Outgoing Longwave Radiation (OLR): AVHRR
OLR (Outgoing Longwave Radiation) is a measure of the amount of energy emitted to space by earth's surface, oceans and atmosphere. As such, it is a critical component of the earth's radiation budget. In a different context, OLR values are often used as a proxy for convection in tropical and subtropical regions since cloud top temperatures (colder is higher) are an indicator of cloud height. OLR observations are made via the Advanced Very High Resolution Radiometer (AVHRR) instrument aboard the NOAA polar orbiting spacecraft. The raw ascending and descending swath data have been spatially and temporarally interpolated onto grids to facilitate use.
OLR estimates are a key component for the standard Madden-Julian Oscillation (MJO) CLIVAR diagnostics which are used to study the MJO and for climate model evaluation.
Key Strengths
Long time series of up-to-date OLR values
High quality data access site
Key Limitations
2.5x2.5 resolution may be too coarse for certain studies
Key Figures
Daily interpolated OLR anomalies for 31 Dec. 2013. Anomalies are relative to the 1981-2010 daily climatology. (Source ESRL/PSD)
Daily non-interpolated OLR anomalies for 3 Sept 2014. Anomalies are relative to the 1981-2010 daily climatology. (Source ESRL/PSD)
Raw and smoothed daily OLR for 26-years (1980-2005) of daily data. OLR anomalies are used in many standardized MJO CLIVAR diagnostics (Climate Data Guide; D. Shea)
20-100 day band passed OLR anomalies for 1996-1997. (Climate Data Guide; D. Shea)
Spatial patterns for 31 Dec 1996: (top) OLR anomaly for each grid point; (bottom) 20-100 day band-pass filtered for the data. (Climate Data Guide; D. Shea)
OLR and zonal wind anomaly cross-spectra: coherence-squared and phase relationships in wavenumber-frequency space. (Climate Data Guide; D. Shea)
OLR average wavenumber-frequency spectra for all the summer seasons 1980-2005. (Climate Data Guide; D. Shea)
Life cycle of 20-100 day band passed filtered anomaly OLR, U850, V850 for the years 1995-1999. (Climate Data Guide; D. Shea)
Other Information
NOAA Polar Orbiting Satelite series (AVHRR)
2.5x2.5