Data files for some examples
Example pages containing:
CloudSat: Cloud Vertical Structure
is a satellite mission designed to measure the vertical structure of clouds
from space. The radar data produces detailed images of cloud structures
which will contribute to a better understanding of clouds and climate.
CloudSat along with
Aura form a satellite
constellation known as the A-Train. The satellites fly in a nearly
circular orbit with an equatorial altitude of approximately 705 km.
The orbit is sun-synchronous, maintaining a roughly fixed angle between
the orbital plane and the mean solar meridian. CloudSat maintains a
close formation with Aqua and a particularly close formation with
CALIPSO, providing near-simultaneous and collocated observations
with the instruments on these two platforms.
(Note that PARASOL was maneuvered to leave its position inside the A-Train on December 2, 2009.)
(Cloud Feedback Model Intercomparison Program) has designed a protocol to evaluate clouds in climate and weather prediction models based on satellite observations.
The documentation for the 2B-CLDCLASS files is at:
HDF Group Comprehensive Examples
The HDF-Group has created a suite of
NCL, Matlab, IDL and Python examples
which includes both scripts and the created graphical images.
They also provide NCL specific comments
This site is updated so CloudSat examples may be added in the future. Please check.
Table 5. File Specification for 16-Bit cloud scenario
16 Bit Cloud Scenario File Specification
Bit Field Description Key Result
0 Cloud scenario flag 0 = not determined
1 = determined
1-4 Cloud scenario 0000 = No cloud
0001 = cirrus
0010 = Altostratus
0011 = Altocumulus
0100 = St
0101 = Sc
0110 = Cumulus
0111 = Ns
1000 = Deep Convection
5-6 Land/sea flag 00 = no specific
01 = land
10 = sea
11= snow (?)
7-8 Latitude flag 00 = tropical
01 = midlatitude
10 = polar
9-10 Algorithm flag 00 = radar only
01 = combined radar and MODIS
11-12 Quality flag 00 = not very confident
01 = confident
13-14 Precipitation flag 00 = no precipitation
01 = liquid precipitation
10 = solid precipitation
11 = possible drizzle
(1) Average "CloudSat Radar Reflectivity" over the period 200606-200612
at user specified levels; (2) Radar reflectivity in the vertical at user
specified (lat,lon) locations; (3) User specified cross sections.
The last cross section uses
to a series of arbitrary points. The gc_latlon
is used to generate the points on a great circle path.
The file used in this example was obtained from:
This file is CLOUDSAT 2B-CLDCLASS. The variable being plotted cloud_scenario is "Algorithm outputs (cloud type and different flags) are combined into a 16 bit cloud_scenario." Hence, the variable is a bit non-sensical to plot directly.
However, at the time this plot (and Example 3) was generated, the packing information was not readily available.
The ncl_filedump command line operator was used to examine the file prior to use.
The generic .hdf extension 'hides' the fact that this is a HDF-EOS file. Further, the file
contains a satellite swath (GROUP=SwathStructure).
ncl_filedump 2010153190053_21792_CS_2B-CLDCLASS_GRANULE_P_R04_E03.hdf | less
file global attributes:
HDFEOSVersion : HDFEOS_V2.5
StructMetadata_0 : GROUP=SwathStructure
Since this is a HDF-EOS file, the file is read with a ".he2" or ".hdfeos" extension
in the addfile
function. This tells NCL to read the file with
both the standard HDF and HDF-EOS read software. NCL merges the information
so user have one unified view of the file.
This script reads a variable and plots the entire swath. A color contour map which uses 'white'
for smaller values is specified to 'hide' lower values. For 'fun' the figure is replicated
to show both horizontal and vertical label bars.
CLOUDSAT 2B-CLDCLASS info: http://www.cloudsat.cira.colostate.edu/dataSpecs.php?prodid=11
See opening statement for Example 2.
Same data file as Example 2. Plot the total trajectory. Specify a region of interest
and plot an outline of the area. Then plot only data which occurred in the region of interest.
Manually specify a finer contour interval.
NOTE: The satellite is within the specified region at the beginning and end
of the time interval.