> fluxes derived from satellite data: a survey using OMI, GOME-2, IASI and MODIS

2013 ◽  
Vol 13 (12) ◽  
pp. 5945-5968 ◽  
Author(s):  
N. Theys ◽  
R. Campion ◽  
L. Clarisse ◽  
H. Brenot ◽  
J. van Gent ◽  
...  
Keyword(s):  
Satellite Data ◽  
Volcanic Eruptions ◽  
Thermal Infrared ◽  
Primary Objective ◽  
High Spectral Resolution ◽  
Satellite Measurements ◽  
Explosive Volcanic Eruptions ◽  
Spectral Ranges ◽  
Remote Sensing Methods ◽  
Satellite Instruments

Abstract. Sulphur dioxide (SO2) fluxes of active degassing volcanoes are routinely measured with ground-based equipment to characterize and monitor volcanic activity. SO2 of unmonitored volcanoes or from explosive volcanic eruptions, can be measured with satellites. However, remote-sensing methods based on absorption spectroscopy generally provide integrated amounts of already dispersed plumes of SO2 and satellite derived flux estimates are rarely reported. Here we review a number of different techniques to derive volcanic SO2 fluxes using satellite measurements of plumes of SO2 and investigate the temporal evolution of the total emissions of SO2 for three very different volcanic events in 2011: Puyehue-Cordón Caulle (Chile), Nyamulagira (DR Congo) and Nabro (Eritrea). High spectral resolution satellite instruments operating both in the ultraviolet-visible (OMI/Aura and GOME-2/MetOp-A) and thermal infrared (IASI/MetOp-A) spectral ranges, and multispectral satellite instruments operating in the thermal infrared (MODIS/Terra-Aqua) are used. We show that satellite data can provide fluxes with a sampling of a day or less (few hours in the best case). Generally the flux results from the different methods are consistent, and we discuss the advantages and weaknesses of each technique. Although the primary objective of this study is the calculation of SO2 fluxes, it also enables us to assess the consistency of the SO2 products from the different sensors used.

scholarly journals Hyperspectral Imaging Retrieval Using MODIS Satellite Sensors Applied to Volcanic Ash Clouds Monitoring

2019 ◽  
Vol 11 (11) ◽  
pp. 1393 ◽  
Author(s):  
Luis Arias ◽  
Jose Cifuentes ◽  
Milton Marín ◽  
Fernando Castillo ◽  
Hugo Garcés
Keyword(s):  
Large Scale ◽  
Volcanic Ash ◽  
Classical Method ◽  
Relative Concentration ◽  
Principal Component ◽  
Volcanic Eruptions ◽  
Hyperspectral Images ◽  
High Spectral Resolution ◽  
Accurate Information ◽  
Basis Vectors

In this paper, we present a method for hyperspectral retrieval using multispectral satellite images. The method consists of the use of training spectral data with a compressive capability. By using principal component analysis (PCA), a proper number of basis vectors are extracted. These vectors are properly combined and weighted by the sensors’ responses from visible MODIS channels, achieving as a result the retrieval of hyperspectral images. Once MODIS channels are used for hyperspectral retrieval, the training spectra are projected over the recovered data, and the ground-based process used for training can be reliably detected. To probe the method, we use only four visible images from MODIS for large-scale ash clouds’ monitoring from volcanic eruptions. A high-spectral resolution data of reflectances from ash was measured in the laboratory. Using PCA, we select four basis vectors, which combined with MODIS sensors responses, allows estimating hyperspectral images. By comparing both the estimated hyperspectral images and the training spectra, it is feasible to identify the presence of ash clouds at a pixel-by-pixel level, even in the presence of water clouds. Finally, by using a radiometric model applied over hyperspectral retrieved data, the relative concentration of the volcanic ash in the cloud is obtained. The performance of the proposed method is compared with the classical method based on temperature differences (using infrared MODIS channels), and the results show an excellent match, outperforming the infrared-based approach. This proposal opens new avenues to increase the potential of multispectral remote systems, which can be even extended to other applications and spectral bands for remote sensing. The results show that the method could play an essential role by providing more accurate information of volcanic ash spatial dispersion, enabling one to prevent several hazards related to volcanic ash where volcanoes’ monitoring is not feasible.

