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Supporting data for: The setup and relaxation of spring upwelling in a deep, rotationally influenced lake

Citation

Roberts, Derek; Schlaodow, S. Geoffrey (2020), Supporting data for: The setup and relaxation of spring upwelling in a deep, rotationally influenced lake, Dryad, Dataset, https://doi.org/10.25338/B8033N

Abstract

Supporting data for the manuscript "The setup and relaxation of spring upwelling in a deep, rotationally influenced lake" accepted for publication in Limnology and Oceanography in November 2020. The data herein were collected at Lake Tahoe, CA/NV, USA in May-June, 2018 as part of a collaboration between the UC Davis Tahoe Environmental Research Center, the UC Davis Bodega Marine Lab, and the Stanford Environmental Fluid Mechanics Laboratory. The goal of this data collection effort was to characterize the dynamics associated with spring upwelling at the upwind shore (west/southwest) of Lake Tahoe.

Supporting Data Files:

Roberts_et_al_2020_DeploymentMap.png - deployment map, reference to UPWELL_DeploymentLog.xlsx
 
UPWELL_DeploymentLog.xlsx - log of mooring locations, deployment times, and instrumentation/instrument setup.
Note that not all instrumentation shown in this log is included in the shared data. Datasets collected
during the experiment but not used in the manuscript are not shared in this repository. 
 
UPWELL_Thermistor_MetersBelowP.xlsx - reference file of the spacing of thermistors from the associated
pressure sensor. 

General Data:

Sensor data are included as compressed .7z sets of folders. Data are organized into sub-folders to delineate processing levels (raw data and data at each procesing level are included). Since Dryad does not allow for folder structures, the folder sets were compressed for posting. Archived .7z files can be decompressed using software openly available at 7-zip.org. 

ADCP.7z - folders of acoustic doppler current meter data. See README_ADCP.txt within the folder structure for details on processing at each level. See UPWELL_DeploymentLog.xlsx for additional detail. 

Pressure.7z - folders of pressure sensor data. See README_P.txt within the folder structure for details on processing at each level. See UPWELL_DeploymentLog.xlsx for additional detail.

Temperature.7z - folders of temperature sensor data. See README_T.txt within the folder structure for details on processing at each level. See UPWELL_DeploymentLog.xlsx for additional detail.

Note: Data at higher processing levels are generally provided as .mat files; more broadly accessible .txt or .csv
data are provided at lower processing levels. However, ADCP data are provided only as raw and .mat files because
of the more complex and multi-dimensional structuring of the data. Please contact the corresponding author
for data in non-.mat output if needed.

Manuscript Abstract:

Strong and sustained winds can drive dramatic hydrodynamic responses in density-stratified lakes, with the associated transport and mixing impacting water quality, ecosystem function, and the stratification itself. Analytical expressions offer insight into the dynamics of stratified lakes during severe wind events. However, it can be difficult to predict the aggregate response of a natural system to the superposition of hydrodynamic phenomena in the presence of complex bathymetry and when forced by variable wind patterns. Using an array of current, temperature, and water quality measurements at the upwind shore, we detail the hydrodynamic response of deep, rotationally influenced Lake Tahoe to three strong wind events during late spring. Sustained southwesterly winds in excess of 10 m/s drove upwelling at the upwind shore (characteristic of non-rotational upwelling setup), with upward excursions of deep water exceeding 70 m for the strongest event. Hypolimnetic water, with elevated concentrations of chlorophyll-a and nitrate, was advected toward the nearshore, but this water rapidly returned to depth with the relaxation of upwelling after the winds subsided. The relaxation of upwelling exhibited rotational influence, highlighted by an along-shore, cyclonic front characteristic of a Kelvin wave-driven coastal jet, with velocities exceeding 25 cm/s. The rotational front also produced downwelling to 100 m, transporting dissolved oxygen to depth. More complex internal wave features followed the passage of these powerful internal waves. Results emphasize the complexity of these superimposed hydrodynamic phenomena in natural systems, providing a conceptual reference for the role upwelling events may play in lake ecosystems.Strong and sustained winds can drive dramatic hydrodynamic responses in density-stratified lakes, with the associated transport and mixing impacting water quality, ecosystem function, and the stratification itself. Analytical expressions offer insight into the dynamics of stratified lakes during severe wind events. However, it can be difficult to predict the aggregate response of a natural system to the superposition of hydrodynamic phenomena in the presence of complex bathymetry and when forced by variable wind patterns. Using an array of current, temperature, and water quality measurements at the upwind shore, we detail the hydrodynamic response of deep, rotationally influenced Lake Tahoe to three strong wind events during late spring. Sustained southwesterly winds in excess of 10 m/s drove upwelling at the upwind shore (characteristic of non-rotational upwelling setup), with upward excursions of deep water exceeding 70 m for the strongest event. Hypolimnetic water, with elevated concentrations of chlorophyll-a and nitrate, was advected toward the nearshore, but this water rapidly returned to depth with the relaxation of upwelling after the winds subsided. The relaxation of upwelling exhibited rotational influence, highlighted by an along-shore, cyclonic front characteristic of a Kelvin wave-driven coastal jet, with velocities exceeding 25 cm/s. The rotational front also produced downwelling to 100 m, transporting dissolved oxygen to depth. More complex internal wave features followed the passage of these powerful internal waves. Results emphasize the complexity of these superimposed hydrodynamic phenomena in natural systems, providing a conceptual reference for the role upwelling events may play in lake ecosystems.

Methods

These data are the result of a six-week mooring deployment in Lake Tahoe in May-June 2020. Mooring deployments included thermistor chains, acoustic doppler current profilers, acoustic Doppler velocimeters, dissolved oxygen probes, and pressure sensors, among other equipment.

An overview of the deployment, including maps and profile views is included in the manuscript "The setup and relaxation of spring upwelling in a deep, rotationally influenced lake," Limnology & Oceanography (doi: 10.1002/lno.11673). See README files included in the dataset for instrument configuration and data processing details. 

Usage Notes

See README files included in the dataset. 

README.txt - general meta data file. 

README_ADCP.txt - detailed metadata on deployment of acoustic Doppler current profiles and processing of associated data. 

README_P.txt - detailed metadata on deployment of pressure sensors and processing of associated data. 

README_T.txt - detailed metadata on deployment of temperature sensors and processing of associated data.