Physics Of Stratocumulus Top (POST) Jul-Aug 2008 UC Irvine Data Set Funding Agency: National Science Foundation (Award Number ATM-0734323) I. Header of UCI POST 2008 ASCII 40-Hz data files Version: 08January2009 01. t (s) elapsed Time in seconds since 0 UTC of flight (data file) start day 02. ap (m) Pressured altitude (adjusted to radar altitude) 03. lat (degN) LATitude from UCI's C-MIGITS III 04. lon (degE) LONgitude from UCI's C-MIGITS III 05. hdg (deg) true HeaDinG from UCI's C-MIGITS III range [0 360] deg 06. wx (m/s) Wind component in the east direction (X-axis) 07. wy (m/s) Wind component in the north direction (Y-axis) 08. wz (m/s) Wind component in the vertical direction (Z-axis) 09. ah (g/m3) Absolute Humidity [TO01-TO04: Chilled mirror; TO05-TO17 LI-COR 7500] (see note 1) 10. ta (deg C) static Ambient Temperature from UCI's Rosemount fast-response sensor 11. td (deg C) ambient Dewpoint Temperature from CIRPAS's Edgtech Chilled mirror sensor 12. ts (deg C) Sea surface Temperature from CIRPAS's downlooking Heiman KT 19.85 IR sensor 13. ps (hPa) Static atmospheric Pressure from fuselage flush ports and Setra 270 transducer 14. tas (m/s) True Air Speed (Dry Air) 15. rhoa (kg/m^3) Moist Air density 16. mr (g/kg) Mixing Ratio from UCI's LI-COR 7500 [TO01-TO04: Chilled mirror; TO05-TO17 LI-COR 7500] (see note 1) 17. thet (K) potential temperature (theta) 18. tvir (deg C) VIRtual Temperature 19. thete (K) Equivalent potential temperature (thetae) 20. tirup (deg C) Temperature from UCI's IR UPward-looking temperature sensor 21. flip (V) FLIP-flop 1/2 Hz GPS synchronisation signal from 1-Hz CIRPAS C-MIGITS III pulse 22. tdl (deg C) Dewpoint Temperature from UCI's LI-COR 7500 [TO01-TO04: NaN] (see note 1) On a spreadsheet, the columns of the 40-Hz data files are arranged as indicate below: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 A B C D E F G H I J K L M N O P Q R S T U t ap lat lon hdg wx wy wz ah ta td ts ps tas rhoa mr thet tvir thete tirup flip tdl s* m degN degE deg m/s m/s m/s g/m3 degC degC degC hPa m/s kg/m3 g/kg K degC K degC V degC II. Header of the "limited" UCI POST 100-Hz (interpolated from native 40Hz) data files Version: 08January2009 1. t (s) elapsed Time in seconds since 0 UTC of flight (data file) start day 2. ap (m) Pressured altitude (adjusted to radar altitude) 3. wx (m/s) Wind component in the east direction (X-axis) 4. wy (m/s) Wind component in the north direction (Y-axis) 5. wz (m/s) Wind component in the vertical direction (Z-axis) 6. ta (deg C) static Ambient Temperature from UCI's Rosemount fast-response sensor 7. mr (g/kg) Mixing Ratio from UCI's LI-COR 7500 (see note 1) 8. flip (V) FLIP-flop 1/2 Hz GPS synchronisation signal from 1-Hz CIRPAS C-MIGITS III pulse On a spreadsheet, the columns of the 100-Hz data files are arranged as indicate below: 1 2 3 4 5 6 7 8 A B C D E F G H t ap wx wy wz ta mr V s* m m/s m/s m/s degC g/kg flip Note (1): UCI's LI-COR 7500 H2O, CO2 gas analyser (variables ah, mr, tdl) was installed on July 28, 2009 (Flight TO05) and was operational through the last flight of August 15, 2009 (TO17). Prior to TO05 (TO01-TO04 i.e., flights 080716, 080717, 080719 and 080721), variables ah and mr are calculated using data from the chilled mirror dewpointer and variable tdl values are filled with "NaN" (Not a Number). %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% IMPORTANT INFORMATION TO USERS: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% A. The POST data policy specified by Hermann Gerber in his e-mail message of 1/14/2008 (Communication #5) applies to the UCI POST data set as quoted below: 1. POST P.I.s have ready access to the data produced by the other P.I.s. 2. The POST data is not available to the public for 1 year. 3. POST P.I.s can provide at any time copies of their probe's/sensor's data to whomever they chose. 4. One year after the field study the archived data becomes public. 