near-surface climate extremes in the past 50+ years yun fan huug van den dool cpc/ncep/noaa noaa...
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Near-Surface Climate Extremes in the Past 50+ Years
Yun Fan & Huug van den Dool
CPC/NCEP/NOAA
NOAA 32th Annual Climate Diagnostic & Prediction Workshop 22-26 October, 2007, Tallahassee, FL
...Now the wind grew strong and hard,it worked at the rain crust
in the corn fields.
Little by little the sky was darkened by the mixing dust,
and the wind felt over the earth, loosened the dust and carried it away.
...from The Grapes of Wrath, written by John Steinbeck.
From NCDC/NOAA
From NCDC/NOAA
1931 present
a. What is a climate extreme event?
b. How about the spatial distribution of extreme events?
c. How do hydrological extremes respond to observed P & T extremes?
d. What are the capability and uncertainty of current land surface data analysis systems to faithfully describe extreme events?
Motivation
A climate extreme event is an anomalous event that departs significantly from its normal state in frequency, magnitude, temporal and spatial extent
What is a climate extreme event?
How to measure a climate extreme event?
Goal: to establish an objective definition based on some thresholds
WMO climatology to define “anomaly”Frequency <= N of recurrence Rarity or small probability of occurrence
Amplitude => N * STDmaxima or minima, exceed threshold, break record
Temporal extent => N*Months time duration or lasting time
Spatial extent => # grid boxes impacted area or region Severity, ……impact (harder: such as loss of life and properties)
10 Land Surface Datasets:
2. Four 50+ Year Retrospective Offline Runs
3. Four Reanalysis Datasets
1. Observations • CPC Monthly Global Land Surface Air Temperature Analysis (1948- present) Y. Fan & H. van den Dool, 2007 • CPC Monthly Global Land Surface Air Temperature Analysis (1948- present) Chen et al 2003
RR - North American Regional Reanalysis (1979 - present) F. Mesinger et al, 2003, 2005
R1 – NCEP-NCAR Global Reanalysis I (1948 - present) E. Kalnay et al, 1996 & R. Kistler et al 2001
R2 – NCEP-DOE Global Reanalysis II (1979 - present) M. Kanamitsu et al, 2002
• ERA40 – ECMWF Reanalysis 40 Project (1957-2002) S. Uppala et al 2005
Noah - Noah LSM Retrospective N-LDAS Run (1948-2002) – present Y. Fan, H, van del Dool, D. Lomann & K. Mitchell, 2003
VIC - VIC LSM Retrospective N-LDAS Run (1950-2000) E. Maurer, A. Wood, J. Adam, D. Lettenmaier & B. Nijssen, 2002
LB - CPC Leaky Bucket Soil Moisture Datasets US_CD: 1931-present: J. Huang, H. van den Dool & K. Georgakakos, 1996, Globe: 1948-present: Y. Fan & H. van den Dool, 2004
Driest Precipitation (1948-present) Wettest
Time
Location
Dry Precipitation Wet
Increase
threshold
# of ‘rare’ events
2.0*sd
3.0*sd
2.5*sd
3.0*sd
2.5*sd
2.0*sd
Precipitation -- Decadal variation of dry extreme (anom < -2mm, 2*sd)
# of ‘rare’ events
1950s
1960s
1970s
1980s
1990s
2000s
# of ‘rare’ events
Precipitation -- Decadal variation of wet extreme (anom>2mm, 2*sd)
1950s
1960s
1970s
1980s
1990s
2000s
Coldest T2m (1948-present) Warmest
Location
Time
Cold T2m Warm
2.0*sd
3.0*sd3.0*sd
2.5*sd 2.5*sd
2.0*sd
T2m -- Decadal variation of cold extreme (anom<30C, 2*sd)
1950s
1960s
1980s
1990s
2000s1970s
T2m -- Decadal variation of warm extreme (anom>30C, 2*sd)
1950s
1960s
1970s 2000s
1990s
1980s
Driest Soil Moisture from CPC Leaky Bucket Wettest (1948-present)
Location
Time
Dry Soil Moisture Wet
2.0*sd
2.5*sd
3.0*sd
2.0*sd
2.5*sd
3.0*sd
SM -- Decadal variation of dry extreme (anom<-10mm, 2*sd)
1950s
1960s
1970s
1980s
1990s
2000s
SM -- Decadal variation of wet extreme (anom>10mm, 2*sd)
1950s
1960s
1970s
1980s
1990s
2000s
1948 present
SM anom: shaded
Disaster right now
Temp increase is a factor!
Most Deadly heat wave in European history
1948 present
Concluding Remarks
1) We are only beginning
2) Climate extreme weather extremes
3) Timing is everything!
4) Due to climate change: +ve T anomalies stronger recently in general
5) Reliability + length of data sets is obviously important
Thanks!
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