Climate change significantly impacts the hydrology and water resources of any region especially high mountain areas including cryosphere that consist of glaciers. Numerous studies report that glaciers are retreating and losing volume with time causing serious concerns over freshwater availability in the basins they feed water to. Assessment of these changes and their relationship with various climatic aspects are crucial to understand and tackle such challenges. Long-term trends in temperature and precipitation and their spatio-temporal distribution, for the mountainous state of Uttarakhand in India were assessed, utilizing the India Meteorological Department’s gridded precipitation and temperature datasets for the period 1951-2023. Mann-Kendall trend test was performed at 90% significance level, for each grid, to check monthly trends, which gave critical insights upon shifts in seasonal meteorology. Results reveal notable changes in the monthly distribution of precipitation with many grids reporting a decreasing winter precipitation (Oct-Jan) and many showing an increasing precipitation for May and August. Global warming impact is much visible through changes in minimum temperatures for almost all the grids, reporting a strong positive trend for February, March, August, September and November. Importantly, these changes are more prominent for the high-altitude areas, which highlights elevation dependent climate change pattern. Evidently, the precipitation is shifting from winters to summers and the minimum temperatures are increasing towards the end of ablation season (Aug-Sep), decreasing the chances of receiving solid precipitation or snowfall. Consequently, a decrease in snow cover is expected in the future, which from a hydrological perspective, would lead to a reduction in snowmelt discharge and its contribution to streamflow of the Himalayan perennial rivers. Moreover, the increasing temperature and precipitation during summers can generate huge discharges from glacierized catchments due to increased simultaneous contribution of glacier-melt and rainfall, causing destructive flash floods and debris flow events, as being witnessed in the recent past. Combination of decreased precipitation in winter months and increased temperatures overall, can prove detrimental to glaciers’ health as they will melt more, whereas their replenishment will be lesser, leading to negative mass balances. Climate change is certainly having an adverse effect on the mountain hydrology, especially that of the Himalayan cryosphere. The glaciated catchments are expected to have more glacier-melt and rainfall-runoff contribution and less snow-melt contribution in the near-future. The glaciers, present in the region, are expected to retreat and lose mass more rapidly, considering the meteorological changes in the high elevation areas. Small glaciers might deplete faster, which would lead to problems of freshwater availability in the nearer downstream areas dependent on the melt-runoff water. While there seems no immediate solution to the prevailing scenario of climate change, community-based measures can be adopted to tackle problems of water availability. Water conservation and springshed management in the mountainous regions are some focus areas to work upon, in order to ensure water security under the changing climate.

How to cite: Thapliyal, M., Singh, S., and Patel, L.: Climate Change and its Impact on the Hydrology of a Glaciated Mountainous Region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4832, https://doi.org/10.5194/egusphere-egu25-4832, 2025.

This study investigates the spatio-temporal variability and long-term warming trends in sea surface temperature (SST) across the Arabian Sea from 2000 to 2019, using daily AVHRR satellite observations with a 1°x1° spatial resolution. Seasonal and interannual SST dynamics reveal patterns shaped by monsoonal processes and global climate phenomena, such as El Niño and La Niña. Wavelet spectrum analysis highlights periodic fluctuations and dominant frequencies associated with interannual climate variability, further emphasizing the influence of seasonal processes. Spring (MAM) exhibits the most pronounced interannual warming, particularly in the central and northern regions, while autumn (SON) demonstrates significant warming trends, especially in the southern basin. Monsoonal processes influence seasonal variability, with winter (DJF) cooling in the northern Arabian Sea and summer (JJA) upwelling along Oman and Somalia, resulting in localized cooling amidst broader warming trends in central and southern regions. Wavelet power spectra from critical regions, including the Gulf of Oman, Balochistan Coast, and Mumbai, indicate dominant periodicities of interannual warming, with variations corresponding to regional oceanographic processes. For instance, the Balochistan Coast displays the highest warming rate (0.0519°C/year), underscored by strong wavelet power at periodicities tied to El Niño–Southern Oscillation (ENSO) cycles. Similarly, the Gulf of Oman and Mumbai exhibit distinct spectral peaks, reflecting localized climate dynamics and variability. Regionally, the warming trend varies significantly. The Gulf of Aden (0.0181°C/year), Gulf of Oman (0.0164°C/year), and Gulf of Kutch (0.0269°C/year) exhibit moderate warming rates, while areas like the Balochistan Coast and South of Salalah (0.023°C/year) highlight significant localized warming. Southwestern Arabian Sea regions west of Kochi (0.0209°C/year) and Mangalore (0.0323°C/year) also demonstrate notable trends. In contrast, regions like Minicoy (0.0162°C/year) and the Male-Maldives area (0.0073°C/year) show relatively weaker warming. These findings underscore the critical role of spatial and seasonal variability in shaping SST changes and their implications for regional climate patterns, monsoonal behavior, marine ecosystems, and fisheries. The pronounced warming in key regions, coupled with insights from wavelet spectrum analysis, highlights the influence of localized oceanographic processes, such as upwelling, heat transport, and climate-induced variability. These results necessitate further study to assess future impacts and develop mitigation strategies for sensitive marine biodiversity and economic resources in the Arabian Sea . 

