DISCOVER-AQ continues to get conditions in California that were expected during the winter experiment. DISCOVER-AQ is a NASA sponsored field experiment involving two aircraft, the NASA P3-B and the NASA B200. The goal of the experiment is to relate column measured air quality measures, such as AOD, at the same time a profile of extinction from lidars and aircraft is obtained. The intent is to relate these column measurements to the concentrations at the surface, to which the public is exposed.
The San Joaquin Valley is exposed to high concentrations of aerosols, ammonia, nitrates, formaldehyde, CO and other pollutants at this time of year. The experiment is exposing the causes: very low boundary layer heights and very poor dispersion. The lidar results at Porterville, where Hoff and Orozco from UMBC are based, shows that the morning boundary layer is extremely shallow, often 100m at sunrise and only rising to a few hundred meters during the day. On the week of January 14, boundary layer heights of 400 m were common. This shallow box does not allow pollutants generated in the valley to escape.
At the same time, there is little to no wind in the San Joaquin Valley. Our colleagues who are hosting us at the Penn State University NATIVE trailer in Porterville release two ozonesondes a day. Not one of those sondes has done much other than go straight up. One balloon burst at over 30,000 feet and fell within a mile of the site. So with no appreciable wind and the High Sierras to our east, the pollution just sloshes around in the SJV for days. We are in day five of a pollution event and have watched the light scattering rise from 10 Mm^-1 (about 40km visibility) to 200 Mm^-1 (about 2km visibility) over a five day period.
Saturday was cloudy over the SJV and Sunday started with heavy ground fog. That fog is now burning off and by game time, we will be creating even more photochemical pollution in the Valley. Monday, DISCOVER flies again for the ninth of ten flights and we expect the pollution to be as bad as we've seen so far. The Porterville Recorder continues to follow the experiment and a Spanish version of this article is also available. UMBC's data in near real time can be found here.
The AIRNOW PM AQI readings show that Unhealthy for Sensitive Groups (Orange) continues in Northern California and in the lower San Joaquin Valley. On the right is Saturday's PM2.5 readings in Porterville from the California Air Resources Board information system.
It is not getting better in the SJV. At game time, Porterville (the middle of the three orange spots) was still Unhealthy for Sensitive Groups. By the end of the game, we have 81 µg m-3 and hit code red or purple (Unhealthy or hazardous). Tomorrow should be interesting in Porterville. The rightmost image below is AQUA Modis's RGB channel which shows the haze clearly. The helicopter pilots we watched the game with said that their partners had to land in Bakersfield because Porterville was too hazy for a VFR approach.
And thanks to the Ravens and 49'ers for a most entertaining Superbowl!