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Publications (10 of 15) Show all publications
Pfreundschuh, S., Eriksson, P., Duncan, D., Rydberg, B., Håkansson, N. & Thoss, A. (2018). A neural network approach to estimating a posteriori distributions of Bayesian retrieval problems. Atmospheric Measurement Techniques, 11(8), 4627-4643
Open this publication in new window or tab >>A neural network approach to estimating a posteriori distributions of Bayesian retrieval problems
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2018 (English)In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 11, no 8, p. 4627-4643Article in journal (Refereed) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-4937 (URN)10.5194/amt-11-4627-2018 (DOI)000441169000002 ()
Available from: 2018-08-21 Created: 2018-08-21 Last updated: 2018-08-21Bibliographically approved
Håkansson, N., Adok, C., Thoss, A., Scheirer, R. & Hörnquist, S. (2018). Neural network cloud top pressure and height for MODIS. Atmospheric Measurement Techniques, 11(5), 3177-3196
Open this publication in new window or tab >>Neural network cloud top pressure and height for MODIS
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2018 (English)In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 11, no 5, p. 3177-3196Article in journal (Refereed) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-4686 (URN)10.5194/amt-11-3177-2018 (DOI)
Available from: 2018-06-11 Created: 2018-06-11 Last updated: 2018-06-11Bibliographically approved
Wu, D. L., Baum, B. A., Choi, Y.-S., Foster, M. J., Karlsson, K.-G., Heidinger, A., . . . Watts, P. (2017). TOWARD GLOBAL HARMONIZATION OF DERIVED CLOUD PRODUCTS. Bulletin of The American Meteorological Society - (BAMS), 98(2), ES49-ES52
Open this publication in new window or tab >>TOWARD GLOBAL HARMONIZATION OF DERIVED CLOUD PRODUCTS
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2017 (English)In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 98, no 2, p. ES49-ES52Article in journal (Refereed) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-4047 (URN)10.1175/BAMS-D-16-0234.1 (DOI)000395826700001 ()
Available from: 2017-04-12 Created: 2017-04-12 Last updated: 2017-11-29Bibliographically approved
Sporre, M. K., O'Connor, E. J., Håkansson, N., Thoss, A., Swietlicki, E. & Petaja, T. (2016). Comparison of MODIS and VIIRS cloud properties with ARM ground-based observations over Finland. Atmospheric Measurement Techniques, 9(7), 3193-3203
Open this publication in new window or tab >>Comparison of MODIS and VIIRS cloud properties with ARM ground-based observations over Finland
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2016 (English)In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 9, no 7, p. 3193-3203Article in journal (Refereed) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-3229 (URN)10.5194/amt-9-3193-2016 (DOI)000381094100015 ()
Available from: 2016-09-27 Created: 2016-09-27 Last updated: 2017-11-21Bibliographically approved
Roebeling, R., Baum, B., Bennartz, R., Hamann, U., Heidinger, A., Meirink, J. F., . . . Watts, P. (2015). Summary of the Fourth Cloud Retrieval Evaluation Workshop. Bulletin of The American Meteorological Society - (BAMS), 96(4), ES71-ES74
Open this publication in new window or tab >>Summary of the Fourth Cloud Retrieval Evaluation Workshop
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2015 (English)In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, no 4, p. ES71-ES74Article in journal (Refereed) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-1983 (URN)10.1175/BAMS-D-14-00184.1 (DOI)000355413200001 ()
Available from: 2016-04-26 Created: 2016-03-03 Last updated: 2017-11-30Bibliographically approved
Hamann, U., Walther, A., Baum, B., Bennartz, R., Bugliaro, L., Derrien, M., . . . Wind, G. (2014). Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms. ATMOSPHERIC MEASUREMENT TECHNIQUES, 7(9), 2839-2867
Open this publication in new window or tab >>Remote sensing of cloud top pressure/height from SEVIRI: analysis of ten current retrieval algorithms
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2014 (English)In: ATMOSPHERIC MEASUREMENT TECHNIQUES, ISSN 1867-1381, Vol. 7, no 9, p. 2839-2867Article in journal (Refereed) Published
Abstract [en]

