Abstract
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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1429-1452 |
| Number of pages | 24 |
| Journal | Journal of the Atmospheric Sciences |
| Volume | 75 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2018 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Atmospheric Science
Cite this
Heating and moistening of the MJO during DYNAMO in ECMWF reforecasts. / Kim, Ji Eun; Zhang, Chidong; Kiladis, George N.; Bechtold, Peter.
In: Journal of the Atmospheric Sciences, Vol. 75, No. 5, 01.05.2018, p. 1429-1452.Research output: Contribution to journal › Article
}
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
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.
UR - http://www.scopus.com/inward/record.url?scp=85047096310&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85047096310&partnerID=8YFLogxK
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 -