GLA14 Records

Follow the links in the table below to the GLAS Altimetry Data Dictionary for details of each record, including units and scaling factors. The GLAS science team created this dictionary. Units and scaling factors with a "d" indicate double-precision constants; for example, a value of "1.0d5" is equivalent to 100,000. Nearly all integers are signed; exceptions are noted below.

The following codes are used to denote data types throughout the remainder of this document.

i1b: 1-byte integer
i2b: 2-byte (short) integer
i4b: 4-byte (long) integer
r4b: 4-byte real
r8b: 8-byte real

Values in parentheses indicate the record size, for example:

i2b(39): 39 records of 2-byte integers
i1b(48,40): 48-record x 40-record array of 1-byte integers

When comparing data from different products, the record index is consistent as long as all products represent the same release of data. If you want to compare different products with different releases, you should update your oldest product to the latest release. For example, if you want to compare data from a GLA05 Release-12 file and GLA12 Release-18 file, you should order a new GLA05 Release-18 file to replace the older release. The ICESat/GLAS Data Releases page describes characteristics and temporal coverage of each version of data.

Name Short Description Byte Offset Data Type Total Bytes
i_rec_ndx GLAS record index 0 i4b 4
i_UTCTime Transmit time of first shot in frame in J2000 4 i4b(2) 8
i_transtime One-way transmit time 12 i2b 2
i_Spare1 Spares 14 i1b(2) 2
i_deltagpstmcor Delta GPS time correction 16 i4b 4
i_dShotTime Laser shot time deltas (shots 2-40) 20 i4b(39) 156
i_lat Coordinate data, latitude, specific to land range 176 i4b(40) 160
i_lon Coordinate data, longitude, specific to land range 336 i4b(40) 160
i_elev Land surface elevation 496 i4b(40) 160
i_campaign Campaign 656 i1b(2) 2
i_spare40 i_spare40 658 i2b 2
i_cycTrk Cycle and Track 660 i4b 4
i_localSolarTime Local apparent solar time 664 i4b 4
i_spare41 Spare 41 668 i4b(7) 28
i_deltaEllip Delta Ellipsoid 696 i4b(40) 80
i_beamCoelv Co-elevation 776 i4b(40) 160
i_beamAzimuth Azimuth 936 i4b(40) 160
i_d2refTrk Distance to the reference ground track 1096 i4b(40) 160
i_SigBegOff Signal Begin Range Increment 1256 i4b(40) 160
i_DEM_hires_src High Resolution Source Flag 1416 i1b(40) 40
i_DEMhiresArElv DEMhiresArElv 1456 i2b(9,40) 720
i_ElevBiasCorr Elevation Bias Correction 2176 i2b(40) 80
i_spare42 Spare 42 2256 i2b(4,40) 320
i_sigmaatt Attitude quality indicator 2576 i2b(40) 80
i_Azimuth Local azimuth 2656 i4b 4
i_SolAng Solar incidence angle 2660 i4b 4
i_tpintensity_avg Transmit pulse intensity - frame average 2664 i4b 4
i_tpazimuth_avg Transmit pulse azimuth - frame average 2668 i2b 2
i_tpeccentricity_avg Transmit pulse eccentricity - frame average 2670 i2b 2
i_tpmajoraxis_avg Transmit pulse major axis - frame average 2672 i2b 2
i_poleTide Pole Tide 2674 i1b(2) 2
i_gdHt Geoid 2676 i2b(2) 4
i_erElv Earth Tide Elevation 2680 i2b(2) 4
i_spElv Tide elevations, specific 2684 i2b(4) 8
i_ldElv Load tide elevation 2692 i2b(4) 8
i_spare12 Spares 2700 i2b(2) 4
i_wTrop Range correction - wet troposphere 2704 i2b(2) 4
i_dTrop Range correction - dry troposphere 2708 i2b(40) 80
i_surfType Region type (view byte structure) 2788 i1b 1
i_spare11 Spare 11 2789 i1b (3) 3
i_DEM_elv DEM elevation 2792 i4b(40) 160
i_refRng Reference range 2952 i4b(40) 160
i_spare47 Spare 47 3112 i4b(40) 160
i_ldRngOff Land range offset 3272 i4b(40) 160
i_SigEndOff Signal end range offset 3432 i4b(40) 160
