Ice in Clouds Experiment (ICE-L) 6 Nov - 16 Dec 2007 Wyoming Cloud Radar Data Status Report Content: General Notes WCR configuration Radar Status/Problems Calibration Notes Data File Information Terminology and other notes ................................................................................ General Notes: * Quick look images of co-pol reflectivity for all the flights are stored on the project WCR web site in their corresponding directories(mmmDD) as pdf files. * WCR raw data is archived on a disk array in the UW DAS and a mass storage at NCAR. Quicklooks, dataquality, and calibration data are also archived. Radar processed data files in NetCDF format are available usually within 2 months after the conclusion of the experiment (preliminary version may be available earlier). The NetCDF files are available via the Internet. They may be protected with a password. Contact the PI for access. ................................................................................ WCR configuration: WCR is installed on NSF/NCAR C130 with 3-antenna configuration: Antenna 1 2,4 and no polarization capability. Antenna ports are: Ant1 (up) - H1, Ant2 (near nadir) - V2, Ant4 (down-aft) - H2; H/V stands for the receiver used (there are 2 receivers). Cross-channels (HXVX and VXHX channels) have no meaning for this configuration. ................................................................................ Radar Status/Problems * Waveguide installation for the "UP" antenna The new up-pointing antenna setup causes vertical displacement of regular waveguide (connecting the low-loss waveguide to the RF) in the order of 1" (at the maximum flown 26 Kft altitude) due to fuselage ballooning at higher altitudes (displacement increases with the increase of pressure differential between cabin and outside pressure). Change in the installation of the low-loss waveguide (lowering the supporting trough and allowing the low-loss waveguide to float within the trough) needs to be implemented. * IRIG time stamps jumps occured frequently for all flights until Dec10. Dec10 and Dec16 had no time glitches and Dec11 and Dec13 had one each. It appears that the end of the time glitches on Dec 10 coincides with 3 events. i) Jorgen Jensen tolld me that the AC data had a lot of noise until Dec 10; ii) CAPS probe was replaced, and iii) Jum Hudson (DRI) old rack was swapped for a new one. The equipment replacements took place between the RF08(Dec04) and RF09(Dec10). Time jump segments are removed from the processed data. I have found the following types of jumps: 1) At the top of the second the TFP does not change to the next second; fractional seconds appear to be unaffected 2) Negative time jumps to 00:00:00.xx of the 1st day of the year (like reset to the TFP IRIG time, which always starts from the beginning of the year - no info about the year); fractional second are not reset but are incorrect. 3) Negative time jumps to the beginning of the year, but without full reset, e.g., hhmmss are not reset, but are not correct either 4) Negative time jumps in the order of ~1e7 sec (but not going to to the beginning of the year), fractional sec may be correct. It appears that time jumps fully recover in less than 3 sec. However I have found one case for whcih there was no recovery untill the end of the data file the jump occured (from the analysis of this case it appears likely that the first jump actually started after ending the previous file and before the beginning of this file). Chris Webster said that RAF had time spikes with their IRIG card (under their old data system) and they have identified that vibration was the more likely cause. I have been checking the time when running the radar on the ground before a flight and on Nov 29 (1st time out of 3-4 runs) there was a time glitch (jump in the order of 1e7 sec). * The temperature in the back of C130 was in the 60-70F range during the flights. The 2 fans on the right side of the RF (where the radar control board is located) were