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METR112 Global Climate Change. Lecture 3: Earth Hydrological Cycle. Earth Hydrological Cycle. Prof. Menglin Jin, San Jos é State University. What is hydrology?. All components formed by H 2 O is part of Hydrology cycle. Relations between heat and water cycles. Jim Hansen:. - PowerPoint PPT Presentation
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Earth Hydrological Cycle Lecture 3: Earth Hydrological Cycle
Prof. Menglin Jin, San José State University
METR112 Global Climate Change
What is hydrology?
All components formed by H2O is part of Hydrology cycle
Relations between heat and water cycles
• Temperature change and hydrology cycle
Video
http://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-wmv/hydrological%20cycle/DTS-9.wmv
Jim Hansen:
Notes: While watching this video, think what sub-components of hydrological cycle is mentioned.
What are hydrological components?
The hydrological cycle. Estimates of the main water reservoirs, given in plain font in 103 km3, and the flow of moisture through the system, given in slant font in103 km3/yr, equivalent to Exagrams (1018 g) per year. (Trenberth et al. 2006a).
Major components of hydrological cycle Precipitation Evaporation & evapotranspiration Atmospheric transport Runoff and ground water flow Water reservoir (ocean, lake,
glacier, soil water, etc.)
Precipitation: Rain gauge
Standard rain gauge used in observing precipitation
Precipitation: Radar & satellite
Radar detecting the cloud by collecting reflected microwaves
Satellite observe earth in microwave or infrared channels from space and estimate precipitation using retrieval techniques
Modern Observing approach
TRMM: Unprecedented Views of Hurricanes
Show video of “Katrina” and “global snow coverage” in class
Precipitation: Observations show great spatial variation
U.S. WSR-88D Frequency of Rainfall Occurrence for 1998 - 2000
Precipitation: Observations show decadal variation of precipitation change
Precipitation:
IPCC AR4
Changes are not spatially uniform
General increase of precipitation in most areas in mid- and high latitude,
Decreased precipitation in the Western, Southern Africa and Sahel
With mixed signs in Eurasia
Precipitation increases in Northwest India
Source: IPCC AR4 - Chapter 3, Adopted from: Richard CJ Somerville, APRU World Institute Workshop, 2007
Precipitation variation is complex over the land
Increases
Decreases
Video
• http://www.met.sjsu.edu/metr112-videos/MET%20112%20Video%20Library-MP4/hydrological%20cycle/
DTS-3.mp4
Figure 3.35. Annual values of the East Asia summer monsoon index derived from MSLP gradients between land and ocean in the East Asia region. The definition of the index is based on Guo et al. (2003) but was recalculated based on the HadSLP2 (Allan and Ansell, 2006) data set. The smooth black curve shows decadal variations.
Significant decrease in East Asian Monsoon index since 1976/77 climate shift
Figure 3.35
East Asian summer monsoon index: Sum of mean sea level pressure differences between 110o and 160oE for 20o to 50oN with 5o difference.
Rainfalldecrease
Figure 3.36
Figure 3.36. Time series of northern Australian (north of 26°S) wet season (October–April) rainfall (mm) from 1900/1901 to 2004/2005. The individual bar corresponds to the January of the summer season (e.g., 1990 is the summer of 1989/1990). The smooth black curve shows decadal variations. Data from the Australian Bureau of Meteorology.
Current global climate a boon for Australian Monsoon? Statistically significant rainfall show up in predominantly northern parts of Australia Primarily due to additional southern Australian land heat up while no/cold Anomalous changes in oceans
Figure 3.37
Figure 3.37. Time series of Sahel (10ºN –20ºN, 18ºW–20ºE) regional rainfall (April–October) from 1920 to 2003 derived from gridding normalised station anomalies and then averaging using area weighting (adapted from Dai et al., 2004a). The smooth black curve shows decadal variations.
African Monsoon shows clear signal due to changes in ENSO
Both tropical Pacific and Atlantic SSTs have effects on African Monsoon Many studies show deforestation would amplify draught signals
Evaporation (evapotranspiration) observations are limited
Pan evaporation observes the potential evaporation
Bowen ratio system observes evapotranspiration using energy balance
(Trenberth and Stepaniak 2003)
Would distribution of annual averaged Latent heat flux from 1979 to 2001 from reanalysis
Trend of pan evaporation in US from 1950 to 2001
annual
Warm season
Blue (red) is decrease (increase), circle is sig at 90%
Hobbins and Ramirez 2004
ERA15 (solid curve), COADS (dashed), CE91-95 (dotted curve)
Zonally-averaged annual evaporation shows an M-shaped distribution
15-year ECMWF reanalysis
Garnier et al. 2000
One way of measuring soil moisture: gravimetric method
Two types of augers used for gravimetric soil moistureobservations, sitting on a neutron probe. The one on the left is pounded into the ground and used when the ground is frozen. The one on the right is twisted into the ground
Robot et al. 1999
soils.usda.gov/use/worldsoils/mapindex/smr.html
Major soil moisture climate regimes
Seasonal cycles of soil moisture for various areas
Robot et al. 1999
The most recent monthly averaged soil moisture for US
Decreased spring snow covered area in Northern America
Statistically significant decline in annual SCA for 2.7x10^4 km^2 SCA maximum shift from February to January and earlier snow melt Melting season shift two weeks earlier from 1972 to 2002
Snow:
Snow cover anomalies in from 1966 to 2006 for northern America
http://www.arctic.noaa.gov/detect/ice-snow.shtml
Snow cover anomalies in from 1966 to 2006 for Eurasia
http://www.arctic.noaa.gov/detect/ice-snow.shtml
Arctic sea ice extent decreases in the last 20 years
annual: -2.7%/dec
Sea ice:
The annual sea ice extent decrease steadily from 1980
summer: -7.4%/dec
Most remarkable change is the summer sea ice diminish, in which the interannual to decadal variability is associated with the variability of atmospheric circulation
Summer sea ice decrease in tremendous in the last 20 years
Glacier and ice cap mass loss in response to 1970 warming
(Science basis, Chap.4, Fig.4.15)
Strong negative specific mess balances in Patagonia, Alaska after mid 90s, cumulative balance equivalent to 10m of water (11m of ice)
Total mass loss are contributed mainly from Alaska (0.24 mm/yr of SLE), Arctic (0.19 mm/yr of SLE) and Asia high mountains (0.1 mm/yr of SLE)
Glacier:
Video: Himalayas
Muir glacier , Alaska
1941 2004
Decreased ice extent in Kilimanjaro
Aggressive retreat of Antarctica peninsula ice shelf
Greenland melt extent seeing from satellite
2005 summer ice extent set a record during 27-year period. 2005 also shows a especially long melting season (until late Sep) compared to previous years according to Steffen et al. 2004, Hanna et al. 2005
Greenland melt area during summer time increases from 1979 to 2005
Shrinking of Greenland ice-sheet in a warmer climate
Evolution of Greenland surface elevation and ice sheet volume versus time in the experiment of Ridley et al. (2005) with the UKMO-HadCM3 AOGCM coupled to the Greenland Ice Sheet model of Huybrechts and De Wolde (1999) under a climate of constant quadrupled pre-industrial atmospheric CO2.
Class Participation 9/4/2013
• Work with your group-mates to
Discuss why changes in temperature can lead to changes in hydrological cycle (in terms of rainfall, soil moisture, EP, and snow coverage sea level)