delta O18

The stable isotope amount effect: New insights from NEXRAD echo tops, Luquillo Mountains, Puerto Rico

Scholl, Martha A., James B. Shanley, Jan Paul Zegarra, and Tyler B. Coplen. 2009. The stable isotope amount effect: New insights from NEXRAD echo tops, luquillo mountains, puerto rico. Water Resources Research 45 (DEC 11): W12407.

Abstract: 
The stable isotope amount effect has often been invoked to explain patterns of isotopic composition of rainfall in the tropics. This paper describes a new approach, correlating the isotopic composition of precipitation with cloud height and atmospheric temperature using NEXRAD radar echo tops, which are a measure of the maximum altitude of rainfall within the clouds. The seasonal differences in echo top altitudes and their corresponding temperatures are correlated with the isotopic composition of rainfall. These results offer another factor to consider in interpretation of the seasonal variation in isotopic composition of tropical rainfall, which has previously been linked to amount or rainout effects and not to temperature effects. Rain and cloud water isotope collectors in the Luquillo Mountains in northeastern Puerto Rico were sampled monthly for three years and precipitation was analyzed for d18O and d2H. Precipitation enriched in 18O and 2H occurred during the winter dry season (approximately December–May) and was associated with a weather pattern of trade wind showers and frontal systems. During the summer rainy season (approximately June–November), precipitation was depleted in 18O and 2H and originated in low pressure systems and convection associated with waves embedded in the prevailing easterly airflow. Rain substantially depleted in 18O and 2H compared to the aforementioned weather patterns occurred during large low pressure systems. Weather analysis showed that 29% of rain input to the Luquillo Mountains was trade wind orographic rainfall, and 30% of rainfall could be attributed to easterly waves and low pressure systems. Isotopic signatures associated with these major climate patterns can be used to determine their influence on streamflow and groundwater recharge and to monitor possible effects of climate change on regional water resources.

Stable isotope ratios of rain and vapor in 1995 hurricanes

Lawrence, JR, SD Gedzelman, XP Zhang, and R. Arnold. 1998. Stable isotope ratios of rain and vapor in 1995 hurricanes. Journal of Geophysical Research-Atmospheres 103 (D10) (MAY 27): 11381-400.

Geologic implications of the oxygen isotope profile of the toa-baja drill hole, puerto-rico

SMITH, BM. 1991. Geologic implications of the oxygen isotope profile of the toa-baja drill hole, puerto-rico. Geophysical Research Letters 18 (3) (MAR): 549-52.

CARBON AND OXYGEN STABLE ISOTOPES IN THE TOA BAJA WELL, PUERTO RICO: IMPLICATIONS FOR BURIAL DIAGENESIS AND HYDROCARBON GENERATION

GONZALEZ, LA. 1991. Carbon and oxygen stable isotopes in the toa-baja well, puerto-rico - implications for burial diagenesis and hydrocarbon generation rid D-5476-2011. Geophysical Research Letters 18 (3) (MAR): 533-6.

Abstract: 
The Toa Baja Well was drilled on the coastal plains of northern Puerto Rico with a total depth of 2705m [Larue, 1990]. Interstratified limestone, quartz-bearing calcareous sandstones, and shales dominate the uppermost 580 m and are separated from underlying rocks by an unconformity. Below this unconformity continuing tototal depth, lithologies encountered consist of volcaniclastic sandstones/siltstones, pelagic carbonates, volcanic flows and either plutonic rocks or coarse-grained immature sandstones derived from plutonic bodies....

Paleoclimate proxy perspective on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability

Kilbourne, K. H., T. M. Quinn, R. Webb, T. Guilderson, J. Nyberg, and A. Winter (2008), Paleoclimate proxy perspective
on Caribbean climate since the year 1751: Evidence of cooler temperatures and multidecadal variability, Paleoceanography, 23,
PA3220, doi:10.1029/2008PA001598.

Abstract: 
Annually resolved coral delta O-18 and Sr/Ca records from southwestern Puerto Rico are used to investigate Caribbean climate variability between 1751 and 2004 C. E. Mean surface ocean temperatures in this region have increased steadily by about 2 degrees C since the year 1751, with Sr/Ca data indicating 2.1 +/- 0.8 degrees C and delta O-18 data indicating 2.7 +/- 0.5 degrees C. Coral geochemical records from across the tropics demonstrate that regional variability is important for understanding climate variations at centennial time scales. A strong multidecadal salinity signal in the oxygen isotope data correlates with observed multidecadal temperature variations in the Northern Hemisphere. Instrumental wind and precipitation data indicate that the most recent coral isotopic variations are caused by expansion and contraction of the steep regional salinity gradient, forced by trade wind anomalies through meridional Ekman transport. The timing of the fluctuations suggests that the multidecadal-scale wind and surface circulation anomalies might play a role in Atlantic temperature variability and meridional overturning circulation, but further work is needed to confirm this suggestion.
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