often disconnested during the flight in order to maintain tube temperature above 70F. * The 2 down-antenna beams were not available from 14 to 28 Nov due to crack in the nadir port rexolite window (see Nov 13 status below). New window thickness was ordered the same as the original: 0.495"+-0.001", but was actually machined to 0.4965". During the installation on Nov 19 (no flight that day) it cracked. A new installation design (no holes in the rexolite window and using brackets to hold it in place - there is about 1/2" minimum clearance at the edges of both down beams) was proposed by Mark Lord. The brackets were built on Nov 20. The new cracked window was cut to the new dimwnsions on Nov 21 and the installation was finished on Nov 28. Spare windows for both up and nadir ports will be machined before VOCALS. * When flying at lower altitudes ground returns from the nadir antenna leak into the "up" and "down-slant" returns. This is due to finite circulator isolation between the beams. The ground leakage can show above the noise up to 3 km range but it is significant in the 1st km only. The leak is stronger in the slanted beam than in the up beam. ______ Oct 29 = During the test flight Jeff reported that 1) The EIK and modulator temperatures were barely into the 70s F 2) The regular waveguide for the up antenna was moving as much as 1" in vertical (appeared to be altitude dependent) = Time stamps have several glitches ______ Nov 01 = Time stamps have several glitches ______ Nov 05 = Kipp Eagan (RAF) checked the displacement of the up antenna waveguide during the flight. He confirmed that the regular piece of waveguide connecting the low-loss waveguide to the RF moves vertically about 0.5" and reaches the top edge of the RF access hole in the RF wall. After that there is another ~0.25" upward motion that is taken by bending the part of the regular waveguide between the RF wall and the low-loss waveguide connection. The maximum displacement is reached at the C130 maximum flown altitude of about 24 Kft and is in the order of 0.75". The displacement of the waveguide does not appear to overstress the circulator network and does not cause a permanent bend in the waveguide. Thus, no correcting action is planned for now. For long-term use Mark Lord suggests that the problem is corrected to avoid possible permanent damage to the waveguide due to repeated pressure cycles. He recommends that the low-loss waveguide trough is lowered by 1" to allow the low-loss waveguide to float. = TFP card and the adaptor card were reseated (does not appear to have any effect in reducing the time jumps. The time stamps have several glitches ______ Nov 07 = Time stamps have several glitches = The aircraft flew at 26 Kft and Jeff reported additional displacement of the waveguide by another ~0.2" ______ Nov 13 = Nadir port rexolite window cracked during the flight (likely during a turbulence episode -moderate turbulence; the rest of the flight was smooth) at the end of the flight. Both down-antenna channels will not be available until the window is replaced = Time stamps have several glitches ______ Nov 16 = Only Up antenna channel available. The 2 rexolite sheets were delivered today and one was sent for machining;thickness: 0.495"+-0.001" = Time stamps have several glitches ______ Nov 18 = Only Up antenna channel available. = Time stamps have several glitches = Teresa Campos and Kipp Egan reported hearing noise coming from the up-antenna mounting area. Teresa thought it sounded like a el static noise, while Kipp could not identify the type of the noise. ______ Nov 20 (am and pm flights) = Only Up antenna channel available. = Time stamps have several glitches ______ Nov 29 = Nadir port rexolite window is on and all 3 antennas are functional = Time stamps have several glitches ______ Nov 30 = Time stamps have several glitches = There are several gaps in the data. Jeff reported that the DSPs printed messages warrning about "Q-full error". He established that these