CPC New OLR Data Set

Outgoing longwave radiation (OLR) is a primary component of the global and regional
energy transfer and budget. Estimation of OLR made from satellite measurements has been
widely at CPC and other climate centers for the monitoring of tropical convections and
global climate. Current version of the CPC operational OLR data production was developed
about 40 years ago, based on the AVHRR (Advanced Very High-Resolution Radiometer)
satellite radiation products generated by the NESDIS Operations. However, NESDIS is
retiring the AVHRR radiation products. The objective of this work is to develop a new OLR
data to replace the outgoing AVHRR OLR data.
Our group have developed a new OLR data set taking advantage of existing
products/techniques as much as possible. It has below important features: 1) long-term
record with reasonable quantitative accuracy and temporal homogeneity back to at least
1991; 2) fine temporal/spatial resolution resolving major weather/ climate phenomena over
the entire globe (daily, and 0.25deg lat/lon grid); 3) updated real-time in a 7/24 operational
environment (production latency no longer than 24 hours).
Depending on the sources of the input of satellite measurments, the historical OLR data are
seperated to two periods. The first period convers prior to year 2000, and is based on the
High-Resolution Infrared Radiation Sounder (HIRS) developed by Dr. Hai-Tien Lee. The
second period is based on the NASA Clouds and the Earth's Radiant Energy System (CERES)
broadband measurements, and covers the time of after year 2000 until the most recent
availabilty of CERES (3-4months to date). In addition to the historical data, we also
continuously produce the real-time OLR data based on a couple of hyperspectral sensors:
Atmospheric Infrared Sounder (AIRS), Infrared Atmospheric Sounding Interferometer (IASI),
and Cross-track Infrared Sounder (CrIS). The real-time OLR data will be replaced by the
CERES broadband OLR once it is avaiable. Since the NASA CERES broadband OLR is regarded
as the most reliable satellite observation of OLR, all other satellite measurements of OLR are
calibrated against it to reduce their systematic biases. Furthermore, one advantage of the
new OLR data is that the diurnal cycle of the OLR has been taken care of by making use of
information from the geostationary OLR data.
At the conference, we will report the construction of the historical record and real-
time production of the new OLR data and illustrate its applications in the monitoring of
ENSO, MJO and global monsoons.