AIRS observations of conditions preceding and during Russian fires of 2010
In late July – early August 2010, large areas between Moscow and Niznij Novgorod were impacted by raging wild fires (Figure 1). Data retrievals from the Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's Aqua satellite revealed a notably anomalous weather pattern preceding and during the first days of the fires.
Figure 1. AIRS visible false-color image of fires, July 31, 2010. The “+”
symbols here and in the following figures indicate, clockwise, Moscow,
Niznij Novgorod, and Voronezh. Locations of clusters of major fires
are indicated with triangles.
The last days of July 2010 over east/central Russia were characterized by a persistent atmospheric high surface pressure ridge, as revealed by NCEP Global Forecast System (GFS) output. Mean sea-level pressures, and surface winds at 10m, were used to compute a simple 12-day average for the period July 20-31, and are presented in Figure 2. The same period is used in the AIRS data analyses below.
Figure 2. NCEP GFS model output, averaged for the period of
July 20 – July 31. The “+” symbols indicate, clockwise, Moscow,
Niznij Novgorod, and Voronezh.
This high pressure system is identifiable by its clockwise rotation. This system was well-defined, and was of an enormous size. It was almost statically "anchored" over the region, as the 12-day average in Figure 2 demonstrates, thus playing a strong "blocking" role. At its southern edge (between the 1012-1016 isobars) the system was driving easterly winds from the deep continent into the affected regions. Conditions were set for long-term, nearly cloud-free weather, with southeast winds carrying warmer and drier air into the affected region.
AIRS retrievals reveal a notably anomalous weather pattern preceding and during the first days of the fires. AIRS anomalies are calculated by subtracting 8-year climatologies for the month of July from the corresponding average quantities for the period July 20-31. The anomalies for this period unambiguously demonstrate much warmer than usual temperatures of both the surface air layer and the surface itself (Figures 3 and 4).
Figure 3. AIRS daytime surface air temperature anomaly
(AIRS data set "SurfAirTemp_A").
Figure 4. AIRS daytime skin temperature anomaly
(AIRS data set "SurfSkinTemp_A").
The AIRS total precipitable water vapor anomaly shows that the absolute amounts of water vapor (atmospheric moisture content) above Moscow and Niznij were larger (Figure 5). Strong evaporation driven by anomalously high temperatures, along with converging surface winds, contributed to the positive moisture anomaly. Nevertheless, the extremely high temperatures and the persistent high pressure system caused severe shortages of precipitation in the region (Figure 6).
Figure 5. AIRS daytime total integrated water vapor burden anomaly
(AIRS data set "TotH2OVap_A").
Figure 6. AIRS precipitation anomaly for July 2010, shown as a percentage
of “normal” precipitation (based on the July climatology of AIRS precipitation).
Areas east of Moscow and Niznij Novgorod were short of almost a month of normal precipitation for July. The persistent drought and the wildfires in these regions of Russia created concerns for the wheat crop, leading to price hikes in the world markets. Western parts of Kazakhstan were also short of precipitation and developed numerous fires. The impact of these, however (being far from densely populated areas) was limited and less reported in the media.
Finally, apart from the water vapor and temperatures, AIRS observations also yield valuable data on trace gases. A relevant data product in this case is the concentration of carbon monoxide (CO). Figure 7 links to a movie that demonstrates the transport of CO released from the Russian fires. Vector winds at 300 mb from the NCEP GFS are overlaid to approximately identify the existence and location of the polar and subtropical jet streams, major drivers of synoptics like surface winds and vertical mixing, and hence the plume transport. Every frame in the movie is a 2-day average. Apparently, the cloud of CO persisted for a month, and by the second week of August stretched over thousands of kilometers, across the entire territory of Russia and into parts of Northern China (c.f. the frames for August 11-13)
Figure 7. AIRS observations of carbon monoxide (CO) during the period
July 20 - August 27, 2010.
(click on the figure to launch gif-movie)