errors happen when he was doing other work (moving windows, etc.) We have seen this error in the past and generally it is better to avoid running other processes during acquisition time. ______ Dec 04 = Time stamps have several glitches = Jeff French reported that the cracking noise coming from an area around the up antenna is not associated with the radar (suspected possibility of arching in the low-loss waveguide-pretty much discareded as an option, or arching in antenna feed - also unlikely). The radar transmitter was shut down when the noise came up. ______ Dec 11 = Time stamps have 1 glitch ______ Dec 13 = Time stamps have 1 glitch ................................................................................ Calibration notes: **************************************************************************** Power Calibration: * Calibration constants for this experiment as of 1 Feb 2008 Calibration constants (250 ns pulse, 5 MHz IF filter, dynamic range > 70 dB; for 500 ns pulse subtract 3.5 dB): Ant. 1 (side/up), HHcal1 = 57.5 Ant. 2 (nadir), VVcal2 = 51.5 Ant. 4 (down-aft), HHcal2 = 52.0 Notes: 1) Nadir rexolite window was replaced on Nov 28. The new window thickness is 0.4965", while the old one was 0.4950". 2) Calibration constant precision over the whole dynamic range (no less than 70 dB) is about +-1.5 dB for both receivers 3) The absolute accuracy of the calibration constant for the nadir antenna is estimated to be around +-2.5 dB (based on the overall variability of the calibration constant from CR measurements and the expected drift in the receivers and transmitted power). Transmitted power drift is estimated to be in the order of 1 dB for less than 2 hour flight and no more than 1.5 dB for longer flights. Receiver gain drift is estimated to be less than 1 dB. 4) The accuracy of the calibration constant for the slanted antenna is about +-3.0 dB. Cloud data are used for relative calibration of this antenna w.r.t. nadir antenna. Slanted antenna is mostly intended for Doppler velocities. 5) The accuracy of the power calib. for the "up" beam (HHcal1) is not well established due to larger uncertainties in its relative calibration w.r.t. the nadir beam returns and lack of direct CR calibration. The difference w.r.t. nadir beam is between 6 and 8 dB. Cross-channel Isolation > 50 dB Antenna Coupling Separation: better than 50 dB; weak coupling between side and nadir antenna is possible for strong(close range) surface returns) * Calibration constants used for the quick look images: Ant. 1 (side/up), calHH1 = 58.0@ 250ns Ant. 2 (nadir), calVV2 = 52.0@ 250ns Ant. 4 (down-fore), calHH2 = 52.0@ 250ns **************************************************************************** Beam angles calibration: * Unit beam angles(in AC coordinates) for this experiment as of 31 Jan 2008 X(along AC) Y(right wing) Z(down) Ant. 1 (up): 0.0436195, 0.0, -0.9990482 Ant. 2 (nadir): -0.0349, 0.00977, 0.999344 Ant. 4 (down-fore): -0.5771, 0.011, 0.8166 The accuracy of the beam angles for 'up' beam is not known due to lack of calib data. The accuracy of the down beams is within 0.4 deg. **************************************************************************** ................................................................................ WCR Data File Information: ************************************************************************** oct29 (tf01): Test Flight Total data: 1.2 GB Alg/Pulse Antennas Notes 146M W2007-10-29-18-33-35 pp6,250,U,D,D very few cloud returns 28M W2007-10-29-18-42-14 pp4,500,U,D 66M W2007-10-29-18-46-05 pp6,500,U,D,D 619M W2007-10-29-18-50-30 pp6,250,U,D,D time glitches: 1)18:47:16, 2)18:50:40, 3)19:01:21, 4)19:04:23 prof # events: 1) 4296-4313 -2.0 days 2) 10909-10987 3) 33691-33726 1 sec 4) 39974-40054 +2sec,-0.2sec,+1sec 281M W2007-10-29-19-25-11 pp6,250,U,D,D few cloud returns; ground ************************************************************************** nov01 (tf02): Test Flight (beam calibration) Total data: 1.6 GB Alg/Pulse