Section 2: Aircraft Data A variety of research aircraft were flown during the ERICA Field Study. A more detailed description of these aircraft can be found in Appendix E: Aircraft Instrumentation Descriptions, which was taken directly from Appendix C of the ERICA FOP. The ERICA Field Phase Summary (FPS) includes flight tracks and summary information for all ERICA missions; a table which lists all of the ERICA aircraft missions, their start and stop times, objectives, etc., can be found in Appendix A of the ERICA FPS. There were four aircraft which operated out of Naval Air Station Brunswick (NASB), Maine: two NOAA WP-3Ds, the NCAR Electra, and the NCAR SabreLiner. In addition, several Air Weather Service (AWS) aircraft operated from Dover AFB, Delaware. Sondes were dropped by the WP-3Ds, the Electra, and the AWS WC-130s; dropsonde data are covered in chapter 3 of this Guide. Several of the aircraft data sets were compacted at the Data Center to make them more easily accessible and cheaper to distribute. The wide variety of parameters from aircraft to aircraft make any digital combination of these sets (as was done with the sounding data, for example) impractical. The length of the missions and the high frequency of the data dictate a time series sort. 2.1 NOAA WP-3D Data Both of NOAA's WP-3Ds participated in ERICA, flying 8-10 hour missions out of NASB. There were 26 WP-3D missions during ERICA. 2.1.1 WP-3D Compressed Flight Level Data and One-Minute Data Form: digital Size: 120 Mbytes Volume: 1 tape This set includes digital data from all of the 26 ERICA WP-3D missions at one-second and one-minute resolutions. Digital data with one-second observations of 76 parameters were provided by NOAA's Office of Aircraft Operations (OAO - now called the Aircraft Operations Center) for all of the ERICA WP-3D missions. At the Data Center we removed the raw engineering data and calibration constants to produce this more compact data set. All 26 missions fit on one tape. The original format includes six types of records: 1) headers, 2) raw data transformation records (required to convert type 4 records into type 5 records), 3) converted data transformation records (required to put decimal points in type 5 records), 4) original (raw) data records, 5) converted data records, and 6) trailer records. In this compressed data set records of type 2 and 4 are not included, vastly reducing the bulk of the data set. Also included on the tape are files containing one-minute (coarse resolution) data for 33 of the parameters to provide a quick look at the missions, allowing researchers to quickly identify missions and portions of missions which are of interest. The original OAO tapes, including the raw data and calibration constants, are also available (see section 2.1.2). 2.1.2 WP-3D Flight Level Data Form: digital Size: 520 Mbytes Volume: 26 1600 bpi tapes These are the original data set from NOAA's Office of Aircraft Operations (OAO). Each of the 26 ERICA WP-3D missions is provided on one tape (1600 bpi). These tapes include the 76 parameters measured and the raw engineering data and calibration data. Researchers might find it more convenient to use the WP-3D Compressed Flight Level Data (section 2.1.1) which does not include the calibration and engineering data, but does include coarse resolution data. 2.1.3 WP-3D Radar Data Form: digital Size: 6.8 Gbytes Volume: 63 tapes These data come from the WP-3Ds' tail and belly radar systems, and include both reflectivity and Doppler velocities plus aircraft navigation and orientation data. The 196 original tapes (1600 bpi) have been compressed to 63 tapes (6250 bpi) at the Data Center. There has been no post-processing of these data. Interested researchers should also see section 2.1.4 below, Color Slides of P3 Radar Data. 2.1.4 Color Slides of WP-3D Radar Data Form: slides Size: 35 mm Volume: about 300 These slides were shot from the HP system at NOAA/OAO in Miami by Owen Hertzman. There are about 300 slides from IOPs 1, 2, 4, and 8. The slides do not comprise a comprehensive data set, because of radar malfunctions and occasional errors in the photography. There are slides from both the lower fuselage (LF) and the tail (TA) radars. On each slide is the scan time, plane's location and track, the plane's heading relative to the ground, and a color scale of dBZ, which represents the precipitation intensity. The LF radar gives horizontal (or plane) views of the 5 cm radar echo in an approximately 240 x 240 km box, with the aircraft at the center. It can be used to locate the precipitation features with respect to the aircraft, and also (cautiously) to determine relative intensities, sizes, and alignments of various precipitation features. The TA radar gives elevation views of the 3 cm radar echo and Doppler radial velocity in a smaller region: a box which is approximately 15 km vertically by 75 km horizontally. It can be used to examine size scales and spacing of convective elements, the height and intensity of melting layers, and the relative intensity of echo to the left and right of the aircraft. The tail radar velocity can be used to determine vertical shear zones of the horizontal wind component perpendicular to the aircraft track. Since there were many failures of the tail radar, it is recommended that researchers consult the radar operators' notes when working with these data (note: the quality and quantity of radar operators notes vary widely, and they are not available for all flights). The tilt of both radars was controllable on board, and a change in tilt may explain sudden differences between two consecutive slides. Researchers should also be cautious with slides from flight legs during which there were steep ascents or descents. 