Outgoing Longwave Radiation (OLR)

Outgoing Longwave Radiation (OLR) data at the top of the atmosphere are observed from the Advanced Very High Resolution Radiometer (AVHRR) instrument aboard the NOAA polar orbiting spacecraft. Data are centered across equatorial areas from 160°E to 160°W longitude. The raw data are converted into a standardized anomaly index. Negative (Positive) OLR are indicative of enhanced (suppressed) convection and hence more (less) cloud coverage typical of El Niño (La Niña) episodes. More (Less) convective activity in the central and eastern equatorial Pacific implies higher (lower), colder (warmer) cloud tops, which emit much less (more) infrared radiation into space. More information can be found at the Climate Prediction Center OLR page.

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Source: http://www.cpc.ncep.noaa.gov/data/indices/olr

Download: xml csv json
DateOLR (W/m2)
197406+1.1
197407+0.1
197408+1.1
197409+1.1
197410+1.2
197411+1.2
197412+0.3
197501-0.1
197502+1.1
197503+1.1
197504+0.7
197505+1.4
197506+1.0
197507+1.3
197508+1.5
197509+1.4
197510+1.5
197511+1.5
197512+2.1
197601+1.2
197602+1.2
197603+0.3
197604+0.7
197605+0.4
197606-0.3
197607-0.4
197608-0.5
197609-0.2
197610-0.4
197611+0.4
197612-0.6
197701-0.6
197702+0.6
197703-1.2
197704-0.1
197705+0.4
197706+0.4
197707-0.1
197708+0.1
197709+0.1
197710-0.1
197711-0.5
197712-1.7
197801-0.8
197802-0.9
197803-999.9
197804-999.9
197805-999.9
197806-999.9
197807-999.9
197808-999.9
197809-999.9
197810-999.9
197811-999.9
197812-999.9
197901-0.6
197902-0.6
197903-0.3
197904+0.3
1979050.0
197906+0.4
197907+0.6
197908+0.3
1979090.0
197910-0.6
197911-0.3
197912-0.3
198001+0.7
198002+0.4
198003-1.1
1980040.0
198005-0.2
198006-0.7
198007-0.2
198008-0.8
198009+0.2
198010-0.2
198011-0.1
198012+0.5
198101+0.5
198102-0.7
198103-1.0
198104-0.9
198105+0.5
198106+0.4
198107+0.2
198108+1.0
198109+0.1
198110+0.3
198111+0.5
1981120.0
198201+1.1
198202+0.1
198203-0.6
1982040.0
198205+0.4
198206-0.2
198207-1.1
198208-1.6
198209-1.3
198210-1.7
198211-1.8
198212-0.7
198301-1.4
198302-0.7
1983030.0
198304+0.3
198305-0.9
198306-0.9
198307-0.9
1983080.0
1983090.0
198310+0.5
198311+0.4
198312+1.3
198401+1.9
198402+1.9
198403+1.2
198404+1.1
198405+0.7
198406+0.5
198407+0.2
198408+0.3
198409+0.4
198410+0.3
1984110.0
198412+0.3
198501+0.3
198502+1.2
198503-0.7
198504+0.8
198505+1.1
198506+0.5
198507+0.5
198508+0.5
198509+0.1
198510+0.3
198511+0.1
198512+0.2
198601+0.3
198602+0.9
198603+1.1
198604+0.4
198605+0.3
198606-0.2
198607-0.1
198608+0.3
198609-0.9
198610-0.6
198611-1.3
198612-2.2
198701-2.2
198702-2.3
198703-1.4
198704-1.3
198705-1.9
198706-1.2
198707-2.1
198708-1.5
198709-0.5
198710-1.0
198711-0.4
198712-1.1
198801-0.8
198802-0.7
198803+0.4
198804+0.2
198805+0.5
198806+0.9
198807+1.0
198808+1.2
198809+1.2
198810+1.0
198811+1.4
198812+1.8
198901+1.8
198902+1.7
198903+1.3
198904+0.6
198905+0.4
198906+0.7
198907+0.5
198908+0.6
198909+0.7
198910+0.4
198911-0.4
1989120.0
199001-0.9
199002-1.0
199003-1.5
199004-0.8
1990050.0
199006+0.1
199007-0.1
199008-0.6
199009-0.6
1990100.0
199011-0.2
199012-0.3
199101-0.3
199102-0.6
199103-0.4
1991040.0
199105-0.1
199106-0.2
199107-0.4
199108-0.9
199109-0.6
199110-0.4
199111-2.3
199112-1.6
199201-2.1
199202-1.3
199203-2.1
199204-1.7
199205-1.8
199206-1.0
199207-0.3
199208-0.1
199209+0.1
199210-0.4
199211-0.9
199212-1.3
199301-0.6
199302-1.6
199303-1.0
199304-2.1
199305-1.5
199306-1.4
199307-1.2
199308-0.5
