Flight summary, Dryden-Kona transit 02/26/2001
Title: Aged Asian pollution and MOPITT mid-latitudes validation
Objectives: (1) to sample aged Asian fossil fuel and biomass burning
pollution plumes, forecast to have been lifted frontally to the
middle/upper troposphere and transported in less than 4 days across
the Pacific at mid-latitudes; (2) to conduct a MOPITT validation
experiment for this air mass.
Execution: The MOPITT validation experiment was conducted at (40N,
132W, 2005 UTC) above a solid stratus deck with tops at 3.5Kft. The
DC-8 arrived in position at cloud top at 1945 UTC and spiraled
up to 35Kft, arriving there at 2007 UTC. It then spiraled back
down along the same track to 0.5K to demonstrate the stationarity
of the vertical profile. From there the DC-8 flew W and then SW
to Hawaii, with four full vertical profiles along the way.
Results: Our objectives were met. (1) We observed considerable
Asian pollution influence from 40N to Hawaii; the location of the
plumes was consistent with the model forecast although CO concentrations
were higher than predicted, often exceeding 200 ppbv. By
successive vertical profiling at different latitudes we observed
a range of photochemical processing of Asian pollution, with ozone
concentrations in excess of 100 ppbv at the low latitudes. There
was evidence that this pollution represented a combination of fossil
fuel and biomass burning (high PAN, high C2Cl4, high cyanides,
high SO2, high non-volatile aerosol), with stronger contribution
from the latter at low latitudes. (2) the MOPITT validation
experiment was a success. Skies were 100% clear above a solid
stratus deck. The two spirals successfully demonstrated the
stationarity of the air mass. The profile showed a large
Asian pollution CO enhancement from 12 to 24Kft with values up
to 270 ppbv. The top altitude reached by the aircraft (35Kft)
corresponded to the tropopause, as indicated by in situ and lidar
ozone, although CO there was still relatively high (120 ppbv).
Meteorological Summary DC-8 Dryden to Kona
Relevant Flow Patterns
Lower troposphere-A closed low
pressure area near Dryden brought cloudy skies and considerable precipitation
to that area. A high pressure area was centered over Hawaii, with a ridge extending
northeast toward Canada.
Middle troposphere-The closed low near California was better defined
than near the surface. Split flow was evident over the eastern
Pacific, with ridging to the north and troughing to the south. Closed
low pressure was located just southwest of Hawaii. Subtropical
highs were located southeast of Hawaii and west of Hawaii, with
its ridge line extending all the way to Southeast Asia.
Upper troposphere-The split flow pattern and closed flow near
California continued. The only major anticyclone was midway
between Hawaii and Southeast Asia. It dominated the flow over the
western tropical Pacific. The jet stream was well north of
the flight area-near 35oN.
Cloud Patterns
Low
clouds were widespread over the flight area. Mid and upper
level clouds were associated with the closed low near California.
In addition, a major cloud band stretched northeast to southwest
across the area. Its southern end was just south of Hawaii. This
band moved slower than forecast, and was in the process of dissipating. A
few slight showers were located near 33o30N, 149oW
The
area of the MOPITT overpass was free of middle and high level clouds. There
was a uniform deck of stratus/stratocumulus with tops of ~3500
ft.