How to cite: Saha, S. and Mukherjee, A.: Unraveling the Arabian Sea’s Thermal Pulse: Seasonal and Interannual SST Variability Amidst Climate Dynamics, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12429, https://doi.org/10.5194/egusphere-egu25-12429, 2025.

SnowMapPy is a Python-based package developed to streamline the collection, preparation, and analysis of MODIS NDSI data, specifically from the Terra and Aqua satellite products. By automating essential steps (data clipping, reprojection, filtering, and time series generation), SnowMapPy improves the efficiency and precision of snow hydrology research. The protocol allows users to work with both local and Google Earth Engine cloud-based datasets, enabling flexible data acquisition and processing tailored to the needs of snow hydrology, water resource management, and climate change studies. Designed for accessibility and flexibility, SnowMapPy supports large-scale, high-resolution snow cover analysis with minimal configuration. The package facilitates customized workflows through its modular structure, making it a valuable tool for researchers aiming to understand snow dynamics and their impact on seasonal water resources. 

How to cite: Elyoussfi, H., Boudhar, A., Belaqziz, S., Bousbaa, M., Bechri, H., Sproles, E. A., and Benzhair, F.: SnowMapPy v1.0: A Python Package for Automated Snow Cover Mapping and Monitoring in Mountain Regions , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20632, https://doi.org/10.5194/egusphere-egu25-20632, 2025.

Breaking internal gravity waves cause small-scale turbulent mixing, which changes water mass properties, affects biogeochemical cycles, and contributes to driving the large-scale overturning circulation. Ocean general circulation models do not resolve this process and thus rely on a parameterization. The state-of-the-art IDEMIX (Internal wave Dissipation, Energy and MIXing) model predicts the propagation and dissipation of internal wave energy based on external forcing functions that represent the main generation mechanisms, notably the internal tide generation at the sea floor and the near-inertial wave generation at the sea surface. By linking small-scale mixing to internal wave energetics, IDEMIX allows the consistent parameterization of wave-induced mixing in ocean models. Its basic incarnation treats all internal waves as part of a horizontally homogeneous continuum and was shown to successfully reproduce observed turbulent kinetic energy dissipation rates and internal wave energy levels. In a newer configuration (IDEMIX2), the internal wave field is compartmentalized, distinguishing between a high-mode continuum on the one hand and low-mode near-inertial wave and internal tide compartments, whose horizontal propagation is explicitly resolved in wavenumber angle space, on the other hand. We present the evaluation of the IDEMIX2 model with a particular focus on the impact of applying an anisotropic internal tide forcing. So far, parameterizations of internal tide-driven mixing have not taken the strong anisotropy of the internal tide generation process into account. We demonstrate the need for doing so, showing a notable impact on the modeled internal wave energetics and predicted mixing when changing from the previous isotropic to the new anisotropic tidal forcing in IDEMIX2. 

How to cite: Pollmann, F., Eden, C., Olbers, D., Nycander, J., and Zhao, Z.: Anisotropic internal tide forcing in the consistent internal wave mixing scheme IDEMIX, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8764, https://doi.org/10.5194/egusphere-egu25-8764, 2025.

This study is part of a doctoral research project aimed at characterizing coastal sediments in relation to the presence of microplastics and marine litter. Within this framework, the present research seeks to establish an up-to-date knowledge base regarding the geochemical characterization of sediments across different seasons along the Ferrara coastal area, specifically at Lido degli Estensi (Ferrara, Italy). The objective is to identify potential vulnerabilities and/or critical aspects related to environmental pollution that require further investigation. Building upon the methodology of Aquilano et al. (2023) and adapting it to the experimental requirements of the current study, a research area was selected at Lido degli Estensi, outside zones allocated for tourism-related public concessions. This site is located on the southern side of the Porto Garibaldi navigation channel (Comacchio municipality, Ferrara), in a coastal section experiencing accretion due to the construction of artificial jetties at the port-channel entrance. These jetties trap sediment transported from the south as a result of longshore drift. Given the beach's width (approximately 150 m), a cross-shore profile was divided into five zones based on specific geomorphological characteristics: swash zone, lower backshore, upper backshore, dune scarp, and dune. Along this beach profile, variations in carbonate content, major oxide composition, and heavy metal concentrations were investigated across different seasons using eight sampling points per season. To evaluate sediment quality in terms of heavy metal contamination, the following indices were employed: Enrichment Factor (EF; Reinmann and De Caritat, 2005), Geoaccumulation Index (Igeo; Buccolieri et al., 2006), Contamination Factor (CF; Loska et al., 2004), and Pollution Load Index (PLI; Ferreira et al., 2022). Furthermore, heavy metal concentrations detected in the samples were compared with the limits established by current Italian legislation (Legislative Decree 152/06). This study was conducted as part of the ECS_00000033_ECOSISTER project, funded under the National Recovery and Resilience Plan (NRRP), Mission 04 Component 2 Investment 1.5 – NextGenerationEU (Call for Tender No. 3277, dated 30/12/2021).

