WATER CYCLE IN BASINS OF SIBERIAN RIVERS: CHANGES IN XX AND XXI CENTURIES FROM MODEL SIMULATIONS
Igor I. Mokhov (1), Vyacheslav Ch. Khon (1)
(1) A.M.Obukhov Institute of Atmospheric Physics RAS
Water cycle changes in the Siberian rivers basins, including rivers runoff into the Arctic Ocean, from transient runs of coupled general circulation models (ECHAM4/OPYC3 and HadCM3) and IAP RAS climate model of intermediate complexity for the period since the middle XIX century up to the end of XXI century with the greenhouse gases changes are analyzed. There is a general agreement between model simulations and
observations (1930-1995) for mean values of the Ob, Yenisei and Lena rivers runoff, except for Lena in IAP RAS CM with a significant runoff underestimation. On the other hand IAP RAS CM shows quite good agreement with observations for interannual variance of the Lena river runoff. The best simulation of mean values for Lena river runoff exhibits HadCM3. Spectral analysis shows the best agreement with observations of the Yenisei river runoff from ECHAM4/OPYC3 simulations. In general, model results exhibit an increase of mean values and variances of regional precipitation in the Ob, Yenisei and Lena rivers watersheds and rivers runoff to the Arctic Ocean in the XXI century relative to XX century.
Alongside with such a general tendency a remarkable interdecadal variations of regional water cycle characteristics have been noted from model simulations. For instance, ECHAM4/OPYC3 and HadCM3 exhibit some decrease of the Ob and Yenisei rivers runoff in the first half of the XXI century. Changes in spectra of regional precipitation and rivers runoff due to global warming are also estimated. In particular, CHAM4/OPYC3 simulations show a remarkable increase of decadal variability of Yenisei and Lena rivers runoff in the XXI century. Relationships of Siberian rivers runoff with Arctic Oscillation and North Atlantic Oscillation and also with characteristics of Siberian High and Aleutian Low from observations and model simulations are analyzed.
