http://www.cartoonstock.com/directory/e/el_nino.aspThe El Nio and La Nia Effects on the Hydrology of TexasAndy ChanCE 394K.2 Surface Water Hydrology

NORMAL CONDITIONhttp://www.cpc.noaa.gov/products/analysis_monitoring/ensocycle/meanrain.shtml

EL NIO CONDITIONhttp://www.cpc.noaa.gov/products/analysis_monitoring/ensocycle/enso_schem.shtml

LA NIA CONDITIONhttp://www.cpc.noaa.gov/products/analysis_monitoring/ensocycle/lanina_schem.shtml

EL NIO AND LA NIA YEARS24 El Nio years16 La Nia years

1901191119211931194119511961197119811991200119021912192219321942195219621972198219922002190319131923193319431953196319731983199320031904191419241934194419541964197419841994190519151925193519451955196519751985199519061916192619361946195619661976198619961907191719271937194719571967197719871997190819181928193819481958196819781988199819091919192919391949195919691979198919991910192019301940195019601970198019902000

PALMER DROUGHT SEVERITY INDEX(PDSI)The underlying concept of the [PDSI] The difference between the actual precipitation and the [precipitation required for the near-normal operation of the established economy of an area] represents a fairly direct measure of the departure of the moisture aspect of the weather from normal. When these departures are properly weighted, the resulting index numbers appear to be of reasonably comparable local significance both in space and time.

Palmer, W. C., 1965: Meteorological drought. Weather Bureau Res. Paper 45, U.S. Department of Commerce, Washington, DC, P.58.

PALMER DROUGHT SEVERITY INDEX(PDSI)P = ET + R + RO L

P = CAFEC PrecipitationET = CAFEC EvapotranspirationR = CAFEC Soil Moisture RechargeRO = CAFEC RunoffL = CAFEC Soil Moisture Loss

d = P P

d = Moisture departure for a particular monthP = Areal average precipitation for a particular monthCAFEC = Climatically Appropriate For Existing Conditions

TEXAS CLIMATE DIVISIONSHigh PlainsLow Rolling PlainsNorth Central TexasEast TexasTrans-PecosEdwards PlateauSouth Central TexasUpper CoastSouth TexasLower Valley

1915 (La Nia -1)1916 (La Nia)1917 (La Nia +1/El Nio -1)1918 (El Nio)1919 (El Nio +1)EXAMPLE: PDSI MAPS

1915 (La Nina -1)SPRING

1915 (La Nina -1)SUMMER

1915 (La Nina -1)FALL

1915 (La Nina -1)WINTER

1916 (La Nina)SPRING

1916 (La Nina)SUMMER

1916 (La Nina)FALL

1916 (La Nina)WINTER

1917 (La Nina +1/El Nino -1)SPRING

1917 (La Nina +1/El Nino -1)SUMMER

1917 (La Nina +1/El Nino -1)FALL

1917 (La Nina +1/El Nino -1)WINTER

1918 (El Nino)SPRING

1918 (El Nino)SUMMER

1918 (El Nino)FALL

1918 (El Nino)WINTER

1919 (El Nino +1)SPRING

1919 (El Nino +1)SUMMER

1919 (El Nino +1)FALL

1919 (El Nino +1)WINTER

TAKE HOME MESSAGEEl Nio Wetter than normal starting from late El Nio year to late El Nino +1 year Higher precipitation, temperature, and streamflow Lower evaporation

La Nia Dryer than normal starting from late La Nia year to late La Nia +1 year Lower precipitation, temperature, and streamflow Higher evaporation

These relationships are not strong enough for use in accurately predicting streamflow or droughts, they may be useful if they are expressed as probabilities of exceedance threshold levels (Piechota 1996)

http://www.cartoonstock.com/directory/f/forces_of_nature.aspQUESTIONS?

SEA SURFACE ANOMALIES (C) OF E. PACIFIC BASIN

YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ1950-1.8-1.5-1.4-1.4-1.4-1.2-0.9-0.8-0.8-0.8-0.9-11951-1-0.8-0.6-0.4-0.20.10.40.50.60.70.70.619520.30.10.10.10-0.2-0.3-0.3-0.1-0.2-0.2-0.119530.10.30.40.50.50.40.40.40.40.40.30.319540.30.2-0.1-0.5-0.7-0.7-0.8-1-1.1-1.1-1-11955-1-0.9-0.9-1-1.1-1-1-1-1.5-1.8-2.1-1.71956-1.2-0.8-0.7-0.6-0.6-0.6-0.7-0.8-0.9-0.9-0.9-0.81957-0.5-0.10.20.60.70.80.90.90.80.91.21.519581.61.51.10.70.50.50.40.1000.10.319590.40.40.30.20-0.3-0.4-0.5-0.4-0.4-0.3-0.31960-0.3-0.3-0.3-0.2-0.1-0.100-0.1-0.2-0.3-0.21961-0.2-0.2-0.2-0.10.10.10-0.3-0.6-0.6-0.5-0.51962-0.5-0.5-0.5-0.5-0.4-0.3-0.2-0.3-0.4-0.6-0.7-0.71963-0.6-0.300.10.10.30.60.80.80.91119640.80.4-0.1-0.5-0.7-0.7-0.8-0.9-1-1.1-1.1-11965-0.8-0.5-0.300.20.611.21.41.51.61.519661.21.10.80.50.20.10.10-0.2-0.3-0.3-0.4