SGP/RL/C1 - Interference filter replaced temporarily

The sensitivity of the Raman lidar has been degrading since the fall of 2005.  One 
possible source of the degradation is the interference filters; i.e., their transmission could 
be becoming smaller for some reason.  To evaluate this hypothesis, we removed the 
interference filter from the narrow field-of-view nitrogen channel (i.e., the N2 high channel) on 
3/9/2007, and replaced it with its spare.  

The original filter was sent to the manufacturer for evaluation.  Its transmission was 
measured by the manufacturer to be nearly identical to its original performance; in other 
words, the filter is not responsible for the lidar's loss of sensitivity.  The original 
interference filter was reinstalled in the system on 3/23/2007.  

The temporary use of the spare interference filter in the high N2 channel should not 
affect the data quality, as the transmission characteristics of the spare and the original 
filter are nearly identical.

• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_1 profile(aod_1_max_ht)
• Uncertainty of the aerosol extinction coefficient profile calculated from the
  aerosol backscatter coefficient(extinction_from_backscatter_error)
• Aerosol extinction coefficient profile from the high N2 channel data(extinction_high)
• Aerosol extinction coefficient profile created by marrying the merged extinction
  from N2 data with the extinction from backscatter data(extinction_married1)
• Uncertainty of the aerosol extinction coefficient profile from the low N2
  channel(extinction_low_error)
• Error in the aerosol optical depth calculated from the
  extinction_from_backscatter profile(aod_bscat_error)
• Vertical resolution of the low aerosol extinction coefficient profile data(extinction_low_resolution)
• Ratio of aerosol extinction to aerosol backscatter(Sa_1)
• Aerosol optical depth from the surface computed from the married1 extinction
  profiles(aod_married1_profile)
• Ratio of aerosol extinction to aerosol backscatter(Sa_2)
• Number of lidar pulses summed(shots_summed)
• Aerosol optical depth calculated from the extinction_from_backscatter profile(aod_bscat)
• -180.0 - +180.0(alt)
• North Latitude(lat)
• Vertical resolution of the high aerosol extinction coefficient profile data(extinction_high_resolution)
• Aerosol optical depth calculated from the extinction_married1 profile(aod_married1)
• Error in the aerosol optical depth calculated from the extinction_married1
  profile(aod_married1_error)
• Uncertainty of the aerosol extinction coefficient profile from the high N2
  channel(extinction_high_error)
• Aerosol extinction coefficient profile calculated from backscatter and the
  extinction-to-backscatter ratio(extinction_from_backscatter)
• Aerosol optical depth from the surface computed from the extinction_1 profiles(aod_1_profile)
• lon(lon)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Mask indicating from where the extinction value came from in the aerosol
  extinction coefficient profile created by marrying the merged extinction from N2
  data w(extinction_married1_mask)
• Uncertainty of the aerosol extinction coefficient profile created by merging the
  two N2 channels extinction profiles(extinction_1_error)
• Vertical resolution of the merged aerosol extinction coefficient profile data(extinction_1_resolution)
• Aerosol optical depth from the surface computed from the
  extinction_from_backscatter profiles(aod_bscat_profile)
• Error in the aerosol optical depth calculated from the extinction_1 profile(aod_1_error)
• Aerosol backscatter coefficient at 355 nm - smoothed to N2 extinction resolution(smoothed_backscatter)
• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_from_backscatter profile(aod_bscat_max_ht)
• Aerosol extinction coefficient profile from the low N2 channel data(extinction_low)
• Uncertainty of the married aerosol extinction coefficient profile(extinction_married1_error)
• Uncertainty in the aerosol backscatter coefficient at 355 nm(backscatter_error)
• Mode index(mode)
• Height range of the high channel aerosol scattering ratio profile(height_high)
• Uncertainty in the aerosol backscatter coefficient at 355 nm - smoothed to N2
  extinction resolution(smoothed_backscatter_error)
• Time offset from base_time(time_offset)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Maximum altitude used in the calculation of the aerosol optical depth from the
  extinction_married1 profile(aod_married1_max_ht)
• base time in epoch(base_time)
• Height range of the low channel aerosol scattering ratio profile(height_low)
• Aerosol extinction coefficient profile created by merging the two N2 channels
  extinction profiles(extinction_1)
• Aerosol optical depth calculated from the extinction_1 profile(aod_1)
• Uncertainty of the aerosol extinction coefficient profile from the overlap
  corrected high N2 channel(extinction_high_olap_corrected_error)
• Aerosol extinction coefficient profile from the high N2 channel data, where the
  low N2 channel was used to correct for the overlap of the high channel(extinction_high_olap_corrected)
• Average laser energy of the ensemble shots(average_energy)

