Search

Climate-induced natural hazards are thought to be happening more frequent and more intense under an increasingly warmer Earth. Earth-observing satellites including the ones operate in constellations and deliver accurate and sub-daily high-resolution/stereo multispectral satellite imagery, provide an opportunity to rapidly monitoring and quantifying the magnitude of disasters. Planet PBC’s Dove/SuperDove, SkySat, RapidEye (retired in March 2020) satellite constellations have at present over 150 CubeSats providing daily/sub-daily sampled 0.5-5-meter resolution images globally. Here, we use the available multispectral images from Planet CubeSat constellations, other geodetic and remote sensing data with the objective to conduct a feasibility study to monitor hazards. In particular, our goal is to identify, track, and quantify the scopes of active wildfires and rapid flood events even at relatively small scales and relatively short-durations worldwide, to study the feasibility of using timely and multi-platform satellite observations to complement informed disaster responses. In this study, we provide case studies and demonstrations of example brush fire and flood hazards to examine the feasibility of a satellite observation-based decision-support disaster response and management tool., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

On February 6, 2023, a sequence of earthquakes with Mw 7.8 and Mw 7.5 occurred in southern central Turkey near the northern border of Syria about in 9 hours. The disastrous earthquake sequence and its other aftershocks caused heavy human casualties and devastating building collapses. We employ the Empirical Orthogonal Function (EOF) analysis to capture coherent spatiotemporal features of co-seismic deformation for three components (N, E, U), which is based on the time series of 1-Hz GPS solutions at 20 permanent stations spatially well-distributed around the ruptured Anatolian fault system. The solved EOF modes show patterns which would help to investigate co-seismic rupture of the seismogenic faults. We compare the EOF-derived co-seismic displacement to the modeling results, which is computed from the spherical, elastic dislocation theory and finite fault model inverted from teleseismic waves records. Both GPS-observed and the modeled displacements show high consistency except for that at station EKZ1 (Ekinözü) where ~4.7 m of westward motion was estimated from GPS which we believe does not entirely represent the crustal motion; some other phenomena such as a local co-seismic landslide or a relative motion of the pillar with respect to the ground might have occurred. Moreover, this sequence is a large typical strike-slip faulting, which can generate gravity change above the threshold proposed by some theoretical simulation based on the satellite gravimetry observations. We also compute forward-modeled coseismic gravity changes, and discuss the plausible detection by instrument onboard of GRACE Follow-On gravimetry mission., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

Starting from April 2002, Gravity Recovery and Climate Experiment (GRACE) and, its successor mission GRACE-FO (FollowOn) have provided irreplaceable data for monitoring mass variations within the hydrosphere, cryosphere, and oceans, and with unprecedented accuracy and resolution for over two decades. However, the long-term products of mass variations prior to GRACE-era may allow for a better understanding of spatiotemporal changes in climate-induced geophysical phenomena, including terrestrial water cycle, ice sheet and glacier mass balance, sea level change and ocean bottom pressure. In this study, total water storage anomalies (TWSA) are simulated/reconstructed globally at 1.0°x1.0° spatial and monthly temporal resolutions from January 1994 to December 2020 with an in-house developed hybrid Deep Learning (DL) architecture using GRACE/-FO mascon and SLR gravimetry, ECMWF Reanalysis-5 (ERA5) data. We validated our simulated mass change data products both over land and ocean, not only through mathematical performance metrics (internal validations) such as RMSE or NSE along with comparisons to previous studies, but also external validations with non-GRACE datasets such as El-Nino and La-Nina patterns, barystatic global mean sea level change, degree (d) 2 order (o) 1 spherical harmonic coefficients (C21, S21) retrieved from Earth orientation parameters, Greenland Ice sheet mass balance and in-situ Ocean Bottom Pressure measurements were carried out. The overall validations show that the proposed DL paradigm can efficiently simulate high-resolution monthly global gravity field both in GRACE/GRACE-FO and pre-GRACE era. The resulting simulated data products are available as monthly mass change grids as well as spherical harmonic models up to d/o 180., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)