The role of clouds remains the largest uncertainty in climate projections. They influence solar and thermal radiative transfer and the earth's water cycle. Therefore, there is an urgent need for accurate cloud observations to validate climate models and to monitor climate change. Passive satellite imagers measuring radiation at visible to thermal infrared (IR) wavelengths provide a wealth of information on cloud properties. Among others, the cloud top height (CTH) - a crucial parameter to estimate the thermal cloud radiative forcing - can be retrieved. In this paper we investigate the skill of ten current retrieval algorithms to estimate the CTH using observations from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) onboard Meteosat Second Generation (MSG). In the first part we compare ten SEVIRI cloud top pressure (CTP) data sets with each other. The SEVIRI algorithms catch the latitudinal variation of the CTP in a similar way. The agreement is better in the extratropics than in the tropics. In the tropics multi-layer clouds and thin cirrus layers complicate the CTP retrieval, whereas a good agreement among the algorithms is found for trade wind cumulus, marine stratocumulus and the optically thick cores of the deep convective system. In the second part of the paper the SEVIRI retrievals are compared to CTH observations from the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and Cloud Profiling Radar (CPR) instruments. It is important to note that the different measurement techniques cause differences in the retrieved CTH data. SEVIRI measures a radiatively effective CTH, while the CTH of the active instruments is derived from the return time of the emitted radar or lidar signal. Therefore, some systematic differences are expected. On average the CTHs detected by the SEVIRI algorithms are 1.0 to 2.5 km lower than CALIOP observations, and the correlation coefficients between the SEVIRI and the CALIOP data sets range between 0.77 and 0.90. The average CTHs derived by the SEVIRI algorithms are closer to the CPR measurements than to CALIOP measurements. The biases between SEVIRI and CPR retrievals range from -0.8 km to 0.6 km. The correlation coefficients of CPR and SEVIRI observations vary between 0.82 and 0.89. To discuss the origin of the CTH deviation, we investigate three cloud categories: optically thin and thick single layer as well as multi-layer clouds. For optically thick clouds the correlation coefficients between the SEVIRI and the reference data sets are usually above 0.95. For optically thin single layer clouds the correlation coefficients are still above 0.92. For this cloud category the SEVIRI algorithms yield CTHs that are lower than CALIOP and similar to CPR observations. Most challenging are the multi-layer clouds, where the correlation coefficients are for most algorithms between 0.6 and 0.8. Finally, we evaluate the performance of the SEVIRI retrievals for boundary layer clouds. While the CTH retrieval for this cloud type is relatively accurate, there are still considerable differences between the algorithms. These are related to the uncertainties and limited vertical resolution of the assumed temperature profiles in combination with the presence of temperature inversions, which lead to ambiguities in the CTH retrieval. Alternative approaches for the CTH retrieval of low clouds are discussed.

National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-141 (URN)10.5194/amt-7-2839-2014 (DOI)000343119600004 ()
Available from: 2015-04-09 Created: 2015-03-26 Last updated: 2015-04-09Bibliographically approved
Roebeling, R., Baum, B., Bennartz, R., Hamann, U., Heidinger, A., Thoss, A. & Walther, A. (2013). EVALUATING AND IMPROVING CLOUD PARAMETER RETRIEVALS. Bulletin of The American Meteorological Society - (BAMS), 94(4), ES41-ES44
Open this publication in new window or tab >>EVALUATING AND IMPROVING CLOUD PARAMETER RETRIEVALS
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2013 (English)In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 94, no 4, p. ES41-ES44Article in journal, Editorial material (Other academic) Published
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-382 (URN)10.1175/BAMS-D-12-00041.1 (DOI)000318074700002 ()
Available from: 2015-04-07 Created: 2015-03-31 Last updated: 2017-12-04Bibliographically approved
Schulz, J., Albert, P., Behr, H.-D. -., Caprion, D., Deneke, H., Dewitte, S., . . . Zelenka, A. (2009). Operational climate monitoring from space: the EUMETSAT Satellite Application Facility on Climate Monitoring (CM-SAF). Atmospheric Chemistry And Physics, 9(5), 1687-1709
Open this publication in new window or tab >>Operational climate monitoring from space: the EUMETSAT Satellite Application Facility on Climate Monitoring (CM-SAF)
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2009 (English)In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 9, no 5, p. 1687-1709Article in journal (Refereed) Published
Abstract [en]

The Satellite Application Facility on Climate Monitoring (CM-SAF) aims at the provision of satellite-derived geophysical parameter data sets suitable for climate monitoring. CM-SAF provides climatologies for Essential Climate Variables (ECV), as required by the Global Climate Observing System implementation plan in support of the UNFCCC. Several cloud parameters, surface albedo, radiation fluxes at the top of the atmosphere and at the surface as well as atmospheric temperature and humidity products form a sound basis for climate monitoring of the atmosphere. The products are categorized in monitoring data sets obtained in near real time and data sets based on carefully intercalibrated radiances. The CM-SAF products are derived from several instruments on-board operational satellites in geostationary and polar orbit as the Meteosat and NOAA satellites, respectively. The existing data sets will be continued using data from the instruments on-board the new joint NOAA/EUMETSAT Meteorological Operational Polar satellite. The products have mostly been validated against several ground-based data sets both in situ and remotely sensed. The accomplished accuracy for products derived in near real time is sufficient to monitor variability on diurnal and seasonal scales. The demands on accuracy increase the longer the considered time scale is. Thus, interannual variability or trends can only be assessed if the sensor data are corrected for jumps created by instrument changes on successive satellites and more subtle effects like instrument and orbit drift and also changes to the spectral response function of an instrument. Thus, a central goal of the recently started Continuous Development and Operations Phase of the CM-SAF (2007-2012) is to further improve all CM-SAF data products to a quality level that allows for studies of interannual variability.

