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    Level 1B
    1B-CPR
    Level 2B
    2B-CLDCLASS 2B-CLDCLASS-LIDAR 2B-CWC-RO 2B-CWC-RVOD 2B-FLXHR 2B-FLXHR-LIDAR 2B-GEOPROF 2B-GEOPROF-LIDAR 2B-TAU 2B-TB94
    Level 2C
    2C-ICE 2C-PRECIP-COLUMN 2C-RAIN-PROFILE 2C-SNOW-PROFILE
    Level 2D
    2D-CLOUDSAT-POES 2D-CLOUDSAT-TRMM
    Level AUX
    AMSR2-AUX CRYOSPHERE-AUX ECMWF-AUX MOD06-1KM-AUX MOD06-5KM-AUX MODIS-AUX OCO2CLD-LIDAR-AUX
    Level 3
    3F-RMCP / 3S-RMCP
  • Community Products
    Arctic Observation and Reanalysis Integrated System CloudSat Reflectivity Product CloudSat Tropical Cyclone Product (2D-TC) CloudSat-TRMM and CloudSat-GPM Coincidence Dataset CloudSat/CALIPSO Cloud Cover CloudSat/CALIPSO Cloud Fraction PCFLOS Product Warm Rain Rate Estimates from AMSR 89 GHz and CloudSat Year of Tropical Convection (YOTC)
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    Start Here

Current Epoch: Epoch 10

Start: 16 Dec 2021 (Day 350) 14:27:41 | End: Present

Active Release: R05

R04 products will be available until all R05 products have been released.

CloudSat Epoch Information

Epoch 10

After a second reaction wheel anomaly on 26 August 2020 CloudSat returned to operation in December of 2021 in ACT-TWO (Attitude Control Through Two Wheel Operations) DO-Op (Daylight-Only Operations) mode, no longer in formation with CALIPSO.

Start: 16 Dec 2021 (Day 350) 14:27:41
End: Present

Epoch 09

Starting on July 5th, 2019 and continuing through August 26th, 2020, the apparent height of the surface in the radar profiles is not consistent with the Digital Elevation Map (DEM) that has been used with all CloudSat operational products throughout the mission. The mismatch is a result of an error in the satellite pointing or timing data or both. While still under investigation, the present the cause has not been isolated. Rather than further delaying the release of these data, they are being released as-is with the pointing/timing error. Fundamentally, this means there is a substantially larger uncertainty in the location where the radar beam intersects the surface that may be as large as 10 km.

Start: 11 Jul 2019 (Day 192) 00:00:00
End: 26 Aug 2020 (Day 239) 19:25:23

Epoch 08

CloudSat is joined by CALIPSO, forming the C-Train.

Start: 10 Oct 2018 (Day 283) 00:00:00
End: 10 Jul 2019 (Day 191) 23:59:59

Epoch 07

CloudSat exited the A-Train on February 22nd, 2018 after a reaction wheel anomaly.

Start: 3 May 2018 (Day 123) 07:25:00
End: End: 10 Oct 2018 (Day 283) 00:00:00

Epoch 06

Although CloudSat continues to only operate during the sunlit portion of the orbit, epoch 06 started when CloudSat returned to the A-Train formation on May 15th, 2012. Data products once again use MODIS and CALIPSO ancillary data although the overlap with CALIPSO is degraded because fewer formation flying maneuvers are performed.

Start: 15 May 2012 (Day 136) 00:49:00
End: 12 Jan 2018 (Day 12) 15:15:56

Epoch 05

A battery anomaly on April 17th, 2011 caused the spacecraft to stop collecting data and lose formation with the A-Train. The radar was turned back on in November 2011 and now collects data only during the sunlit portion of the orbit. Epoch 05 represents this new operating paradigm. In addition, the spacecraft remained outside of the A-Train formation so all data products were processed in radar-only mode without MODIS or CALIPSO data. The impact of the missing MODIS data on the CloudSat products is still being assessed and the combined radar/lidar products (2B-GEOPROF-LIDAR, 2B-CLDCLASS-LIDAR, and 2B-FLXHR-LIDAR) are not available.

Start: 27 Oct 2011 (Day 300) 23:28:21
End: 15 May 2012 (Day 136) 00:49:00

Epoch 04

Marks the beginning of a period where the CPR pulse rate will be periodically reduced, or increased, to manage the power draw on the battery (due to the reduced power margin as the battery ages). The increased or reduced pulsing with induce a slight change in sensitivity. The number of pulses can be found in the 1B-CPR field RayStatus_pulsesTx. The pulse rate will likely continue to be adjusted, seasonally, for the duration of the mission.

