Environmental Engineering Reference
In-Depth Information
developing products capable of supporting climate services including monitoring
climate trends. Accurate calibration is required to meet the needs of today's users,
and access to this more accurate data has expanded the user community to include
climate scientists. To support new requirements for more tailored products and
services, an international Global Space-based Inter-Calibration System (GSICS)
working group coordinates the activities of participating nations to improve the overall
calibration of all the satellites in the international constellation. The GSICS Working
Group was established in 2005 by the WMO and the Coordinating Group for Meteo-
rological Satellites (CGMS) for the purpose of monitoring, improving, and
harmonizing the quality of observations from operational weather and environmental
satellites of the Global Observing System (GOS). The goal is to provide consistent
accuracy among space-based observations worldwide for climate monitoring and
weather forecasting. (Information about the US GSICS Coordination Center and its
international role was derived from
http://www.star.nesdis.noaa.gov/smcd/GCC/
index.php
and
http://gsics.wmo.int/
).
1.5 Using Satellite Data to Understand Climate
With the intercalibrated satellite data as the global foundation data source, an
improved understanding of the environment can be derived from the information.
Understanding the movement of water in the Earth system is important for many
applications of satellite data. Passive microwave observations and the products
derived from them are routinely available and widely used in meteorological
analyses and forecasting applications requiring rainfall, total precipitable water
(TPW), and snowfall rate products, for example. These measurements and products
form the foundation for initializing satellite and climate models. Ferraro et al.
(
2010
) provides a summary of example applications within NOAA. However,
simply generating satellite-based products is not sufficient. For climate purposes,
the measurements must be stable and consistent across the period of the
observations. For snow and snow cover, Romanov (
2011
) shows how the tools
developed for monitoring global snow cover could be used to support agricultural
applications with specific application in Ukraine to assess crop yield impacts.
To address the needs of the climate community, improved calibration is the
essential stepping stone. Intercalibration techniques were the first step and com-
pared a reference satellite instrument with another satellite instrument. In Yang
et al. (
2011
), intercalibration was accomplished between the Defense Meteorologi-
cal Satellite Program Special Sensor Microwave Imagers (SSM/I) on F13 and F15
and the Tropical Rainfall Monitoring Mission (TRMM). The reduced biases for
total precipitable water (TPW) products were significant. Intersensor TPW biases
were reduced by 75% over the global ocean and 20% over the tropical ocean. In
addition, intersensor calibration reduced biases by 20.6, 15.7, and 6.5% for oceanic,
land, and global precipitation, respectively (Yang et al.
2011
). The removal of
biases between measuring systems is extremely important for assessing accurate
climate trends and establishing measurement uncertainties.
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