Ocean data assimilation system and El Niño prediction model were replaced with new ones described below in March 2008.
From the Jan.2007 issue onward, atmospheric anomalies are calculated based upon the climatological normal derived from the JRA-25 dataset, in place of the ERA-15 that was in use theretofore. Find out more.
|Monthly mean SST (°C)||27.2||27.0||26.5||25.8||25.2||24.9||25.2||25.0||25.1||25.9||27.2||27.3|
|SST deviation (°C)||+0.1||+0.5||+0.8||+0.7||+0.3||0.0||+0.2||-0.2||-0.5||-0.5||+0.1||-0.2|
|5-month mean (°C)||+0.3||+0.4||+0.5||+0.5||+0.4||+0.2||0.0||-0.2||-0.2||-0.3||not yet||not yet|
JMA defines that the El Niño (La Niña) is such that the 5-month running mean SST deviation for NINO.3 continues +0.5ºC (-0.5ºC) or higher (lower) for six consecutive months or longer.
5-month mean values with underlines indicate above +0.5ºC, and italic ones below -0.5ºC.
The latest SST and SOI are a preliminary value.
Fig.1 Time series of sea surface temperature (SST) deviations from the climatological mean based on a sliding 30-year period for NINO.3, (the 2nd panel), Southern Oscillation Index (the 3rd panel), SST deviations for NINO.WEST (the 4th panel), and SST deviations for IOBW (the bottom panel). (each region is shown in the top panel).
Thin lines indicate a monthly mean value, and smoothed thick curves, a 5-month running mean. Red shaded areas denote El Niño periods, and blue, La Niña ones.
Fig.2 Monthly mean SST and anomalies in the Pacific and Indian Oceans. Base period for normal is 1981-2010.
Fig.3 Depth-longitude cross sections of temperature and anomalies along the equator in the Indian and Pacific Oceans by the ocean data assimilation system. Base period for normal is 1981-2010.
Fig.4 Time-longitude cross section of SST anomalies along the equator in the Indian and Pacific Oceans. Base period for normal is 1981-2010.
Fig.5 Time-longitude cross section of ocean heat content (OHC; vertically averaged temperature in the top 300 m) anomalies along the equator in the Indian and Pacific Oceans by the ocean data assimilation system. Base period for normal is 1981-2010.
Fig.6 Monthly mean outgoing longwave radiation (OLR) and anomalies. Base period for normal is 1981-2010. Original data were provided by NOAA.
Fig.7 Time series of OLR index around the International Date Line (OLR-DL), equatorial zonal wind index at 200 hPa in the central Pacific (U200-CP), equatorial zonal wind index at 850 hPa in the central Pacific (U850-CP), and equatorial zonal wind index at 200hPa in the Indian Ocean (U200-IN) (from upper to lower). Base period for normal is 1981-2010. Red shaded areas denote El Niño periods, and blue, La Niña ones.
Fig.8 Time-longitude cross sections of velocity potential anomalies at 200 hPa (left) and zonal wind anomalies at 850 hPa (right) along the equator. Base period for normal is 1981-2010. Normal is calculated from JRA-25.
These figures indicate a time series of the monthly sea surface temperature (SST) deviation for NINO.3 (5ºN-5ºS, 150ºW-90ºW), NINO.WEST (10ºN-EQ, 130ºE-150ºE), and IOBW (20ºN-20ºS, 40ºE-100ºE). Thick line with closed circle shows the observed SST deviation and boxes show the predicted one for the next six months by the El Niño prediction model. Each box denotes the range where the SST deviation will be included with the probability of 70%.
Fig.9 Outlook of the SST deviation for NINO.3 by the El Niño prediction model.
Fig.10 Outlook of the SST deviation for NINO.WEST by the El Niño prediction model.
Fig.11 Outlook of the SST deviation for IOBW by the El Niño prediction model.
ReferencesOGCM (MRI.COM; Ishikawa et al. 2005) Resolution: •horizontal: 1.0º longitude 1.0º latitude except near the equator (0.3º) •vertical : 50 levels Physical processes: •vertical mixing turburent closure scheme (Noh and Kim, 1999) •isopycnal thickness diffusion (Gent and McWilliams, 1990) Atmospheric forcing: •heat, momentum and fresh water fluxes derived from the operational JMA climate data assimilation system (JCDAS) Ocean data: •subsurface temperature and salinity data obtained from GTS sea surface height data Assimilation method: •3-D VAR (coupled temperature-salinity EOF modes are employed as control variables) •Incremental Analysis Update Details of Ocean data assimilation system are described in Usui et al. (2006)
Flux exchanges between AGCM and OGCM are done every 1 hour. Climatic drift is suppressed by flux correction. Initial data for ocean are derived from the ocean data assimilation system. Initial data for the atmosphere are produced by the climate data assimilation system. The outlook of NINO.3 SST deviations is derived from the ensemble prediction with 30 members based on the combination of the perturbations and the LAF (Lagged Averaged Forecast) method (6 initial dates, each of which has 5 members). The prediction frequency of each member is 6 times per month, and lags of the members range from about 0 to 25 days.AGCM (low resolution version of the previous JMA operational model; JMA, 2007) Resolution: •horizontal: TL95 (about 180 km) •vertical : 40 levels Physical processes: Arakawa-Schubert cumulus convection scheme OGCM (MRI.COM; Ishikawa et al. 2005) Same as the OGCM used in ocean data assimilation system.
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