Post on 31-Dec-2015
description
transcript
Preliminary Whistler HR-ToF-AMS Data
Shao-Meng Li, John Liggio, Kathy Hayden, Qi Zhang
Others:
D. Worsnop, R. Leaitch, A.Macdonald, D. Halpin, J.Deary, M. Cubisan.
ToF-AMS Instrument Details
• Provides detailed particle mass spectra with high time resolution ( 5 min @ whistler)
• Quantifies particle sulfate, nitrate, ammonium, and total organic mass (< ~1 um diameter)
• Quantification based on relative Ionization efficiency (IE)• size segregated mass distribution for every m/z• Higher mass range than Q-AMS (~800 amu)• Two modes of operation:
– V-mode: High sensitivity (20X more than Q-AMS), better than unit mass resolution
– W-mode: Lower sensitivity (~same as Q-AMS), high mass resolution (~5000 vs 20 for the Q-AMS)
– Alternated between modes (5 min each)
Status of HR-ToF data
• April 19 @18:20 – May 16 @18:35, ~66% data recovery, data gaps due to many different instrument problems
• Particle concentrator was used intermittently • Concentrator on/off time periods in the data have been defined
– Δ[SO42-] used as indicator and to determine enhancement factor
• Ionization efficiency (IE) nominally determined, nominal factors have been applied to data
• Particle time-of-flight calibration function analyzed, but size distributions need work – (need to develop a routine to minimize effect of noisy m/z’s)
Case 2: Possible Valley Influence (biogenic component?)
High organics, May 15 evening to May 16 evening
Case 1: Possible Transport Layer
High sulphate, May 15 morning to afternoon
Transport Layer
Case 1:Case 2:
*
Cessna 207 Aircraft ProfilesFlight 30, May 15, late evening (~6pm)
0
1000
2000
3000
4000
5000
6000
-5 0 5 10 15 20 25
PCASP divided by 100
AMS Sulphate
AMS Organics
Temp
PCASP <0.6um massest.
0
1000
2000
3000
4000
5000
6000
-5 0 5 10 15 20 25
PCASP divided by 100
AMS Sulphate
AMS Organics
Temp
PCASP <0.6um massest.SO4+Org
UP
DOWN
•boundary layer ~2000 m
•SO42- increased between 2600-
2900 m, above boundary layer (UP)
•layered elevated organics: 2200-2900m and 3000-4000 m
•at tail end of high SO42- observed at
Whistler site (Case 1)
•transport layer
100
80
60
40
20
0
Inte
nsi
ty
100806040200
m/z
(CH
4SO
3)+
(CH
3SO
2)+
(SO
2)+
(SO
)+
(CH3)+
(CH
3O)+
(HS
O3)
+
MSA (NIST) MSA (AMS)
(HS
O2)
+
Path ForwardPath Forward• Quantify biogenic sulphur – ie: MSA in particles with AMS
CH3 S
O
O
OH