Abstract: This data set contains observations of the down-welling short wave irradiance spectrum from a network of custom-made multi-band radiometers at the Falkenberg site from June 14 to 30, 2021. The main variable is the global horizontal irradiance, which is calibrated against a high quality sun tracker at Falkenberg. Additional data includes raw measurements, pre-calibrated spectra (with limitations, see quality), and total column water vapor from spectra. Within the two weeks, we provide (with varying temporal coverage) cloud camera images at 5 seconds interval, which is helpful for interpreting the irradiance measurements (among other things). The strength of this data set is not the absolute accuracy, but rather the spatial measurements and ability to catch variability with high resolution.

Note: This entry includes the level0 radiometer data, the level1 radiometer data / spectra and, as the main product for this the descriptions given here applies, the level2 product.

TableOfContents: (for level2 only)

Irradiance: solar irradiance; quality
water vapor: atmosphere_mass_content_of_water_vapor; quality

Technical Info: dimension: 864001 x N [10 Hz sampling] 86400 x N [1 second sampling] 1440 x N [1 minute sampling]; temporalExtent_startDate: 2021-06-14 00:00:00; temporalExtent_endDate: 2021-06-30 00:00:00; temporalResolution: 0.1 [10 Hz sampling] 1 [1 second sampling] 60 [1 minute sampling]; temporalResolutionUnit: seconds; spatialResolution: none; spatialResolutionUnit: none; horizontalResolutionXdirection: none; horizontalResolutionXdirectionUnit: none; horizontalResolutionYdirection: none; horizontalResolutionYdirectionUnit: none; verticalResolution: none; verticalResolutionUnit: meters; horizontalStart: 0; horizontalStartUnit: meters; horizontalEnd: 0; horizontalEndUnit: meters; instrumentNames: FROST version 1; instrumentType: https://doi.org/10.5194/egusphere-2022-726; instrumentLocation: Falkenberg; instrumentProvider: none

Methods: Measurements were taken in a small scale grid setup at Falkenberg: 20 sensors in 4 by 5 grid with a 50 meter grid spacing. Another 4 sensors were placed in all direction about 5 km away from the main grid at Falkenberg. The sampling rate is 10 Hz, with accurate GPS clock synchronisation, to catch all cloud-induced irradiance variability. Measurements were taken for 2 weeks, from June 14 to 30, 2021. For more details on the sensor itself, please see the (accepted for publication) pre-print here: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-726/.

Quality: Data gathering, quality, calibration (The global horizontal irradiance is calibrated against a high quality sun tracker at Falkenberg.), and performance is covered in detail in the manuscript https://doi.org/10.5194/egusphere-2022-726 and other to be publications specified later.

Units: (for level2 only)

Irradiance: W/m²; 1
water vapor: kg/m²; 1

geoLocations:

BoundingBox: westBoundLongitude: 14.071 degrees East; eastBoundLongitude: 14.204 degrees East; southBoundLatidude: 52.1534 degrees North; northBoundLatitude: 52.1704 degrees North; geoLocationPlace: Germany, UTM zone 33U
Location: 52.165 °N; 14.120 °E; between 0.4 m and 0.9 m above ground; between 53 m and 67 m above mean sea level

Size:

Level0: ~1.2 GB (zip archive)
Level1: ~0.115 GB (zip archive, radgrid data); 23.843 GB zip-archives, cloudcam images)
Level2: ~0.292 GB (4 zip-archives)

Format: netCDF; cloudcam images: jpg

DataSources: Single site ground-based measurements.

Contact:  Wouter Mol, email: wbmol (at) wur.nl

Webpage: https://www.cen.uni-hamburg.de/en/icdc/data/atmosphere/samd-st-datasets/samd-st-fesstval/fval-wur-radgrid-l2-v1.html

Funding: Dutch Research Council (NWO), Shedding Light On Cloud Shadows: VI.Vidi.192.068

Provenance & History: This new version 2 includes updated metadata for the existing data set, and additional level 0, 1, and 2 data + cloud camera images.

Project: FESSTVaL (Field Experiment on submesoscale spatio-temporal variability in Lindenberg), a measurement campaign initiated by the Hans-Ertel-Center for Weather Research.