scholarly journals Evaluation of Total Ozone Column from Multiple Satellite Measurements in the Antarctic Using the Brewer Spectrophotometer

2021 ◽  
Vol 13 (8) ◽  
pp. 1594
Author(s):  
Songkang Kim ◽  
Sang-Jong Park ◽  
Hana Lee ◽  
Dha Hyun Ahn ◽  
Yeonjin Jung ◽  
...  
Keyword(s):  
Satellite Data ◽  
Total Ozone ◽  
Spatiotemporal Pattern ◽  
Satellite Measurements ◽  
Austral Spring ◽  
Total Ozone Column ◽  
Brewer Spectrophotometer ◽  
The Antarctic ◽  
Ozone Column

The ground-based ozone observation instrument, Brewer spectrophotometer (Brewer), was used to evaluate the quality of the total ozone column (TOC) produced by multiple polar-orbit satellite measurements at three stations in Antarctica (King Sejong, Jang Bogo, and Zhongshan stations). While all satellite TOCs showed high correlations with Brewer TOCs (R = ~0.8 to 0.9), there are some TOC differences among satellite data in austral spring, which is mainly attributed to the bias of Atmospheric Infrared Sounder (AIRS) TOC. The quality of satellite TOCs is consistent between Level 2 and 3 data, implying that “which satellite TOC is used” can induce larger uncertainty than “which spatial resolution is used” for the investigation of the Antarctic TOC pattern. Additionally, the quality of satellite TOC is regionally different (e.g., OMI TOC is a little higher at the King Sejong station, but lower at the Zhongshan station than the Brewer TOC). Thus, it seems necessary to consider the difference of multiple satellite data for better assessing the spatiotemporal pattern of Antarctic TOC.

scholarly journals The vertical distribution of volcanic SO<sub>2</sub> plumes measured by IASI

2016 ◽  
Vol 16 (7) ◽  
pp. 4343-4367 ◽  
Author(s):  
Elisa Carboni ◽  
Roy G. Grainger ◽  
Tamsin A. Mather ◽  
David M. Pyle ◽  
Gareth E. Thomas ◽  
...  
Keyword(s):  
Volcanic Eruptions ◽  
Maximum Amount ◽  
The Other ◽  
High Spectral Resolution ◽  
Explosive Eruptions ◽  
Atmospheric Processes ◽  
Atmospheric Sounding ◽  
Volcanic Emission ◽  
The Vertical Distribution ◽  
Atmospheric Constituent

Abstract. Sulfur dioxide (SO2) is an important atmospheric constituent that plays a crucial role in many atmospheric processes. Volcanic eruptions are a significant source of atmospheric SO2 and its effects and lifetime depend on the SO2 injection altitude. The Infrared Atmospheric Sounding Interferometer (IASI) on the METOP satellite can be used to study volcanic emission of SO2 using high-spectral resolution measurements from 1000 to 1200 and from 1300 to 1410 cm−1 (the 7.3 and 8.7 µm SO2 bands) returning both SO2 amount and altitude data. The scheme described in Carboni et al. (2012) has been applied to measure volcanic SO2 amount and altitude for 14 explosive eruptions from 2008 to 2012. The work includes a comparison with the following independent measurements: (i) the SO2 column amounts from the 2010 Eyjafjallajökull plumes have been compared with Brewer ground measurements over Europe; (ii) the SO2 plumes heights, for the 2010 Eyjafjallajökull and 2011 Grimsvötn eruptions, have been compared with CALIPSO backscatter profiles. The results of the comparisons show that IASI SO2 measurements are not affected by underlying cloud and are consistent (within the retrieved errors) with the other measurements. The series of analysed eruptions (2008 to 2012) show that the biggest emitter of volcanic SO2 was Nabro, followed by Kasatochi and Grímsvötn. Our observations also show a tendency for volcanic SO2 to reach the level of the tropopause during many of the moderately explosive eruptions observed. For the eruptions observed, this tendency was independent of the maximum amount of SO2 (e.g. 0.2 Tg for Dalafilla compared with 1.6 Tg for Nabro) and of the volcanic explosive index (between 3 and 5).

