Forests provide multiple ecosystem services including water and soil protection, biodiversity conservation, carbon sequestration, and recreation, which are crucial in sustaining human health and wellbeing. Global changes represent a serious threat to Mediterranean forests, and among known impacts, there is the spread of invasive pests and pathogens, often boosted by climate change and human pressure. Remote sensing can provide support to forest health monitoring, which is crucial to contrast degradation and adopt mitigation strategies. Here, different multispectral and SAR data are used to detect the incidence of ink disease driven by Phytophthora cinnamomi in forest sites in central Italy, dominated by chestnut and cork oak respectively. Sentinel 1, Sentinel 2, and PlanetScope data, together with ground information, served as input in Random Forests to model healthy and disease classes in the two sites. The results indicate that healthy and symptomatic trees are clearly distinguished, whereas the discrimination among disease classes of different severity (moderate and severe damage) is less accurate. Crown dimension and sampled spectral regions are a critical factors in the selection of the sensor; better results are obtained for the larger chestnut crowns with Sentinel 2 data. In both sites, the red and near infra-red bands from multispectral data resulted well suited to monitor the spread of the ink disease.

Particle-particle and particle-gas processes significantly impact planetary precursors such as dust aggregates and planetesimals. We investigate gas permeability (kappa) in 12 granular samples, mimicking planetesimal dust regoliths. Using parabolic flights, this study assesses how gravitational compression - and lack thereof - influences gas permeation, impacting the equilibrium state of low-gravity objects. Transitioning between micro- and hyper-gravity induces granular sedimentation dynamics, revealing collective dust-grain aerodynamics. Our experiments measure kappa across Knudsen number (Kn) ranges, reflecting transitional flow. Using mass and momentum conservation, we derive kappa and calculate pressure gradients within the granular matrix. Key findings: (i) As confinement pressure increases with gravitational load and mass flow, kappa and average pore space decrease. This implies that a planetesimal's unique dust-compaction history limits subsurface volatile outflows. (ii) The derived pressure gradient enables tensile strength determination for asteroid regolith simulants with cohesion. This offers a unique approach to studying dust-layer properties when suspended in confinement pressures comparable to the equilibrium state on planetesimals surfaces, which will be valuable for modelling their collisional evolution. (iii) We observe a dynamical flow symmetry breaking when granular material moves against the pressure gradient. This occurs even at low Reynolds numbers, suggesting that Stokes numbers for drifting dust aggregates near the Stokes-Epstein transition require a drag force modification based on permeability.

Context. The solar wind impinging on the lunar surface results in the emission of energetic neutral atoms. This particle population is one of the sources of the lunar exosphere. Aims. We present a semi-empirical model to describe the energy spectra of the neutral emitted atoms. Methods. We used data from the Advanced Small Analyzer for Neutrals (ASAN) on board the Yutu-2 rover of the Chang'E-4 mission to calculate high-resolution average energy spectra of the energetic neutral hydrogen flux from the surface. We then constructed a semi-empirical model to describe these spectra. Results. Excellent agreement between the model and the observed energetic neutral hydrogen data was achieved. The model is also suitable for describing heavier neutral species emitted from the surface. Conclusions. A semi-analytical model describing the energy spectrum of energetic neutral atoms emitted from the lunar surface has been developed and validated by data obtained from the lunar surface.

Following spacecraft encounters with comets 67P/C-G and 1P/Halley, it was surprising that O2, expected to be a very minor species in their comas, was observed to outgas at a few percent abundance during their ice sublimation phases. This challenged the direct connection suggested between comets and material in the interstellar medium (ISM), which exhibits a very low O2/H2O gas-phase abundance, leading to a number of papers suggesting novel sources for O2. Since these eccentrically orbiting comets have lost significant amounts of their evaporating surfaces over their lifetimes, the O2 observed must have been stably trapped down to significant depths in these primordial icy bodies. O2 was also seen in the coma by Rosetta, along with other volatiles, long after water ice sublimation began to subside. Here we note that the extensive observations of the icy satellites of Jupiter (Europa, Ganymede, and Callisto) exhibit radiolytic and outgassing processes that provide certain direct parallels to interpretations of recent comet observations. Given that O2 is consistently observed in the atmospheres of icy Jovian satellites, as well as stably trapped as 'bubbles' (Johnson and Jesser, 1997) in their water ice surfaces, their spectral observations can help constrain the environment in which Jupiter-family and Oort cloud comets formed given that the observed O2/H2O abundances at both types of comets and icy moons are nearly identical. Based on the approximate charged particle radiation required to produce the observed steady-state concentrations of O2, we suggest that comets likely formed in a far more energetic environment than the ISM. While grains can be irradiated for longer timescales in the neutral ISM, small grains are expected to erode before significant O2 formation and trapping occurs. Independent of celestial dynamics then, an unknown radiation source, may provide insight to the first population of oxidized water ice grains in the early solar system.

