At the request of Judy Curry, high-rate data files were generated for each of the sixteen research flights flown by the NCAR/NSF during SHEBA. These files contain only data for specifically-requested variables and for time periods of interest outlined by Judy Curry.

In general, each of the high-rate files contains variables from the categories of wind speed and direction, ambient temperature and dewpoint temperature, atmospheric humidity (mixing ratio and relative humidity), altitude and ambient pressure. The following table lists the exact names of the variables, along with their output sample rates, included in each of the files:

Users will note in examining the above table that some variables with a maximum output rate of 1 sample/second have been included in the high-rate data files. These are variables corresponding to instruments for which high-rate output is not possible. The decision was made to go ahead and include these low-rate variables in the high-rate data files so that users will have these data readily available for comparison with high-rate data for variables in the same measurement category (humidity, etc.).

Listed in the table below are the names of the high-rate data files and the corresponding processed time segments generated for users of the SHEBA data set:

A quality-checking review of the high-rate data in the above-listed files was conducted prior to the release of the data. In general, the data were found to be of good quality. However, two specific problems/limitations were discovered and are noted here:

1. A review of the high-rate wind data (i.e., the variables, UI, VI, XUIC, XVIC, etc.) revealed that significant oscillations are present in the wind data for brief time periods during aircraft turns. These oscillations do not show up when longer time periods of data (greater than approximately 10-15 seconds) are plotted but are visible when shorter time periods (less than approximately 10 seconds) are examined. While the RAF has not located the exact cause of this problem, it is known that the oscillations are introduced into the calculated wind variables by oscillations in the variables VEW, VNS, and (to a lesser degree) VSPD. The RAF is presently investigating the source of the oscillations in VEW, VNS, and VSPD. Users of the high-rate wind data are advised to avoid using the high-rate wind data for critical analyses during time segments when the C-130 was turning and to generally be alert for time segments of data when oscillations in the wind variables are present.
2. A review of the high-rate MRUV (UV hygrometer) data and spectra revealed that the MRUV data are unusable (due to excessive noise) at sampling frequencies greater than 1 Hz (1 sample/second). Users are advised to only use the low-rate (1 sample/second) MRUV data in critical analyses. In comparison, the high-rate MRLA and MRLA1 (Lyman-Alpha sensor) data appear to be of good quality and should therefore prove useful for studies involving high-rate humidity measurements.

Users of the high-rate C-130 data products are strongly encouraged to notify the RAF of any additional problems and/or limitations they may discover while working with the data. Such problems should be brought to the attention of either Krista Laursen, the SHEBA C-130 Project Manager, phone: (303)497-1031 or email, or Ron Ruth.

Users of the SHEBA C-130 data set are reminded that high-rate data for time segments and variables other than those included in the files listed above will be made available on an "as requested" basis only. Individuals interested in working with high-rate data should first examine the files listed above to see if the variables and time periods of interest have already been generated. If additional variables and/or time segments are needed, a specific request (listing the flight numbers, variables of interest, and time periods of interest) for these data must be submitted to Ron Ruth.