Planetary Hydrology - Lecture Slides | ESM 203, Study notes of Environmental Science

Download Planetary Hydrology - Lecture Slides | ESM 203 and more Study notes Environmental Science in PDF only on Docsity! 10/29/2002 ESM 203 - Planetary hydrology 1 ESM 203: Planetary Hydrology 1 Jeff Dozier & Tom Dunne Fall 2007 Earth System Science Earth consists of system components “Solid” planet Atmosphere Ocean 2 Cryosphere Hydrosphere Continental “near surface” (pedosphere and biosphere) “Technosphere” Earth System Hydrology Planetary hydrologic processes Land-atmosphere interactions modulated by plants and soils 3 Subterranean water The hydrologic role of snow and ice Water Supplies Hydrologic Cycle The continual transfer of water, in various phases, among reservoirs (stores) in the 4 atmosphere, ocean, and continents Earth System: physical climate and biogeochemical systems, coupled by the hydrologic cycle 5 Asrar and Dozier The hydrologic cycle is driven by … Solar energy Exchanges of this energy within the Earth system results in evaporation/condensation, freezing/thawing, changes of density Internal Earth energy (residual heat and radioactivity) 6 Locally near surface and more extensively at great depth, geothermal heat causes density changes and convection in groundwater Gravity Wind (pressure gradients caused by gravity) Rivers/glaciers flowing downhill Groundwater moving because of potential energy gradients in the water 10/29/2002 ESM 203 - Planetary hydrology 2 Water on Earth (approx. 1.4 x 109 km3) Oceans 97.2% Ice 2.0 Groundwater - deep (750-4000m) 0.4 Groundwater shallow (<750m) 0 3 7 – . Lakes 0.01 Soil 0.005 Atmosphere 0.001 Rivers 0.0001 Biosphere 0.00004 Read: Black, P.E. On the critical nature of “useless” resources; Water Resources Bulletin (1995) Never at Rest …. Evaporation from the ocean, precipitation onto the ocean, transfer of a portion over continents Precipitation on continents (rain, snowfall, snowpack storage and meltwater release) Water moves continually between the reservoirs by a number of processes: 8 Evaporation from continents (if it occurs directly from a water surface or soil surface), evapotranspiration if the evaporation is modulated by plant processes. Infiltration Percolation through soils and rocks Streamflow (stormflow and baseflow); flow through lakes Flow through the ocean Evaporation from the ocean ….. etc., etc. Energy (and its spatial variability) is the key to the continual transfer of water mass Fluxes between stores Note that the ocean area is about twice the land area; these numbers are in volumes per unit area of surface) Evaporation from ocean 117 cm/yr Precipitation onto ocean 107 cm/yr Precipitation onto land 74 cm/yr Evaporation from land 49 cm/yr 9 Runoff from land 25 cm/yr Over the ocean, E > P Over land, P > E. Suggests that the storage of water on land causes some kind of “resistance” to evaporation, so that some of the precipitated water “escapes” evaporation and survives to run off the continents as streamflow (R). Traditional view of the hydrologic cycle Modern view of the hydrologic cycle Complete planetary hydrologic cycle 10/29/2002 ESM 203 - Planetary hydrology 5 Satellite maps of average monthly sea surface temperatures http://www.pmel.noaa.gov/tao/elnino/la- nina-pacific.html Southern Oscillation mechanism 26 http://ess.geology.ufl.edu/u sra_esse/El_Nino.html Satellite maps of average monthly sea surface temperatures 27 http://www.pmel.noaa.gov/tao/elnino/la- nina-pacific.html Persistent climatic/hydrologic conditions Glantz, M. H., The use of analogies in forecasting ecological and societal responses to global warming; Environment, 33(5), 9-33, 1991. Southern Oscillation Index for each month Based on mean monthly sea-level pressure difference (Pdiff) between Tahiti and Darwin, Australia )P(Dev.St PPSOI diff diffavdiff −= Negative values of the SOI often indicate El Niño episodes. Warming of the central and eastern tropical Pacific, decrease in the strength of the Trade Winds, and a reduction in rainfall over E and N Australia, etc., etc. (readings) Positive values of the SOI stronger Pacific trade winds and warmer sea temperatures over SE Asia and N Australia ( La Niña ) http://www.cpc.noaa.gov/products/analysis_monitoring/impacts/enso.html Southern Oscillation Index 30http://www.bom.gov.au/climate/current/soi2.shtml 10/29/2002 ESM 203 - Planetary hydrology 6 Correlations between river flows in Australia, India, and N.E. Africa with Rainfall in E. Pacific and S. America 31 Correlations between river flows in Australia, India, and N.E. Africa with Southern Oscillation Index 32 Pacific Decadal Oscillation Index (PDO) Based on monthly winter sea surface temperatures Cool phase Δ Sea Surface Temperature Warm phase Strongest PDO impacts are in the Pacific Northwest, where warm-phase PDO periods are associated with below-average rainfall and above-average temperatures. During the cool phase of the PDO, there are typically cooler-than-average temperatures and above-average rainfall. Farther away from the Pacific Northwest, the impacts are less distinct. 33 Pacific Decadal Oscillation (based on monthly winter sea surface temperatures) 34 North Atlantic Oscillation Positive NAO Index Stronger subtropical high pressure center and deeper Icelandic low. Increased pressure difference 35 results in more and stronger winter storms crossing the Atlantic Ocean on a more northerly track. Warm, wet winters in Europe and cold and dry winters in Canada and Greenland Eastern US –mild, wet winters http://www.ldeo.columbia.edu/NAO/ North Atlantic Oscillation Negative NAO Index Weak subtropical high and a weak Icelandic low. Reduced pressure gradient results in fewer and weaker 36 winter storms crossing on a more west-east pathway. Bring moist air into the Mediterranean and cold air to northern Europe Eastern US --- more cold air outbreaks and snowy weather conditions. Greenland milder 10/29/2002 ESM 203 - Planetary hydrology 7 North Atlantic Oscillation 37 Extra uncertainties about future perturbations outside of the range of the historical record E.g., CO2 levels will be higher than at any time in the period of record Global warming of ≥ 2-4°C expected, perhaps 10- 15°C in the Arctic Does this cause more or less streamflow, lake storage or groundwater? [See Harte and Wigley 38 models in Dingman, the reader, lecture notes, and later slides. Harte is a global view; Wigley a hypothetical regional view.] Globally more evaporation, so more precipitation, but Probably concentrated in tropical oceans Interiors of continents hotter and dry? But…… Where do we go for guidance? Envisioning potential future climate change based on historical evidence Glantz, M. H., The use of analogies in forecasting ecological and societal responses to global warming; Environment, 33(5), 9-33, 1991. Envisioning climate change (Dec-Feb and July-Aug Average temperatures) through Global Circulation Models Predicted changes in western snowpack based on temperature predictions and history of snow course observations Climate Change Impacts on the United States, US Global Change Research Program National Assessment Synthesis Team, Cambridge Univ. Press, 2000 Predicted changes in Columbia R. basin snow cover Climate Change Impacts on the United States, US Global Change Research Program National Assessment Synthesis Team, Cambridge Univ. Press, 2000