Pentad Outgoing Longwave Radiation Anomaly

This is a Hovmöller diagram (Longitude x Time) showing five-day average outgoing longwave radiation (OLR) anomalies averaged over 5°S to 5°N, for the past year across the equatorial Pacific Ocean.

The OLR anomalies are contoured at an interval of 20 W/m2, and the contours and shading start at +/- 10 W/m2. Negative anomalies (in shades of green) imply increased cloudiness and an enhanced likelihood that there is precipitation. Positive anomalies (in shades of brown) imply decreased cloudiness and precipitation. The relationship between OLR anomaly and precipitation is most reliable in tropical regions. The base period used to calculate the anomalies is 1991-2020. The longitude domain extends from 120°E to 70°W. On this chart the last year is shown, and time increases vertically.

Dataset Documentation

Pentad Outgoing Longwave Radiation Anomaly

Data

NCEP CPC pentad OLR anomalies on a 2.5° lat/lon grid

Data Source

NOAA National Centers for Environmental Prediction (NCEP) Climate Prediction Center (CPC) (Outgoing Longwave Radiation)

Analysis

Equatorial average of pentad-average outgoing longwave radiation anomalies (1991-2020 base period), displayed as a longitude x time Hovmöller diagram

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