• Aerosol scattering ratio profile created by merging the two Calibrated channels(cal_asr_1)
• Scale factor added to the low aerosol scattering ratio at each time sample(scale_add_lo)
• Vertical scale factor for statistical T-test sanity check on high channel data(vert_scale_hi_2)
• Uncertainty of the Calibrated aerosol scattering ratio profile from the low
  channel(cal_asr_error_low)
• Uncertainty of the aerosol scattering ratio profile from the high channel(asr_error_high)
• Calibration factor applied to the low aerosol scattering ratio at each time
  sample(cal_factor_lo)
• North Latitude(lat)
• Calibrated Aerosol scattering ratio profile from the low channel(cal_asr_low)
• -180.0 - +180.0(alt)
• Aerosol backscatter coefficient uncertainty(bscat_err)
• lon(lon)
• Scale factor added to the high aerosol scattering ratio at each time sample and
  height(scale_add_hi)
• Average laser energy of the ensemble shots(average_energy)
• Temperature used for calculation(temperature)
• Aerosol scattering ratio profile from the low channel(asr_low)
• Height range of the low channel aerosol scattering ratio profile(height_low)
• Differential transmission correction for aerosols(diff_trans_aerosol_corr)
• Type of calibration used to compute the high channel calibration at each time
  interval(hi_cal_type)
• Aerosol volume backscattering coefficient at 355 nm(backscatter)
• Uncertainty of the aerosol scattering ratio profile created by merging the two
  channels(asr_1_error)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Vertical scale factor to make shape of high channel profile match low channel(vert_scale_hi)
• Uncertainty of the aerosol scattering ratio profile created by merging the two
  Calibrated channels(cal_asr_1_error)
• Number of lidar pulses summed(shots_summed)
• Height range of the high channel aerosol scattering ratio profile(height_high)
• Aerosol scattering ratio profile created by merging the two channels(asr_1)
• Calibrated Aerosol scattering ratio profile from the high channel(cal_asr_high)
• base time in epoch(base_time)
• Uncertainty of the Calibrated aerosol scattering ratio profile from the high
  channel(cal_asr_error_high)
• Uncertainty of the aerosol scattering ratio profile from the low channel(asr_error_low)
• Cloud mask(cloud_mask)
• Aerosol scattering ratio profile from the high channel(asr_high)
• Scale factor added to the high aerosol scattering ratio at each time sample and
  height (2nd iteration)(scale_add_hi_2)
• Time offset from base_time(time_offset)
• Corrected Aerosol volume backscattering coefficient at 355 nm - removed negative
  vals(corr_bscat)
• Calibration factor applied to the high aerosol scattering ratio at each time
  sample(cal_factor_hi)

• lon(lon)
• Water vapor mixing ratio profile from the low channel(mixing_ratio_low)
• Mode index(mode)
• Vertical resolution of bright mode (mode == 2) data(vertical_resolution_bright_mode)
• North Latitude(lat)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  channels(mixing_ratio_1_error)
• Random error in the precipitable water vapor observed by the Raman lidar(pwv_rl_err)
• Height(height)
• Water vapor mixing ratio profile created by merging the two calibrated channels
  together with the surface in-situ measurements(mixing_ratio_3)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  calibrated channels(mixing_ratio_2_error)
• Water vapor mixing ratio profile created by merging the two calibrated channels(mixing_ratio_2)
• Water vapor mixing ratio profile created by merging the two channels(mixing_ratio_1)
• Average laser energy of the ensemble shots(average_energy)
• Cloud base height(cloud_base_height_other)
• Time offset from base_time(time_offset)
• Suggested maximum altitude to use the water vapor data from the Raman lidar(wv_rl_max_height)
• Water vapor mixing ratio profile from the high channel(mixing_ratio_high)
• Uncertainty of the water vapor mixing ratio profile from the high channel(mixing_ratio_error_high)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Calibration factor used to match the high channel mixing ratio to the low
  channel mixing ratio(calib_high_low)
• Height range of the low channel aerosol scattering ratio profile(height_low)
• Number of lidar pulses summed(shots_summed)
• Uncertainty of the water vapor mixing ratio profile created by merging the two
  calibrated channels(mixing_ratio_3_error)
• Precipitable water vapor from microwave radiometer(pwv_mwr)
• Vertical resolution of normal mode (mode == 1) data(vertical_resolution_normal_mode)
• Calibration factor for entire profile(calib_factor)
• Flag indicating whether or not there was a sample from the temperature_source
  dataset during the lidars averaging interval (1) or not (0)(sample_times_other)
• Height range of the high channel aerosol scattering ratio profile(height_high)
• Derived pressure(pressure)
• Relative humidity over ice calculated from the merged water vapor mixing ratio
  data(relative_humidity_over_ice)
• Relative humidity calculated from the merged water vapor mixing ratio data(relative_humidity)
• base time in epoch(base_time)
• Differential transmission correction for aerosols(diff_trans_aerosol_corr)
• Water vapor mixing ratio(mixing_ratio_other)
• Cloud liquid water vapor by the microwave radiometer(liq_mwr)
• -180.0 - +180.0(alt)
• Fraction of the total precipitable water vapor in the column sensed by the Raman
  lidar(pwv_rl_fraction)
• Temperature used for calculation(temperature)
• Uncertainty of the water vapor mixing ratio profile from the low channel(mixing_ratio_error_low)
• Precipitable water vapor observed by the Raman lidar(pwv_rl)

