TY - JOUR
T1 - Heating and moistening of the MJO during DYNAMO in ECMWF reforecasts
AU - Kim, Ji Eun
AU - Zhang, Chidong
AU - Kiladis, George N.
AU - Bechtold, Peter
N1 - Funding Information:
The authors thankWalter Hannah, Scott Powell, and an anonymous reviewer for their insightful and constructive comments on an early version of the article. JEK thanks the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) for hosting her visit during which this manuscript was drafted. This study was supported by NSF Grant AGS-1450582 (JEK and CZ) and NOAA Grant NA13OAR4310161 (CZ). This paper is PMEL Contribution 4669. The IFS reforecast data are available from NCAR EOL. Other data are available online [http://johnson.atmos.colostate.edu/ dynamo (DYNAMO soundings), https://mirador. gsfc.nasa.gov (TRMM 3B42), ftp://ftp.cgd.ucar. edu/archive/PRECIP (GPCP), https://www.arm.gov/ research/campaigns/amf2011amie-gan (CombRet), and https:// ceres.larc.nasa.gov (CERES)]. REFERENCES
Funding Information:
Acknowledgments. The authors thank Walter Hannah, Scott Powell, and an anonymous reviewer for their insightful and constructive comments on an early version of the article. JEK thanks the Joint Institute for the Study of the Atmosphere and Ocean (JISAO) for hosting her visit during which this manuscript was drafted. This study was supported by NSF Grant AGS-1450582 (JEK and CZ) and NOAA Grant NA13OAR4310161 (CZ). This paper is PMEL Contribution 4669. The IFS reforecast data are available from NCAR EOL. Other data are available online [http://johnson.atmos.colostate.edu/ dynamo (DYNAMO soundings), https://mirador. gsfc.nasa.gov (TRMM 3B42), ftp://ftp.cgd.ucar. edu/archive/PRECIP (GPCP), https://www.arm.gov/ research/campaigns/amf2011amie-gan (CombRet), and https:// ceres.larc.nasa.gov (CERES)].
PY - 2018/5/1
Y1 - 2018/5/1
N2 - Reforecasts produced by the ECMWF Integrated Forecast System (IFS) were used to study heating and moistening processes associated with three MJO events over the equatorial Indian Ocean during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign. Variables produced by and derived from the IFS reforecast (IFS-RF) agree reasonably well with observations over the DYNAMO sounding arrays, and they vary smoothly from the western to eastern equatorial Indian Ocean. This lends confidence toward using IFS-RF as a surrogate of observations over the equatorial Indian Ocean outside theDYNAMO arrays. The apparent heat source Q1 and apparent moisture sink Q2 produced by IFS are primarily generated by parameterized cumulus convection, followed by microphysics and radiation. The vertical growth of positive Q1 and Q2 associated with the progression of MJO convection can be gradual, stepwise, or rapid depending on the event and its location over the broader equatorial Indian Ocean. The time for convective heating and drying to progress from shallow (800 hPa) to deep (400 hPa) can be < 1 to 6 days. This growth time of heating and drying is usually short for convective processes alone but becomes longer when additional microphysical processes, such as evaporative moistening below convective and stratiform clouds, are in play. Three ratios are calculated to measure the possible role of radiative feedback in the MJO events: amplitudes of radiative versus convective heating rates, changes in radiative versus convective heating rates, and diabatic (with and without the radiative component) versus adiabatic heating rates. None of them unambiguously distinguishes the MJO from non-MJO convective events.
AB - Reforecasts produced by the ECMWF Integrated Forecast System (IFS) were used to study heating and moistening processes associated with three MJO events over the equatorial Indian Ocean during the Dynamics of the Madden-Julian Oscillation (DYNAMO) field campaign. Variables produced by and derived from the IFS reforecast (IFS-RF) agree reasonably well with observations over the DYNAMO sounding arrays, and they vary smoothly from the western to eastern equatorial Indian Ocean. This lends confidence toward using IFS-RF as a surrogate of observations over the equatorial Indian Ocean outside theDYNAMO arrays. The apparent heat source Q1 and apparent moisture sink Q2 produced by IFS are primarily generated by parameterized cumulus convection, followed by microphysics and radiation. The vertical growth of positive Q1 and Q2 associated with the progression of MJO convection can be gradual, stepwise, or rapid depending on the event and its location over the broader equatorial Indian Ocean. The time for convective heating and drying to progress from shallow (800 hPa) to deep (400 hPa) can be < 1 to 6 days. This growth time of heating and drying is usually short for convective processes alone but becomes longer when additional microphysical processes, such as evaporative moistening below convective and stratiform clouds, are in play. Three ratios are calculated to measure the possible role of radiative feedback in the MJO events: amplitudes of radiative versus convective heating rates, changes in radiative versus convective heating rates, and diabatic (with and without the radiative component) versus adiabatic heating rates. None of them unambiguously distinguishes the MJO from non-MJO convective events.
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U2 - 10.1175/JAS-D-17-0170.1
DO - 10.1175/JAS-D-17-0170.1
M3 - Article
AN - SCOPUS:85047096310
VL - 75
SP - 1429
EP - 1452
JO - Journals of the Atmospheric Sciences
JF - Journals of the Atmospheric Sciences
SN - 0022-4928
IS - 5
ER -