Ice and cloud streets in the Sea of Okhotsk
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Ice and cloud streets in the Sea of Okhotsk

February 3, 2011
On January 28, 2011 the Terra satellite flew over the Sea of Okhotsk, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard to capture this impressive true-color image of the winter landscape of the Russian Far East. The snow cover etches the features of Kharbarovsk Krai in bright white and delicate pale blues. The brightest white snow marks the area of heaviest cover, generally the tops and western slopes of mountains.

The ice sheet which covers the Sea of Okhotsk is thickest just off the coast and to the south, then thins and eventually dissipates in open waters. In most years, the Sea is frozen from October to March. This long freeze-up is enabled by the inflow of very large quantities of fresh water, which drops the salinity of the shallow, salty Sea enough to raise the freezing point. For this reason, the freeze-up of the Sea of Okhotsk is notably longer and more complete than other waters at the same latitude, such as the Gulf of Alaska.

The biggest contributor of fresh water to the Sea is the Amur River, seen as a frozen, bright icy-white waterway in the lower left corner of the image. This river flows across northeast Asia for over 4,400 km, draining a remarkably large watershed. The Amur empties into the Strait of Tatary, and the frozen mouth, facing Sakhalin Island, is clearly visible. The effect of the salinity-reducing capability of the Amur is also evident, as the ice appears whitest - and thus is the thickest - in the Strait of Tatary and the surrounding Sea waters.

The flow of the bitter Arctic air and its effect on the sea and the atmosphere are illustrated in this image. Just off the coast, the sea ice has been sculpted by the prevailing winds, forming more thickly (whiter) where the wind drops the sea surface temperatures. To the east, the winds comb the clouds into long, parallel rows which align with the prevailing winds. These formations are called cloud streets. In this image, the streets can be seen to align in various directions, illustrating the complexity of the winds that blow off Russia's Far Eastern coast.

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