Geoscience Reference
In-Depth Information
Undercatch of snow, in combination with increases in winter precipitation (Bulygina et al.
2009
; Rawlins et al.
2009
), is also a potential contributing factor.
The wide spread in discharge responses to precipitation changes indicates a need for
further concerted modeling and field investigation efforts aimed at increasing the process
knowledge of hydrological regimes particular to the Arctic domain, including the simu-
lations of evapotranspiration and permafrost processes, considering also the effects of scale
(Rennermalm et al.
2012
). Improved parameterization, in particular with precipitation
focus, is also critical to the development of GCMs, and continued water-balance assess-
ments and closure experiments in Arctic catchments are motivated.
The extended water budget change over the entire PADB and its drainage into the
Arctic Ocean, including glacier contributions, also has implications for the global climate
system. The fact that the increase in the river freshwater contribution is of the same order
of magnitude as the increase in meltwater from MG&IC or from GRIS underlines the
importance of better understanding the reasons for the river flow changes, and the
potentially contributing components of frozen and liquid water storage changes in major
Arctic basins (e.g., Muskett and Romanovsky
2009
). Such changes could have large
implications for the pan-Arctic hydro-climatic system, for example, through ground sub-
sidence from permafrost degradation and/or altered soil moisture conditions, but also
beyond the Arctic through contribution to sea-level rise and thermohaline circulation.
6.3 Pan-Arctic Drainage Basin Monitoring
The analysis of hydrological and hydrochemical data accessibility points to some major
shortcomings, but also to opportunities and results of relevance for future research and
monitoring improvements.
The synthesis of monitoring data shows a particular lack of water chemistry data,
whereas discharge data are more extensively accessible. The range of spatial monitoring
coverage, sampling frequency and length of time series for water chemistry data overall
compare negatively with the corresponding attributes for discharge data. Together, these
shortcomings imply that the full potential of translating existing discharge data to also
calculate mass fluxes of biogeochemically important water constituents is hindered.
Furthermore, the difference in characteristics of hydrologically monitored areas evident
from this analysis shows that existing monitoring data are not representative of the PADB
as a whole. This constitutes a limitation to the input/validation data, and thereby also to
reliability of the modeling that must be used to interpret and project AHC changes in
unmonitored areas. It also limits the ability to improve GCM parameterizations and land
surface schemes for the region, due to the lack of data to establish a ground truth to
compare with.
From the perspective of an integrative pan-Arctic analysis, the limited accessibility to
water chemistry data is remarkable, given the high profile of and international commitment
to research into Arctic environmental changes. While discharge data have been compiled
into pan-Arctic data sets [most importantly, R-ArcticNET (Lammers et al.
2001
) and the
ARDB (
http://ardb.bafg.de
)] and also made accessible in near real time through the Arc-
ticRIMS project (
http://rims.unh.edu
)
, water chemistry data remain fragmented, although
the recent continuation of the PARTNERS project as the Arctic Great Rivers Observatory
(
http://www.arcticgreatrivers.org
) constitutes a substantial improvement.
Several factors may explain these results. Firstly, although the research community
emphasizes a system perspective on the pan-Arctic domain, no international body has
formal responsibility for an integrated water monitoring system. Instead, monitoring efforts