How to cite: Buoninsegni, J., Marrocchino, E., Tassinari, R., Tessari, U., and Vaccaro, C.: Geochemical characterization of coastal sediments: a preliminary study of seasonal variations at Lido degli Estensi (Ferrara, Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3582, https://doi.org/10.5194/egusphere-egu25-3582, 2025.

We have previously developed a 12-sample environmental DNA (eDNA) sampler designed for use in the marine surface. The sampler can collect and store eDNA samples on filter cartridges according to scheduled sequences. Communicating via mobile phone networks also makes it possible to collect samples on demand. For the underwater eDNA sample-return missions, we have designed and developed a compact eDNA sampler with an oil-filled (pressure-balanced) configuration, enabling its deployment at various depths. Field trials for the underwater eDNA sampler were performed using underwater platforms such as deep-sea landers. Here, we introduce the newly developed compact eDNA sampler and discuss its potential applications in mid- to deep-ocean layers, focusing on eDNA sample-return missions targeting jellyfish and other marine species.

How to cite: Fukuba, T. and Lindsay, D.: Development of an underwater eDNA sampler and its potential application in jellyfish eDNA detection, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14703, https://doi.org/10.5194/egusphere-egu25-14703, 2025.

The coastal ecosystems, including estuaries and mangroves, are highly vulnerable to anthropogenic intervention, particularly due to activities such as urbanization, wastewater discharge, and industrial development, which can alter their ecosystem services and affect habitat quality. In order to evaluate the impact of these interventions through the carbon and nitrogen isotopic composition of two macroalgae Boodleopsis verticillata and Bostrychia spp in four coastal ecosystems of the Colombian Pacific (Valencia - VAL, San Pedro - SPE, Chucheros – CHU with low intervention, and Piangüita - PIA with high intervention) were used to understand the sources of these elements. δ¹⁵N values is a commonly used to providing information about nitrogen sources in primary producers. δ¹³C values is used to investigate carbon sources i.e. terrestrial or marine. Samples were collected during 2014, 2015, and 2016, and analyzed by isotope ratio mass spectrometer. The results show that the δ¹³C values ranged from -33.97 to -31.93 ‰ in VAL, -33.78 to -30.09 ‰ in SPE, -31.12 to -28.45 ‰ in CHU, and -33.32 to -21.71 ‰ in PIA. δ¹⁵N values ranged from 0.32 to 3.18 ‰ in VAL, 0.57 to 5.47 ‰ in SPE, 1.82 to 3.39 ‰ in CHU, and 2.32 to 10.16 ‰ in PIA. Significant differences were found among the four areas with mean δ¹³C values by locality (VAL -30.21 ‰, SPE -31.71 ‰, CHU -30.09 ‰, and PIA -30.52 ‰) and δ¹⁵N values (VAL 1.74 ‰, SPE 2.30 ‰, CHU 2.40 ‰, and PIA 4.47 ‰) reflecting the impacts of human activities on the coastal ecosystems. This work contributes to understanding the effects of anthropogenic intervention on pollution and wastewater discharge in coastal ecosystems, providing key tools for the development of environmental management policies that support conservation in the Colombian Pacific.

How to cite: Arce-Sánchez, R. S., Medina-Contreras, D., and Sánchez-Gonzalez, A.: Primary producers as indicators of anthropogenic intervention in the Colombian Pacific, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7292, https://doi.org/10.5194/egusphere-egu25-7292, 2025.