scholarly journals Permit to work: the Integrated Safe System of Work

2010 ◽  
Vol 50 (1) ◽  
pp. 665
Author(s):  
Ally Oliver
Keyword(s):  
Large Scale ◽  
Success Factors ◽  
Formal System ◽  
Modern Technology ◽  
Primary Objective ◽  
Facility Management ◽  
Business Rules ◽  
Core System ◽  
Working Practices ◽  
New System

A permit to work (PTW) system is a formal system used to control certain types of work that are identified as potentially hazardous. It is also a means of communication between facility management, plant supervisors and operators, and those who carry out the hazardous work. The essential features of a PTW system are: • Clear identification for who may authorise particular jobs, and who is responsible for specifying the necessary precautions; • Training and instruction in the issue and use of permits; and, • Monitoring and auditing to ensure that the system works as intended. PTW systems are the key to ensuring safe execution of activities at site, yet there are many approaches to how permit systems can, and should, work. Each approach has its own merits and weaknesses. Woodside recognised that, as part of its ongoing program to improve the safety of its workers, there existed significant scope for a new and better work management system. After many years of incremental evolution of the PTW and the fragmentation of the parent system as each facility developed its own variation, it was evident that a completely new system embracing modern technology would provide the best result, while simultaneously standardising Woodside with one common and centralised system. The divergence of the systems over time caused increasing difficulty in managing changes to the PTW system across all sites and in benchmarking to determine best practice. A centralised system would remove accountability from facilities for the development of the business rules, and instead ensure they focussed on compliance with the rules. The new system would adopt key learnings from the industry’s history and address root causes of past incidents. It would also enable the ability to adopt future learnings and become a conduit for rapid integration into the working practices on all sites. The Integrated Safe System of Work (iSSoW) developed by Woodside adopts best practices from permit systems worldwide and combines them with new innovative management features. The system is administered through a simple-to-use computer interface, with incorporation of many of the business rules into the software package. The iSSoW is now in place on all Woodside facilities (platforms, not-normally manned installations, FPSO’s and onshore plants). With nearly 4,000 users, the implementation has required careful coordination, and been supported by a comprehensive training programme. The system has been demonstrated to be both effective and efficient. Effectiveness—the improvement of safety performance—was the primary objective. The system has raised work party hazards awareness, and has resulted in significant improvements in working practices company-wide. Efficiency was a secondary goal, and is made possible through streamlining in the user-interface. The introduction of the new system complements Woodside’s work to develop an improved safety culture, and brings consistency across all sites and all shifts—essential features as our industry struggles to deal with the growing scarcity of skills and experience. The system is now being reviewed by organisations across many industry and service sectors in Australia, and has been implemented in the power industry. This paper discusses the attributes of the system, the many challenges associated with development and large-scale implementation of such a core system, and the additional opportunities the system presents. Using a case study of implementation of iSSoW onto the Woodside operational facilities, it highlights the critical success factors of introducing iSSoW on a company-wide basis.