Start: 15 Feb 2011 (Day 46) 18:06:30
End: 17 Apr 2011 (Day 107) 18:17:31

Epoch 03

Epoch 02 ended when a battery anomaly forced the CPR offline. It was brought back into operations with a slightly reduced pulse rate that decreases the radar sensitivity by approximately 0.25 dB. Epoch 03 tags the modified operating parameters.

Start: 15 Jan 2010 (Day 15) 18:24:56
End: 15 Feb 2011 (Day 46) 18:06:30

Epoch 02

Increased specular reflection due to the nadir-pointing instrument caused an increase in ground clutter, so the spacecraft orientation was changed again so that the CPR pointed 0.16 degrees in the forward (along-track) direction.

Start: 15 Aug 2006 (Day 227) 20:56:31
End: 7 Dec 2009 (Day 341) 11:43:22

Epoch 01

The pointing error was corrected and the spacecraft was oriented so that the CPR pointed to nadir.

Start: 7 Jul 2006 (Day 188) 14:14:02
End: 15 Aug 2006 (Day 227) 20:56:31

Epoch 00

During the initial phase of the mission it was unknown that the CPR was pointing off-nadir 1.7021 degrees in the forward (along-track) direction and 0.1314 degress to the right (across-track).

Start: 2 Jun 2006 (Day 153) 13:42:23
End: 7 Jul 2006 (Day 188) 14:14:02

Data Products

(For an overview of what the products themselves measure, click here)

CloudSat data products are made available in HDF-EOS format and are created with HDF-EOS 2.5 based on HDF 4.1r2. Later versions of the HDF and HDF-EOS libraries should be able to manipulate the files as long as they are in the HDF 4 series. Files delivered through the online ordering system are compressed (.zip). The file naming convention is as follows:

R04 files: YYYYDDDHHMMSS_NNNNN_CS_2B-TAU_GRANULE_S_RVV_EVV.hdf
R05 files: YYYYDDDHHMMSS_NNNNN_CS_2B-TAU_GRANULE_S_RVV_EVV_F00.hdf

  • YYYYDDDHHMMSS = Year, Julian day, hour, minute, second of the first data contained in the file (UTC)
  • NNNNN = Granule number
  • CS = Literal "CS" indicating the CloudSat mission
  • 2B-TAU = Product name
  • GRANULE = Indicates the data subset ("GRANULE" if the data are not subset)
  • S_RVV = Version including the processing iteration ("P", "P1", "P2", etc.) and release ("R04", "R05", etc.). For example: P_R04.
  • EVV = Epoch number
  • F00 = Fix number (for reprocessed files within a version - R05 only)
  • .hdf = HDF-EOS file suffix

Organization of fields and attributes in the HDF-EOS files

The HDF-EOS files are organized into heirarchical groups. The file contains a swath, which for the CloudSat mission has the same name as the product. The swath contains three groups: geolocation, data, and swath metadata. The fields listed on the product pages are organized into the geolocation and data groups. If there are any product-specific metadata fields then a swath metadata group will be shown as well.

The attributes shown for each field are stored in the swath metadata group. They are stored in the format [field name].[attribute name]. For example, Radar_reflectivity.factor contains the scale factor for the 2B-GEOPROF radar reflectivity field.

Field Attributes

Name Description
[fieldname].factor scale factor (4-byte floating-point)
[fieldname].offset offset (4-byte floating-point)
[fieldname].units units (character string)
[fieldname].long_name field description (character string)
[fieldname].valid_range valid range (two element array [min,max] same type as the field)
[fieldname].missing missing data value (same type as the field)
[fieldname].missop indicates that missing data are <, <=, ==, >=, or > the missing value (character string)

Scaling

Although most fields use 1 and 0 as the scale factor and offset, some fields are scaled to fit into a smaller type when written to the file. For example, Radar_reflectivity is a 4-byte floating-point number, but is multiplied by 100 and converted to a 2-byte integer when it is written to the file. The scaling equation is:

DATA_FILE_VALUE = (SCIENCE_VALUE * FACTOR) + OFFSET
- or -
SCIENCE_VALUE = (DATA_FILE_VALUE - OFFSET) / FACTOR

Swath Attributes

Name Description
ID_SITE (CIRA)
ID_CENTER (CloudSat DPC)
ID_URL (http://cloudsat.cira.colostate.edu)
ID_ACCOUNT account that created the file
ID_CREATED date and time the file was created
algorithm_version algorithm version number
product_version product version number
start_time YYYYMMDDHHmmss of the first profile in the file
end_time YYYYMMDDHHmmss of the last profile in the file

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