The Moon encountered an extreme space weather event (NOAA G5 class) on 10 May 2024, caused by a series of coronal mass ejections (CMEs). Chandra's Atmospheric Composition Explorer-2 (CHACE-2), a neutral gas mass spectrometer on board Chandrayaan-2 orbiter, made in situ observations of the lunar exosphere during this period. Observations show an increase in total pressure around the arrival time of the CME impact on the Moon. The corresponding total number densities derived from these observations show an enhancement in the total number densities by more than an order of magnitude. The increase in lunar exospheric number densities by a factor > 10, due to the solar wind ion sputter process, is consistent with earlier theoretical modeling. This is the first observational confirmation of the enhancement in lunar exospheric densities during a CME impact.

Altitude profiles of the mass concentrations of aerosol black carbon (BC) have been obtained,up to an altitude of 12 km, from in situ measurements over Hyderabad (17.47 degrees N, 78.57 degrees E, 557 m amsl;a tropical station in the central Indian peninsula), using three successive high altitude balloon ascents during winter and early summer seasons of 2023-2024. The profiles revealed predominant peaks at around 8 and 11 km, where the BC concentrations were reaching as high as nearly three times the surface concentrations (2.82, 2.76, and 2.60 mu g m-3, respectively), persistently in all the three flights. Detailed analyses using official data of air traffic movement, aviation statistics and emission inventory revealed a strong linkage with the emissions from commercial aircraft that touch Hyderabad and overfly the region. These elevated BC layers will have large implications to atmospheric radiative forcing and possible contributions to modification of the cirrus cloud properties.

It is believed that dust formations above the lunar surface, manifested via sunlight scattering and detected in-situ, are of too low density to pose threats to lunar missions. However, occasionally prolonged fading/kindling of the immersing/emerging stars near the lunar limb indicates much denser low-altitude dust clouds. We performed statistical analysis of such abnormal stellar occultation events (ASOEs), found in the Lunar Occultation Archive. Specific dependence of their duration on selenographic position reveals an impact-plume like shape of dust clouds and excludes visual illusions, terrestrial cloudiness, and double stars as causes of the observed starlight extinction. The probability of the long-lasting ASOEs peaks during the Perseid meteor shower in August, confirming the impact-related nature of most of the related dust clouds. At the same time, additional semi-monthly periodicity of ASOEs points to a complementary mechanism of dust lifting due to, for example, lunar outgassing triggered by solar tides.

Future anthropogenic land use change (LUC) may alter atmospheric carbonaceous aerosol (black carbon and organic aerosol) burden by perturbing biogenic and fire emissions. However, there has been little investigation of this effect. We examine the global evolution of future carbonaceous aerosol under the Shared Socioeconomic Pathways projected reforestation and deforestation scenarios using the CESM2 model from present-day to 2100. Compared to present-day, the change in future biogenic volatile organic compounds emission follows changes in forest coverage, while fire emissions decrease in both projections, driven by trends in deforestation fires. The associated carbonaceous aerosol burden change produces moderate aerosol direct radiative forcing (-0.021 to +0.034 W/m2) and modest mean reduction in PM2.5 exposure (-0.11 mu g/m3 to -0.23 mu g/m3) in both scenarios. We find that future anthropogenic LUC may be more important in determining atmospheric carbonaceous aerosol burden than direct anthropogenic emissions, highlighting the importance of further constraining the impact of LUC.

We present the first full-wavelength numerical simulations of the electric field generated by cosmic ray impacts into the Moon. Billions of cosmic rays fall onto the Moon every year. Ultra-high energy cosmic ray impacts produce secondary particle cascades within the regolith and subsequent coherent, wide-bandwidth, linearly-polarized radio pulses by the Askaryan Effect. Observations of the cosmic ray particle shower radio emissions can reveal subsurface structure on the Moon and enable the broad and deep prospecting necessary to confirm or refute the existence of polar ice deposits. Our simulations show that the radio emissions and reflections could reveal ice layers as thin as 10 cm and buried under regolith as deep as 9 m. The Askaryan Effect presents a novel and untapped opportunity for characterizing buried lunar ice at unprecedented depths and spatial scales.

