================================================================================ APEX19 WCR Level 1 Processed Data Directory Catalog ================================================================================ Last Update: 29 May 2019 ................................................................................ Directory FileDescriptors Comment Total Size File Size WCR.ExpName.YYYYMMDD...nc Antenna ID: H0: side beam h-pol H1: up beam h-pol V0: side beam v-pol V1: up beam v-pol H2: down_fore antenna V2: down antenna ................................................................................ rf01_may07 total 1.8 GB 1.1G WCR_L1.APEX19.20190507.015816_022206.CPP-H1V2H2.nc 687M WCR_L1.APEX19.20190507.022205_023736.CPP-H1V2H2.nc ................................................................................ rf02_may10 total 0.9 GB 928M WCR_L1.APEX19.20190510.034345_040442.CPP-H1V2H2.nc ................................................................................ rf03_may14 total 1.9 GB 1.1G WCR_L1.APEX19.20190514.031607_033957.CPP-H1V2H2.nc 847M WCR_L1.APEX19.20190514.033956_035903.CPP-H1V2H2.nc ................................................................................ rf04_may17 total 1.9 GB 1.1G WCR_L1.APEX19.20190514.031607_033957.CPP-H1V2H2.nc 847M WCR_L1.APEX19.20190514.033956_035903.CPP-H1V2H2.nc ................................................................................ rf05_may20 total 1.9 GB 1.1G WCR_L1.APEX19.20190517.032104_034454.CPP-H1V2H2.nc 886M WCR_L1.APEX19.20190517.034453_040453.CPP-H1V2H2.nc ................................................................................ rf06_may22 total 0 GB - radar data not recorded ................................................................................ rf07_may24 total 5.1 GB 1.1G WCR_L1.APEX19.20190524.030535_032924.CPP-H1V2H2.nc 1.1G WCR_L1.APEX19.20190524.032923_035313.CPP-H1V2H2.nc 1.1G WCR_L1.APEX19.20190524.035312_041702.CPP-H1V2H2.nc 1.1G WCR_L1.APEX19.20190524.041701_044050.CPP-H1V2H2.nc 1.0G WCR_L1.APEX19.20190524.044049_050329.CPP-H1V2H2.nc ................................................................................ rf08_may28 total 2.2 GB 1.1G WCR_L1.APEX19.20190528.031516_033906.CPP-H1V2H2.nc 1.1G WCR_L1.APEX19.20190528.033905_040254.CPP-H1V2H2.nc 63M WCR_L1.APEX19.20190528.040253_040419.CPP-H1V2H2.nc ................................................................................ rf09_may29 total 2.9 GB 1.1G WCR_L1.APEX19.20190529.031920_034310.CPP-H1V2H2.nc 1.1G WCR_L1.APEX19.20190529.034309_040659.CPP-H1V2H2.nc 776M WCR_L1.APEX19.20190529.040658_042429.CPP-H1V2H2.nc ................................................................................ The files listed above can be requested via a data request form on the WCR web page (select Data link under User Information). 672K WCR_L1_UserNotes.pdf WCR data user manual 37K WCR_L1_APEX19.20171117.cdl Processing cdl file 18K wcr3conf_apex19.pro WCR configuration file ................................................................................ ================================================================================ APEX19 WCR L1 Processed Data Files Release Notes ================================================================================ * Revision history: = RevisionDate: = RevisionNumber = 1 = Revision_1: Reflectivity, Doppler velocity = ProcessAuthor: Samuel Haimov (haimov@uwyo.edu, atsc-kapm@uwyo.edu) * All WCR Level 1 data product files (L1 processed data) are in NetCDF 3.5 and are cataloged above. Additional information about the variables and attributes in the files is provided in the netcdf prototype file WCR_L1_....cdl Detailed information about the radar configuration and calibration is given in wcr3conf_....pro. Short user manual about the radar processed data is available in WCR_L1_UserNotes.pdf * The data files are saved in L1/ sub-directories rfXX_mmmDD representing the research flight number and month and date of the flight using the WCR. * Quick looks of radar reflectivity and radial Doppler velocity corrected for the radar platform motion contribution are available via the WCR web project pages. The quick looks are located in directories named the same as the processed data directories (rfXX_mmmDD). The quick look images show only pixels for targets with reflectivity exceeding 3 standard deviations above the mean noise. The up- and down-pointing beam images, whenever both are availabe, are combined in a single image. The data is interpolated to represent the target in a vertical plane in altitude, but the velocities are not corrected for contamination from the horizontal wind (if any). The flight level is marked as black dotted line in the image. The area around the flight level without any signal represents the radar "blind" zone, which is about 100 m, depending on the transmitted pulse width. The sub-terrain pixels (when