Large Eddy Simulations of Staggered Parallel-Plate Flows

2005 ◽  
Author(s):  
M. V. Pham ◽  
F. Plourde ◽  
S. K. Doan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Heat Transfer Enhancement ◽  
Parallel Plate ◽  
Large Scale ◽  
Primary Objective ◽  
Transfer Enhancement ◽  
Turbulent Structures ◽  
Wide Range ◽  
Large Eddy

Heat transfer enhancement is a subject of major concern in numerous fields of industry and research. Having received undivided attention over the years, it is still studied worldwide. Given the exponential growth of computing power, large-scale numerical simulations are growing steadily more realistic, and it is now possible to obtain accurate time-dependent solutions with far fewer preliminary assumptions about the problems. As a result, an increasingly wide range of physics is now open for exploration. More specifically, it is time to take full advantage of large eddy simulation technique so as to describe heat transfer in staggered parallel-plate flows. In fact, from simple theory through experimental results, it has been demonstrated that surface interruption enhances heat transfer. Staggered parallel-plate geometries are of great potential interest, and yet many numerical works dedicated to them have been tarnished by excessively simple assumptions. That is to say, numerical simulations have generally hypothesized lengthwise periodicity, even though flows are not periodic; moreover, the LES technique has not been employed with sufficient frequency. Actually, our primary objective is to analyze turbulent influence with regard to heat transfers in staggered parallel-plate fin geometries. In order to do so, we have developed a LES code, and numerical results are compared with regard to several grid mesh resolutions. We have focused mainly upon identification of turbulent structures and their role in heat transfer enhancement. Another key point involves the distinct roles of boundary restart and the vortex shedding mechanism on heat transfer and friction factor.

A Case Study of a Ross Ice Shelf Airstream Event: A New Perspective*

2009 ◽  
Vol 137 (11) ◽  
pp. 4030-4046 ◽  
Author(s):  
Daniel F. Steinhoff ◽  
Saptarshi Chaudhuri ◽  
David H. Bromwich
Keyword(s):  
Large Scale ◽  
Model Performance ◽  
Thermal Infrared ◽  
Integrated Approach ◽  
Cloud Formation ◽  
Synoptic Scale ◽  
Ice Shelf ◽  
Low Level ◽  
Ross Ice Shelf

Abstract A case study illustrating cloud processes and other features associated with the Ross Ice Shelf airstream (RAS), in Antarctica, is presented. The RAS is a semipermanent low-level wind regime primarily over the western Ross Ice Shelf, linked to the midlatitude circulation and formed from terrain-induced and large-scale forcing effects. An integrated approach utilizes Moderate Resolution Imaging Spectroradiometer (MODIS) satellite imagery, automatic weather station (AWS) data, and Antarctic Mesoscale Prediction System (AMPS) forecast output to study the synoptic-scale and mesoscale phenomena involved in cloud formation over the Ross Ice Shelf during a RAS event. A synoptic-scale cyclone offshore of Marie Byrd Land draws moisture across West Antarctica to the southern base of the Ross Ice Shelf. Vertical lifting associated with flow around the Queen Maud Mountains leads to cloud formation that extends across the Ross Ice Shelf to the north. The low-level cloud has a warm signature in thermal infrared imagery, resembling a surface feature of turbulent katabatic flow typically ascribed to the RAS. Strategically placed AWS sites allow assessment of model performance within and outside of the RAS signature. AMPS provides realistic simulation of conditions aloft but experiences problems at low levels due to issues with the model PBL physics. Key meteorological features of this case study, within the context of previous studies on longer time scales, are inferred to be common occurrences. The assumption that warm thermal infrared signatures are surface features is found to be too restrictive.

scholarly journals Application of global models and satellite data for smaller-scale groundwater recharge studies

2016 ◽  
Author(s):  
Rogier Westerhoff ◽  
Paul White ◽  
Zara Rawlinson
Keyword(s):  
New Zealand ◽  
Satellite Data ◽  
Input Data ◽  
Large Scale ◽  
Regional Scale ◽  
Global Scale ◽  
Global Models ◽  
Scale Models ◽  
Boundary Issues ◽  
Rainfall Recharge

