TY - JOUR
T1 - Isotopic changes due to convective moistening of the lower troposphere associated with variations in the ENSO and IOD from 2005 to 2006
AU - Lee, Jeonghoon
AU - Worden, John
AU - Noone, David
AU - Chae, Jung Hyo
AU - Frankenberg, Christian
N1 - Publisher Copyright:
© 2015 J. Lee et al.
PY - 2015
Y1 - 2015
N2 - We use the tropospheric emission spectrometer measurements of the isotopic composition of water vapour (δD) in the lower troposphere to examine how changes in the distribution of convection and precipitation control water vapour amount and its isotope over the Indian Ocean. Measurements of the outgoing longwave radiation and vertical velocity from NCEP/NCAR Reanalysis and cloud ice water content from the Microwave Limb Sounder show distinct variations in convection due to a phase shift of both El Niño - Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). These variations in convection are associated with changes in precipitation and water amount over the Western Indian Ocean (WIO) and Eastern Indian Ocean (EIO), depending on the phases of ENSO and/or the IOD. Over the EIO in 2006, induced by the interplay of both positive ENSO and IOD, it is drier and less isotopically depleted due to less frequent and/or weaker deep convective activity and subsequent precipitation compared to 2005. By contrast, over the WIO in 2006, an increase in water vapour and precipitation but little isotopic fractionation in water vapour of clear sky compared to 2005 is likely associated with an increase in both enhanced deep and shallow convection, caused by the positive IOD. Therefore, paleoarchives of water isotopes near Africa will be more difficult to relate to a single process because changes in convective activity result in changes in precipitation but do not have a significant impact on the isotopic composition of the source vapour based on this case analysis.
AB - We use the tropospheric emission spectrometer measurements of the isotopic composition of water vapour (δD) in the lower troposphere to examine how changes in the distribution of convection and precipitation control water vapour amount and its isotope over the Indian Ocean. Measurements of the outgoing longwave radiation and vertical velocity from NCEP/NCAR Reanalysis and cloud ice water content from the Microwave Limb Sounder show distinct variations in convection due to a phase shift of both El Niño - Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD). These variations in convection are associated with changes in precipitation and water amount over the Western Indian Ocean (WIO) and Eastern Indian Ocean (EIO), depending on the phases of ENSO and/or the IOD. Over the EIO in 2006, induced by the interplay of both positive ENSO and IOD, it is drier and less isotopically depleted due to less frequent and/or weaker deep convective activity and subsequent precipitation compared to 2005. By contrast, over the WIO in 2006, an increase in water vapour and precipitation but little isotopic fractionation in water vapour of clear sky compared to 2005 is likely associated with an increase in both enhanced deep and shallow convection, caused by the positive IOD. Therefore, paleoarchives of water isotopes near Africa will be more difficult to relate to a single process because changes in convective activity result in changes in precipitation but do not have a significant impact on the isotopic composition of the source vapour based on this case analysis.
KW - ENSO
KW - IOD
KW - TES
KW - Water vapour isotope
UR - http://www.scopus.com/inward/record.url?scp=84930959763&partnerID=8YFLogxK
U2 - 10.3402/tellusb.v67.26177
DO - 10.3402/tellusb.v67.26177
M3 - Article
AN - SCOPUS:84930959763
SN - 0280-6509
VL - 67
JO - Tellus, Series B: Chemical and Physical Meteorology
JF - Tellus, Series B: Chemical and Physical Meteorology
IS - 1
M1 - 26177
ER -