Antennas Notes 66M W2007-11-01-21-12-36 pp4,250,D,D ground after take off (no clouds) 73M W2007-11-01-21-20-13 pp4,250,U,D a bit more ground (no clouds) 100M W2007-11-01-21-40-44 pp4,250,U,D no useful signal time glitches: 1076-1107, ~2.6e7 16059-16133, ~10^7,1sec,0.4 sec 223M W2007-11-01-21-54-13 pp4,250,U,D in mid-cloud (~0dBZ) time glitch 29672-29707, 1sec,(~22:08:20) 548M W2007-11-01-22-14-07 pp6,250,U,D,D in mid-cloud(~0-5 dBZ) 340M W2007-11-01-22-45-06 pp6,250,U,D,D time glitch 5178-5212 ground only (nadir) 75M W2007-11-01-23-04-07 pp6,250,U,D,D ground only(both down ants) 214M W2007-11-01-23-08-48 pp4,250,D,D beam calib 23:15:30-23:30:10(end) ************************************************************************** nov05 (tf03): Test Flight Total data: 2.4 GB Alg/Pulse Antennas Notes 418M W2007-11-05-20-38-48 pp6,250,U,D,D no clouds; ground in the beginning time glitch: 41940-41975 42004-42038 1sec 263M W2007-11-05-21-03-33 pp6,250,U,D,D no useful signal time glitch: 13870-13905 communic. interf: 21:17-21:18 88M W2007-11-05-21-18-36 pp6,250,U,D,D no clouds; some ground time glitch: 8932-8967 400M W2007-11-05-21-23-48 pp6,250,U,D,D a little bit of cloud(nadir);ground time glitch: 26683-26718 1sec 426M W2007-11-05-21-46-22 pp6,250,U,D,D few tiny clouds; ground; vnoise spikes 512M W2007-11-05-22-10-14 pp6,250,U,D,D almost no clouds; ground 285M W2007-11-05-22-38-52 pp6,250,U,D,D no clouds; ground ************************************************************************** nov07 (rf01): Total data: 3.2 GB Alg/Pulse Antennas Notes 403M W2007-11-07-18-07-36 pp6,250,U,D,D no cloud returns; ground 288M W2007-11-07-18-30-40 pp6,250,U,D,D no useful returns time glitch: 18243-18278 450M W2007-11-07-18-46-46 pp6,250,U,D,D 130M W2007-11-07-19-12-19 pp6,250,U,D,D 40M W2007-11-07-19-22-00 pp6,250,U,D,D no useful returns 116M W2007-11-07-19-24-43 pp4,250,U,D time glitch: 12847-12882 1sec 262M W2007-11-07-19-35-12 pp6,250,U,D,D time glitch: 21776-21811, ~1e7 21824-21859 - 1 sec recovery 468M W2007-11-07-19-50-07 pp6,250,U,D,D not much cloud returns time glitch: 1479 +2 sec(no recovery) 32166-32201 1sec 15M W2007-11-07-20-17-23 spp,500,U not much cloud returns 147M W2007-11-07-20-24-10 pp4,500,U,D 543M W2007-11-07-20-39-18 pp6,500,U,D,D 2nd trip ground interf.(down-slant) 25M W2007-11-07-21-12-31 pp6,500,U,D,D 2nd trip ground interf(down-slant) 365M W2007-11-07-21-14-23 pp6,250,U,D,D 2nd trip ground interf(down-slant) vnoise: spikes,2 long spike(ground) time glitch: 10281-10316 1sec ************************************************************************** nov13 (rf02): Total data: 3.5 GB Alg/Pulse Antennas Notes 393M W2007-11-13-16-07-16 pp6,250,U,D,D ground only 399M W2007-11-13-16-29-13 pp6,250,U,D,D one small cloud(nadir) 236M W2007-11-13-16-52-43 pp6,500,U,D,D nothing; comm.interf. 393M W2007-11-13-17-07-33 pp6,250,U,D,D 457M W2007-11-13-17-29-27 pp6,250,U,D,D time glitch 46534-46568 429M W2007-11-13-17-55-03 pp6,250,U,D,D 404M W2007-11-13-18-19-21 pp6,250,U,D,D time glitch 44368-44402 396M W2007-11-13-18-42-00 pp6,250,U,D,D time glitch 34727-34761 407M W2007-11-13-19-04-04 pp6,250,U,D,D time glitch 42266-42287 69M W2007-11-13-19-28-47 pp6,250,U,D,D ************************************************************************** nov16 (rf03): Total data: 917 MB Alg/Pulse Antennas Notes 129M W2007-11-16-17-01-10 spp,500,U time glitch,nothing useful 243M W2007-11-16-17-54-32 spp,250,U 424M W2007-11-16-19-26-36 spp,250,U 121M W2007-11-16-22-07-36 spp,250,U pretty much nothing ************************************************************************** nov18 (rf04): Total data: 683 MB Alg/Pulse Antennas Notes 87M W2007-11-18-19-21-26 spp,250,U time glitches: 3557-3584: 1 sec 33079-33107: 2.8e7 82M W2007-11-18-19-54-19 spp,250,U time glitch, no useful signal 6574-6602: 1 sec 106M W2007-11-18-20-25-08 spp,250,U time glitch 6460-6487 2.8e7 94M W2007-11-18-21-05-09 spp,250,U time glitch, no useful signal 25096-25124: 1 sec 174M W2007-11-18-21-40-49 spp,250,U 