TY  - JOUR
A1  - Rösch, Moritz
A1  - Plank, Simon
T1  - Detailed mapping of lava and ash deposits at Indonesian volcanoes by means of VHR PlanetScope change detection
JF  - Remote Sensing
N2  - Mapping of lava flows in unvegetated areas of active volcanoes using optical satellite data is challenging due to spectral similarities of volcanic deposits and the surrounding background. Using very high-resolution PlanetScope data, this study introduces a novel object-oriented classification approach for mapping lava flows in both vegetated and unvegetated areas during several eruptive phases of three Indonesian volcanoes (Karangetang 2018/2019, Agung 2017, Krakatau 2018/2019). For this, change detection analysis based on PlanetScope imagery for mapping loss of vegetation due to volcanic activity (e.g., lava flows) is combined with the analysis of changes in texture and brightness, with hydrological runoff modelling and with analysis of thermal anomalies derived from Sentinel-2 or Landsat-8. Qualitative comparison of the mapped lava flows showed good agreement with multispectral false color time series (Sentinel-2 and Landsat-8). Reports of the Global Volcanism Program support the findings, indicating the developed lava mapping approach produces valuable results for monitoring volcanic hazards. Despite the lack of bands in infrared wavelengths, PlanetScope proves beneficial for the assessment of risk and near-real-time monitoring of active volcanoes due to its high spatial (3 m) and temporal resolution (mapping of all subaerial volcanoes on a daily basis).
KW  - lava
KW  - volcanoes
KW  - PlanetScope
KW  - change detection
KW  - object-based image analysis
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-262232
SN  - 2072-4292
VL  - 14
IS  - 5
ER  - 
TY  - JOUR
A1  - Dech, Stefan
A1  - Holzwarth, Stefanie
A1  - Asam, Sarah
A1  - Andresen, Thorsten
A1  - Bachmann, Martin
A1  - Boettcher, Martin
A1  - Dietz, Andreas
A1  - Eisfelder, Christina
A1  - Frey, Corinne
A1  - Gesell, Gerhard
A1  - Gessner, Ursula
A1  - Hirner, Andreas
A1  - Hofmann, Matthias
A1  - Kirches, Grit
A1  - Klein, Doris
A1  - Klein, Igor
A1  - Kraus, Tanja
A1  - Krause, Detmar
A1  - Plank, Simon
A1  - Popp, Thomas
A1  - Reinermann, Sophie
A1  - Reiners, Philipp
A1  - Roessler, Sebastian
A1  - Ruppert, Thomas
A1  - Scherbachenko, Alexander
A1  - Vignesh, Ranjitha
A1  - Wolfmueller, Meinhard
A1  - Zwenzner, Hendrik
A1  - Kuenzer, Claudia
T1  - Potential and challenges of harmonizing 40 years of AVHRR data: the TIMELINE experience
JF  - Remote Sensing
N2  - Earth Observation satellite data allows for the monitoring of the surface of our planet at predefined intervals covering large areas. However, there is only one medium resolution sensor family in orbit that enables an observation time span of 40 and more years at a daily repeat interval. This is the AVHRR sensor family. If we want to investigate the long-term impacts of climate change on our environment, we can only do so based on data that remains available for several decades. If we then want to investigate processes with respect to climate change, we need very high temporal resolution enabling the generation of long-term time series and the derivation of related statistical parameters such as mean, variability, anomalies, and trends. The challenges to generating a well calibrated and harmonized 40-year-long time series based on AVHRR sensor data flown on 14 different platforms are enormous. However, only extremely thorough pre-processing and harmonization ensures that trends found in the data are real trends and not sensor-related (or other) artefacts. The generation of European-wide time series as a basis for the derivation of a multitude of parameters is therefore an extremely challenging task, the details of which are presented in this paper.
KW  - AVHRR
KW  - Earth Observation
KW  - harmonization
KW  - time series analysis
KW  - climate related trends
KW  - automatic processing
KW  - Europe
KW  - TIMELINE
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-246134
SN  - 2072-4292
VL  - 13
IS  - 18
ER  -