SIO15: Topic 21 Long- and Short-term Climate if bright in June, rain - - PowerPoint PPT Presentation

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SIO15: Topic 21 Long- and Short-term Climate if bright in June, rain - - PowerPoint PPT Presentation

Sep 14, 2023 12 likes •133 views

SIO15: Topic 21 Long- and Short-term Climate if bright in June, rain plentiful, sow in October if dim, dry spell, sow 6 weeks later modern science: Pleiades (within Taurus) invisible low-density, high-altitude clouds (cirrus) linked

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SIO15: Topic 21 Long- and Short-term Climate

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SIO15: Topic 21 Long- and Short-term Climate

Pleiades (within Taurus)

if bright in June, rain plentiful, sow in October if dim, dry spell, sow 6 weeks later modern science:

  • invisible low-density, high-altitude

clouds (cirrus) linked to El Nino

  • cirrus don’t make rain
  • 1/3 less rainfall
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SIO15: Topic 21 Long- and Short-term Climate

El Nino normal

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SIO15: Topic 21 Long- and Short-term Climate

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SIO15: Topic 21 Long- and Short-term Climate

  • about every 5-7 years
  • recurrence time complex due to other ocean circulations

(e.g. decadal oscillation)

  • particularly strong El Ninos:
  • 1972/73
  • 1982/83
  • 1991/92
  • 1997/98
  • strong El Niños seem to bring wet seasons to California;
  • therwise 50/50
  • may have global effects but affects Pacific Region most strongly

DROUGHT:

  • Indonesia
  • Australia
  • high Andes

WET:

  • central America
  • California?

(strong El Ninos only)

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SIO15: Topic 21 Long- and Short-term Climate

  • W. Pacific:

trade winds push air to west

  • low pressure in Indonesia
  • E. Pacific:
  • trade winds pull away warm water
  • upwelling of cold, deep, nutrient

rich water

  • weakening of trade winds
  • shift in low pressure system from

Indonesia to Central Pacific

  • reversal of equatorial ocean

circulation

  • drought in Indonesia
  • cut-off of deep nutrient-rich water
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SIO15: Topic 21 Long- and Short-term Climate

La Nina normal La Nina has cooler than normal SST

2007 La Nina conditions drier winters in SoCal

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SIO15: Topic 21 Long- and Short-term Climate

research done at SIO

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SIO15: Topic 21 Long- and Short-term Climate

  • 1997 El Nino

wet in East Africa, Europe, Americas; Drought in Amazon Basin

  • 1998 La Nina

dry in Africa, Europe,

  • N. America
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SIO15: Topic 21 Long- and Short-term Climate

from NOAA

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SIO15: Topic 21 Long- and Short-term Climate

El Nino and Climate in the U.S.

Fall (SON) Winter (DJF) Spring (MAM) Summer (JJA)

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SIO15: Topic 21 Long- and Short-term Climate

Temperature and Precipitation last 100 years

  • T is simple;
  • precipitation is not!