199309-0.8
199310-1.4
199311+0.1
199312-0.5
1994010.0
199402+0.6
199403+0.2
199404-0.4
199405-0.2
199406+0.1
199407-0.2
199408-0.5
199409-0.9
199410-0.4
199411-1.2
199412-2.6
199501-1.6
199502-0.6
1995030.0
199504+0.2
199505+0.2
199506+0.5
199507+0.5
199508+0.8
199509+0.5
199510+1.0
199511+1.1
199512+1.2
199601+1.9
199602+1.6
199603+1.0
199604+0.4
199605+0.4
199606+0.5
199607+0.6
199608+0.6
199609+0.8
199610+0.6
199611+0.8
199612+0.9
199701+0.6
199702+0.5
199703-1.0
199704-1.2
199705-1.7
199706-0.9
199707-1.4
199708-1.6
199709-1.2
199710-2.4
199711-0.4
199712-1.3
199801-0.6
199802-0.3
199803+0.1
199804+1.0
199805-0.4
1998060.0
199807+0.6
199808+0.7
199809+1.0
199810+0.9
199811+1.3
199812+1.5
199901+1.9
199902+1.2
199903+1.4
199904+1.0
199905+0.7
199906+0.6
199907+0.3
199908+0.8
199909+1.1
199910+1.0
199911+0.9
199912+2.0
200001+1.9
200002+2.2
200003+1.7
200004+1.1
200005+0.4
200006+0.8
200007+0.9
2000080.0
200009+0.7
200010+0.5
200011+0.9
200012+1.2
200101+1.7
200102+0.6
200103+0.8
2001040.0
200105-0.2
2001060.0
200107+0.1
200108-0.3
200109+0.4
2001100.0
200111-0.2
200112-1.6
200201-0.1
200202-1.2
200203-1.0
200204+0.2
200205+0.1
200206-0.7
200207+0.3
200208-1.5
200209-1.8
200210-1.3
200211-1.6
200212-1.4
200301-2.2
200302-1.1
200303-0.8
200304+0.3
200305+0.1
200306+0.8
200307-0.1
200308+0.6
200309+0.1
200310+0.1
200311+0.7
200312+0.1
200401-0.8
200402+0.4
200403-0.5
200404-0.9
200405+0.2
200406-1.1
200407+0.3
200408-0.3
200409-0.2
200410-0.2
200411-0.5
200412+0.1
2005010.0
200502-2.2
2005030.0
200504-0.5
200505-0.2
200506+0.1
200507-0.5
200508+0.4
2005090.0
200510+0.1
200511+0.7
200512+1.0
200601+1.0
200602+0.4
200603+1.0
200604+0.3
200605+0.7
200606-0.4
200607+0.1
200608-0.4
200609-0.4
200610-0.9
200611-0.5
200612-0.6
200701-1.3
200702-0.1
200703+0.4
200704-0.1
2007050.0
200706+0.4
200707+0.8
200708+0.5
200709+0.6
200710+1.1
200711+0.5
200712+1.7
200801+0.7
200802+2.1
200803+1.8
200804+1.2
200805+0.9
200806+0.3
200807+0.6
200808+0.4
200809+0.2
200810+0.9
200811+0.8
200812+1.8
200901+1.4
200902+1.3
200903+0.9
200904+0.7
200905+0.6
200906-999.9
200907-999.9
200908-999.9
200909-999.9
200910-999.9
200911-999.9
200912-2.4
201001-2.0
201002-2.3
201003-1.5
201004-0.3
201005+0.6
201006+1.0
201007+0.9
201008+1.1
201009+1.4
201010+1.5
201011+1.7
201012+2.4
201101+2.1
201102+2.3
201103+1.7
201104+1.1
201105+0.2
201106-0.1
201107+0.1
201108+0.3
201109+0.3
201110+1.1
201111+1.0
201112+1.7
201201+1.8
201202+1.9
201203+0.8
201204+0.1
201205-0.1
201206+0.2
201207-0.7
201208+0.2
201209-0.4
201210-0.2
2012110.0
201212+0.7
201301-0.2
201302+0.1
201303-0.3
201304+0.6
201305+0.6
201306+0.4
201307+0.7
201308+0.9
201309+0.4
201310+0.2
201311+0.8
201312+0.9
201401+0.4
201402+0.2
201403-1.1
201404-1.0
201405-0.1
201406-0.7
201407-0.1
201408+0.4
201409+0.2
201410-0.1

Calculation of SOI

Note the anomalies are departures from the 1951-1980 base period.

SOI = (Standardized Tahiti - Standardized Darwin)
MSD

where

Standardized Tahiti = (Actual Tahiti SLP - Mean Tahiti SLP)
Standard Deviation Tahiti

where

Standard Deviation Tahiti = ∑ (actual Tahiti SLP - mean Tahiti SLP)² / N

where

N = number of months

and

Standardized Darwin = (Actual Darwin SLP - Mean Darwin SLP)
Standard Deviation Darwin

where

Standard Deviation Darwin = ∑ (actual Darwin SLP - mean Darwin SLP)² / N

where

N = number of months

and

MSD = Monthly Standard Deviation = ∑ (Standardized Tahiti - Standardized Darwin)² / N

where

N = number of summed months