Climate change and underwater light: Large-scale changes in UV transparency associated with intensifying wet-dry cycles

Ultraviolet radiation (UV) is the most energetic waveband of incident solar radiation and has wide-ranging effects in the aquatic environment. Our analysis of an 18-year record of underwater irradiance and related limnological variables in sub-alpine, ultra-oligotrophic Lake Tahoe revealed orders of magnitude changes in UV transparency associated with interannual climate perturbations. The largescale shifts between years were caused by pronounced changes in the loading of allochthonous particulate matter and colored dissolved organic matter (CDOM) associated with regional dry-wet cycles, while chlorophyll a combined with autochthonous CDOM controlled the seasonal variations in UV under average weather conditions. Water clarity in the photosynthetically available radiation (PAR) waveband showed less variation, resulting in large interannual differences in the UV:PAR ratio. Clear-water lakes are likely to experience increasingly large fluctuations in underwater UV and spectral irradian..., , , # Climate change and underwater light: large-scale changes in UV transparency associated with intensifying wet-dry cycles

[https://doi.org/10.5061/dryad.905qftttj](https://doi.org/10.5061/dryad.905qftttj)

The data set include all optical, limnological, and metrological data used in the manuscript \"Climate change and underwater light: large-scale changes in UV transparency associated with intensifying wet-dry cycles\" submitted to Limnology and Oceanography - Letters.

The value \"n/a\" stands for not available (missing value = sample not collected or analysis failed).

Description of the data and file structure

## 1. Tahoe\_UVPAR.csv

Calculated attenuation coefficient values for all measured wavebands (305, 320, 380, and PAR).

Col 1: Event_ID The ID number of the sampling event.
Col 2: Date Date of sampling in YYYY-MM-DD
Col 3: Kd305 The diffuse attenuation coefficient of downward irradiance at 305 nm in m^-1
Col 4: Kd320 The diffuse attenuation coefficient of downward irradiance at 3...