EasyFlux DL Eddy-Covariance Datalogger Program
Fully Corrected Fluxes
Datalogger program that computes fully corrected fluxes of CO2, latent heat, and sensible heat
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications

Overview

EasyFlux™ DL is a free CRBasic program that enables a datalogger to report fully corrected fluxes of CO2, latent heat (H2O), sensible heat, and momentum from a Campbell Scientific open-path eddy-covariance (EC) system. Final fluxes are processed from raw high frequency time series data by applying commonly used corrections found in scientific literature.

In the past, Campbell Scientific's datalogger EC programs roughly estimated fluxes, and PC post-processing software was used to fully correct the flux measurements. Now with the EasyFlux™ DL program, fully corrected fluxes are processed by the datalogger and reported at the end of each EC averaging interval.

EasyFlux™ DL has been tested at several stations in various environments, including irrigated alfalfa, grassland, maize, open water, forest, and desert. The results have shown good agreement with fluxes processed using traditional PC-based software applications.

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Benefits and Features

  • Accesses final fluxes quickly without the burden of post-processing
  • Produces flux output tables that are smaller than time series tables, which allows flux data to be frequently collected using cellular, radio, or other lower-bandwidth telemetry options
  • Available at no charge; see Downloads section on web page
  • Matches the fluxes provided by PC post-processing software packages (assuming same filtering of raw data and same selection of correction procedures)
  • Saves high frequency time series to removable media in case reprocessing is later needed
  • Includes data quality and footprint characteristics
  • Reports uncorrected and intermediate values in an auxiliary output table for more detailed data inspection
  • Provides for CR6 program fully processed data output in AmeriFlux format

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Detailed Description

Provides fully corrected outputs of CO2 flux, latent heat flux, and sensible heat flux at a user-defined interval (e.g., 30 minutes). Also provides many other variables of atmospheric properties, instrument diagnostics, intermediate corrections, and other energy balance or biomet sensors. Comparisons of flux outputs have shown good agreement with other common post-processing software packages when applying the same set of corrections.

Main correction and processing procedures:

  • Despike and filter high frequency time series data using sonic anemometer and gas analyzer diagnostic codes, signal strengths, and measurement output range thresholds.
  • Apply coordinate rotations with an option to use the double rotation method (Tanner and Thurtell, 1969) or planar fit method (Wilczak et al., 2001).
  • Lag CO2 and H2O measurements against sonic wind measurements for maximization of CO2 and H2O fluxes (Horst and Lenschow, 2009; Foken et al., 2012), with additional constraints to ensure lags are physically possible.
  • Apply frequency corrections using commonly used cospectra (Moore, 1986; van Dijk, 2002; Moncrieff et al., 1997) and transfer functions for block averaging (Kaimal et al., 1989), line/volume averaging (Moore, 1986; Moncrieff et al., 1997; Foken et al., 2012; van Dijk, 2002), time constants (Montgomery, 1947; Shapland et al., 2014; Geankoplis, 1993), and sensor separation (Horst and Lenschow, 2009; Foken et al., 2012).
  • Apply a modified SND correction (Schotanus et al., 1983) to derive sensible heat flux from sonic sensible heat flux following the implementation as outlined in van Dijk (2002). Additionally, fully corrected sensible heat flux computed from a fine-wire thermocouple is provided if our FW05, FW1, or FW3 is used.
  • Apply correction for air density fluctuations using Webb et al., 1980.
  • Assign data quality classifications (QC) based on steady state conditions and surface layer turbulence characteristics following Foken et al., 2002 to conform to AmeriFlux format. In addition, Foken et al., (2012) is also followed to include wind direction. An additional set of QC is provided.
  • Calculate footprint characteristics using Kljun et al., 2004 or Kormann and Meixner, 2001.
  • If energy balance sensors are used, calculate energy closure based on energy balance measurements and corrected sensible and latent heat fluxes.
  • Sonic shadow correction is optional.
  • CO2 spectroscopic correction using air temperature at high frequency nature as default and at convention as an option. CO2 values corrected using different air temperature are all stored at the measured frequency.

