Altiplano Climate. Making Sense of 21st century Scenarios. A. Seth J. Thibeault C. Valdivia

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1 Altiplano Climate Making Sense of 21st century Scenarios A. Seth J. Thibeault C. Valdivia

2 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

3 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

4 CMIP3 Data Archive Data Availability Summary (as of 27 February 2008) shaded area indicates that at least some but not necessarily all fields are available for data type indicated time-independent land surface 3-hourly atmosphere >1 1 Extreme Indices >1 1 monthly-mean atmosphere time-independent ocean Forcing daily-mean atmosphere >1 1 monthly-mean ocean ISCCP Simulator BCC-CM1, China BCCR-BCM2.0, Norway CCSM3, USA CGCM3.1(T47), Canada CGCM3.1(T63), Canada CNRM-CM3, France CSIRO-Mk3.0, Australia CSIRO-Mk3.5, Australia ECHAM5/MPI-OM, Germany ECHO-G, Germany/Korea FGOALS-g1.0, China GFDL-CM2.0, USA GFDL-CM2.1, USA GISS-AOM, USA GISS-EH, USA GISS-ER, USA INGV-SXG, Italy INM-CM3.0, Russia IPSL-CM4, France MIROC3.2(hires), Japan MIROC3.2(medres), Japan MRI-CGCM2.3.2, Japan PCM, USA UKMO-HadCM3, UK UKMO-HadGEM1, UK Picntrl PDcntrl 20C3M Commit SRESA2 SRESA1B SRESB1 1%to2x 1%to4x Slab cntl 2xCO2 AMIP

5 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

6 Simulated Altiplano Climate

7 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

8 Analysis for South America South American Monsoon analysis - Vera et al., Geophys. Res. Let Li et al., J Geophys. Res much disagreement among models for Amazon Large scale circulation changes: - Vecchi and Soden, J Climate Neelin et al., PNAS 2006 some coherent large scale changes

9 Large scale changes? weakening of tropical circulation via reduction in strength of Walker Circulation strengthened, poleward shifted sub tropical highs upped ante e.g., Neelin et al 2006 from Vecchi and Soden, JClimate 2007 F. 7. The multimodel (a) ensemble-mean and (b) ensemble-mean change in per degree global

10 Projected Temperatures B1: low A1B: medium A2: high

11 Projected Precipitation B1: low A1B: medium A2: high

12 Annual Cycle Precipitation Drier early season Wetter peak season Is this believable? Seth, Garcia &Thibeault, 2008: GRL, submitted

13 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

14 Extreme Indices Table 1. Ten indicators of climate extremes Frich et al. [2002] Tebaldi et al. [2006]. Indicator Definition Units Extreme temperature range (ETR) Difference between the highest and lowest K temperature observations within a given year Frost days (FD) Total number of days with minimum temperature days <0 C Growing Season Length (GSL) Number of days between the first period when mean T day >5 C for >5 d and the first period when mean T day <5 C for >5 d days Heat wave duration index (HWDI) Max. period of at least 5 d when T max >5 C days above the daily T max average Warm nights (Tn90) Percent of time in a year when T min >90 th % percentile of minimum temperature for a particular calendar date Precip >10 mm (R10) Number of days with precip. 10 mm d 1 days Consecutive dry days (CDD) Maximum number of consecutive dry days days (R day <1 mm) 5 day precipitation (R5d) Maximum 5-day precipitation total mm Precip >95 th percentile (R95T) Fraction of total annual precipitation from % events >the th percentile Precipitation intensity (SDII) Annual total precipitation divided by the number of days with precip. 1 mm d 1 mm d 1

15 Temperature Indices

16 Shifts in PDFs (Probability Distribution Functions) extreme temperature range (B1) extreme temperature range (A1B) extreme temperature range (A2) (C) (C) (C) frost days (B1) frost days (A1B) frost days (A2) days days days

17 Shifts in PDFs heat waves (B1) heat waves (A1B) heat waves (A2) days days days warm nights (B1) warm nights (A1B) warm nights (A2) % % %

18 Precipitation Indices

19 Shifts in PDFs dry days (B1) dry days (A1B) dry days (A2) days days days 5!day precipitation (B1) 5!day precipitation (A1B) 5!day precipitation (A2) mm mm mm

20 Shifts in PDFs precip > 95th percentile (B1) precip > 95th percentile (A1B) precip > 95th percentile (A2) % % % precipitation intensity (B1) precipitation intensity (A1B) precipitation intensity (A2) mm/d mm/d mm/d

21 Observed trends from Haylock et al., JClimate 2006 Ex.1day F. 2. Sign of the linear trend in rainfall indices as measured by Kendall s Tau. An increase is shown by a plus V. Heavy P days % days V. heavy % days Ex. heavy

22 Overview Coupled Model Intercomparison Project (CMIP3) How do models represent Altiplano climate? What do models project for 21st century? - Changes in annual cycle of temperature, precipitation - Changes in extremes Caveats and Cautions

23 Caveats and Cautions Caveats - Climate models are currently low resolution. Do not capture elevations of Altiplano, too much moisture from Amazon. Discussion ongoing about generation of climate scenarios will be higher resolution for improved regional evlauation. IPCC AR5 - Climate models include evolution of oceans and atmosphere. Ocean dynamics have important impact on South America and are the causes of differences between models. - Still disagreement about changes in ENSO, important for variability!

24 Caveats and Cautions Changes in Annual Cycle? - Temperature: C increase in mean by mid century. 4-5 C increases by end of century unless global mitigation strategies are implemented. - Precipitation: possible small decrease in SON, increase in DJF. Both larger by end of century. Dependent on large scale changes in Pacific Ocean and South American monsoon.

25 Caveats and Cautions Changes in Extremes? - Temperature: increases in Extreme Temp Range and Warm Nights. - Decrease in Frost Days not reliable due to warm bias and low elevation in the models. - Increase in Heat Waves - will be more meaningful with new calculation using percentile rather than threshold. - Precipitation: increases in Dry Days, Max 5 day, Simple Intensity, and Heavy precipitation - in accordance with Patacamaya. Work with SENAHMI to verify recent period.

Using observations to constrain climate project over the Amazon - Preliminary results and thoughts

Using observations to constrain climate project over the Amazon - Preliminary results and thoughts Rong Fu & Wenhong Li Georgia Tech. & UT Austin CCSM Climate Variability Working Group Session June 19,