A field study was carried out to investigate the seasonal variations in alfalfa (Medicago sativa L.) water use efficiency (WUE) using Eddy Covariance (EC) measured CO2 and H2O fluxes, aiming at optimizing the use of irrigation water under hyper arid conditions. The EC system used for this study was installed on a center pivot-irrigated 50 ha alfalfa field. Results revealed that the net EC estimated CO2 uptake ranged from 65,00 kg ha−1 (in winter) to 21,500 kg ha−1 (in summer). While, H2O flux was 4,147 m3 ha−1 (in winter) and 20,157 m3 ha−1 (in summer). This resulted in an estimated alfalfa WUE of 1.57 and 1.07 kg m−3 for winter and summer seasons, respectively. However, the actual WUE of harvested alfalfa was calculated at 0.70 and 0.71 kg m−3 for winter and summer, respectively. Therefore, attaining an actual crop WUE of 33–55% lower than the EC measurement (i.e. more water losses were due to leaching and deep-percolation processes, as the EC system could only estimate evapotranspiration over agricultural fields) emphasizes the need of precision irrigation practices, which will enable farmers to apply irrigation water and agrochemicals more precisely and site-specifically to match soil and plant status and needs.

Recently, the Antarctic Peninsula has received more attention due to the pronounced warming in that region. Non-glaciated coastal areas on the Peninsula can be significant energy sources for the atmosphere when they are exposed during summer despite the high degree of cloud associated with the frequent passage of low pressure systems. An eddy covariance system was established in December 2002 to evaluate the turbulent energy exchanges between the atmosphere and a non-glaciated coastal area on King George Island. Monthly average downward shortwave radiation was less than 210 Wm-2 in summer. Due to the low albedo of 0.12, monthly average net radiation reached > 130 Wm-2, a magnitude that was significantly larger than the reported magnitudes of < ~70 Wm-2 at glaciated areas with a high albedo on the Peninsula. The sum of monthly average sensible heat (< 64 Wm-2) and latent heat (< 20 Wm-2) fluxes amounted up to ~80 Wm-2, which was an order of magnitude larger than those at glaciated areas on the Antarctic Peninsula. Given that non-glaciated areas should be enlarged if the warming continues, more attention may need to be paid to the role of non-glaciated areas in the local climate to predict climate change on the Antarctic Peninsula.