National Center for Atmospheric Research

IHOP_2002 ISFF 5-minute ASCII Data Access

The ISFF IHOP_2002 5-minute dataset contains means, covariances and derived quantities of all sampled variables, except CO2 and the soil profiles.

We recommend combining these to obtain more statistically-significant averages over longer time periods.

Status of Dataset

Initial Release, October 17, 2002

Initial version of the ISFF 5-minute statistics are available for download in NetCDF and ASCII form. The following corrections have been applied to these statistics. Links are provided to pertinent sections of project report.

The term "edited" below means that apparent bad data values were replaced with a missing-data value for time periods when a variable is not recoverable due to malfunction of a sensor or data system.

All variables edited based on value of data transmission checksum.
All affected variables set to missing data value during periods that mast was lowered.
Site 6 sonic u and v components edited.
Site 9 sonic data edited.
False tips removed from rain rate data at all sites.
Bad data edited from near-surface soil variables at sites 1, 8 and 9.
Bad values edited from radiometer data at sites 1, 2, 8 and 9.
Bad values edited from IR surface temperature data at sites 1, 2, 3, 4, 6.
Computed 5-minute vector wind speed at all sites from U.10m and V.10m. Edited bad wind directions at sites 5 and 6.
Pressure data at site 8 estimated during periods of missing data.
New calibration factors applied to long-wave radiometer thermopile values.
New calibrations applied to CS615 soil water content data.
Fixed data to account for incorrect pyranometer and/or pyrgeometer coefficients at site 3 prior to May 12, site 5 prior to May 11, and site 9 prior to May 9.
Long wave radiation variables Rlw.in, Rlw.out have been calculated from radiometer thermopile and case and dome temperatures. Incoming short wave contamination has been removed from incoming long wave radiation using results from shadow tests performed in the field.
Wind data from sonic anemometers has been corrected for sonic tilt and bias. More information on the sonic tilt correction can be found at NCAR ISFF Sonic Anemometer Tilt Correction
Wind vectors from sonic anemometers have been rotated from instrument coordinates to geographic coordinates (+u is wind to the east, +v is wind to the north).

Second Release, April 17, 2003

In addition to the above, the following corrections were applied to the 5 minute dataset released on April 17th, 2003.

In the October 17 data release, a gain correction was applied to the net radiation at site 2 from May 13-18, and it should have been applied from June 13-18. This has now been corrected.
Fixed data to account for an incorrect gain coefficient for the incoming short wave radiometer at site 1 prior to May 12.
Corrected incoming short-wave radiation coefficients at site 1 to account for a sensor swap on June 1.
Bad sonic anemometer data (spikes) edited at all sites. The spikes are typically the result of signal attenuation due to rain.
Bad krypton hygrometer data edited.
Bad values edited from IR surface temperature data at site 9 (in addition to 1, 2, 3, 4 and 6, in the first release).
Edited spikes in air temperature, T, and relative humidity, RH, at sites 1, 2, 5 ,6, 7 and 8.
Edited spikes in barometric pressure, P, at site 1.
New linear gain factors were applied to the short wave radiation variables, Rsw.in and Rsw.out. These factors were determined from a calibration done at NOAA in April, 2002.
Applied correct conversion factors to krypton hygrometer data during periods when hygrometers were being swapped between sites.
Derived covariances for <w't'> and <w'mr'> have been provided, where mr is the water vapor mixing ratio. These derived covariances contain the conversion from virtual to true temperature, oxygen correction, WPL correction and the spatial separation correction, as described under Corrections to Sensible and Latent Heat Flux Measurements.
Surface heat flux, Gsfc is provided, as described in the calculation of fluxes section of the IHOP02 report.

The 5 minute dataset does not contain flux estimates other than Gsfc and the 5-minute eddy covariances: <u'w'> <w't'> <w'mr'>, etc. The turbulent heat fluxes have been computed on a 30 minute time scale.

The dataset also does not contain the soil profiles or the CO2 data. Contact Richard Cuenca for the profiles or Scott Richardson for the CO2.

Java Applet and Plugin

Downloading ASCII data (.txt) uses a Java applet for selecting variables and time periods. Your browser must have support for (at least) Java version 1.2 to run the applet. If your browser does not have support for Java 1.2, you should be redirected to a web site where you can download a plug-in for Netscape, Mozilla or Internet Explorer. The plug-in is available for Linux, Solaris and Windows.

Version 1.2 of Mozilla will not redirect you to the plug-in download page if the plug-in is needed. You must click on the java.sun.com link, below to get the plugin.

Java Plug-in Information

Netscape/Mozilla users can enter a URL of about:plugins, or click on Help->About Plug-ins to display the plug-ins which have been installed.

The current Java run-time environment (JRE) which includes the Java plugin for Windows (IE/Netscape/Mozilla), Linux (Netscape/Mozilla) and Solaris (Netscape/Mozilla) is available at http://java.sun.com/j2se/1.4.2/download.html.

If that link is broken, try http://java.sun.com/j2se.

Download the JRE (Java Runtime Enviromment) from the latest version of the J2SE. You don't need the extra stuff, like NetBeans.

Installation instructions are available at http://java.sun.com/j2se/1.4.2/jre/install.html.

Some Notes about the Java plugin on Various Platforms

Java Applet User Interface

The data selection applet provides four areas for user input.

A "Times" section for selecting the start and end times of your request, in Central Daylight Time CST (5 hours earlier than GMT).

A "Variables" section for selecting the variables of interest. The variables are grouped under folder tabs by station name, height, and (loosely) by variable type.

An "Output Format" section for choosing the format of the ASCII output

A Download button. The browser will popup a file selection menu where you can enter the desired file name.

Sample of top part of applet. Click to enlarge.

Sample of bottom part of applet. Click to enlarge.

Download Problems

If you experience problems downloading data click here.

ISFF IHOP_2002 5min Dataset Access

The IHOP_2002 ISFF dataset is publically available. However, we ask users to provide their name and email address when they first download data, so that they may be notified of discovered errors or new releases of the dataset.

If you have provided this information before for this dataset, leave the fields blank.

Contact Gordon Maclean if the Java applet does not work after installing the plugin, or if you have any other feedback about the download process.

Please contact your system administrator if you have problems installing the Java plugin in your browser.

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