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The Wildfire Event - Terra Mission - Data - Tools - CD Home |
| CERES Instrument Data |
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The Earth Radiation Budget Experiment (ERBE)-like Instantaneous Top-of-Atmosphere (TOA) Estimates (ES-8) product contains filtered radiances recorded every 0.01 second for the total (TOT), shortwave (SW), and window (WN) channels and the unfiltered SW, longwave (LW), and WN radiances. The SW and LW radiances at spacecraft altitude are converted to TOA fluxes with a scene identification algorithm and Angular Distribution Models (ADMs) that are "like" those used for ERBE. The TOA fluxes, scene identification, and angular geometry are included on the ES-8. CERES CER_ES8_Terra_Edition1 Data Quality Summary Use the menubar to go to the "Tools" page for step-by-step instructions on the use of the Collage and Data and Information Access Link (DIAL) tools. |
CERES Data Provided
The DIAL tool provides digital image processing to display
CERES metadata and data as text on the screen.
Sample CERES Structural Metadata, generated earlier by the DIAL tool. Sample CERES Core Metadata, generated earlier by the DIAL tool. Note: CERES data are NOT geolocated image data. Collage shows only arrays of numbers. CERES products can be viewed with an analysis tool such as view_hdf.
This sample is a subset of data for one day, August 30, 2000. The data subset covers the geographical areas of the continental United States (CONUS) and most of Canada only. The subset boundaries are 20N to 70N and 40W to 140W. The subset contains the same 19 Scientific data Sets (SDSs) as the full granule, but the arrays are smaller. The arrays are in the same sequence in the subset and the granule. The sample includes clear-sky observations, observations with clouds in the field of view, and observations with wildfire smoke and haze in the field of view. The full-sized
ES-8 granule contains 24-hours of single scanner, instantaneous
CERES footprints for the entire globe. Detailed information about
this product is found in the CERES Data Products Catalog at
http://eosweb.larc.nasa.gov/PRODOCS/ceres/DPC/DPC_ES8_R4V1.pdf.
"We usually
check for widespread atmospheric effects by looking at the cloud
forcing, which subtracts the all-sky observations from the clear-sky
ones.
"We think of
the data as belonging to time series with physical phenomena. We
generally average over a month separately for all sky conditions
and for clouds. We have to be careful about physical phenomena that
affect the shortwave (reflected sunlight) and longwave fluxes, so
our average includes both the increase of albedo as the sun gets
closer to the horizon (with a variability that depends on what scene
type we're looking at) and the fact that clear deserts warm up during
the day more than cloudy ones do. Even our validation approaches
use monthly statistics rather than individual days.
"We have a
tendency to think in terms of global or zonal averages on monthly
data. While the "cloud forcing" we are interested in is the difference
between clear-sky fluxes and all-sky fluxes, we are very aware that
we can't get a sensible estimate of clear-sky fluxes until we have
a month of data - and usually regionally averaged over 1 to 2 degree
(say 100 km to 200 km in size). That's because only about 5% of
the footprints we observe in 24 hours are clear. Even with monthly
averages, there are some parts of the Earth that are so cloud covered
that we don't observe any clear-sky conditions in an entire month.
In addition, as a community we often collect a history of clear-sky
observations that we use to compare with current observations to
improve our detection of clouds.
"In addition,
our data products are all "multi-parameter" products - in which
the community will usually treat each footprint as a multi-parameter
record and use some of the parameter values to select others."
From:
Bruce B. Barkstrom
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