CAS – total LWC comparison

warm clouds

Assumptions

• Instruments time synchronization info isn't available for this period.

• Some of the instruments were not synchronized during this early stage of the campaign.

• I assume the positive mixing ratio coincide with onset of LWC measurements in CAS.

Limitations

• Horizontal sampling line – low penetration efficiency for big droplets and drops

• High concentrations and screening of big droplets by small droplets or particles cause lower LWC content.

• Presented CAS LWC data for droplets >3m.

Equations (+10C)

r≡Density of dry air𝐶𝐴𝑆𝐿𝑊𝑀𝑅=𝐶𝐴𝑆𝑔𝑟 /𝑚3

1000𝑔𝑟 /𝐾𝑔 ∙ 𝜌 (𝑇 ,𝑃 ) 𝐾𝑔/𝑚3 ⌊ 𝐾𝑔 /𝐾𝑔 ⌋

𝑟1=0.622 ∙(( (𝑅 .𝐻 𝑖𝑛𝑖𝑡𝑖𝑎𝑙/100) ∙100 ∙6.1121 ∙𝑒(18.678− 𝑇10𝐶− 273.15

234.5 ) ∙( 𝑇10𝐶− 273.15257.14+ (𝑇 10𝐶− 273.15 ))

𝑃 𝑖𝑛𝑖𝑡𝑖𝑎𝑙[𝑃𝑎] )−( 100 ∙6.1121 ∙𝑒(18.678− 𝑇− 273.15234.5 )∙( 𝑇 −273.15

257.14+ (𝑇 −273.15 ) )𝑃 (𝑡 ) [𝑃𝑎 ] ))[ 𝐾𝑔𝐾𝑔 ]

Liquid Water Mixing Ratio +10C:

Liquid water mixing ratio measured by CAS:

𝑟2=0.622 ∙(( 100∙6.1121 ∙𝑒(18.678−𝑇 𝐷𝑒𝑤 (𝑡 )− 273.15234.5 )∙( 𝑇 𝐷𝑒𝑤 (𝑡 )− 273.15

257.14 +(𝑇 𝐷𝑒𝑤 (𝑡 )− 273.15 ))𝑃 (𝑡) [𝑃𝑎 ] )−( 100 ∙6.1121 ∙𝑒(18.678− 𝑇 (𝑡 )−273.1 5

234.5 )∙( 𝑇 (𝑡 )−273.1 5257.14 +(𝑇 (𝑡 )− 273.15 ) )

𝑃 (𝑡 )[𝑃𝑎] ))[ 𝐾𝑔𝐾𝑔 ]

Assumption: changing chamber pressure at saturation, flux from the walls:

Runs details

Date Time Expansion CCN Temp [°C] O3 SO2 Isoprene UV fan alpha-pin CCN [cm^-3] Run type AMS MS

17/11/2013 15:10:00 1 H2SO4 10 82 ppb 18 ppb 17.5 ppt off on 1630 1243.04 GCR H2SO4

17:09:00 2 H2SO4 10 125 ppb 18 ppb 18 ppt off off 530 1243.06 GCRH2SO4

18:46:00 3 H2SO4 10 120 ppb 20 ppb 17 ppt off off 170 1243.08 GCRH2SO4

18/11/2013

02:35:40 1 (NH4)2SO4? 10 135 ppb 20 ppb 17 ppt off off 4510 1245.01 GCRH2SO4

04:32:16 2 (NH4)2SO4? 10 125 ppb 20 ppb ?? off off 1660 1245.03 GCRH2SO4

19:32:57 1 H2SO4/? 10 180 ppb 0.8 ppb 51 ppb off ? 970 1247.01 NH2SO4

23:02:04 2 H2SO4/? 10 118 ppb 0.9 ppb 53 ppb off ? 7980 1247.05 GCR(NH4)2SO4

19/11/2013 00:56:09 3 H2SO4/? 10 140 ppb 0.7 ppb 34 ppb off ? 2990 1247.07 CIGAR(NH4)2SO4

16:09:37 1 (NH4)2SO4 10 130 ppb 24 ppb 19 ppt off off 3060 1248.13 N(NH4)2SO4

20/11/2013 02:36:28 2 (NH4)2SO4 10 136 ppb 2 ppb 13 ppt off ? 2190 1249.03 GCR(NH4)2SO4

08:42:56 3 (NH4)2SO4 10 136 ppb 2.2 ppb 12.5 ppt off ? 3380 1249.09 GCR = CF 0.1kV(NH4)2SO4

1243.04 P[mb],RH[%],T[K]

seconds

Conditions

1243.04 [Kg/Kg]

1243.06

1243.06

1243.08

1243.08

1245.01

1245.01

1245.03

1245.03

1247.01

1247.01

1247.05

1247.05

1247.07

1247.07

1248.13

1248.13

1249.03

1249.03

1249.09

1249.09

conclusions

• Possible reasons for discrepancies in LWC measurements:

-CAS limitation that were mentioned -wrong measurement of Pressure change -wrong measurement of MBW_dew -wall losses

• Should be compared to WELAS LWC