In the mountainous headwaters of the Colorado River episodic dust deposition from adjacent arid and disturbed landscapes darkens snow and accelerates snowmelt, impacting basin hydrology. Patterns and impacts across the heterogenous landscape cannot be inferred from current in situ observations. To fill this gap daily remotely sensed retrievals of radiative forcing and contribution to melt were analyzed over the MODIS period of record (2001-2023) to quantify spatiotemporal impacts of snow darkening. Each season radiative forcing magnitudes were lowest in early spring and intensified as snowmelt progressed, with interannual variability in timing and magnitude of peak impact. Over the full record, radiative forcing was elevated in the first decade relative to the last decade. Snowmelt was accelerated in all years and impacts were most intense in the central to southern headwaters. The spatiotemporal patterns motivate further study to understand controls on variability and related perturbations to snow water resources.

The high latitudes cover similar to 20% of Earth's land surface. This region is facing many shifts in thermal, moisture and vegetation properties, driven by climate warming. Here we leverage remote sensing and climate reanalysis records to improve understanding of changes in ecosystem indicators. We applied non-parametric trend detections and Getis-Ord Gi* spatial hotspot assessments. We found substantial terrestrial warming trends across Siberia, portions of Greenland, Alaska, and western Canada. The same regions showed increases in vapor pressure deficit; changes in precipitation and soil moisture were variable. Vegetation greening and browning were widespread across both continents. Browning of the boreal zone was especially evident in autumn. Multivariate hotspot analysis indicated that Siberian ecoregions have experienced substantial, simultaneous, changes in thermal, moisture and vegetation status. Finally, we found that using regionally-based trends alone, without local assessments, can yield largely incomplete views of high-latitude change.

River-controlled permafrost dynamics are crucial for sediment transport, infrastructure stability, and carbon cycle, yet are not well understood under climate change. Leveraging remotely sensed datasets, in-situ hydrological observations, and physics-based models, we reveal overall warming and widening rivers across the Tibetan Plateau in recent decades, driving accelerated sub-river permafrost thaw. River temperature of a representative (Tuotuohe River) on the central Tibetan Plateau, has increased notably (0.39 degrees C/decade) from 1985 to 2017, facilitating heat transfer into the underlying permafrost via both convection and conduction. Consequently, the permafrost beneath rivers warms faster (0.37 degrees C-0.66 degrees C/decade) and has a similar to 0.5 m thicker active layer than non-inundated permafrost (0.17 degrees C-0.49 degrees C/decade). With increasing river discharge, the inundated area expands laterally along the riverbed (16.4 m/decade), further accelerating permafrost thaw for previously non-inundated bars. Under future warmer and wetter climate, the anticipated intensification of sub-river permafrost degradation will pose risks to riverine infrastructure and amplify permafrost carbon release.

Accelerating creep before catastrophic failure commonly follows a power-law velocity-acceleration relationship, with the exponent typically near 2 but often evolving from 1 to 2 at a certain point, indicating a dynamic transition. The underlying mechanisms, however, remain unclear. Here we investigate this transition by monitoring the slip displacement of clayey soil during fluid-injection creep experiments. This transition is discontinuous in the first run but becomes continuous in the initially pre-sheared sample. Using a regularized rate-and-state friction model, we explicitly examine the relationship between the exponent and the frictional properties of the soil. This model describes the dynamic transition, with the exponent evolving from 1 to 2 across a broad range of frictional parameters. Furthermore, by incorporating idealized shear localization processes, the model qualitatively reproduces the shear-history-dependent transition. Our study demonstrates that a combination of structural evolutions and frictional properties may explain slow and fast slips observed in various shear systems.

Tropical cyclones (TCs) pose a substantial threat to human life and property, with China being among the most affected countries. In this study, a significant increasing trend is detected for TC destructiveness, primarily measured by precipitation, and for TC-induced damage, measured by direct economic losses (DELs), in the inland areas of East China. In contrast, a similar trend cannot be observed in the coastal regions. The rapid increase of TC-induced damage in the inland areas of East China is directly related to an increase of the annual number of disastrous TCs, which is a result of the increased TC landfall frequency and the increased TC decay timescale after landfall. The increase in specific humidity, soil moisture, and the decrease in vertical wind shear in East China favor the survival of TCs inland. Our results highlight the significance of TC disaster prevention in the inland regions.