Time series of annual water temperature
Water temperature time series
Two sets of temperature data have been used to compile temperature time series. The Arctic-GRO database contains temperature, but is only relatively recent and focusses on the six largest rivers. Furthermore Lammers et al. (2007) have compiled a temperature data set for 17 Russian drainage basins (ARDAT). This data covers a period from 1929 to 2003.
Measurements of temperatures are more scarce over the winter. However, the temperature of the discharge drops to zero degrees (C) from November until April. Therefore this temperature can be assumed over winter (e.g. Whitefield et al., 2015). The average climatology for the Rivers in ARDAT is shown in the figure below from Whitefield et al. (2015).
Fig. 2. Climatologies for (a) integrated discharge (+- 1 standard deviation) for all rivers in ARDAT, (b) mean river temperature (+- 1 standard deviation) for the "Big 6" Arctic rivers and one sub-Arctic river (Kuskokwim), (c) calculated heat flux (+- 1 standard deviation) using integrated discharge from all rivers in ARDAT and mean river water temperatures. Numbers on top axes of (a) and (b) denote total number of monthly-mean observations for each month.
The ‘rivers-challenge’ requests time series of yearly averages of the water temperatures from Arctic rivers. Yearly average temperatures have not been found in sources because it is customary to report the temperature over a smaller interval, usually the instant of daily temperatures are reported. In order to create a time series of yearly averaged temperatures the available data sets have been averaged to the requested aggregation level. These time series are presented below for the 6 largest rivers, together with the input data. It can be seen that the input data is not homogenously sampled over time. There are for example more measurements in summer, which results in strong bias of the average temperature. The supplied graphs therefore only serve to illustrate that reporting a yearly average water temperature is not straightforward and a careful reconstruction of the yearly temperature cycle is needed before averaging, which is outside the scope of this project.
- Lammers, R.B., J.W. Pundsack, and A.I. Shiklomanov (2007), Variability in river temperature, discharge, and energy flux from the Russian pan-Arctic landmass, J. Geophys. Res. - Biogeosciences, 112, G04S59, doi:10.1029/2006JG000370.
- Whitefield, J., Winsor P., McClelland J., Menemenlis D., A new river discharge and river temperature climatology data set for the pan-Arctic region, Ocean Modelling, Volume 88, 2015, Pages 1-15, ISSN 1463-5003, http://dx.doi.org/10.1016/j.ocemod.2014.12.012.