التفاصيل البيبلوغرافية
| العنوان: |
Synchronous Tropical Andean Hydroclimate Variability During the Last Millennium. |
| المؤلفون: |
Bird, B. W., Steinman, B. A., Escobar, J., Correa‐Metrio, A., Holper, K., Gibson, D. K., Mark, S., Fonseca, H. |
| المصدر: |
Journal of Geophysical Research. Atmospheres; 7/16/2024, Vol. 129 Issue 13, p1-16, 16p |
| مصطلحات موضوعية: |
INTERTROPICAL convergence zone, LITTLE Ice Age, ATMOSPHERIC temperature, METEOROLOGICAL precipitation, RAINFALL, TEMPERATURE control |
| مصطلحات جغرافية: |
ANDES |
| مستخلص: |
The impact of latitudinal variations in the Intertropical Convergence Zone (ITCZ) on northern Andean hydroclimate during the Medieval Climate Anomaly (MCA; 950–1,150 CE) and Little Ice Age (LIA; 1,300–1,850 CE) is uncertain. Synthesis of two new lacustrine paleoclimate records from the Eastern Colombian Andes with existing circum‐Andean records shows that effective moisture anomalies were synchronous and in phase across the tropical Andes during the last millennium. During the MCA, when the ITCZ was shifted northward, topographically controlled responses in the northern Andes to vigorous atmospheric convection resulted in low precipitation and high evaporation, while precipitation was also reduced in the southern tropical Andes. During the LIA, precipitation decreased in the northern Andes as the ITCZ migrated southward but was offset by cooling that lowered evaporation, establishing high effective moisture. In the southern tropical Andes, the southward ITCZ position simultaneously strengthened precipitation, increasing effective moisture. MCA‐like responses to continued warming trends could similarly reduce northern Andean precipitation while increasing evaporation, thereby lowering effective moisture and possibly reducing water resource availability. Plain Language Summary: The position of the tropical rain belt has been proposed as a leading control on Andean hydroclimate during the Medieval Climate Anomaly (MCA; 950–1,150 CE) and Little Ice Age (LIA; 1,300–1,850 CE), producing opposite hydroclimate conditions in the northern and southern tropical Andes. Using two new paleoclimate records from the eastern Colombian Andes and existing records from the northern and southern tropical Andes, we show that tropical Andean hydroclimate responses were similar, with generally warmer and drier conditions during the MCA and cooler and wetter conditions during the LIA. Whereas southern tropical Andean responses were in line with variations in the tropical rain belt, northern tropical Andean responses were not. For the northern Andes, we propose that slow‐moving, low‐energy convective precipitation during the MCA was blocked by the eastern Andes, resulting in reduced precipitation at elevation and in the interior Andes while warming increased evaporation. Wet conditions in the northern Andes during the LIA were the result of cool atmospheric temperatures that reduced evaporation and increased effective moisture despite low precipitation. This suggests topography and temperature played important roles in the northern Andean hydroclimate and that further warming could reduce effective moisture through topographic precipitation blocking and increased evaporation. Key Points: Tropical Andean hydroclimate variability was synchronous and in‐phase between the northern and southern hemispheres during the last millenniumOrographic influences on atmospheric convection‐controlled precipitation in the northern tropical Andes during the last millenniumMean annual temperatures controlled effective moisture in the northern tropical Andes vis‐à‐vis evaporation [ABSTRACT FROM AUTHOR] |
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