Gennady A. Platov, Elena N. Golubeva, Victor I. Kuzin The influence of the inter-annual variability of Siberian rivers run-off on the redistribution of the fresh water fluxes in the Arctic Ocean and North Atlantic ИВМиМГ Gennady A. Platov, Elena N. Golubeva, Victor I. Kuzin

Topics The fresh water balance in Arctic: How does it change? The major consequences of fresh water balance changes The Atlantic response to the fresh water balance changes All results are based on the numerical simulations using ICM&MG model (Novosibirsk)

Total Water Transport (switching off Arctic rivers discharge) Although the total Arctic river discharge is small, the redistribution of water transport between straits could reach 10 times higher volumes

Fresh water content (volume) +10% -10% +10% Fresh water content changes are more sensitive to the river discharge rate. The absence of rivers provides about 1/3 drop of FWC in 60 years. The response to the river discharge changes is non-linear. -10%

Fresh water transport

Fresh water content S1 h S2 h’ S0 (S1h+S2h’)/(h+h’) h+h’ FWC could increase only due to the sources: rivers, ice-melt, precipitation Any mixing (vertical turbulence, horizontal diffusion) lower the FWC S0

Experiment Russian meteorological station data for Ob, Yenisey and Lena discharge (1936-1990) (R-ArcticNet – A Database of Pan-Arctic River Discharge) Period of Great Salinity Anomaly (GSA) – 60’s and 70’s Trace the response to river discharge changes along the GSA path – regions A, B, C, D Consider the subsurface circulation in the Beaufort Gyre

Siberian river discharge (time integrated difference between measurements and climate) FW deficit from 1955 to 1975 (except 1962-1965) FW excess in 80’s and 90’s contributed by Lena

Cyclonic and Anticyclonic Modes + m/s Correlation between integrated river discharge difference and velocity vector circulation difference about 70%. Correlation between velocity vector circulation difference and Fram Strait FWC outflow is 40% with 2-3 years time-lag

Fresh water balance changes 103 km3 103 km3 The most significant difference appears in 1975 as GSA reaches west European coast What is the mechanism for such a significant and distant response?

FWC anomaly growing along the GSA pathway 103 km3 A 103 km3 B 103 km3 C 103 km3 Most significant signal of FWC anomaly appears in the vicinity of Azores Is. D

Vertical mixing Due to the FWC anomaly the vertical stratification in the vicinity of the Fram Strait is more stable in real data experiment Less water involved in vertical mixing, therefore FWC anomaly is growing The instability close to Gibraltar Strait becomes lower. As a consequence more FWC is preserved from vertical mixing in 1975. 103 km3

Conclusions The variations of Arctic river discharge rate affect the distribution of Arctic water transport through the major straits The cyclonic and anticyclonic modes of Arctic subsurface circulation depends with statistical significance on Arctic river discharge rates The response to the variations of Siberian rivers discharge could be as high as 10 times greater than the original perturbation and as distant as the vicinity of Azores Islands in Atlantic.

Thank You

Property of water passing the Fram Strait From Arctic 0-200 m: T=-1÷10C, S=30÷34 psu 400-1000 m: T=0÷20C, S=35 psu To Artic 100-600 m: T=1÷20C, S=35 psu 1600-3000 m: T=-1÷00C, S=35 psu