shown) are plotted in black. The immediate 75 m (150 m) above the surface for the down (down-slant) beam image are void of showing any targets. This is done to emphasize the possibility of ground clutter in the return from this near surface layer. Other markings are also possible. Currently, when requested, we mark pixels (with diamonds) in the reflectivity image affected by a reciever saturation. Areas where the down and/or up beam deviate from vertical more than 10 degrees are highlighted along the flight level trace with black squares (frequently it plots as a thick black line). This happens when the aircraft is flying with very large pitch and/or is in turn. For flights below 2.5 km above the surface the strong return from the surface may exceed the cross-channel(antenna) isolation. In the quick looks the pixels that may be affected are blanked out. This happens exclusively for the side/up antenna image with a leak from the down antenna surface return (for more see Reflectivity factor notes below). The ground return in dBZ may slso be plotted (for the up/down reflectivity only) as a straight tick line below the surface cross section (in black) and just above the time axis. * Known specifics of the data in this revision Reflectivity factor: = Reflectivity absolute accuracy is estimated at better than 3 dB. The precision for the full received power dynamic range of the radar is expected to be less than 1 dB. The received power from the up-pointing antenna has been calibrated with a corner reflector with expected accuracy better than 1.5 dB. The down and down-slant channels are calibrated relative to the up-antenna channel using weather targets. The additional uncertainty for the down antenna and down-fore antennas antennas w.r.t. the up antenna is about 1.0 and 1.5 dB, respectively. = Reflectivity of the 1st (closest) range (~105 m for 250 ns pulse) for any of the antennas could be slightly underestimated due to receivers not fully open in receive mode. The error is 1 dB or less. = The receiver stability is better than 0.5 dB/hour when the ambient temperature does not change more than 5 degC/hour. = The transmitter leak to the first few range gates of the received signals is small (estimated to less than 0.3dB above the mean noise) or not detectable. = No receiver saturation is expected from weather target = Cross-antenna talk is possible. Strong down-fore antenna targets may leak to the up antenna return and strong down antenna targets may leak into the down-fore antenna return. The most frequent cross-talk contamination is from surface returns from the down antenna, but is typically below 3 standard devitions of the noise. = Reflectivity in a few range gates above the surface returns (if any) may be cluttered by the surface or near surface targets (typically this is less than 150 m for the down-slant beam and 75 m for the down beam). The clutter is more pronounced for the slant beam. = Reflecitvity is not corrected for attenuation due to absorption and scattering. It could be significant in the presence of cloud liquid water and precipitation. Velocity: = Corrected Doppler velocity from the down-pointing beams may have bias of up to +- 1.0 m/s and uncertainty of up to +-1.0 m/s. Typical bias and uncertainty are less than +-0.5 m/s. It is our belief that the bias is mainly due to changes in the antennas pointing angles caused by flexing of the aircraft fuselage not represented in the IRS data. In addition the fuselage expands with altitude and this also changes slightly the antenna pointing directions. = Corected Doppler velocity accuracy from the up-pointing antenna is not quantified with a known reference target. The analysis of appropriate weather targets suggests a maximum bias of less than 1 m/s. = The errors in the beam pointing angles for the up and down beams as well as some other errors lead to possible discontinuity in the mean vertical Doppler velocity profile at the flight level. The discrepancy is generally less than 0.3 m/s and typically within 0.1 m/s. It is not established which beam is contributing more to this error. Given that the aircraft may flex/expand differently at the up/side antenna location and the two down antenna locations as well as the dependence of these distortions on the altitude and attitude of the aircraft there is no single optimal correction (optimal single set of beam angles) for all conditions. = The Doppler data occasionally exhibit folded velocity regions (mostly in the slanted beam return). We do not make an attempt to unfold due to difficulties of automating this process. Typically unfolding any specific data segment is not difficult. For help on this you may contact Samuel Haimov (haimov@uwyo.edu). * Known corrupted data not fixed in this revision: = No known corrupted data ================================================================================