Submarine volcanism in shallow waters (<100 m), particularly in remote settings, is difficult to monitor quantitatively and, in the rare formation of islands, it is challenging to understand the rapid-paced erosion. However, these newly erupted volcanic islands become observable to airborne and/or satellite remote sensing instruments. NASA’s ICESat-2 satellite laser altimeter, combined with visible imagery (optical and microwave), provide a novel method of evaluating the elevation characteristics of newly emerged volcanoes and their subaerial eruption products. Niijima Fukutoku-Okanoba (NFO) is a submarine volcano 1300 km south of Tokyo (Ogasawara Archipelago of Japan) that periodically breaches the ocean surface to create new islands that are subsequently eroded. The recent eruption in August 2021 is a rare opportunity to investigate this island evolution using high-resolution satellite datasets with geodetic-quality ICESat-2 altimetry. Lansdat-8 and Planet imagery provide a qualitative analysis of the exposed volcanic deposits, while ICESat-2 products provide elevation profiles necessary to quantify the physical surface structures. This investigation determines an innovative application for ICESat-2 data in evaluating newly emerged islands and how the combination of satellite remote sensing (visible and lidar) to investigate these short-lived volcanic features can improve our understanding of the volcanic island system in ways not previously possible.

Daedalia Planum contains numerous young lava flows with diverse flow morphology. Previous thermal infrared studies avoided this region because of the moderately high visible albedo, assumed to be caused by optically thick dust, and overall low thermal inertia. The Daedalia Planum flows, however, have some of the roughest surfaces on Mars and display an unusual thermophysical behavior that most likely indicates different areal percentages of dust, sand, and lava outcrops. Recent studies suggest that these surfaces contain significant proportions of lava outcrops rising above low‐lying regions of sand with a spatially discontinuous dust layer. A multi‐instrument, multispectral approach combined with prior morphological mapping is applied here to discriminate between individual flows and determine the variation of thermophysical units on the surface. High‐resolution ConTeXt Camera and High‐Resolution Imaging Science Experiment data are used to investigate the flow surfaces and degree of mantling. Thermal Emission Imaging System and Thermal Emission Spectrometer thermal infrared data are analyzed to quantify the thermophysical variations between flows, identify surfaces with minimally mantled lava outcrops, and apply a thermophysical classification to differentiate the surface units. The results demonstrate that the observed thermal variations are due to different distributions of blocky lavas and sand infill. A majority of lava flows with rough surfaces display a diurnal and thermal inertia response indicative of a larger areal percentage of those outcrops versus that of sand and dust. This approach identifies surfaces with more exposed lava outcrops, promising targets for future composition analysis, in regions previously thought to be too dusty for such studies using thermal infrared data.

The Ice, Cloud and Land Elevation Satellite-2 (ICESat-2), on-orbit for nearly 3 years, continues to provide global elevation measurements to the broad science community. One of the most transformative discoveries during early mission operations was the realization that ICESat-2 could provide bathymetry in addition to the planned surface-specific data products for land ice, sea ice, ocean and land/vegetation. This is an important capability for coastal science, maritime intelligence and shallow water benthic monitoring at the global scale. ICESat-2 elevations are also becoming a critical component of satellite-derived bathymetry where multispectral imagery uses the measurements to create broad spatial maps with absolute vertical bathymetric depths. This article will highlight some of the most salient bathymetric observations and quantitative analyses of this space-based photon counting lidar that includes sea floor elevation retrievals but also environmental characterization such as wave structure and turbidity and monitoring of benthic habitats.

Apparent thermal inertia (ATI) is a remote sensing-based thermophysical approximation used to estimate surface properties such as particle size or soil moisture, but is subject to oversimplifications if uniform surface materials are assumed. Geological surfaces realistically contain multiple types of materials that are represented by mixed pixels in a digital image that can dramatically affect the derived thermal response. Thus, the current surface uniformity assumption can lead to erroneous calculations. To define how these mixed particle size surfaces affect ATI, a multi-instrument, multi-spectral study was conducted at the North Coulee rhyolite flow, Mono Domes (California). This flow is compositionally homogenous with particle sizes ranging from silt size to boulders, making it an ideal location to understand the relationship between particle size distributions and ATI. Multispectral data from orbital sensors with increasing spatial resolutions were analyzed in combination with samples, GPS, and photogrammetry data collected in the field. The surface particle size characteristics divided into three broad categories (fine, moderate, and coarse) were mapped based on WorldView-2 visible data and field observations. Broad categories were validated using a 3-dimensional point cloud derived from structure-from-motion (SfM) methods using field photographs. The areal percentage of each category within an ATI pixel was derived to populate a lookup table (LUT) with the corresponding ATI values to quantify the effect of mixed pixels. Lower ATI values are dominated by fine particles (sand and dust) as expected, however, surfaces with the highest values were predominately moderate-sized cobbles. Pixels with a high areal percentage of coarse sizes display an intermediate ATI value, suggesting that either self-shadowing or trapping of fines lowers the ATI value. Alternatively, areas with a majority of moderate particle sizes have less shadowing and efficient vertical sorting of smaller material, as seen in field data, leaving a thermal derived response indicative of the dominating particle size. This study demonstrates how a uniform property assumption can cause erroneous derived thermal modeling, particularly over surfaces with a high percentage of boulders and large particle sizes. Future thermophysical studies of Earth or other planetary surfaces can greatly benefit from a multi-sensor approach combined with a higher spatial resolution visible dataset.