86M W2007-11-18-22-46-51 spp,250,U time glitch 30274-30302-30330 2 sec(recover) 55M W2007-11-18-23-19-18 spp,250,U ************************************************************************** nov20a (rf05): Total data: 367 MB Alg/Pulse Antennas Notes 53M W2007-11-20-17-13-06 spp,250,U nothing 99M W2007-11-20-17-33-12 spp,250,U 91M W2007-11-20-18-10-39 spp,250,U 95M W2007-11-20-18-45-01 spp,250,U nothing,time glitch 58185-58213 10^7 30M W2007-11-20-19-33-49 spp,250,U nothing ************************************************************************** nov20b (rf05): Total data: 488 MB Alg/Pulse Antennas Notes 80M W2007-11-20-21-20-47 spp,250,U 94M W2007-11-20-21-50-59 spp,250,U time glitch 30326-30353 +10^7 91M W2007-11-20-22-26-28 spp,250,U 85M W2007-11-20-23-00-41 spp,250,U 140M W2007-11-20-23-32-55 spp,250,U ************************************************************************** nov29 (rf06): Total data: 4.7 GB Alg/Pulse Antennas Notes 108M W2007-11-29-14-37-41 spp,250,U on the ground before takeoff time glitches: 14105-14133,14139-14167 19875-19902,19911-19939 494M W2007-11-29-16-19-27 pp6,U,D,D time glitch(16:29:49-16:29:50): 22826-22861,22871-22906 388M W2007-11-29-16-47-03 pp6,U,D,D time glitch(16:59:09-16:59:11): 26479-26514 525M W2007-11-29-17-08-43 pp6,U,D,D 436M W2007-11-29-17-39-00 pp4,U,D 28M W2007-11-29-18-22-10 pp8,U,D no useful signal 220M W2007-11-29-18-26-02 pp6,U,D,D 445M W2007-11-29-18-38-41 pp8,U,D time glitches(18:40:44,19:06:42,19:14:01) 4209-4236,4258-4285 46023-46050,46072-46099 57876-57903 1sec 110M W2007-11-29-19-24-52 pp8,U,D 454M W2007-11-29-19-36-37 pp6,U,D,D 229M W2007-11-29-20-28-59 pp6,U,D,D 1.1G W2007-11-29-20-42-50 pp4,U,D beam calibration data (ground) time glitch(20:43:41,20:46:37): 3652 +60 ms 11105-11147 Acqtime=14ms: mode fixed(Nov 30) 225M W2007-11-29-21-16-46 pp4,U,D beam calibration data (ground) time glitch(21:21:43-21:21:46): 10257-10288, 10294-10325 ************************************************************************** nov30 (rf07): Total data: 4.1 GB Alg/Pulse Antennas Notes 343M W2007-11-30-16-06-29 pp4,U,D gap: 16:19:20,16:25:35 2sec gap: 16:27:45 10s (DSP Q-full ?) 480M W2007-11-30-16-41-43 pp6,U,D,D 431M W2007-11-30-17-09-35 pp6,U,D,D 274M W2007-11-30-17-34-06 pp4,U,D gap: 17:56:45 12 sec (DSP Q-full) 157M W2007-11-30-18-02-09 pp6,U,D,D 165M W2007-11-30-18-11-49 pp6,U,D,D gap: 18:19:20 2 sec (DSP Q-full) 526M W2007-11-30-18-21-27 pp6,U,D,D time glitch: 60689-60724,60743-60778 ~1e7 431M W2007-11-30-18-50-47 pp6,U,D,D 456M W2007-11-30-19-14-53 pp6,U,D,D 460M W2007-11-30-19-40-20 pp6,U,D,D time glitch: 20-40 ~1e7 36317-36352,36373-36408 ~1e7 409M W2007-11-30-20-06-00 pp6,U,D,D ************************************************************************** dec04 (rf08): Total data: 1.8 GB Alg/Pulse Antennas Notes 432M W2007-12-04-17-35-41 pp6,U,D,D gap: 17:40 140ms (DSP Q-full) 165M W2007-12-04-18-01-46 pp6,U,D,D 227M W2007-12-04-18-11-36 pp8,U,D nothing useful,time glitches: 6627-6654, 6664-6691 ~1e7 20185-20212, 20219-20246 ~1e7 465M W2007-12-04-18-35-04 pp8,U,D time glitch: 4152- 4179, 4182- 4209 10020-10047, 10072-10099 35998-36025-36053 ~1e7 (new event) 65109-65136, 65155-65182 119M W2007-12-04-19-30-27 pp6,U,D,D nothing useful, comm. interf. 43M W2007-12-04-19-37-06 pp6,U,D,D nothing useful, Tx shutdown:193745-3810 301M W2007-12-04-19-43-31 pp6,U,D,D time glith: 19:58 30-31 30709-30748-30783 ~1s (new event) ************************************************************************** dec10 (rf09): Total data: GB Alg/Pulse Antennas Notes 309M W2007-12-10-17-04-31 pp8,U,D 535M W2007-12-10-17-37-17 pp6,U,D,D 370M W2007-12-10-18-08-05 pp8,U,D 108M W2007-12-10-18-46-34 pp8,U,D 483M W2007-12-10-18-58-07 pp6,U,D,D 476M W2007-12-10-19-24-59 pp6,U,D,D ************************************************************************** dec11 (rf10): Total data: 4.4 GB Alg/Pulse Antennas Notes 735M W2007-12-11-19-13-00 pp6,U,D,D time glitches: 36325-36435 42280-42310 65020-65120 240M W2007-12-11-19-54-05 