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.