4 research outputs found
Automated Satellite-Based Landslide Identification Product for Nepal
Landslide event inventories are a vital resource for landslide susceptibility and forecasting applications. However, landslide inventories can vary in accuracy, availability, and timeliness as a result of varying detection methods, reporting, and data availability. This study presents an approach to use publicly available satellite data and open source software to automate a landslide detection process called the Sudden Landslide Identification Product (SLIP). SLIP utilizes optical data from the Landsat 8 OLI sensor, elevation data from the Shuttle Radar Topography Mission (SRTM), and precipitation data from the Global Precipitation Measurement (GPM) mission to create a reproducible and spatially customizable landslide identification product. The SLIP software applies change detection algorithms to identify areas of new bare-earth exposures that may be landslide events. The study also presents a precipitation monitoring tool that runs alongside SLIP called the Detecting Real-time Increased Precipitation (DRIP) model that helps identify the timing of potential landslide events detected by SLIP. Using SLIP and DRIP together, landslide detection is improved by reducing problems related to accuracy, availability, and timeliness that are prevalent in the state-of-the-art of landslide detection. A case study and validation exercise was performed in Nepal for images acquired between 2014 and 2015. Preliminary validation results suggest 56% model accuracy, with errors of commission often resulting from newly cleared agricultural areas. These results suggest that SLIP is an important first attempt in an automated framework that can be used for medium resolution regional landslide detection, although it requires refinement before being fully realized as an operational tool
A shot in the Dark (Ages): a faint galaxy at confirmed with JWST
The appearance of galaxies over the first billion years after the Big Bang is
believed to be responsible for the last dramatic change in the state of the
Universe. Ultraviolet photons from galaxies within this time period - the Epoch
of Reionization - ionized intergalactic Hydrogen, rendering the Universe
transparent to UV radiation and ending the so-called cosmic Dark Ages, sometime
after redshift . The majority of ionizing photons in the first few
hundred Myrs of cosmic history are thought to derive from galaxies
significantly fainter than the characteristic luminosity . These faint
galaxies are thought to be surrounded by sufficient neutral gas to prevent the
escape of the Lyman- photons that would allow confirmation with current
observatories. Here we demonstrate the power of the recently commissioned James
Webb Space Telescope to transform our understanding of the sources of
reionization, by reporting the first spectroscopic confirmation of a very low
luminosity () galaxy at , observed 480 Myr after the
Big Bang, via the detection of the Lyman-break and redward continuum with the
NIRSpec and NIRCam instruments. The galaxy JD1 is gravitationally magnified by
a factor of by the foreground cluster A2744. The power of JWST and
lensing allows us to peer deeper than ever before into the cosmic Dark Ages,
revealing the compact (150 pc) and complex morphology and physical
properties of an ultrafaint galaxy ().Comment: Submitted to Nature. 34 pages, 4 main figures, 1 supplementary
figure, 2 supplementary tables. Comments are welcom