August 10, 2009
We will launch our 3rd ozonesonde today, Monday, 10 August 2009. Weather conditions this year have not been so favorable for sampling air from China. For the first week, high pressure in the Sea of Japan blocked transport from the mainland. Now a low to the NE, a typhoon to the S, and a high to the E continue to suppress transport from the mainland. A picture from Friday, 7 August 2009 shows just how hazy it has been here, as the air mass remains in place over Hokkaido day after day, recirculating the air mass. On the plus side, we’re getting a good chance to measure the local contribution to the pollution profile.
August 6, 2009
On Wednesday, 5 August, we launched our first dual sonde of 2009. The weather was mostly clear and sunny, with temperatures in the mid to upper 20’s (C) — a perfect day for our first launch this year. We will be launching 10 of the dual sonde instruments this year between now and the end of August. The data are available on our project web site. Here’s a photo of the launch team
at Hokkaido University, including Valparaiso University students Nathan Kellams (physics) & Ted Pietrzak (meteorology). And here’s a shot of the balloon just as it leaves the ground.
July 31, 2009
We have returned to Japan for part 2 of our study. This year, two undergraduate students from Valparaiso University have accompanied me to help with the balloon launches. Our plan for this year is to launch 10 dual SO2/O3 sondes during the month of August. This year will serve as the “control” case for our study, while last year’s launches were done while China was implementing pollution controls in and around Beijing.
We have set up a new page on our project website for this year’s data. Last year’s data can be found on this web site. We have improved our trajectory forecast model this year. For the forward trajectories from Beijing, we start 3 days in the past and run to 1 day in the future. For the first 2.5 days, the calculations used NCEP reanalysis meteorological data, while for only the last 1.5 days, the calculations use NCEP forecast meteorological data. This should improve the accuracy of our forecasting of air masses from Beijing to Hokkaido.
Our launches will begin during the week of Aug. 3 – 9.
I will also be posting updates on our research progress during the spring, while I was not attending to this blog. In particular, I will comment on the Special Session at the Spring AGU Meeting in Toronto (see page 50 of the PDF document) that dealt with pollution in and around Beijing, China before, during, and after the Olympics. You might be interested in a recent paper that came out in AJP by Wang et al.
Stay tuned for more.
December 17, 2008
Using the NASA Goddard Kinematic Trajectory model, I have examined flow out of the Beijing region during the month of August from 1998 – 2008 in an effort to put this year’s outflow (see earlier post) in context. You will find PDF files on the project website summarizing the distribution of the outflow. The contours indicate the number of parcel-quarter days found in each grid box. Here’s a link to the outflow from Beijing in the Boundary Layer (< 2.5 km) and another in the Lower Free Troposphere (2.5 – 5.0 km).
More details of the model:
NCEP data from 1998 – 2001 are once daily; from 2002 – 2005 are twice daily; from 2006 – 2008 are four times daily.
Beijing box is 5 deg. lat by 8 deg. lon centered on 38.5 N, 115.5 E, with parcels every 0.5 deg. lat. and 0.5 deg. lon.
Gridded map in PDF files runs from 25 N ot 50 N and 105 E to 150 E, with a 1 deg. lat. by 1.5 deg. latitude grid cell.
In the boundary layer, flow from China to Japan from 1999 – 2002 was relatively weak, with few areas of Japan experiencing much influence from air over Beijing. In 1998, however, much of Honshu and all of Kyushu were influenced by Beijing air. In particular, Northern and Southern Honshu and Kyushu saw substantial flows from Beijing. In the lower free troposphere, when flows to Japan are strong (1998, 2000, 2003, 2006, 2007), Northern Honshu sees the most air from Beijing.
In the lower free troposphere, 1999, 2000, 2001, 2003, 2005, and 2008 are years with relatively weaker influences in Hokkaido from Beijing. In the boundary layer, the weaker years are 1999, 2000, 2001, and 2008. Thus, analysis of this summer’s pollution data need take into account the fact that outflow from China to Japan was relatively weak compared to previous years within the last decade.
November 27, 2008
In my last post, I discussed and showed the summary statistics for trajectories out of Beijing and Shanghai during August 2008. Here, I now add links to the quicktime movies: Beijing outflow; Shanghai outflow.
The Beijing movie shows several periods during which boundary layer air over Japan likely had origins in China. 31 July – 1 August — most of Hokkaido and Honshu see air from China between 2 and 4 km, some of which may have become entrained in the afternoon mixed layer over Japan, influences surface ozone concentrations. We will only be able to confirm the influences of such air masses 2 years from now, when all the Japanese surface monitor data becomes public. 2 – 3 August — most of Hokkaido. 3 – 5 August — lower Honshu. 6 – 7 August — Hokkaido and upper Honshu, here with air below 2 km, and on this occasion, we saw elevated ozone in Sapporo, both at the surface and aloft. 10 – 11 August — Hokkaido, above 2 km. 15 August — upper Honshu and Hokkaido from 2 – 6 km. 17 – 21 August — Kyushu and Honshu from 2 – 4 km. 23 – 24 August — nearly all of Japan. This makes about 9 days in total on which the influence of air from Beijing may have been detectable in Hokkaido, although most of the events brought the air over at 2 – 4 km altitude, the one notable exception being the 6 – 7 August case.