pp6,U,D,D 371M W2007-12-11-20-07-27 pp6,U,D,D 474M W2007-12-11-20-28-09 pp6,U,D,D 151M W2007-12-11-20-54-36 pp6,U,D,D 443M W2007-12-11-21-03-01 pp6,U,D,D 615M W2007-12-11-21-27-47 pp6,U,D,D 525M W2007-12-11-22-02-08 pp6,U,D,D time glitch: 61001-61035 1 sec 364M W2007-12-11-22-31-26 pp6,U,D,D straight leg in precip 22:45-22:53 the AC is too close to cloud top 551M W2007-12-11-22-51-46 pp6,U,D,D VAD spiral(2 circ): 22:53:35-22:59:10 ************************************************************************** dec13 (rf11): Total data: 3.4 GB Alg/Pulse Antennas Notes 440M W2007-12-13-16-12-12 pp6,U,D,D ground only (climb after takeoff) 141M W2007-12-13-16-37-20 pp4,U,D 509M W2007-12-13-16-50-46 pp8,U,D 379M W2007-12-13-17-43-34 pp8,U,D 457M W2007-12-13-18-22-48 pp8,U,D time glitch: 51435-51462,51466-51493 561M W2007-12-13-19-10-39 pp4,U,D 599M W2007-12-13-19-59-50 pp4,U,D 333M W2007-12-13-20-52-17 pp4,U,D ************************************************************************** dec16 (rf12): Total data: 1.5 GB Alg/Pulse Antennas Notes 190M W2007-12-16-16-48-02 pp4,U,D 483M W2007-12-16-17-07-46 pp4,U,D vnoise4 spike 446M W2007-12-16-17-50-25 pp8,U,D 42M W2007-12-16-18-37-00 pp4,U,D 38M W2007-12-16-18-41-34 pp6,U,D,D 260M W2007-12-16-18-44-08 pp8,U,D ................................................................................ Terminology and other notes: Other Notes: * WCR data acquisition system (DAQ) records time stamps from the vxi IRIG card which is slaved to the master C130 data system time server. The recorded time stamps are UTC time. * The zero range gate, when at 75 m, is contaminated with the transmitter pulse leakage which appears at levels as high as -35 dBm@500ns (+15 dBZ). On the other hand very stong returns at 0 and 1st range gates are slightly undervalued (1 dB or less) due to receiver protection switches still residually closed. This range is in the far field for the two 12" 'down-pointing' antennas. Far fields for the 15" 'up' antenna is 91 m. * When maximum unambiguous range is 7.5 km, the data can be contaminated from second trip echoes, mostly from surface. * Average DSP jumps (data jumps between two consecutive profiles due to data acquisition DSPs) are mostly near zero for low power returns but frequently high power return (as indicated by the leak) exhibit jumps as high as 1-2 dB and thus averaging at least two profiles is recommended to reduce calibration errors. Terminology used to acknowledge data quality for each data file reported under Data file indormation: 1) SPIKES are defined as short lasting (less than a few secs), large excursions in positive or negative direction (higher than 2-3 dB). 2) ELEVATED NOISE (including short spikes) is defined as occasional change in the mean noise that exceeds 2-3 dB and lasts from fraction of a second to more than a minute. It is usually associated with ground hits and/or multi-trip echoes. It is observed for side looking mode only. 3) NOISE JUMPS/SPIKES (up to 10-20 sec). Probably some sort of short interference not necessarily in both channels and in some cases associated with the mirror position change or A/C radio communications at freqs close to 120MHz 3) NOISE DRIFT is up to 2dB slow drift in the noise channel; likely due to drift in the receivers gain. Usually it does not exceed 0.5 dB. 4) BAD DATA refer to corrupted data or improbable data behavior. 5) DATA SHIFT means that all data channels are shifted one range gate to the right for one or both of the DSPs. 6) DATA GAPS: gaps between profiles exceeding several times the average time interval between profiles 7) TIME STAMP ERROR: known fixed shift in the time stamps. 8) TIME JUMPS/GLITCHES: sync problem in the time which results in time stamps jumps including negative jumps 9) DATA DISCONTINUITY: unexpected jumps in reflectivity occurring thru all range gates from one profile to another. 10) V/H-MISSING or V/H severely attenuated reffer to unidentified problem causing severe attanuation or lack of signal from a target