GSFC STROZ Lidar at MOHAVE 2009 Laurence Twigg, Thomas J. McGee and Grant Sumnicht Code 613.3, Goddard Space Flight Center MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Lidar Trailer at TMO for MOHAVE-2009 MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite NDACC Mobile Lidar  Originally Ozone, Aerosol and Temp instrument  XeCl Excimer laser nm  Nd-YAG 355 nm  nm and 387 Lo channels added for water vapor demonstration at MLO  2005 – campaign at TMF – first comparisons with other lidar  WAVES Campaign 2008  2009 MOHAVE Campaign MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Significant Changes in STROZ-Lite Mobile Lidar (Between MOHAVE 2007 and MOHAVE 2009)  Change Spectra-Physics YAG for Continuum – higher power; better polarization characteristics  Excimer Laser had new pressure vessel installed  New PMT bases (Licel)  Mini Receiver for H 2 O channels – low altitude return  Calibration Lamp  AT lidar – new beam splitter (not tested during MOHAVE- 2009) MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ NDACC Mobile Lidar Status during MOHAVE-2009  Major problems with laser systems (YAG and Excimer)  Continuous testing lead to many configuration changes  These changes included FOV settings, PMT changes as well as blocker filter use for H2O test  By Last third of campaign achieved “stability”  T-O3 configurations alternated with 355 blocker filter use for H2O fluorescence testing. Thus time coincidences with sonde launches were used for both O3 and H2O profile comparisons.  AT lidar – similar problems led to only 1 night with 2 hrs of engineering data, thus changes to test elimination of H2O fluorescence problem were never tested. MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ System Parameters MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al. ParameterSTROZ MOHAVE STROZ Now Laser Power 355) Hz HZ Telescope Area0.47 m**2 Field Of View *1.0 mRad0.7/2.3 mRad (fixed) WV IF Bandwidth1.0 nm0.25 nm Cal. MethodSonde Norm. R. 10/50 ppm~3-6% / ~2%???? Low Alt Limit~200 m AGL * During MOHAVE, both the STROZ and the AT Lidar used an iris to provide a variable Field of View. These are the calculated FOV used for WV measurements based on a measurement of the iris diameter at the various détentes. Recent data indicate that this introduces errors. New fixed apertures installed

STROZ-Lite –TMF-2005 Calibration STROZ  Lidar calibrated against local, synchronous RS-92 launches  Calibration constant determined between 2 – 3 km above lidar  If sharp features were noted, a different range was selected  STROZ H2O Measurements at 2.3 mRad FOV STROZ Hi-Pair Calibration Constant Mean = SD = 14.4 (6.6%) MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite MOHAVE-2009 Calibration Factors STROZ STROZ  During MOHAVE-2009, The STROZ lidar operated in two modes – the Ozone Mode with FOV 2.3; and the Water vapor mode – FOV 1.0  The Mean value of the Lo- Pair Cal Factor was /- 9%, which leads to a value for the Hi-Pair Cal Factor of 215 +/- 5%  Compare this with the MOHAVE-2005 value of 217 +/- 7 MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Fluorescence in STROZ WV MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al. October 20/21, 2009

STROZ-Lite vs. RS92-Corr. Sonde Blocked Unblocked MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. CFH BlockedUnblocked MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ vs. JPL-WV UnblockedBlocked MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. ALVICE BlockedUnblocked MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Issues Noted during MOHAVE and Later Tests  One PMT showed long term increase in output with “constant” signal – needed to replace PMT but not base – Not a WV channel  All channels in the AT system are apparently not aligned the same – showed up in changing ratios with change in FOV  Changing the AT FOV was not repeatable –Detents not “kinematic” –Vanes in iris may stick  A constant signal does not give the same number of counts in different Licel photon counting modules –Cal lamp signal into one channel was moved from one counter to another –All PMT parameters kept the same –The same discriminator setting was used for all counters MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

AT and STROZ-Lite H2O profiles GSFC on 10/8/2010 – 2 Hr Averages MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