The Shanghai movie also shows several periods of influence over Japan as well: 1 – 6 August — a prolonged period during which the 5-day forward trajectories were over Japan, with many below 2 km. Early on, the air mass covered from central Honshu north to Hokkaido, mostly above 4 km. Later on, the air mass covered lower Honshu below 3 km. 15 – 20 August — another wave of air covers most of Japan, from 1 – 4 km. The further north you go in Japan, the higher the air mass tends to be. 22- 27 August — again, nearly all of Japan appears to have some influence from the Shanghai region, with many of the trajectories arriving below 2 km altitude. Southern Japan tends to get most of this outflow.
So, the trajectory study would seem to indicate that influences from both the Shanghai region and the Beijing region can be found on the air mass over Japan from the surface up to 4 – 5 km during August. About half the days in August saw the Shanghai air mass over some part (and frequently most) of Japan. Also for nearly half the days in August, the Beijing air mass was over some part of Japan, most frequently in the northern part.
The next step is to mine the surface data (two years from now) and the balloon data to identify influences of Chinese pollution. We can start the analysis of the latter now.
November 25, 2008
To answer this question, I ran Mark Schoeberl’s NASA GSFC trajectory model (Schoeberl and Sparling, 1995) in a kinematic mode, initializing a grid of parcels every 0.5 deg. latitude by 0.5 deg. longitude around Beijing and Shanghai every 500 m vertically from 500 m to 3.0 km. The Beijing box ran from 36 – 41 N and 111.5 – 119.5, while the Shanghai box ran from 29 – 33 N and 117 – 123 E. You can see the boxes on my google map here. The model was run in forward mode using the NCEP reanalysis meteorological fields. Trajectory model output was produced every 6 hours for each 5-day forward run. A grid from 25 – 50 N and 105 – 150 E with 1 deg. latitude by 1.5 deg. longitude boxes was produced, and counts of the frequency with which each grid box contained air parcels over the period 1 – 31 August 2008 was determined. Below, I show the plots of the plumes from Shanghai and Beijing below 2.5 km and from 2.5 – 5.0 km.
At the lower levels, both plumes seem to impact Southern Japan most frequently. At the higher levels, the plume is dispersed over a wider area, and impacts in Japan are shifted further north. The Beijing plume seems to center on northern Honshu this year at the upper levels, while the Shanghai plume remains focused on southern Japan (southern to central Honshu).
To better see the apportionment of air arriving in Japan from these two important source regions, a ratio was taken between the air Beijing frequency in each box and the Shanghai frequency. It should be noted at this stage that the Beijing box has ~60% more particles, which results in a ratio of 1.6 if influences from the two regions are identical. Below are maps of the ratios for both the lower (0.1 – 2.5 km) and upper (2.5 – 5.0 km) air masses. The thick lines are the 1:1 lines. Contours are shown for ratios of 2.0, 3.0, 4.0, 5.0, 10.0. Negative numbers indicate the dominance of the Shanghai plume while positive numbers indicate the dominance of the Beijing plume.
Not surprisingly, at the lower levels, southern Japan tends to be dominated by the Shanghai plume while northern Japan tends to see more of the Beijing air. At the higher levels, the dominance of the Shanghai plume is even greater over southern Japan, and its influence is equal to or stronger than that of the Beijing plume throughout Honshu. Important for this study is that the Beijing plume tends to dominate the Shanghai plume in Hokkaido (where we took our measurements this summer).
The next step will be to identify individual days on which the influence of the Beijing plume dominated over Japan, and to identify if any of the ozone features observed in our ozonesonde data for August 2008 can be linked to plumes from either of these major industrial centers in China.
November 21, 2008
I have recently run Mark Schoeberl’s NASA Goddard Trajectory Model in kinematic mode using the NCEP reanalysis data for the meteorological fields to simulate the spread of the SO2 cloud from the eruption of Mt. Kasatochi. Click here for the simulation. The model was run with 0.025 day time-steps forward from 7 August 2008 through 22 August 2008. I’ve injected parcels on a 2 deg. lat by 4 deg. lon grid centered on Kasatochi (52.18 N, 175.51 W) from 12 – 15 km on 7 – 8 Aug, then from 6 – 12 km on 8 – 9 Aug, based on observations posted on the Alaska Volcano Observatory web site. While the simulation is not perfect, it does match many of features seen in the OMI SO2 data.