Compatibility

Required Equipment

  • IRGASON Integrated CO2 and H2O Open-Path Gas Analyzer and 3-D Sonic Anemometer OR EC150 CO2 and H2O Open-Path Gas Analyzer with CSAT3A 3-D Sonic Anemometer  
  • CR6 datalogger (with CDM-A116 for channel expansion to accommodate energy balance sensors) or CR3000
  • NL115, NL116, or CFM100 (CR3000 only)
  • CFMC2G or 27158 (2 GB) or 33288 (8 GB) microSD Flash SLC Memory Card (CR6 only) or CFMC16G CompactFlash card (CR3000 only)

Supported Optional Sensors*

  • CDM-A116 for CR6 with energy balance sensors
  • FW05, FW1, or FW3 Fine-Wire Thermocouple
  • HC2S3 or HMP155A Temperature and Relative Humidity Probe
  • CNR4, NR01, or NR-LITE2 Net Radiometer
  • CS300 or LI200RX Pyranometer
  • LI190R Quantum Sensor
  • SI-111 Infrared Radiometer
  • TE525MM Tipping Bucket Rain Gage 
  • TCAV Averaging Soil Thermocouple Probe (quantity up to two)
  • CS616 or CS650 Water Content Reflectometer (quantity up to two)
  • HFP01 or HFP01SC Soil Heat Flux Plate (quantity up to four)
  • GPS to synchronize time for a station in a network

*It may be possible to add non-standard sensors to the program upon request and for a fee.

Downloads

EasyFlux DL for CR6 v.1.03 (70.7 KB) 04-04-2018

CR6 datalogger program for Campbell open-path eddy-covariance systems.

EasyFlux DL for CR3000 v.1.2 (50.1 KB) 04-04-2018

CR3000 datalogger program for Campbell open-path eddy-covariance systems.

Frequently Asked Questions

Number of FAQs related to EasyFlux DL: 8

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  1. EasyFlux™ DL has been tested in a variety of landscapes including forest, open water, short crops, and desert. It has been found to work well in all landscapes, assuming the instruments are properly maintained. 

  2. EasyFlux™ DL samples the eddy-covariance sensors at 10 Hz. It is possible to measure at 20 Hz using EasyFlux™ DL C6OP running on a CR6 datalogger.

  3. In most cases it is possible to adapt the EasyFlux™ DL program for other biomet or energy balance sensors. Contact Campbell Scientific to discuss the possibility of customization and to request a quote. 

  4. EasyFlux™ DL in its native form only supports Campbell Scientific open-path gas analyzers (that is, IRGASON or EC150). In some cases it may be possible to adapt the EasyFlux™ DL program for a particular gas analyzer. Contact Campbell Scientific to discuss the possibility of customization and to request a quote. 

  5. To set up EasyFlux™ DL, follow these steps:

    1. Open EasyFlux™ DL in a text editor, such as the CRBasic Editor.
    2. Set the instrument constants (for example, which sensors are being measured). 
    3. Load EasyFlux™ DL just like any other datalogger program using LoggerNet software.
    4. After all the sensors are installed and wired, use the CR3000 keypad or CR1000KD (for CR6) to set or fine-tune the station variables (for example, measurement height, canopy height). The instruction manual provides step-by-step instructions for this process.
  6. It is the responsibility of the user to ensure data quality and fitness for publication. When the instruments are properly maintained and conditions are well-suited for open-path EC measurements, most likely the flux results are in their final and usable form, but the user should still verify that the corrections were appropriate for the site and that the data are fit for further use. The raw time-series data are always stored on a CompactFlash card, so a user may reprocess raw data with a post-processing software package.

  7. EasyFlux™ DL in its native form only supports the IRGASON or CSAT3A sonic anemometers. It is possible to adapt the EasyFlux™ DL program to support other Campbell Scientific sonic anemometers (for example, CSAT3 or CSAT3B). The program cannot be adapted to other non-Campbell sonic anemometers.

  8. EasyFlux™ DL is now available for both the CR3000 and CR6 dataloggers.