Monitoring the MJO and Tropical Waves
Updated: 17 Jul, 2014

Global Maps of Totals & Anomalies

	OLR		HIRS UTWV
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

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Hovmöllers

	OLR			HIRS UTWV
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

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Paneled Global Maps of Recent and Forecast Data

	OLR	HIRS UTWV
Total	1d • 3d • 5d - 7d • 15d	1d • 3d • 5d • 7d • 15d
Anomaly	1d • 3d • 5d • 7d • 15d	1d • 3d • 5d • 7d • 15d
MJO	5d • 7d	5d • 7d
Kelvin Waves	1d • 2d	1d • 2d
Symmetric Kelvin Waves	1d • 2d	1d • 2d
ER Waves	3d • 5d	3d • 5d
Symmetric ER Waves	3d • 5d	3d • 5d
MRG Waves	1d	1d
Anti-Symmetric MRG Waves	1d	1d
TD-type Disturbances	1d	1d
Sum of Waves	3d • 5d • 7d	3d • 5d • 7d

Outgoing Longwave Radiation (OLR)

• OLR is frequently used as a proxy for tropical convection.

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

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

Upper Tropospheric Water Vapor (UTWV)

• These brightness temperatures are observed with the HIRS sensor on the NOAA and MetOp polar-orbiting satellites.

• Orbital swath data are obtained from NOAA/CLASS.

• Inter-satellite calibration is performed following Shi & Bates (2011, JGR), which was developed as part of the Climate Data Record program.

• The calibrated data are binned into daily 2.5° latitude—longitude grids.

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)

• NOAA/CPC Global Tropical Hazards Assessment

• NOAA/CPC Global Hazards Briefing

• CAWCR’s Current Climate Charts (by Matt Wheeler)

• TAO/TRITON Data Display

• NOAA/ESRL/PSD Map Room

• CIMSS Tropical Cyclones

• Navy/NRL Tropical Cyclone Page

• Paul Roundy’s Tropical Waves

• Carl Schreck’s Tropical Rainfall and Winds