Geoscience Reference
In-Depth Information
0.50
0.50
0.40
0.40
0.30
0.30
0.20
0.20
0.10
0.10
0.00
0.00
J
FM
A
M
J
JASOND
J
FM
A
M
JJASOND
0.50
0.50
Lena
Mackenzie
0.40
0.40
0.30
0.30
0.20
0.20
0.10
0.10
0.00
0.00
J
FM
A
M
J
JASOND
J
FM
A
M
JJASOND
Figure 6.13.
Mean monthly precipitation recycling ratio (P
m
/P) for four domains
chosen to approximate represent the Ob, the Yenisey, the Lena, and the Mackenzie
basins (from Serreze et al.,
2003a
, by permission of AGU).
is simply discharge divided by the area of the contributing watershed, and hence has
units of depth per unit time. In water balance studies it is common to make use of run-
off as it has the same units typically used for precipitation and evapotranspiration.
The most comprehensive network of discharge gauging stations in the terrestrial
Arctic drainage is represented by R-ArcticNET, which was compiled from original
national sources by investigators at the University of New Hampshire, Durham.
Version 4.0 of R-ArcticNET holds data from more than 3,700 sites.
Figure 6.14
gives the location of the subset of gauges for basins of at least 10
4
km
2
. Also shown
is a digital river network at 30 min x 30 min (longitude x latitude) (known as STN-
30p) developed by C. Vorosmarty et al. (
2000
) for the pan-Arctic drainage. The
lines over the Arctic Ocean roughly indicate the sea basins into which the different
river systems empty. The river network does not include the Greenland ice sheet, but
does include the ice-free portions of Greenland. Within the confines of the terres-
trial Arctic drainage at this resolution there are 1,967 individual drainage systems
discharging to the ocean, encompassing a land area of 22.4x10
6
km
2
. As summa-
rized by R. Lammers et al. (
2001
), typical errors for measured discharge are within
the range of −/+ 2 to 5 percent for non-ice conditions in river cross sections without
floodplains and +/− 5 to 12 percent for rivers with floodplains. Maximum errors are
in mountain rivers and can be as high as 25 percent. When temperatures are low, the
discharge estimates are more uncertain owing to anchor ice, frazil ice, and backwa-
ter conditions, as well as floodplain icings (aufeis, see
Chapter 2
, also see Barry and
Gan,
2011
, chapter 6).
More than 70 percent of the total Arctic drainage area has been monitored by at
least one gauge since 1936 (
Figure 6.15
). However, in the North American part of