2.1.5 WP-3D Cloud Microphysics Data Form: digital Size: 7.3 Gbytes Volume: 44 tapes This set includes PMS FSSP cloud droplet data, PMS 2D-C 25-800 micron particle digital imagery (in standard PMS format), and PMS 2D-P 200-6400 micron particle digital imagery (also in standard PMS format). There are approximately 2 tapes per flight, 44 tapes total, presently stored at AES/ARMP. AES has arranged for Joe Boatman of NOAA to post-process the particle digital imagery for IOPs 4 and 5A. He has produced ASCII files containing particle spectra every 15 seconds, and another set of files for every minute. In addition he will provide hardcopy plots of the spectra at 10 minute intervals, and hardcopy plots of the 2D images. The cost of the analyses was about $5000, and there are no plans at AES to process other IOPs. Anyone interested in funding further processing should contact Walter Strapp. The PMS 2D imagery contain continuous noise (false images), and may require special efforts by image analysis software for noise elimination. The NOAA software run on the IOP 4 and 5A data was tailored for this noise removal. The PMS FSSP data are known to degrade rapidly above aircraft speeds of 100 m/s, resulting in undercounting and undersizing. Some caution should be used in data interpretation at substantially higher WP-3D speeds. 2.2 NCAR Sabreliner and Electra Data The Electra research was led by Dr. Kerry Emanuel of MIT; most missions supported boundary layer studies or dropsonde missions, or both. Ten Electra missions were flown during the field study. The Sabreliner research was headed by Dr. Ron Smith of Yale University, assisted by Paul Gluhosky. Its missions primarily supported upper-tropospheric studies. There were 24 Sabreliner missions during the field study, plus two ferry flights. In addition to the data listed below, both aircraft contained a number of video cameras which operated during the flights. These tapes may be available from Drs. Emanuel and Smith. High-rate data (turbulence data) were also collected (at a rate of up to 20 hertz). These data are available from NCAR. 2.2.1 EL&SL Compressed Flight Level Data and One-Minute Data Form: digital Size: 43 Mbytes Volume: 1 tape This set includes one-second and one-minute data from all of the ERICA Electra and Sabreliner missions. The one-minute (coarse resolution) data include 11 variables (plus time and location) and are provided as a quick-look data set. The one-second data were compressed by reducing the number of included variables from approximately 150 down to 26 (for the Electra) or 23 variables (for the SabreLiner). The original, uncompressed flight level data are also available (see section 2.2.2). 2.2.2 EL&SL Flight Level Data Form: digital Size: 240 Mbytes Volume: 11 1600 bpi tapes There is one tape for each of the ten Electra missions, and one tape which contains all 24 Sabreliner missions, plus two ferry flights. Programs to unpack the data are also provided. Researchers may find the EL&SL Compressed Flight Level Data (see section 2.2.1 above) easier to work with. 2.2.3 EL&SL Standard Output Microfilms Form: microfilm, paper Size: 8.5 x 11(paper) Volume: 17 rolls of microfilm for the EL; 26 rolls of microfilm for the SL The standard NCAR microfilm output is described in NCAR-RAF Bulletin #9, "Standard Output Data Products from the NCAR Research Aviation Facility." Copies of this bulletin are available from the EDC. The microfilms may be borrowed from the EDC; microfilm copying can be arranged by either the Data Manager or the researcher. 2.3 Other Aircraft Data Other aircraft data from ERICA include the flight level data gathered by AWS missions (AWS dropsonde data are covered in section 3.3.3), and data gathered from commercial aircraft equipped with automatic data-reporting equipment. 2.3.1 AWS WC-130 Flight Level Data Form: digital/paper Size: 60 Kbytes Volume: 1 tape These data include height, temperature, relative humidity, and wind speed and direction extrapolated to the nearest mandatory level. High resolution data (1 min.) is available for only three missions (WI12091E, WI12101E and WI12131E). These data are referred to as IWRS data. This set contains data from two sources. The ERICA history tapes (see section 7.1) had AWS flight level and drop data in ADPUPA format. Those data were reformatted, and the flight level data was pulled out. We compared the data from the history tapes with the paper copies of the form filled out by the AWS pilots during the flight. Some data appeared on the paper copies, but not on the history tapes. Our data set is a combination of the history tape data with the extra data from the paper forms added manually. 2.3.2 PIREPS from PROFS, ACARS Form: digital Size: 7 Mbytes Volume: 1 tape Some commercial aircraft automatically record high-quality data on winds and temperature and frequently communicate the data through aeronautical radio. The Data Center has obtained the data from the Aircraft Communications Addressing and Reporting System (ACARS) from the PROFS PIREPS file. There are 72,834 reports in the ERICA region; typically there are 900 reports per six hours in the region 25N to 45N, 70W to 100W, except at night (0300 UTC to 1200 UTC). The vertical distribution of these data in each 11,000 foot layer from the surface to 44,000 feet is: 15%, 13%, 16%, 56%. In terms of equivalent rawinsondes (without humidity), this data set has about 100 soundings every six hours, and so is equivalent to the six hourly soundings at the 400 km spacing of the United States rawinsonde network. PROFS sent 10 1600 bpi tapes to the Data Center which contained the data from the ERICA period and the pre-ERICA case (January 1988) for the continental U.S. only. Parameters reported include altitude, wind speed and direction, temperature, turbulence data, ice data, and cloud data (all parameters will not be available for all reports).