An (almost) unexpected way to detect very thin diffuse (aged An (almost) unexpected way to detect very thin diffuse (aged?) smoke layers in the UTLS T. Leblanc 1 Jet Propulsion Laboratory, California Institute of Technology, Wrightwood, CA © 2018 California Institute of Technology. Government sponsorship acknowledged

Water Vapor Raman Lidar at TMF Designed for long-term monitoring in the UTLS Laser emission at 355 nm Detection of Raman-shifted light by Nitrogen at 387 nm Detection of Raman-shifted light by water vapor at 407 nm Emitter: Tripled Nd:YAG laser  355 nm, 10 Hz, 8 W, 800 mJ/pulse Beam expander (x10), transmitter mirror with pico-motors for auto alignment Receiver: One 91-cm diameter telescope with fiber-free 5-channel receiver (1x355, 2x 387/407) Four 7-cm diameter telescopes for low-intensity channels (355 x 2, 387, 407) 9 Licel transient recorders (PC only) Operations: 3-4 times per week, 2-hour per night 7.5 m x 5 min sampling, degraded to 30-m, 1-2 hour average for NDACC archive 1500+ profiles since 2003 Vertical range: 3.5-20 km (summer/fall) or 3.5-15 km (winter/spring)

From lidar equation to H2O MR (q) r = range dr = sampling resolution Photon counts detected in “nitrogen channel” Photon counts emitted by laser Laser beam extinction on the way up Nitrogen number density Laser beam extinction on the way back Lidar receiver efficiency terms for nitrogen channel N2 Raman cross-section Photon counts detected in “water vapor channel” Photon counts emitted by laser Laser beam extinction on the way up Water vapor number density Laser beam extinction on the way back Lidar receiver efficiency terms for nitrogen channel H2ORaman cross-section  Ratio of the two channels: Calibration needed!

during MOHAVE 2009 Campaign H2O Validation in UTLS during MOHAVE 2009 Campaign October climatological value of ~ 4-5 ppmv

October 2010 ~ 4-5 ppmv

October 2011 ~ 4-5 ppmv

October 2012 ~ 4-5 ppmv

October 2013 ~ 4-5 ppmv

October 2014 ~ 4-5 ppmv

October 2015 ~ 4-5 ppmv

October 2016 ~ 4-5 ppmv

October 2017 10-40 ppmv !!!!

November 2017 10-30 ppmv !!!!

December 2017 7-20 ppmv !!!!

What the heck happened to our TMF H2O lidar since October 2017? When did this start?

22 September 2017 10-70 ppmv !!!!

12 September 2017 10-70 ppmv !!!!

26 August 26 2017 5-6 ppmv….

It started for sure between July 19 and Sept. 12 4-5 ppmv It started for sure between July 19 and Sept. 12

What could this be? Checked H2O signals:  No outstanding signal anomalies such as SIB Checked Rayleigh signals (355 nm):  No outstanding aerosol backscatter anomalies Contacted Dale Hurst, NOAA-FP  No outstanding H2O increase Contacted Bill Read and MLS Team  No outstanding H2O increase Checked CALIPSO BSR curtain plots  No outstanding layers in October, November, etc. Went to AGU, and finally, finally, got (maybe) an answer…  The Mother of All PyroCbs! (thank you Mike Fromm)

Some rare, past studies on the topic The problem: this article shows BSR signatures that we don’t see at TMF

How can this be proved if we don’t see a BSR signatures? Solution: I have a Jens Reichardt 27 August 2018 Jens (DWD, Lindenberg) has a cool toy: A lidar + spectrometer H2O and fluorescence signals can be separated Top-right: Fluorescence Backscatter ratio Bottom-right: H2O profile with fluorescence component extracted

CONCLUSION The H2O anomaly is most likely the signature of fluorescing biogenic material The particles are extremely fine and/or diffuse, so fine that they do not produce any noticeable Mie scattering signature on the 355 nm signals Yet this layer produces huge contamination on the Raman H2O signal, contamination that lasted 3+ months No such contamination has ever been observed before in the 10 year-long data record of the TMF H2O lidar Let’s learn more about the Mother of All PyroCbs: A significant Canadian wildfire event that affected the entire Northern Hemisphere  Mike Fromm presentation now…