每年消融期，冰面湖广泛分布于极地冰盖表面，能够存储大量冰面融水，但部分冰面湖底部破裂后会输送融水进入冰盖底部，从而影响冰盖运动与稳定性。因此，准确测算冰面湖水深信息，进而估算冰面湖体积及其动态变化，对于理解极地冰盖水文过程具有重要意义。然而，实地测量冰面湖深度难度大、成本高、覆盖范围小，通过中低空间分辨率光学遥感影像构建的冰面湖水深反演模型精度不足。该研究综合PlanetScope SuperDove光学小卫星8波段遥感影像（空间分辨率为3 m）与ICESat-2激光测高数据反演冰面湖水深。首先，通过自适应核密度估计分离并拟合湖面与湖底ICESat-2激光测高点云，进而获取冰面湖水深观测结果；其次，利用最佳波段比值分析PlanetScope影像不同波段（组合）与ICESat-2水深数据的相关关系，构建二次函数、指数函数、幂函数与对数函数4种冰面湖水深反演经验公式；最后，选择4个具有同时期PlanetScope和ICESat-2数据覆盖的冰面湖，测试冰面湖水深遥感反演的精度。结果表明PlanetScope绿光I波段是冰面湖水深反演最佳波段，单波段反射率与冰面湖水深相关性最强（R...

每年消融期，冰面湖广泛分布于极地冰盖表面，能够存储大量冰面融水，但部分冰面湖底部破裂后会输送融水进入冰盖底部，从而影响冰盖运动与稳定性。因此，准确测算冰面湖水深信息，进而估算冰面湖体积及其动态变化，对于理解极地冰盖水文过程具有重要意义。然而，实地测量冰面湖深度难度大、成本高、覆盖范围小，通过中低空间分辨率光学遥感影像构建的冰面湖水深反演模型精度不足。该研究综合PlanetScope SuperDove光学小卫星8波段遥感影像（空间分辨率为3 m）与ICESat-2激光测高数据反演冰面湖水深。首先，通过自适应核密度估计分离并拟合湖面与湖底ICESat-2激光测高点云，进而获取冰面湖水深观测结果；其次，利用最佳波段比值分析PlanetScope影像不同波段（组合）与ICESat-2水深数据的相关关系，构建二次函数、指数函数、幂函数与对数函数4种冰面湖水深反演经验公式；最后，选择4个具有同时期PlanetScope和ICESat-2数据覆盖的冰面湖，测试冰面湖水深遥感反演的精度。结果表明PlanetScope绿光I波段是冰面湖水深反演最佳波段，单波段反射率与冰面湖水深相关性最强（R...

每年消融期，冰面湖广泛分布于极地冰盖表面，能够存储大量冰面融水，但部分冰面湖底部破裂后会输送融水进入冰盖底部，从而影响冰盖运动与稳定性。因此，准确测算冰面湖水深信息，进而估算冰面湖体积及其动态变化，对于理解极地冰盖水文过程具有重要意义。然而，实地测量冰面湖深度难度大、成本高、覆盖范围小，通过中低空间分辨率光学遥感影像构建的冰面湖水深反演模型精度不足。该研究综合PlanetScope SuperDove光学小卫星8波段遥感影像（空间分辨率为3 m）与ICESat-2激光测高数据反演冰面湖水深。首先，通过自适应核密度估计分离并拟合湖面与湖底ICESat-2激光测高点云，进而获取冰面湖水深观测结果；其次，利用最佳波段比值分析PlanetScope影像不同波段（组合）与ICESat-2水深数据的相关关系，构建二次函数、指数函数、幂函数与对数函数4种冰面湖水深反演经验公式；最后，选择4个具有同时期PlanetScope和ICESat-2数据覆盖的冰面湖，测试冰面湖水深遥感反演的精度。结果表明PlanetScope绿光I波段是冰面湖水深反演最佳波段，单波段反射率与冰面湖水深相关性最强（R...

