NCDC: Climate of 2002 - September

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Climate of 2002 - September
California Drought

National Climatic Data Center, 11 October 2002

Statewide Overview / Northern California Paleo Perspective

Statewide Overview

This month was the eighth driest September, statewide, in the 108-year record. The persistent dryness of the last nine months has resulted in the driest June-September, third driest year-to-date (January-September), and 26th driest hydrologic year (October-September) on record. The last four hydrologic years have averaged drier than the long-term mean.

Statewide Precipitation Ranks
for California , 2001-2002
Period	Rank
Sep	8^th driest
Aug-Sep	1^st driest
Jul-Sep	1^st driest
Jun-Sep	1^st driest
May-Sep	5^th driest
Apr-Sep	7^th driest
Mar-Sep	3^rd driest
Feb-Sep	5^th driest
Jan-Sep	3^rd driest
Dec-Sep	14^th driest
Nov-Sep	30^th driest
Oct-Sep	26^th driest

Click here for graphic showing California statewide precipitation departures, January 1998 - present

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Click here for graphic showing California statewide Palmer Z Index, January 1998 - present

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Click here for graphic showing California statewide precipitation, October-September 1895-2002

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Click here for graphic showing California statewide Palmer Hydrological Drought Index, January 1900 - September 2002

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Northern California Paleoclimatic Perspective

The graph to the right shows Sacramento River Basin annual (hydrologic year, October-September) precipitation for 1895-2002 compared to reconstructed annual streamflow for 869-1977. The Sacramento annual streamflow was reconstucted to A.D. 869 using tree-ring data in northern California and surrounding areas. The reconstruction is of high quality, reflecting 64% (back to 869) to 81% (back to 1630) of the flow variance in the gage record. The reconstruction suggests that the 1930s drought is representative of extreme 6-10 years droughts in the long-term record. However, the instrumental period may be less representative of extreme droughts that last longer than a decade. Prior to 1400, the reconstruction is characterized by multidecadal periods of persistent low and high flow. Although these periods of persistent high or low flow occur in the earlier and least accurate part of the reconstruction, they would represent challenges to water managers were they to occur today.

Click here for graph showing reconstructed Sacramento annual streamflow-precipitation Chronology, 869-2002

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"Graph showing reconstructed Sacramento annual streamflow-precipitation Chronology, 869-2002" larger image (150 K)

Reference:

Meko, D.M., M. D. Therrell, C. H. Baisan, and M. K. Hughes, 2001. "Sacramento River Flow Reconstructed to A.D. 869 From Tree Rings", Journal of the American Water Resources Association, v.37, No.4, August 2001.

Data and description:

ftp://ftp.ngdc.noaa.gov/paleo/treering/reconstructions/california/sacramento_flow.txt

NCDC / Clim. Monitoring / Climate-2002 / Sep / U.S. Regional Drought / Search / Help

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