• (Raw data stream - documentation not supported)

• Number of photons counted in the high nitrogen channel(nitrogen_counts_high)
• Number of laser shots recorded for the low elastic channel(shots_summed_elastic_low)
• Number of laser shots recorded for the low water channel(shots_summed_water_low)
• Nominal number of seconds of data acquired(acquisition_time)
• base time in epoch(base_time)
• Summed analog signal in the high depolarization channel(depolarization_analog_high)
• Count rate in the high depolarization channel(depolarization_counts_high)
• Count rate in the high water vapor channel(water_counts_high)
• Laser head in use(laser_head)
• Summed analog signal in the low elastic channel(elastic_analog_low)
• Number of laser shots recorded for the high depolarization channel(shots_summed_depolarization_high)
• time_in_seconds_since_volume_start(time)
• Number of laser shots recorded for the high elastic channel(shots_summed_elastic_high)
• Summed analog signal in the high water vapor channel(water_analog_high)
• -180.0 - +180.0(alt)
• Number of laser shots recorded for the high nitrogen channel(shots_summed_nitrogen_high)
• Number of photons counted in the high elastic (aerosol) channel(elastic_counts_high)
• North Latitude(lat)
• Temperature 5 inside the instrument enclosure(temp5)
• Supplemental 4(s4)
• Supplemental 5(s5)
• Temperature 6 inside the instrument enclosure(temp6)
• Temperature 3 inside the instrument enclosure(temp3)
• Supplemental 6(s6)
• Temperature 4 inside the instrument enclosure(temp4)
• Supplemental 7(s7)
• Temperature average, sensor 1(temp1)
• Supplemental 10(s10)
• Temperature average, sensor 2(temp2)
• Supplemental 1(s1)
• Supplemental 2(s2)
• Supplemental 3(s3)
• Wavelength of each of the 6 filters measured by the MFR radiometers(filter)
• Supplemental 8(s8)
• Supplemental 9(s9)
• Laser pulse energy(pulse_energy)
• Number of laser shots recorded for the high water channel(shots_summed_water_high)
• Summed analog signal in the high elastic channel(elastic_analog_high)
• Supplemental 11(s11)
• Supplemental 12(s12)
• Relative Humidity (hybrid-b grid)(rh)
• Number of photons counted in the low elastic (aerosol) channel(elastic_counts_low)
• Number of photons counted in the low water vapor channel(water_counts_low)
• Number of lidar pulses summed(shots_summed)
• Number of photons counted in the low nitrogen channel(nitrogen_counts_low)
• Summed analog signal in the low nitrogen channel(nitrogen_analog_low)
• N2 cloud check value(n2_cloud_check_value)
• Summed analog signal in the high nitrogen channel(nitrogen_analog_high)
• Cloud value check flag(cloud_value_check)
• lon(lon)
• Summed analog signal in the low water vapor channel(water_analog_low)
• Time offset from base_time(time_offset)
• Number of laser shots recorded for the low nitrogen channel(shots_summed_nitrogen_low)

• Cloud base height (for first cloud above height threshold)(cloud_base_height)
• lon(lon)
• Height(height)
• Linear depolarization ratio profile(depolarization_ratio)
• Cloud depth(cloud_depth)
• Average laser energy of the ensemble shots(average_energy)
• Cloud attenuation flag(attenuation_flag)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Altitude of cloud top used in retrieval(cloud_top_height)
• -180.0 - +180.0(alt)
• North Latitude(lat)
• Depolarization calibration factor(calibration_factor)
• Time offset from base_time(time_offset)
• Number of lidar pulses summed(shots_summed)
• Cloud optical thickness computed from aerosol (elastic) data(cloud_optical_thickness_aer)
• Cloud optical thickness computed from nitrogen data(cloud_optical_thickness_n2)
• Uncertainty of the linear depolarization ratio profile(depolarization_ratio_error)
• base time in epoch(base_time)
• Cloud mask(cloud_mask)

