地球科学最新文献

Surface waves are important for remote sensing, air–sea exchange, and underwater acoustics. The short gravity wave spectrum is azimuthally broad and bimodal. However, widely used wave models fail to reproduce the degree of observed spreading and azimuthal bimodality. Recent studies show that an azimuthally narrow spectral breaking dissipation due to long-wave short-wave modulation significantly improves model performance, highlighting the importance of better understanding the directionality of breaking kinematics. We utilized visible stereo imagery to investigate the directional wave-breaking kinematics relative to the energy spectrum under aligned and misaligned winds and dominant waves. The results show that the statistical distribution of wave-breaking kinematics closely aligns with the direction of the dominant waves and is azimuthally unimodal and narrower than the bimodal energy spectrum. These findings confirm the importance of exploring the directionality of breaking to improve our understanding of the spectral energy balance and spectral wave models within the short-gravity range.

Explosive cyclones are intense extratropical synoptic systems associated with severe weather in the mid-to-high latitudes, particularly over the Southern Ocean. This study employs a recently developed ROMS-CICE coupled model, incorporating a cyclone-removal method, to simulate and quantify the response of the upper ocean and sea ice to an explosive cyclone traversing the Southern Pacific Ocean. The modeling results indicate that the maximum instantaneous sea surface warming anomaly reaches up to 0.20°C around the center of the explosive cyclone, while a cooling anomaly of about −0.15°C is observed at the cyclone's periphery. Beneath this surface anomaly, a cooling of up to −0.15°C occurs in the area-averaged subsurface ocean layer at depths of 20–60 m. Concurrently, the sea surface salinity experiences an increasing anomaly of up to 0.20 practical salinity units (psu), accompanied by a decrease in salinity within the subsurface ocean layer at depths of 30–60 m. These anomalies gradually weaken over the subsequent 28–30 days but sustain minor anomalies for more than 1 month, particularly in the subsurface ocean layer. Further analysis of the temperature and salinity tendency equations reveals that advection and vertical diffusion primarily contribute to both the surface and subsurface responses, with vertical diffusion serving as the main driver behind the observed uniform patterns. Additionally, sea ice concentration and thickness demonstrate reductions of more than 25% and 0.2 m near the coast, respectively, resulting from dynamic forcing and the contributions of basal ice melting due to the transport of warmer water currents beneath.

Africa currently accounts for 18% of the world's population yet produces less than 2% of global research. This study examines the barriers faced by African researchers in geoscience and adjacent fields to research productivity and publication, as well as explores how these scientists view collaboration with international partners. A survey instrument was distributed via email through four partnering networks. We surveyed researchers across 12 countries; however, the respondent pool was dominated by those from Nigeria and Ghana. The results of this survey show that insufficient financial support, unreliable internet access, and limited career development opportunities are key barriers to research output. Interestingly, a lack of knowledge on how to collaborate regionally may be a previously underappreciated barrier. Despite many journals offering fee waivers, financial constraints in publishing are perceived to be a substantial barrier. In contrast to previous studies, most respondents did not view language barriers or writing skills as a significant issue. Collaboration with international partners was viewed positively by respondents, the majority of whom also indicated a belief that international collaborations benefit African and international partners equally. African researchers felt they could conduct research without expertise from international partners, but not without financial aid. Further research is needed to explore the potential discrepancy in how African researchers view their ability to write scientifically, and how journal editors may view these skills. In parallel, efforts to enhance the visibility of African researchers in high-impact journals may help ensure broader inclusion of perspectives on challenges facing their continent.

The intensity and frequency of heat extremes is expected to increase with climate change. However, answering questions about their physical mechanisms and how they may evolve in the future is challenging because of their rareness. Here we investigate the evolution of the mechanisms leading to heat extremes in Western Europe with climate change. We use a rare event algorithm to increase the number of extremely hot summers in Western Europe simulated in the IPSL-CM6A-LR climate model under present, SSP2-4.5 and SSP3-7.0 forcings. We show that centennial hot summers arise because of a succession of heatwaves, occurring through the local amplification of a synoptic scale Rossby wave packet and the advection of sensible heat from eastward regions. The atmospheric dynamics of these summers become more local in the future, and more driven by regional diabatic heat fluxes than by the large scale organization of the atmosphere.

Antarctic bed topography influences how the overlying ice sheet responds to climate change and provides a record of long-term glacial history. However, knowledge of the processes that governed the development of the landscape before glacial inception and how this modulated subsequent ice-sheet evolution remains limited. Here we use radio-echo sounding to reveal extensive flat surfaces beneath the ice margin between Princess Elizabeth Land and George V Land, East Antarctica. When their elevations are isostatically adjusted for unloading of the present-day ice load, these surfaces cluster at 200–450 metres above sea level and dip gently in an offshore direction. We show that the surfaces are fragments of a once-contiguous coastal plain formed by fluvial erosion, which dates from between the separation of East Antarctica from Australia (~100–80 Ma) and the onset of Southern Hemisphere ice-sheet glaciation (~34 Ma). The preservation of these landforms indicates a lack of intense, selective erosion of the surfaces throughout Antarctica’s glacial history. Fast-flowing ice has instead been directed through inherited tectonic structures and fluvial valleys, leading to the incision of overdeepened subglacial troughs between the flat surfaces and thus modulating the responsiveness of the ice sheet to climate change.