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GLA15 Records: Release 33

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 ocean range 176 i4b(40) 160
i_lon Coordinate data, longitude, specific to ocean range 336 i4b(40) 160
i_elev Ocean 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 i2b(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_spare45 Spare 45 1416 i1b(40) 40
i_spare46 Spare 46 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 Solid earth tide elevation (at first and last shot) 2680 i2b(2) 4
i_spElv Tide elevations, specific 2684 i2b(4) 8
i_ldElv Load tide elevation 2692 i2b(4) 8
i_bathyElv Bathymetry Elevation 2700 i4b 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_Spare3 Spares 2789 i1b(3) 3
i_MSS_elv Mean Sea Surface Elevation 2792 i4b(40) 160
i_refRng Reference range 2952 i4b(40) 160
i_TrshRngOff Threshold retracker range offset 3112 i4b(40) 160
i_ocRngOff Ocean range offset 3272 i4b(40) 160
i_SigEndOff Signal end range offset 3432 i4b(40) 160
i_cntRngOff Centroid range offset 3592 i4b(40) 160
i_reflctUC reflctUC 3752 i4b(40) 160
i_reflCor_atm Reflectance correction, atmosphere 3912 i4b 4
i_maxSmAmp Peak amplitude of smoothed received echo 3916 i2b(40) 80
i_ocElv Ocean tide elevation (at first and last shot) 3996 i2b(40) 80
i_numPk Number of peaks found in the return 4076 i1b(40) 40
i_skew2 Skewness 4116 i2b(40) 80
i_OcRufRMS RMS of elevations used for 1-sec mean elevation 4196 i4b 4
i_OcMeanElev Mean elevation over 1 sec 4200 i4b 4
i_lowElev Lowest elevation 4204 i4b(40) 160
i_highElev Highest elevation 4364 i4b(40) 160
i_OceanVar Standard deviation of the ocean Gaussian fit 4524 i2b(40) 80
i_ElvuseFlg Elevation use flag (view byte structure) 4604 i1b(5) 5
i_atm_avail Atmosphere availaility flag (view byte structure) 4609 i1b 1
i_spare16 Spare 16 4842 i1b(4) 4
i_cld1_mswf Cloud multiple scattering warning flag (view byte structure) 4614 i1b 1
i_MRC_af Medium resolution cloud availability flag (view byte structure) 4615 i1b 1
i_spare9 spares 4616 i1b(40) 40
i_ElvFlg Elevation definition flag (view byte structure) 4656 i1b(40) 40
i_rng_UQF Range offset quality/use flag. (view byte structure) 4696 i2b(40) 80
i_spare49 Spare 49 4776 i1b(10) 10
i_timecorflg Time correction flag (view byte structure) 4786 i2b 2
i_APID_AvFlg APID data availability flag (view byte structure) 4788 i1b(8) 8
i_AttFlg2 Attitude flag 2 (view byte structure) 4796 i1b(20) 20
i_spare5 Spares 4816 i1b 1
i_FrameQF Altimeter frame quality flag (view byte structure) 4817 i1b 1
i_OrbFlg POD flag (orbit flag) (view byte structure) 4818 i1b(2) 2
i_rngCorrFlg Range correction flag (view byte structure) 4820 i1b(2) 2
i_CorrStatFlg Correction status flag (view byte structure) 4822 i1b(2) 2
i_spare15 Spare 15 4824 i1b(8) 8
i_AttFlg1 Attitude flag 1 (view byte structure) 4832 i2b 2
i_Spare6 Spares 4834 i1b(2) 2
i_satNdx Saturation Index 4836 i1b (40) 40
i_satElevCorr Saturation Elevation Correction 4876 i2b (40) 80
i_satCorrFlg Saturation Correction Flag (view byte structure) 4956 i1b (40) 40
i_satNrgCorr Saturation Energy Correction 4996 i2b (40) 80
i_kurt2 Kurtosis of the Received Echo (standard) 5076 i2b (40) 80
i_gval_rcv Gain Value used for Received Pulse 5156 i2b (40) 80
i_RecNrgAll Received Energy signal begin to signal end 5236 i2b (40) 80
i_FRir_cldtop Full Resolution 1064 Cloud Top 5316 i2b (40) 80
i_FRir_qaFlag Full Resolution 1064 Quality Flag (view byte structure) 5396 i1b (40) 40
i_atm_char_flag Atmosphere Characterization Flag 5436 i2b 2
i_atm_char_conf Atmosphere Characterization Flag Confidence 5438 i2b 2
i_spare48 Spare 48 5440 i1b(36) 36
i_FRir_intsig Full Resolution 1064 Integrated Signal 5476 i2b (40) 80
i_spare14 Spares 5556 i1b (120) 120
i_Surface_temp Surface Temperature 5676 i2b 2
i_Surface_pres Surface Pressure 5678 i2b 2
i_Surface_relh Relative Humidity 5680 i2b 2
i_Surface_wind Surface Wind Speed 5682 i2b 2
i_Surface_wdir Surface Wind Direction Azimuth from North 5684 i2b 2
i_maxRecAmp Max Amplitude of Received Echo 5686 i2b (40) 80
i_sDevNsOb1 Standard deviation of 1064 nm background noise (alternate) 5766 i2b (40) 80
i_spare4 Spares 5846 i1b (160) 160
i_pctSAT Percent saturation 6006 i1b (40) 40
i_TxNrg 1064 nm laser transmit energy 6046 i2b (40) 80
i_eqElv Equilibrium tide elevation (at first and last shot) 6126 i2b (2) 4
i_spare2 Spare 2 6130 i1b (2) 2
i_gASP Global Mean Atmospheric Pressure 6132 i4b 4
i_Spare7 Spare 7 6136 i1b (144) 144

Page last updated: 01/11/13