• Resolution of the aerosol extinction and backscatter profiles(extinction_resolution)
• Random error in the precipitable water vapor observed by the Raman lidar(pwv_rl_err)
• Aerosol optical depth uncertainty(aod_err)
• Maximum altitude used while computing AOD from the extinction profile(aod_max_height)
• Random error in the linear depolarization ratio profile(depol_err)
• Aerosol scattering ratio uncertainty(asr_err)
• Relative Humidity (hybrid-b grid)(rh)
• lon(lon)
• Aerosol backscatter coefficient at 355 nm(bscat)
• Temperature(t)
• Median vertical velocity(w)
• pressure(p)
• Average cloud base height used in the retrieval(cbh)
• Cloud mask from depolarization VAP(cmask)
• Aerosol optical depth at 355 nm(aod)
• Aerosol backscatter coefficient uncertainty(bscat_err)
• North Latitude(lat)
• -180.0 - +180.0(alt)
• base time in epoch(base_time)
• Water vapor mixing ratio from the 60 m tower(twr_w_60m)
• Precipitable water vapor from microwave radiometer(pwv_mwr)
• Time offset from base_time(time_offset)
• Flag indicating whether or not there was a sample from the temperature_source
  dataset during the lidars averaging interval (1) or not (0)(sample_times_other)
• Water vapor mixing ratio from the Raman lidar near 60 m(rl_w_60m)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Number of lidar pulses summed(shots_summed)
• Aerosol scattering ratio(asr)
• Water vapor mixing ratio error from the Raman lidar near 60 m(rl_w_60m_err)
• Resolution of the water vapor profiles(mixing_ratio_resolution)
• Circular depolarization ratio for particulate(depol)
• Aerosol extinction coefficient(ext)
• Precipitable water vapor observed by the Raman lidar(pwv_rl)
• Aerosol optical depth profiles at 355 nm(aod_profile)
• Resolution of the aerosol scattering ratio profile(scattering_ratio_resolution)
• Mode index(mode)
• Random error in the aerosol extinction coefficient profile(ext_err)
• Suggested maximum altitude to use the water vapor data from the Raman lidar(w_max_height)
• Fraction of the total precipitable water vapor in the column sensed by the Raman
  lidar(pwv_rl_fraction)
• Resolution of the depolarization ratio profile(depolarization_resolution)
• Cloud liquid water vapor by the microwave radiometer(liq_mwr)
• Average laser energy of the ensemble shots(average_energy)
• Height(height)
• Random error in the water vapor mixing ratio profile(w_err)

• Random error in the linear depolarization ratio profile(depol_err)
• Average cloud base height used in the retrieval(cbh)
• Fraction of the total precipitable water vapor in the column sensed by the Raman
  lidar(pwv_rl_fraction)
• Resolution of the depolarization ratio profile(depolarization_resolution)
• Precipitable water vapor from microwave radiometer(pwv_mwr)
• Water vapor mixing ratio from the Raman lidar near 60 m(rl_w_60m)
• Aerosol optical depth at 355 nm(aod)
• North Latitude(lat)
• Precipitable water vapor observed by the Raman lidar(pwv_rl)
• -180.0 - +180.0(alt)
• base time in epoch(base_time)
• Aerosol optical depth uncertainty(aod_err)
• Aerosol scattering ratio(asr)
• Maximum altitude used while computing AOD from the extinction profile(aod_max_height)
• Cloud liquid water vapor by the microwave radiometer(liq_mwr)
• Height(height)
• Water vapor mixing ratio error from the Raman lidar near 60 m(rl_w_60m_err)
• Aerosol extinction coefficient(ext)
• Median vertical velocity(w)
• Temperature(t)
• Random error in the aerosol extinction coefficient profile(ext_err)
• pressure(p)
• Aerosol backscatter coefficient uncertainty(bscat_err)
• Flag denoting the occurrence of power or alignment tweaks(tweaks)
• Resolution of the water vapor profiles(mixing_ratio_resolution)
• Time offset from base_time(time_offset)
• Number of lidar pulses summed(shots_summed)
• Circular depolarization ratio for particulate(depol)
• Aerosol backscatter coefficient at 355 nm(bscat)
• Resolution of the aerosol extinction and backscatter profiles(extinction_resolution)
• Cloud mask from depolarization VAP(cmask)
• Water vapor mixing ratio from the 60 m tower(twr_w_60m)
• Suggested maximum altitude to use the water vapor data from the Raman lidar(w_max_height)
• Average laser energy of the ensemble shots(average_energy)
• Aerosol optical depth profiles at 355 nm(aod_profile)
• Random error in the water vapor mixing ratio profile(w_err)
• Random error in the precipitable water vapor observed by the Raman lidar(pwv_rl_err)
• lon(lon)
• Relative Humidity (hybrid-b grid)(rh)
• Mode index(mode)
• Flag indicating whether or not there was a sample from the temperature_source
  dataset during the lidars averaging interval (1) or not (0)(sample_times_other)
• Aerosol scattering ratio uncertainty(asr_err)
• Resolution of the aerosol scattering ratio profile(scattering_ratio_resolution)