greenland climate network (gc-net) - HFT Stuttgart

NASA Greenland Progress Report 9
mer monthly net radiation values have been higher during the new millennium (~ 30 W m -2 )
compared to the previous decade, with the exception of record high values in 1995.
Month
12
11
W m-2
60
10
50
9
40
8
30
7
20
10
6
0
5
-10
4
-20
3
-30
2
-40
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Year
Figure 3.1.2: Interannual variability of net radiation for the Swiss Camp ETH/CU AWS record from 1993 through 2004.
11
Month
10
9
8
7
6
5
4
1
0.9
0.8
0.7
0.6
3
0.5
2
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004
Year
Figure 3. 1.3: Interannual variability of monthly mean albedo at the Swiss Camp ETH/CU station (1993 – 2004).
It is interesting to note, that during the years with maximum insolation (1993 and 1996, figure
not shown), air temperature (Figure 3.1.1) and net radiation did not reveal a significant increase.
This demonstrates how sensitive the surface energy balance is to albedo and cloud cover feedback
during summer months. Monthly mean net radiation values at the equilibrium line altitude are
only positive during June and July, whereas for the remaining part of the year, the sensible heat
flux must compensate for the radiative energy loss by turbulent energy transport from the atmosphere
to the surface.