A high-resolution cellulose δ 18 O record of Pinus merkusii from Cambodia and its climate implications

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1 A high-resolution cellulose δ 18 O record of Pinus merkusii from Cambodia and its climate implications Mengfan Zhu, Lowell Stott University of Southern California Brendan Buckley LDEO, Columbia University

2 Motivation How do tree ring stable isotopes record seasonal ecological and climatological influences? Use water isotopes as tracer in the hydrological cycle. Provide a long and continuous observational data of water isotopes. How has atmospheric circulation evolved in the tropical monsoon region?

3 Introduction: tree ring oxygen isotopes Isotopic composition of soil moisture Relative humidity δ 18 O c : oxygen isotopic ratio of cellulose δ 18 O s : oxygen isotopic ratio of source water ε ao : biochemical autotrophic fractionation factor ε eo : equilibrium fractionation factor for water liquid-vapor phase change ε ko : kinetic fractionation factor for water liquid-vapor phase change f : fraction of leaf water subject to evaporation φ o : fraction of oxygen that exchanges with xylem water h : relative humidity

4 Introduction: tree ring oxygen isotopes Isotopic composition of soil moisture Wet season Relative humidity Dry season

5 Study site

6 Temperature Precipitation Study site Rainy season: May to Oct Dry season: Dec-Jan-Feb Hot season: Mar-Apr-May

7 Methods Tree cores: Pinus merkusii, KRPM15B, KRPM10A. Microtome cutting: multiple samples per ring. α-cellulose extraction: Modified Brendel method (Gaudinski et al., 2002). Isotope analysis: Thermo Finnigan TC/EA, Delta V Advantage IRMS. Precision: ± 0.3.

8 Results: seasonal pattern

9 Results: seasonal pattern IsoGSM: a global rainwater isotopic composition simulation dataset using Scripps Experimental Climate Prediction Center s global spectral model (Yoshimura et al.,2008). GNIP: IAEA s global network of isotopes in precipitation.

10 Results: seasonal pattern max min max min IsoGSM: a global rainwater isotopic composition simulation dataset using Scripps Experimental Climate Prediction Center s global spectral model (Yoshimura et al.,2008). GNIP: IAEA s global network of isotopes in precipitation.

11 Results: seasonal pattern Feb Oct max min max min IsoGSM: a global rainwater isotopic composition simulation dataset using Scripps Experimental Climate Prediction Center s global spectral model (Yoshimura et al.,2008). GNIP: IAEA s global network of isotopes in precipitation.

12 Results: raw cellulose δ 18 O

13 Results: raw cellulose δ 18 O

14 Results: monthly interpolated δ 18 O Tie points: annual maxima as February, annual minima as October. Linear interpolation between tie points. Average the two cores.

15 Results: monthly interpolated δ 18 O October δ 18 O anomalies

16 Results: monthly interpolated δ 18 O October δ 18 O anomalies

17 Discussion: moisture source JJAS: Indian monsoon season, moisture from Indian Ocean-Bay of Bengal. Oct: moisture from South China Sea- Western Pacific Warm Pool.

18 Discussion: moisture source JJAS: Indian monsoon season, moisture from Indian Ocean-Bay of Bengal. Oct: moisture from South China Sea- Western Pacific Warm Pool.

19 Discussion: warm pool convection El Niño: weaker convection over the warm pool, less rainout effect, more enriched moisture δ 18 O.

20 Discussion: warm pool convection Correlation between Oct cellulose δ 18 O and

21 Discussion: warm pool convection Niño-4 Niño-4 Correlation between Oct cellulose δ 18 O and

22 Discussion: warm pool convection Correlation between October cellulose δ 18 O and October Niño-4 SST anomalies: r = 0.56

23 Discussion: warm pool convection Correlation between October cellulose δ 18 O and October Niño-4 SST anomalies: r = 0.56

24 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual rings represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent warm and cold ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region.

25 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual rings represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent warm and cold ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region.

26 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual rings represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent warm and cold ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region.

27 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual ring represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region.

28 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual ring represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region.

29 Conclusions 140-years subannual resolution cellulose δ 18 O has been analyzed for Pinus merkusii from Kirirom National Park in Cambodia. The regular seasonal cycles show depleted δ 18 O during monsoon rainy season and enriched δ 18 O in winter dry season. The cellulose δ 18 O minima of each annual rings represent the δ 18 O of rain water in October, when the moisture source is the South China Sea-WPWP. Most recent ENSO events are identified in the October cellulose δ 18 O. The October δ 18 O is negatively related to the convection intensity over the South China Sea-WPWP region. PhD candidate ZHU, Mengfan mengfanz@usc.edu

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