Abstract. Large-scale models and satellite data are increasingly used to characterise groundwater and its recharge at the global scale. Although these models have the potential to fill in data gaps and solve trans-boundary issues, they are often neglected in smaller-scale studies, since data are often coarse or uncertain. Large-scale models and satellite data could play a more important role in smaller-scale (i.e., national or regional) studies, if they could be adjusted to fit that scale. In New Zealand, large-scale models and satellite data are not used for groundwater recharge estimation at the national scale, since regional councils (i.e., the water managers) have varying water policy and models are calibrated at the local scale. Also, some regions have many localised ground observations (but poor record coverage), whereas others are data-sparse. Therefore, estimation of recharge is inconsistent at the national scale. This paper presents an approach to apply large-scale, global, models and satellite data to estimate rainfall recharge at the national to regional scale across New Zealand. We present a model, NGRM, that is largely inspired by the global-scale WaterGAP recharge model, but is improved and adjusted using national data. The NGRM model uses MODIS-derived ET and vegetation satellite data, and the available nation-wide datasets on rainfall, elevation, soil and geology. A valuable addition to the recharge estimation is the model uncertainty estimate, based on variance, covariance and sensitivity of all input data components in the model environment. This research shows that, with minor model adjustments and use of improved input data, large-scale models and satellite data can be used to derive rainfall recharge estimates, including their uncertainty, at the smaller scale, i.e., national and regional scale of New Zealand. The estimated New Zealand recharge of the NGRM model compare well to most local and regional lysimeter data and recharge models. The NGRM is therefore assumed to be capable to fill in gaps in data-sparse areas and to create more consistency between datasets from different regions, i.e., to solve trans-boundary issues. This research also shows that smaller-scale recharge studies in New Zealand should include larger boundaries than only a (sub-)aquifer, and preferably the whole catchment. This research points out the need for improved collaboration on the international to national to regional levels to further merge large-scale (global) models to smaller (i.e., national or regional) scales. Future research topics should, collaboratively, focus on: improvement of rainfall-runoff and snowmelt methods; inclusion of river recharge; further improvement of input data (rainfall, evapotranspiration, soil and geology); and the impact of recharge uncertainty in mountainous and irrigated areas.

scholarly journals Long range transport and fate of a stratospheric volcanic cloud from Soufriere Hills volcano, Montserrat

2007 ◽  
Vol 7 (2) ◽  
pp. 4657-4672 ◽  
Author(s):  
A. J. Prata ◽  
S. A. Carn ◽  
A. Stohl ◽  
J. Kerkmann
Keyword(s):  
Volcanic Eruptions ◽  
Particle Dispersion ◽  
Volcanic Gases ◽  
Satellite Measurements ◽  
Radiative Balance ◽  
Soufriere Hills Volcano ◽  
Soufrière Hills Volcano ◽  
Soufriere Hills ◽  
Volcanic Cloud ◽  
The Impact

Abstract. Volcanic eruptions emit gases, ash particles and hydrometeors into the atmosphere, occasionally reaching great heights to reside in the stratospheric overworld where they affect the radiative balance of the atmosphere and the earth's climate. Here we use satellite measurements and a Lagrangian particle dispersion model to determine the mass loadings, vertical penetration, horizontal extent, dispersion and transport of volcanic gases and particles in the stratosphere from the volcanic cloud emitted during the 20 May 2006 eruption of Soufriere Hills volcano, Montserrat, West Indies. Infrared, ultraviolet and microwave radiation measurements from two polar orbiters are used to quantify the gases and particles, and track the movement of the cloud for 23 days, over a distance of ~18 000 km. Approximately, 0.1±0.01 Tg(S) was injected into the stratosphere in the form of SO2: the largest single sulfur input to the stratosphere in 2006. Microwave Limb Sounder measurements indicate an enhanced mass of HCl of ~0.003–0.01 Tg. Geosynchronous satellite data reveal the rapid nature of the stratospheric injection and indicate that the eruption cloud contained ~2 Tg of ice, with very little ash reaching the stratosphere. These new satellite measurements of volcanic gases and particles can be used to test the sensitivity of climate to volcanic forcing and assess the impact of stratospheric sulfates on climate cooling.

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