格陵兰冰盖的消融及其对海平面上升的贡献成为国际上研究的热点。每年消融期,格陵兰冰盖表面消融,融水会导致冰面形成冰面湖、冰面河、注水冰裂隙等形态。格陵兰冰面融水规模庞大、结构复杂、变化迅速,区域气候模型难以准确模拟冰面融水分布,中等分辨率卫星影像难以反映冰面融水的时空变化。以PlanetScope为代表的CubeSat小卫星空间分辨率高达3 m,理想情况下重访周期可达1 d,这为精细化动态监测格陵兰冰面融水提供了可能。本研究利用PlanetScope高空间分辨率小卫星遥感影像提取格陵兰冰盖西南部典型流域冰面融水遥感信息,构建了针对PlanetScope遥感影像的冰面融水深度反演公式,对比了MAR v3.11区域气候模型模拟的融水径流量与遥感反演的融水体积。结果表明:在2019年7—8月,流域内冰面融水开放水体比率先上升后下降,在7月12日达到峰值8.7%;流域内冰面融水深度介于0.2～1.5 m之间,冰面湖最深(0.9 m±0.2 m),冰面河干流次之(0.6 m±0.1 m),冰面河支流最浅(0.5 m±0.1 m);遥感观测的开放水体比率、冰面融水体积与区域气候模型MAR模拟的融水日...

格陵兰冰盖的消融及其对海平面上升的贡献成为国际上研究的热点。每年消融期,格陵兰冰盖表面消融,融水会导致冰面形成冰面湖、冰面河、注水冰裂隙等形态。格陵兰冰面融水规模庞大、结构复杂、变化迅速,区域气候模型难以准确模拟冰面融水分布,中等分辨率卫星影像难以反映冰面融水的时空变化。以PlanetScope为代表的CubeSat小卫星空间分辨率高达3 m,理想情况下重访周期可达1 d,这为精细化动态监测格陵兰冰面融水提供了可能。本研究利用PlanetScope高空间分辨率小卫星遥感影像提取格陵兰冰盖西南部典型流域冰面融水遥感信息,构建了针对PlanetScope遥感影像的冰面融水深度反演公式,对比了MAR v3.11区域气候模型模拟的融水径流量与遥感反演的融水体积。结果表明:在2019年7—8月,流域内冰面融水开放水体比率先上升后下降,在7月12日达到峰值8.7%;流域内冰面融水深度介于0.2～1.5 m之间,冰面湖最深(0.9 m±0.2 m),冰面河干流次之(0.6 m±0.1 m),冰面河支流最浅(0.5 m±0.1 m);遥感观测的开放水体比率、冰面融水体积与区域气候模型MAR模拟的融水日...

格陵兰冰盖的消融及其对海平面上升的贡献成为国际上研究的热点。每年消融期,格陵兰冰盖表面消融,融水会导致冰面形成冰面湖、冰面河、注水冰裂隙等形态。格陵兰冰面融水规模庞大、结构复杂、变化迅速,区域气候模型难以准确模拟冰面融水分布,中等分辨率卫星影像难以反映冰面融水的时空变化。以PlanetScope为代表的CubeSat小卫星空间分辨率高达3 m,理想情况下重访周期可达1 d,这为精细化动态监测格陵兰冰面融水提供了可能。本研究利用PlanetScope高空间分辨率小卫星遥感影像提取格陵兰冰盖西南部典型流域冰面融水遥感信息,构建了针对PlanetScope遥感影像的冰面融水深度反演公式,对比了MAR v3.11区域气候模型模拟的融水径流量与遥感反演的融水体积。结果表明:在2019年7—8月,流域内冰面融水开放水体比率先上升后下降,在7月12日达到峰值8.7%;流域内冰面融水深度介于0.2～1.5 m之间,冰面湖最深(0.9 m±0.2 m),冰面河干流次之(0.6 m±0.1 m),冰面河支流最浅(0.5 m±0.1 m);遥感观测的开放水体比率、冰面融水体积与区域气候模型MAR模拟的融水日...