1. 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

2. 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: km (summer/fall) or km (winter/spring)

3. 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!

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

5. October 2010
~ 4-5 ppmv

6. October 2011
~ 4-5 ppmv

7. October 2012
~ 4-5 ppmv

8. October 2013
~ 4-5 ppmv

9. October 2014
~ 4-5 ppmv

10. October 2015
~ 4-5 ppmv

11. October 2016
~ 4-5 ppmv

12. October 2017
10-40 ppmv !!!!

13. November 2017
10-30 ppmv !!!!

14. December 2017
7-20 ppmv !!!!

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

16. 22 September 2017
10-70 ppmv !!!!

17. 12 September 2017
10-70 ppmv !!!!

18. 26 August
5-6 ppmv….

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

20. 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)

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

22. 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

23. 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…