Geoscience Reference
In-Depth Information
Figure 6.17.
Mean hydrographs for the four major Arctic-draining rivers (at the gauge
sites closest to the river mouths) expressed in terms of runoff (mm) (adapted from
Serreze et al.,
2003a
, by permission of AGU).
two years (1980 and 1981) daily time series of precipitation for the Lena basin,
based on averaging data for all monitoring stations within the basin. Also given is
the mean annual cycle, based on monthly means for the 1960-1992 period. It is
clear that the mean annual cycle, even on the large scale of the Lena, is superposed
on highly variable precipitation on a day to day basis. As would be expected, the
largest daily precipitation events tend to be associated with well-defined cyclonic
systems (Serreze and Etringer,
2003
).
Another example is provided by monthly discharge at the mouth of the Lena
River over the 1936-1995 period (
Figure 6.19
)
. One of the key features is the large
year-to-year variability from May through October. This relates to variations in the
water equivalent of the snowpack, temperature as it influences snow melt, and the
relative frequency of widespread and intense precipitation events (such as those just
discussed). The variability is especially pronounced in May, pointing to variations