National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-643 (URN)10.5194/acp-9-1687-2009 (DOI)000264132800010 ()
Available from: 2015-04-22 Created: 2015-04-21 Last updated: 2017-12-04Bibliographically approved
Zhang, J., Kuenzer, C., Tetzlaff, A., Oertel, D., Zhukov, B. & Wagner, W. (2007). Thermal characteristics of coal fires 2: Results of measurements on simulated coal fires. Journal of Applied Geophysics, 63(3-4), 135-147
Open this publication in new window or tab >>Thermal characteristics of coal fires 2: Results of measurements on simulated coal fires
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2007 (English)In: Journal of Applied Geophysics, ISSN 0926-9851, E-ISSN 1879-1859, Vol. 63, no 3-4, p. 135-147Article in journal (Refereed) Published
Abstract [en]

In this paper we present thermal characteristics of coal fires as measured during simulated fires under an experimental setting in Germany in July 2002. It is thus a continuation of the previously published paper "Thermal surface characteristics of coal fire 1: Results of in-situ measurement", in which we presented temperature measurements of real subsurface coal fires in China [Zhang, J., Kuenzer, C., accepted for publication. Thermal Surface Characteristics of Coal Fires 1: Results of in-situ measurements. Accepted for publication at Journal of Applied Geophysics.]. The focus is on simulated coal fires, which are less complex in nature than fires under natural conditions. In the present study we simulated all the influences usually occurring under natural conditions in a controllable manner (uniform background material of known thermal properties, known ventilation pathways, homogeneous coal substrate), creating two artificial outdoor coal fires under simplified settings. One surface coal fire and one subsurface coal fire were observed over the course of 2 days. The set up of the fires allowed for measurements not always feasible under "real" in-situ conditions: thus compared to the in-situ investigations presented in paper one we could retrieve numerous temperature measurements inside of the fires. Single temperature measurements, diurnal profiles and airborne thermal surveying present the typical temperature patterns of a small surface-and a subsurface fire under undisturbed conditions (easily accessible terrain, 24 hour measurements period, homogeneous materials). We found that the outside air temperature does not influence the fire's surface temperature (up to 900 degrees C), while fire centre temperatures of up to 1200 degrees C strongly correlate with surface temperatures of the fire. The fires could heat their surrounding up to a distance of 4.5 m. However, thermal anomalies on the background surface only persist as long as the fire is burning and disappear very fast if the heat source is removed. Furthermore, heat outside of the fires is transported mainly by convection and not by radiation. In spatial thermal line scanner data the diurnal thermal patterns of the coal fire are clearly represented. Our experiments during that data collection also visualize the thermal anomaly differences between covered (underground) and uncovered (surface) coal fires. The latter could not be observed in-situ in a real coal fire area. Subsurface coal fires express a much weaker signal than open surface fires and contrast only by few degrees against the background. In airborne thermal imaging scanner data the fires are also well represented. Here we could show that the mid-infrared domain (3.8 mu m) is more suitable to pick up very hot anomalies, compared to the common thermal (8.8 mu m) domain. Our results help to understand coal fires and their thermal patterns as well as the limitations occurring during their analysis. We believe that the results presented here can practicably help for the planning of coal fire thermal mapping campaigns - including remote sensing methods and the thermal data can be included into numerical coal fire modelling as initial or boundary conditions. (c) 2007 Elsevier B.V. All rights reserved.

Keywords
coal fire simulation, simulated heat sources, thermal analyses, temperature profiles, airborne thermal scanners
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-743 (URN)10.1016/j.jappgeo.2007.08.003 (DOI)000251952700003 ()
Available from: 2015-04-28 Created: 2015-04-22 Last updated: 2017-12-04Bibliographically approved
Kuenzer, C., Zhang, J., Tetzlaff, A., van Dijk, P., Voigt, S., Mehl, H. & Wagner, W. (2007). Uncontrolled coal fires and their environmental impacts: Investigating two arid mining regions in north-central China. Applied Geography, 27(1), 42-62
Open this publication in new window or tab >>Uncontrolled coal fires and their environmental impacts: Investigating two arid mining regions in north-central China
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2007 (English)In: Applied Geography, ISSN 0143-6228, E-ISSN 1873-7730, Vol. 27, no 1, p. 42-62Article in journal (Refereed) Published
Abstract [en]

Uncontrolled coal fires occur worldwide and pose a great threat to the environment. This paper introduces the problem of coal fires referring to two coalfields in north-central China. These areas were regularly investigated during numerous fieldwork campaigns between 2002 and 2005. Emphasis is put on the environmental impacts of the fires, such as atmospheric influences, land subsidence, landscape degradation, as well as the danger for water resources and human health. New approaches for coal fire research are undertaken in numerous national and multi-lateral projects. Research disciplines, addressing the problem of coal fires, include geography, geology, geo-physics, mining-engineering, and remote sensing. In combination, they lead the direction towards a holistic approach to detect, monitor, quantify, and finally extinguish the coal fires. (c) 2006 Elsevier Ltd. All rights reserved.

Keywords
coal fires, coal mining, environmental degradation, remote sensing, China
National Category
Meteorology and Atmospheric Sciences
Research subject
Remote sensing
Identifiers
urn:nbn:se:smhi:diva-766 (URN)10.1016/j.apgeog.2006.09.007 (DOI)000246139100004 ()
Available from: 2015-04-28 Created: 2015-04-22 Last updated: 2017-12-04Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0003-2138-4325

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