TY - JOUR
T1 - Large-scale precipitation tracking and the MJO over the Maritime Continent and Indo-Pacific warm pool
AU - Kerns, Brandon W.
AU - Chen, Shuyi S.
N1 - Funding Information:
TRMM/GPM-based TMPA data were obtained from the Precipitation Processing System public data archive maintained by the NASA Goddard Space Flight Center. The data can be accessed at ftp://pps.gsfc.nasa.gov/ pub/trmmdata. Interpolated OLR data for the OMI index were provided by NOAA/OAR/ESRL PSD, Boulder, CO, at http://www.esrl.noaa.gov/psd/data/ gridded/data.interp_OLR.html. RMM index data were obtained from http:// cawcr.gov.au/staff/mwheeler/map- room/RMM/index.htm. Discussions with George Kalidas, Chidong Zhang, Falko Judt, Ajda Savarin, Hui Su, and David Zermeno have been very helpful during the course of this study. This research was supported by grants from NSF (AGS1062242), NASA OVWST (NNX14AM78G), and NASA PMM (NNX16AE40G).
PY - 2016
Y1 - 2016
N2 - A large-scale precipitation tracking (LPT) method is developed to track convection and precipitation associated with the Madden-Julian oscillation (MJO) using the Tropical Rainfall Measurement Mission 3B42 rainfall data from October to March 1998-2015. LPT uses spatially smoothed 3 day rainfall accumulation to identify and track precipitation features in time with a minimum size of 300,000 km2 and time continuity at least 10 days. While not all LPT systems (LPTs) are attributable to the MJO, among the 199 LPTs, there were 42 with a mean eastward propagation of at least 2ms-1, which are considered to be MJO convective initiation events. These LPTs capture the diversity of the MJO convection, which is not well depicted by the Real-time Multivariate MJO (RMM) index or the outgoing longwave radiation MJO index. During the 17 years, there were 17 instances out of 45 with a MJO signature in the RMM without eastward propagating LPTs. Among the 42 eastward propagating LPTs, 24 propagated across the Maritime Continent (MC), which confirms the MC barrier effect. Among the cases that crossed the MC from the Indian Ocean to the western Pacific (MC crossing), 18 (75%) had a significant MJO signature in the RMM index. In contrast, only six (33%) of the non-MC-crossing cases occurred with a RMM MJO signal. There is a significant seasonal and interannual variability with MC-crossing LPTs occurring in December more commonly than other months. More MC-crossing events were observed during La Niña than El Niño, which is consistent with the observations of stronger and more frequent MJO events identified by RMM during La Niña years.
AB - A large-scale precipitation tracking (LPT) method is developed to track convection and precipitation associated with the Madden-Julian oscillation (MJO) using the Tropical Rainfall Measurement Mission 3B42 rainfall data from October to March 1998-2015. LPT uses spatially smoothed 3 day rainfall accumulation to identify and track precipitation features in time with a minimum size of 300,000 km2 and time continuity at least 10 days. While not all LPT systems (LPTs) are attributable to the MJO, among the 199 LPTs, there were 42 with a mean eastward propagation of at least 2ms-1, which are considered to be MJO convective initiation events. These LPTs capture the diversity of the MJO convection, which is not well depicted by the Real-time Multivariate MJO (RMM) index or the outgoing longwave radiation MJO index. During the 17 years, there were 17 instances out of 45 with a MJO signature in the RMM without eastward propagating LPTs. Among the 42 eastward propagating LPTs, 24 propagated across the Maritime Continent (MC), which confirms the MC barrier effect. Among the cases that crossed the MC from the Indian Ocean to the western Pacific (MC crossing), 18 (75%) had a significant MJO signature in the RMM index. In contrast, only six (33%) of the non-MC-crossing cases occurred with a RMM MJO signal. There is a significant seasonal and interannual variability with MC-crossing LPTs occurring in December more commonly than other months. More MC-crossing events were observed during La Niña than El Niño, which is consistent with the observations of stronger and more frequent MJO events identified by RMM during La Niña years.
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U2 - 10.1002/2015JD024661
DO - 10.1002/2015JD024661
M3 - Article
AN - SCOPUS:84980338851
VL - 121
SP - 8755
EP - 8776
JO - Journal of Geophysical Research: Atmospheres
JF - Journal of Geophysical Research: Atmospheres
SN - 2169-897X
IS - 15
ER -