This dataset contains Sentinel 2 satellite images clipped to 5 high-altitude lakes in the Sierra Nevada Mountain Range, Spain. The images were processed with the following atmospheric correction algorithms: - C2RCC (Brockmann et al. 2016) - SIAC (Yin et al. 2022) - ACOLITE (Vanhellemont & Ruddick, 2018) - 6SV (Vermote et al. 2006)

This dataset contains chlorophyll-a (ug/L) predictions for 4 high-altitude lakes in the Sierra Nevada Mountain Range, Spain. Predictions were made using a simple linear regression model with field sample chlorophyll-a as the dependent variable, and the following Sentinel-2 derived spectral index as the independent variable: B3 - (B4+((B2-B4)*((665-560)/(665-490))) Prediction maps are included as GeoTiffs and NetCDF files. Sentinel-2 data were atmospherically corrected using the following algorithms: - ACOLITE (Vanhellemont & Ruddick, 2018) - 6SV (Vermote et al. 2006)

This dataset presents relative abundance data of subfossil diatoms obtained from sediment cores retrieved from six lakes at Sierra Nevada Mountains (Granada, Spain) during 2008 and 2011. The files show data over the past 180 years approximately. Sediment cores were taken from the deepest part of the lake by a slide-hammer gravity corer (Aquatic Research Instruments, USA), with a 6.9 cm inner diameter during the summer of 2011, except for Río Seco Lake core which was sampled in 2008. The cores were sectioned on-site into 0.25 cm thick layers for the upper sections of the cores and into 0.5 cm intervals for the remainder of the cores, except for Río Seco Lake core which was sectioned at 0.5 cm contiguous intervals for the entire core length. Sediment cores were dated using gamma spectrometry (DSPec, Ortec®) techniques by measuring activities of radioisotopes (210Pb, 214Bi and 137Cs) and sediment ages were estimated from unsupported 210Pb activities using the constant rate of supply (CRS) model. Diatom samples were processed by digesting sediment samples with a 50:50 mixture solution of H2SO4 and HNO3 and mounted onto slides with Naphrax®. For each sample, a minimum of 300 diatom valves were counted using a Leica microscope fitted with a 100× fluotar objective (N.A. = 1.4) and using differential interference contrast optics under oil-immersion at 1000× magnification. Diatoms were identified to the species level or lower using a selection of taxonomic sources and diatom counts were expressed as a percent abundance relative to the total number of diatom valves counted in each sedimentary interval.

This dataset contains high frequency sampling of key parameters to ensure the collection of consistent data for the long-term records in four lakes of Sierra Nevada, Spain (Laguna de la Caldera, Laguna de Río Seco, Laguna Larga, and Laguna-embalse de las Yeguas). A feature that makes Sierra Nevada unique is that lakes undergoes high inputs of nutrient-rich aerosols due to their proximity to the Sahara. Sampling was carried out during the ice-free period of 2022 to monitor biological and biochemical impact of an unusual year of intense aerosol inputs from the Sahara that clouded Sierra Nevada’s shallow lakes “chocolate-coloured” at the beginning of the ice-free period. Parameters include water quality (nutrients, major cations and anions), biological (bacteria and zooplankton) and hydrological data collected in periodic sampling using water samplers, sediment traps and plankton nets. Multiparametric probes provided real-time and continuous data on multiple parameters simultaneously.

This dataset comprises the simultaneous monitoring of about 50 high mountain lakes in the Spanish’s Sierra Nevada carried out in collaboration with government agencies and local communities as part of a citizen science campaign. Standard monitoring protocols were used to collect data on various physical (temperature, pH, dissolved oxygen, water clarity), chemical (nutrients, major cations and anions, chlorophyll a, alkalinity), and biological parameters (bacteria, zooplankton) in two successive years. High mountain lakes are ideal sites to study and understand global change processes. The utilisation of these systems as sentinels of global change can be attributed to various characteristics, such as: modest catchment areas, oligotrophic waters with limited nutrients, remote accessibility, relatively good ecological health, elevated altitudes and harsh environmental conditions, or the presence of relatively uncomplicated biological communities with rapid renewal rates, among others. The involvement of the community in Sierra Nevada Long-Term Monitoring Programs serves as an invaluable complement to scientific endeavours aimed at monitoring environmental changes, as it contributes to alleviate personnel and resource shortcomings (Villar-Argaiz et al. 2022).