The heat of August is now asserting itself in the summer of 2009 in the northeastern United States, but in the previous months of June and July, this region experienced an abnormally cool summer. Anecdotal reports of cold lakes in Maine, chilly temperatures confounding gardeners, and remarkably mild summer conditions during these months are confirmed by Atmospheric Infrared Sounder (AIRS) data archived and distributed at the Goddard Earth Sciences Data and Information Services Center.
Figure 1 shows the departure of the surface air temperature averaged between June and July 2009 from the 7-year average of AIRS data for this period. The figure shows the temperatures in the northeastern states were below normal, but by contrast, temperatures in southeastern states were above normal.
A 7-year monthly time series (Figure 2) for the Washington DC region shows that this region experienced lower-than-normal temperatures in the summers in 2003 and 2004, and higher than normal summer temperatures in 2005 and 2008. Figure 2 also shows that during years with hot summers, temperatures in the winter were generally above normal, except during February 2007.
Figure 3 shows regional temperatures averaged between June and July for the years 2003-2009. Cooler temperatures are evident along the higher elevations of the Appalachian Mountains. Figure 3 reveals that 2003 had the coldest June & July temperatures, and 2005 the hottest June & July temperatures, in the 7-year data history.
Figure 4 (top) shows the difference between 2009 and 2003. In most areas, the temperatures in 2009 are higher than those of 2003, except in the New England area where the temperatures are several degrees cooler. Comparison to the hottest year (2005), shows many cooler areas in the Northeast -- particularly in northern New England -- but hotter in the Southeast. Explanation for the observed patterns requires additional meteorological and climate analysis.
The AIRS surface air temperature (AIRX3STM.005, ascending) data and Giovanni (http://gdata1.sci.gsfc.nasa.gov/daac-bin/G3/gui.cgi?instance_id=AIRS_Level3Month) were used in this report. Giovanni data outputs which were imported to GrADS for further analysis were also used.
[ We would like to note and thank Dr. Zhong Liu of the GES DISC for this analysis of AIRS data. Earlier in the year, soon after his analysis of the winter drought in the Mid-Atlantic states was published in the April 2009 issue of The Giovanni News (PDF), the region experienced elevated amounts of precipitation for the next several weeks. Now that we are experiencing high heat and humidity when this news item is released, we hope that this condition won't last for the next several weeks! ]