Water Vapor during ICARTT 2004: Comparison of AATS14, J31 in situ, Ron Brown sonde measurements

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Water Vapor during ICARTT 2004 Comparison of
AATS-14, J31 in situ, Ron Brown sonde measurements

• NASA Ames Airborne Sunphotometer Team
• SSFR Team
• Presented by John Livingston
• SRI International/NASA Ames

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JETSTREAM-31 during ICARTT 2004
Vaisala HMP243
AATS-14
SSFR
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Calculation of columnar water vapor from AATS-14
For the AATS-14 channel centered at 940.6 nm,
V ? Vo exp -m?other TH2O .
LBLRTM V9.2 was used to calculate water vapor
transmittance, TH2O, as a function of water vapor
slant path, U, by varying the solar zenith angle.
Calculations were performed for a variety of
model atmospheres and a range of aircraft
altitudes.
The water vapor transmittance was modeled as
TH2O c exp -a U b ,
where U is the slant path water vapor in atm-cm.
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Calculation of water vapor density from AATS-14

• The columnar water vapor derived from AATS-14
  measurements obtained during aircraft vertical
  profiles is smoothed with a spline fit and then
  differentiated to yield a corresponding profile
  of water vapor density.
• This profile can be compared with coincident
  in-situ or remote measurements.

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Calculation of relative humidity by the Vaisala
HMP243

• HMP243 consists of a heated composite humidity
  sensor head and an optional sensor head to
  measure ambient temperature
• Both probes mounted on the J31 during the ICARTT
  study
• Primary output is dewpoint, which is calculated
  within HMP243 from humidity and temperature
  readings of composite sensor
• Separate temp probe permits calculation of
  ambient relative humidity
• HMP243 outputs of ambient temperature, Ttotal,
  and relative humidity, RHVaisala, were recorded
  by SSFR data system
• Because the separate temperature probe is subject
  to dynamic heating effects, both Ttotal and
  RHVaisala must be corrected to account for these
  effects

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Calculation of water vapor density from J31
in-situ measurements
Measured quantities Pwing, Pnose, TVaisala
probe2, RHVaisala

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Table of AATS-14 H2O profiles and Ron Brown
radiosonde measurements
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16 Jul F9
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22.2 km
Mean separation
26.0 km
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29 Jul F16
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Mean separation 7.2 km
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Mean separation 7.2 km
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15 Jul F8
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Mean separation 4.0 km
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Mean separation 4.0 km
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31 Jul F18
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Mean separation 14.9 km
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Mean separation 14.9 km
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7 Aug F23
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Mean separation 42.9 km
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Mean separation 42.9 km
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Mean separation 39.9 km
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22 Jul F13
DC-8 coordination
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Mean separation 3.6 km
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3 Aug F21
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Mean separation 15.9 km