CIRPAS Twin Otter UCI 1-Hz Boundary Layer Turbulence Data Project: VOCALS-REx Platform: CIRPAS Twin Otter UC Irvine Data Set Version 2.0, May 1, 2009 PI: Djamal Khelif University of California, Irvine Dept. Mech. & Aerospace Eng. Irvine, CA 92697-3975 USA e-mail: dkhelif@uci.edu Phone: 949 824 7437 Start: 20081016141904 UTC End: 20081113154812 UTC Flt # Flt ID Start (UTC) End (UTC) TO01 081016 20081016141904 20081016183718 TO02 081018 20081018110816 20081018153022 TO03 081019 20081019115552 20081019151757 TO04 081021 20081021110757 20081021154213 TO05 081022 20081022110354 20081022153216 TO06 081024 20081024104749 20081024154102 TO07 081026 20081026104529 20081026155707 TO08 081027 20081027143827 20081027194136 TO09 081029 20081029104153 20081029154406 TO10 081030 20081030104703 20081030154825 TO11 081101 20081101104548 20081101155416 TO12 081102 20081102104831 20081102153720 TO13 081104 20081104104559 20081104154059 TO14 081105 20081105105322 20081105155715 TO15 081108 20081108105342 20081108154548 TO16 081109 20081109104211 20081109154444 TO17 081110 20081110134457 20081110190024 TO18 081112 20081112104501 20081112155055 TO19 081113 20081113104527 20081113154812 List of Variables: In the MATLAB binary format *.mat files, the variables names are as listed below with the following prefixes: f_* Prefix of fast rate (40 Hz) data file name and of variable names in *.mat files s_* Prefix of slow rate (1 Hz, boxcar averages from 40 Hz) data file name and of variable names in *.mat files Also, there is a character array variable "AA_README" within the *mat file with a description of the variables. After loading a given file onto your MATLAB session, just type: AA_README to see the variable list and description. 01 t (s) Elapsed Time in seconds since 0 UTC of flight (data file) start day 02 hr (m) Height from Radar altimeter 03 ap (m) Pressure Altitude (corrected) 04 lat (degN) LATitude from UCI C-MIGITS III 05 lon (degE) LONgitude from UCI C-MIGITS III 06 hdg (deg) true HeaDinG from UCI C-MIGITS III range [0 360] deg 07 wx (m/s) Wind component in the east direction (X-axis) 08 wy (m/s) Wind component in the north direction (Y-axis) 09 wz (m/s) Wind component in the vertical direction (Z-axis) 10 ah (g/m^3) Absolute Humidity from best available sensor * 11 ta (deg C) Temperature Ambient from Rosemount fast-response sensor 12 td (deg C) Temperature Dewpoint from Edgtech Chilled mirror sensor 13 ts (deg C) Temperature sea Surface from Heiman KT 19.85 IR sensor 14 ps (hPa) Pressure Static from fuselage flush ports and Setra 270 transducer 15 tas (m/s) True Air Speed 16 rhoa (kg/m^3)Air density 17 mr (g/kg) Mixing Ratio 18 thet (K) potential temperature (theta) 19 tvir (deg C) VIRtual Temperature 20 thete (K) equivalent potential temperature (thetae) 21 tirup (degC) Temperature from IR UPward-looking temperature sensor 22 flip (V) Flip-flop synchronization signal from CIRPAS C-MIGITS III 23 tdl (deg C) Dewpoint Temp. LI-COR 7500 On a spreadsheet, the columns of the ASCII 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 23 A B C D E F G H I J K L M N O P Q R S T U V W t hr ap lat lon hdg wx wy wz ah ta td ts ps tas rhoa mr thet tvir thete tirup flip tdl s m 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 House-keeping variables in *mat files only z_bad_ndx Its value is 'none' if the 4 variables below do not exist else z_bad_ndx does not exist. z_bad_dpet_ndx Indices of HF noise on dewpoint signal z_bad_dpet_utc UTC of HF noise on dewpoint signal z_bad_ttr_ndx Indices of HF noise on temperature signal z_bad_ttr_utc UTC of HF noise on TT temperature signal (*) The best available humidity sensor is the LI-COR 7500 (closed path mode) for all flights The Campbell Scientific Krypton Hygrometer data will be added soon. Notes: 1. In the file name "f_YYMMDD_sm", the YY, MM and DD are the UTC year, month and day of the start of the flight. 2. In the MATLAB *mat files variables are named as indicated in the list above 3. In the ASCII files, variables from left to right correspond to the variables from top to bottom in the table above. 4. The s_* data are 1-Hz boxcar averages obtained from the original 40-Hz data except for heading angle which are down-sampled using the "pick-up" method to avoid discontinuities at the 0/360 pole. 5. The time t wraps around the day. In other words, if the flight straddles over midnight UTC, t will not start over at 0 sec but it will continue increasing past 86400 sec (86400=24*3600) and remains continuous. (This is convenient for time series plots) %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Re-processing of January, 2009 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 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 (due to closed path configuration). 4. Added the dewpoint variable, tdl, calculated from the LI-COR signal as column (#22) of the 40-Hz ASCII files. 5. The chilled mirror dewpoint was cleaned just before flight 081104 and its data became not reliable since then and for the rest of the missions (although it was gradually improving). 6. Used the LI-COR data for absolute humidity and mixing ratio for all VOCALS-REx flights. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Re-processing of May 1, 2009 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 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. 2. Optimised selection of the flight calibration ranges of both the LI-COR 7500 (ahl) and Krypton KH2O (ahk) hygrometers. 3. Added the humidity correction to true airspeed. This correction increases the airspeed on average by 0.18 m/s for the VOCALS humidity conditions. This correction affects the winds. 4. 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. 4. Below is a list of the latest data files from all 119 flights: File Name Availability_Stamp Size (MB) 081016_sm.mat 01-May-2009 16:54 87 081018_sm.mat 01-May-2009 16:53 91 081019_sm.mat 01-May-2009 16:55 70 081021_sm.mat 01-May-2009 16:55 95 081022_sm.mat 01-May-2009 16:56 93 081024_sm.mat 01-May-2009 16:57 101 081026_sm.mat 01-May-2009 16:58 108 081027_sm.mat 01-May-2009 17:01 105 081029_sm.mat 01-May-2009 17:01 105 081030_sm.mat 01-May-2009 17:02 104 081101_sm.mat 01-May-2009 17:03 107 081102_sm.mat 01-May-2009 17:04 100 081104_sm.mat 01-May-2009 17:05 101 081105_sm.mat 01-May-2009 17:05 105 081108_sm.mat 01-May-2009 17:06 101 081109_sm.mat 01-May-2009 17:07 104 081110_sm.mat 01-May-2009 17:08 109 081112_sm.mat 01-May-2009 17:09 106 081113_sm.mat 01-May-2009 17:09 104 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% IMPORTANT NOTES TO USERS ABOUT DATA POLICY %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 1. P.I.s have ready access to the data produced by the other P.I.s. 2. The data is not available to the public for 1 year. 3. P.I.s can provide at any time copies of their probe's/sensor's data to whomever they chose. 4. Data from a P.I. may not be shared with others without the P.I.'s agreement. 5. Publications using another P.I.'s data give this other P.I. the option of being a co-author. Please register as a UCI VOCALS-REx 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 "VOCALS-REx: 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