This study explores the seasonal and lagged correlations between Chlorophyll-a (Chl-a) concentrations and vertical velocity (wT) to elucidate upwelling's role in driving phytoplankton productivity. In Oman (Region III), an immediate response to upwelling was observed, with the strongest correlation (r = 0.7) at lag 0 during peak upwelling months (June–July). In contrast, Iranian regions (I & II) exhibited delayed responses, with maximum correlations (r = 0.7) at lag 1 (occurring about a month later). This delay may result from processes like nutrient mixing and remineralization. Seasonal trends revealed sustained Chl-a concentrations in Oman, peaking at 2.39 mg m^-3 in September, while Iran showed a steady decline after a July peak of 1.37 mg m^-3. Stratification and horizontal currents modulated Chl-a distributions, with weaker stratification in Oman enabling efficient nutrient delivery. These findings reveal the intricate dynamics of upwelling-driven productivity across both semi -enclosed and open marine ecosystems. By examining regional variations in the context of broader oceanographic processes, this study offers valuable insights for the sustainable management of upwelling systems and for anticipating their responses to climate change.

How to cite: A. Ismail, K. and Salim, M.: Unveiling the Impact of Upwelling on Phytoplankton Productivity in the Arabian/Persian Gulf and Sea of Oman, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20989, https://doi.org/10.5194/egusphere-egu25-20989, 2025.

The Mediterranean Sea, with its unique characteristics as a semi-enclosed and highly stratified basin, serves as a natural laboratory for studying oceanic processes of global relevance. Vertical mixing is a fundamental process regulating the transfer of mass, heat, and nutrients between water column layers, influencing dynamical and biogeochemical processes, and controlling the exchange with the overlying atmosphere. Due to its turbulent nature acting on small spatial and temporal scales, vertical mixing remains challenging to simulate in modern ocean circulation models. Moreover, the interaction between vertical mixing and horizontal diffusion/advection is essential in shaping the transport and distribution of heat, nutrients, and pollutants in marine environments. Finding the optimal vertical mixing parameterizations alongside horizontal advection and diffusion schemes in an ocean circulation model, able to simulate the available observations, presents significant challenges due to the need for consistent scaling, numerical stability, and accurate representation of multi-scale processes.

Here, we use the same system setup as the Mediterranean Forecasting System of the Copernicus Marine Service, that is NEMO (v4.2) general circulation model, including tides, coupled with the WaveWatch III wave model. The model features a horizontal resolution of 1/24° (approximately 4 km) and 141 unevenly spaced vertical levels. We investigate the performance of different numerical vertical closure schemes – a Richardson-number-dependent, a one-equation and a two-equation models – as well as the effect of different lateral advection and diffusion schemes. The role played by the enhanced vertical diffusion due to Camarinal Sill at the Strait of Gibraltar in controlling the exchange of water masses between the Atlantic Ocean and the Mediterranean Sea is also investigated. We validate our model by assessing our ability to reproduce physical processes and by comparing it with in-situ data throughout the Mediterranean basin, across varying seasons and years.

How to cite: Gualtieri, L., Borile, F., Burchard, H., Oddo, P., Miraglio, P., Clementi, E., Goglio, A. C., and Pinardi, N.: Investigating vertical mixing and lateral diffusion parameterizations in the Mediterranean Sea, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8649, https://doi.org/10.5194/egusphere-egu25-8649, 2025.

Measuring relative dispersion in coastal ecosystems is important for both ocean health and society. Submesoscale dynamics interacting with mesoscale eddies influence mixing processes and phytoplankton blooms dispersion. Two-particle dispersion statistics over an initial spatial scale (0.7 - 1 km) are analysed in the Gulf of Gabès (central-southern Mediterranean Sea) using a high-resolution ocean model through a multiple nesting approach. The model is forced by ERA5 atmospheric fields, while the lateral boundary conditions and initial conditions are provided by daily fields from a Mediterranean Sea reanalysis. The analysis focuses on the turbulent fluid aspects of phytoplankton dispersion in coastal areas under bloom and non-bloom conditions. The results are presented in terms of kurtosis (normalized fourth moment of the pair separation distances), relative diffusivity (particles’ spreading velocity) and time scale-dependent pair separation rate (pair velocity scales normalized by separation distance). At the submesoscale (0.7 – 2km), the non-local exponential regime is absent in both bloom and non-bloom conditions, where the dispersion is locally driven by energetic submesoscale structures. For scales ranging 2-15 km, the two-particle statistics follow the theoretical Richardson regime, which is well detected in the case of a bloom. This regime implies the presence of an inverse energy cascade range where energy is transferred from small to large scales. The diffusive regime is absent for all scales and in both bloom and non-bloom conditions.

How to cite: Bouzaiene, M., Menna, M., Dilmahamod, A. F., Delrosso, D., Simoncelli, S., and Fratianni, C.: Two-particle dispersion in the Gulf of Gabès using a high resolution nested ocean model , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11742, https://doi.org/10.5194/egusphere-egu25-11742, 2025.