i_gpCntRngOff Centroid range increment for all six peaks 3592 i4b(6,40) 960
i_reflctUC reflctUC 3752 i4b(40) 160
i_reflCor_atm Reflectance correction, atmosphere 4712 i4b 4
i_maxSmAmp Peak amplitude of smoothed received echo 4716 i2b(40) 80
i_ocElv Ocean tide elevation (at first and last shot) 4796 i2b(40) 80
i_numPk Number of peaks found in the return 4876 i1b(40) 40
i_kurt1 Kurtosis of received echo (alternative) 4916 i2b(40) 80
i_skew1 Skewness of received echo (alternative) 4996 i2b(40) 80
i_spare4 Spares 5076 i1b(160) 160
i_Gamp Amplitude of Gaussians 5236 i4b(6,40) 960
i_Garea Area under Gaussian 6196 i4b(6,40) 960
i_Gsigma Sigma of Gaussians 7156 i4b(6,40) 960
i_nPeaks1 Initial number of peaks in received echo (alternative) 8116 i1b(40) 40
i_LandVar Standard deviation of the land Gaussian fit 8156 i2b(40) 80
i_ElvuseFlg Elevation use flag (view byte structure) 8236 i1b(5) 5
i_atm_avail Atmosphere availaility flag (view byte structure) 8241 i1b 1
i_spare16 Spare 16 4842 i1b(4) 4
i_cld1_mswf Cloud multiple scattering warning flag (view byte structure) 8246 i1b 1
i_MRC_af Medium resolution cloud availability flag (view byte structure) 8247 i1b 1
i_spare9 Spares 8248 i1b(40) 40
i_ElvFlg Elevation definition flag (view byte structure) 8288 i1b(40) 40
i_rng_UQF Range offset quality/use flag. (view byte structure) 8328 i2b(40) 80
i_spare49 Spare 49 8408 i1b(10) 10
i_timecorflg Time correction flag (view byte structure) 8418 i2b 2
i_APID_AvFlg APID data availability flag (view byte structure) 8420 i1b(8) 8
i_AttFlg2 Attitude flag 2 (view byte structure) 8428 i1b(20) 20
i_spare5 Spares 8448 i1b 1
i_FrameQF Altimeter frame quality flag (view byte structure) 8449 i1b 1
i_OrbFlg POD flag (orbit flag) (view byte structure) 8450 i1b(2) 2
i_rngCorrFlg Range correction flag (view byte structure) 8452 i1b(2) 2
i_CorrStatFlg Correction status flag (view byte structure) 8454 i1b(2) 2
i_spare15 Spare 15 5056 i1b(8) 8
i_AttFlg1 Attitude flag 1 (view byte structure) 8464 i2b 2
i_Spare6 Spares 8466 i1b(2) 2
i_spare44 Spare 44 5068 i1b (120) 120
i_satNdx Saturation Index 8588 i1b (40) 40
i_satElevCorr Saturation Elevation Correction 8628 i2b (40) 80
i_satCorrFlg Saturation Correction Flag (view byte structure) 8708 i1b (40) 40
i_satNrgCorr Saturation Energy Correction 8748 i2b (40) 80
i_spare13 Spares 8828 i2b (40) 80
i_gval_rcv Gain Value used for Received Pulse 8908 i2b (40) 80
i_RecNrgAll Received Energy signal begin to signal end 8988 i2b (40) 80
i_FRir_cldtop Full Resolution 1064 Cloud Top 9068 i2b (40) 80
i_FRir_qaFlag Full Resolution 1064 Quality Flag (view byte structure) 9148 i1b (40) 40
i_atm_char_flag Atmosphere Characterization Flag 6068 i2b 2
i_atm_char_conf Atmosphere Characterization Flag Confidence 6070 i2b 2
i_spare48 Spare 48 6072 i1b(36) 36
i_FRir_intsig Full Resolution 1064 Integrated Signal 9228 i2b (40) 80
i_spare14 Spares 9308 i1b (120) 120
i_Surface_temp Surface Temperature 9428 i2b 2
i_Surface_pres Surface Pressure 9430 i2b 2
i_Surface_relh Relative Humidity 9432 i2b 2
i_maxRecAmp Max Amplitude of Received Echo 9434 i2b (40) 80
i_sDevNsOb1 Standard deviation of 1064 nm background noise (alternate) 9514 i2b (40) 80
i_spare8 Spares 9594 i1b (2) 2
i_isRngOff Ice sheet range offset 9596 i4b(40) 160
i_pctSAT Percent saturation 9756 i1b (40) 40
i_TxNrg 1064 nm laser transmit energy 9796 i2b (40) 80
i_eqElv Equilibrium tide elevation (at first and last shot) 9876 i2b (2) 4
i_spare7 Spares 9880 i1b (120) 120

Page last updated: 01/11/13