H2O Summary  Comparison of blocked vs. unblocked STROZ-Lite H2O profiles during MOHAVE-2009 show effects consistent with fluorescence.  Effect seen in comparisons vs. sondes and other lidar systems.  New observations obtained after modifications applied to both AT and STROZ systems show current H2O profiles for both blocked and unblocked observation modes yield the same result!  However – this is still not proof that ALL fluorescence has been eliminated (could different telescope mirrors/coatings be giving the same effect???).  Thus there is a need for a new (TMO) campaign to acquire long integrations at a dark site (no moon) in order to see if any fluorescence still exists in either mobile lidar system.  Need to further examine roles of smoothing window, background definition, residual fluorescence on H2O profiles.  Use corrected RS92 sondes???  Add “Blocked” or “Unblocked” to 60 min files. MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite Temperature Profiles during MOHAVE 2009  Same observational issues as with H2O, i.e. configuration changes, sonde launch time coincidences, etc.  Reminder - changes included FOV settings, PMT changes as well as blocker filter use for H2O test  Last 5 days of campaign – always acquired 2 hr of T-O3 data using large (2.3 mrad) FOV  Reminder – no AT lidar temperature profiles – various system problems led to only 1 night with 2 hrs of engineering data MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. RS92_Corr. Sonde MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. CFH MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. FPH MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite Vs. JPL Temperature MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ-Lite vs. ALVICE Temperature MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Temperature Summary  Good agreement with sondes and other lidar systems.  Some comparisons show ~1-2 cold bias at kms  Limited T data – longer campaign useful  Algorithm changes – time to re-run Thierry’s simulation program??? MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ O 3 at MOHAVE 2009  Ozone Comparisons were made with ECC sondes, and the JPL Stratospheric and Tropospheric lidars  STROZ lidar had new PMT housings and in one case a completely new photomultiplier tube installed for ozone measurements.  Not all ozone measurements were simultaneous with sonde launches due to water vapor measurement constraints and/or system configuration changes. MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ vs JPL Lidars  Nine nights of comparable lidar measurements  Good agreement from 15 to 45 km between STROZ and JPL Stratospheric Lidar  Agreement is not as good below 15 km, especially between STROZ and the JPL Trop Ozone lidar – believed to be related to the need to amplify the 308 signals  Noise in STROZ profile above 45 km also due to weak 308 signals – this is an electronic issue not a laser power issue MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ FPH Ozone Comparisons  3 comparable FPH launches with ECC sondes  Ascent data used for comparisons  Reasonable agreement from 13 km to 27 km (mean difference = -3.4%) MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

STROZ CFH Ozone Comparisons  5 comparable CFH launches with ECC sondes during MOHAVE  Reasonable agreement between 15 and 30 KM – Mean diff = 1.20+/  pump correction errors above 30 km? MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Conclusions and Solutions  A fixed field stop is necessary – the errors introduced from an uncertain aperture size convolved with slight differences in alignment at different channels are too large. SOLUTION: Kinematic mounts to allow for interchangeable, fixed apertures fabricated and installed in both STROZ and AT lidars.  Fluorescence is an issue within the STROZ lidar. SOLUTION: Field lens and collimating lens assembly were fabricated from extremely low fluorescence fused silica – received and installed in STROZ.; may not be necessary for AT  Changing or swapping Licel cards changes the calibration – input pre-amplifier issues?  All of these needed changes were implemented as of Oct 2010 MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.

Conclusions and Solutions (Continued)  H20 looks much better, but needs more observations for verification  O3 looks good above 15 km. Tests indicate that amplification of 308 signals may improve sensitivity below 15 km  Testing underway for limitations of O3 using 0.7 mrad aperture (excimer divergence problems)  T looks to be ~ 1degree cool on average, BUT night-to- night changes in magnitude – smoothing, DTC issues??? MOHAVE 2009 Water Vapor Workshop Bern, Switzerland, Oct , 2010 L. Twigg, et al.