Monitoring the MJO and Tropical Waves

  NOAA CDR HIRS OLR NOAA/ESRL AVHRR OLR
1 day Last Previous Last Previous
3 days Last Previous Last Previous
7 days Last Previous Last Previous
30 days Last Previous Last Previous
60 days Last Previous Last Previous
180 days Last Previous Last Previous
365 days Last   Last  

  NOAA CDR HIRS OLR NOAA/ESRL AVHRR OLR
Northern Narrow 2.5°N – 7.5°N Total Anomaly Waves Total Anomaly Waves
Northern Medium 2.5°N – 17.5°N Total Anomaly Waves Total Anomaly Waves
Northern Wide 2.5°N – 27.5°N Total Anomaly Waves Total Anomaly Waves
Equatorial Narrow 2.5°S – 2.5°N Total Anomaly Waves Total Anomaly Waves
Equatorial Medium 7.5°S – 7.5°N Total Anomaly Waves Total Anomaly Waves
Equatorial Wide 15°S – 15°N Total Anomaly Waves Total Anomaly Waves
Southern Narrow 7.5°S – 2.5°S Total Anomaly Waves Total Anomaly Waves
Southern Medium 17.5°S – 2.5°S Total Anomaly Waves Total Anomaly Waves
Southern Wide 27.5°S – 2.5°S Total Anomaly Waves Total Anomaly Waves

  NOAA CDR HIRS OLR NOAA/ESRL AVHRR OLR
Total 1d3d5d - 7d15d 1d3d5d7d15d
Anomaly 1d3d5d7d15d 1d3d5d7d15d
MJO 5d7d 5d7d
Kelvin Waves 1d2d 1d2d
Symmetric Kelvin Waves 1d2d 1d2d
ER Waves 3d5d 3d5d
Symmetric ER Waves 3d5d 3d5d
MRG Waves 1d 1d
Anti-Symmetric MRG Waves 1d 1d
TD-type Disturbances 1d 1d
Sum of Waves 3d5d7d 3d5d7d

NOAA CDR HIRS OLR

  • These data are NOAA's interim Climate Data Record as obtained from Univ. of Maryland.

  • They are a blend of observations from geostationary satellites and the HIRS sensor on the NOAA polar-orbiting satellites.

NOAA/ESRL AVHRR OLR

  • These data are observed with the AVHRR sensor on the NOAA polar-orbiting satellites.

  • Uninterpolated gridded data are obtained from NOAA/OAR/ESRL/PSD.

  • Gaps between orbital swaths are interpolated following the method of Liebmann and Smith (1996).

The figure above shows the wavenumber—frequency spectrum for OLR, divided by an estimate of the red background following Wheeler & Kiladis (1999, JAS). The panel on the left shows signals that are anti-symmetric about the equator, while the panel on the right shows those that are symmetric. Spectral peaks tend to lie along the dispersion curves for shallow water equatorial waves (black lines).

To identify tropical waves in near real-time, the OLR and UTWV data are filtered following Wheeler & Weickmann (2001 MWR). The daily anomalies are calculated using the first 3 harmonics of the seasonal cycle for 1979–2009. Missing values are then filled using linear interpolation in space and time. The most recent 365 days of anomalies are padded with 659 days of zeroes, and the result is filtered for each wave type.

No equatorial symmetry is imposed here, and the filters differ somewhat from the original ones defined by Wheeler & Kiladis (1999):

Wave Type Color Propagation Direction Wavenumber Period (days) Equivalent Depth (m) Source
Julian Oscillation (MJO) Blue Eastward 0–9 30–96 n/a Kiladis et al. (2005 JAS)
Kelvin Waves Green Eastward 1–14 2.5–17 8–90 Straub & Kiladis (2002, JAS)
Equatorial Rossby (ER) Waves Black Westward 1–10 9–72 0–90 Kiladis et al. (2009, Rev. Geophys.)
Mixed Rossby-Gravity (MRG) Waves Red Westward 1–10 3–10 8–90 Wheeler & Kiladis (1999)
Tropical Depression (TD)-type disturbances Cyan Westward 6–20 2.5–5 n/a Roundy & Frank (2004, JAS)

DISCLAIMER: Please note these pages present experimental analyses developed by researchers at CICS-NC and/or of interest to the CICS-NC community and their collaborators. These analyses are subject to change as our understanding of the Earth’s climate system improves and/or our interests change. There is no guarantee on their future availability.

Created and maintained by Carl Schreck.