lec12-09-watersm - Arctic sea ice animation (Tom Agnew,...

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Arctic sea ice animation ( Tom Agnew, Environment Canada)
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Lecture 12 HAS222d Intro to energy and environment 2009 slides on water in the atmosphere P.B. Rhines
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Satellite image of water vapor (not cloud…it’s gaseous water which is normally invisible). This water vapor carries heat to the Arctic from the tropics. moisture streamers: (1 Sverdrup…10 6 m 3 /sec tranport of water carries 2.2 x 10 15 watt thermal energy) poleward poleward moisture moisture flux at 70N flux at 70N ( Dickson et al. 2000 Dickson et al. 2000)
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Water vapor moves poleward from the tropics, but not everywhere; it is channeled by the oceans, which are the evaporative source
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hydrosphere: 1 Sverdrup = 1 megatonne sec -1 =10 6 m 3 sec -1 liquid water =10 9 kg sec -1 ; 1 km 3 year -1 100/ π m 3 sec -1 units below are 1000 km 3 /yr or 3.18 x 10 4 m 3 /sec…total precip= 16.3 Sverdrups …yet the north-south flow of moisture by the overturning circulation is of order 1 Sverdrup in each hemisphere. Gulf Stream: 30-100 Sverdrups; Antarctic Circumpolar Current: 150 Sverdrups; Amazon River ~ 0.1 Sverdrup westerly winds in winter: 500 Sverdrups of air; Hadley circulations and meridional overturning carry ~ 1 Sverdrup of water
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The next slide shows the predicted pattern of change of precipitation by late this century. The pattern more or less follows the mean, current pattern of rainfall, which has dry latitude bands in the subtropics, and wet latitudes in the tropics near the Equator, and at high latitudes. This corresponds to the poleward flow of moisture in the winds of the overturning circulation of the atmosphere. This prediction is just what we don’t want: more rain where it rains too much and less rain in regions already on the edge of becoming parched desert. While the predictions are not necessarily the truth, the tendency for some dry regions to become even drier seems now to be developing. Australia is a water-starved continent as big as the US. There is plenty of moisture in the air from neighboring seas, but no mountains to grab it and rain it out.
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IPCC 2007
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9 IPCC climate models evaluated at 2080-99; Tibaldi et al., Clim. Change 2005, Meehl et al. Geophysical Research Letters 2005 Predicted change in the atmosphere by late in this century: warmer, shifted storm tracks, enhancement of bands of dry and wet (precipitation) shifting storm tracks, S polar vortex acceleration air descending air descending air rising
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Water Corporation W Australis 2002 1911 1976 2005 Streamflow in Perth, Western Australia: rainfall over the past 30 years is about 50% below normal; rainfall over the past 7 years is 70% below normal.
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mists hang over wetlands in early morning, following a clear night. Without the blanket of clouds, upward infrared radiation cools the
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This note was uploaded on 03/08/2012 for the course H A&S 222b taught by Professor P.b.rhines during the Spring '09 term at University of Washington.

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lec12-09-watersm - Arctic sea ice animation (Tom Agnew,...

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