5. Publications using another P.I.'s POST data give this other P.I. the option of being a co-author. B. Please register as a UCI POST data user to be updated on future modifications to the data set and for possible cooperation in the data analysis and publication of results. To do so, please send a message with "POST: UCI data registration" as the subject and your contact/institution information in the message body to: Djamal Khelif University of California, Irvine Dept. Mech. & Aerospace Eng. Irvine, CA 92697-3975 USA e-mail: dkhelif@uci.edu Phone: 949 824 7437 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% NOTES ON JANUARY 09, 2009 DATA PROCESSING %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Compared to the 22Sep2008 the changes included in the new 08January2009 version are as follows: 1. Changed reference temperature from CIRPAS Rosemount sensor (noisy at high frequencies) to UCI's Rosemount sensor. 2. Recalculated ta, thet, tas and winds due to the reference temperature change. 3. Re-calibrated (using flight data) the LI-COR humidity after correcting for the 0.8 s lag in its signal. 4. Re-calibrated the krypton humidity sensor. However, since its data were not consistent, they were not included in the ASCII files. (This is work in progress...) 5. Used the LI-COR data for absolute humidity and mixing ratio for all flights except for the first 4 flights [080716, 080717, 080719 and 080721] which were carried out before the LI-COR was installed. For these early flights the chilled mirror dewpoint was the ONLY operational humidity measurement available. 6. Added the dewpoint variable, tdl, calculated from the LI-COR signal as last column (#22) of the 40-Hz ASCII files. 7. On flight 081730, the chilled mirror dewpoint was left on "test" instead of "operate" resulting in unusable data. Dewpoint data from the LI-COR data are used instead. (Calibration coefficients obtained from the previous flight, 080729 were used to calculate tdl.) 8. Replaced radar altimeter height by the pressure altitude after adjusting it to the radar altimeter data. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% NOTES ON APRIL 08, 2009 DATA PROCESSING %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1. Accounted for 2.5 s response time lag of the EdgeTech chilled mirror signal before using it as the reference humidity in the calibration of the LI-COR 7500 (ahl) and Krypton KH2O (ahk) hygrometers. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% NOTES ON APRIL 28, 2009 DATA PROCESSING %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1. Optimised selection of the flight calibration ranges of both the LI-COR 7500 (ahl) and Krypton KH2O (ahk) hygrometers. 2. Added the humidity correction to true airspeed. This correction increases the airspeed on average by 0.18 m/s for the POST humidity conditions. This correction affects the winds. 3. Used reverse heading maneuvers from POST and VOCALS to fine-tune the horizontal wind calibration. A true airspeed empirical offset of +0.17 m/s was determined. On average, the new airspeed is about 0.35 m/s more than that of the previous version due to this offset and to the humidity correction. 4. On some flights there are some spikes on the vertical component of the wind. This is due to the ground wire left loose on the angle of attack pressure transducers which ended up picking noise each time the pilots used the radio to communicate with the traffic controllers or the hangar. Luckily, this occurred mostly just after take off and toward end of the ferry prior to lending and did not affect the "research portion" of the flights. 5. By comparing the analog pitch rate data to the GPS-time-stamped pitch rate serial data from the C-MIGITS III INS/GPS navigation unit, it was determined that the UCI DAQ (analog) clock lags the GPS time by 125 ms to 175 ms over the duration of the flight. (The longer the flight the greater the time lag). This was corrected by interpolating all recorded analog signals, including the "flipflop" GPS synchronisation signal. This is why there is some distortions at each step-change of the flipflop signal compared to the "perfect" square wave that was originally recorded. However, the change from one second to the next is still clearly detectable and the synchronisation is very good. Although the step changes of the flipflop signal were a bit distorted when its 40-HZ data were interpolated to produce the 100-Hz data set, it still shows that the synchronisation is very good.