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    2C-ICE 2C-PRECIP-COLUMN 2C-RAIN-PROFILE 2C-SNOW-PROFILE
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    Level AUX
    AMSR2-AUX CRYOSPHERE-AUX ECMWF-AUX MOD06-1KM-AUX MOD06-5KM-AUX MODIS-AUX OCO2CLD-LIDAR-AUX
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    3F-RMCP / 3S-RMCP
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    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

2B-CLDCLASS

Product Availability: Full mission availability except for anomalies and maneuver data gaps

Captioned Figure 1
An example plot of 2B-CLDCLASS on August 19, 2009 showing observed cloud classifications.

Classifying cloud type is an important task for global cloud climatology studies. Different types of clouds are governed by different cloud dynamical processes and have different microphysical properties, which can result in quite different cloud radiative forcings. Because cloud type corresponds to specific cloud physical properties, cloud classification is also needed to apply other algorithms to derive quantitative cloud content and radiative data. 2B-CLDCLASS classifies clouds into either stratus (St), stratus (Sc), cumulus (Cu, including cumulus congestus), nimbostratus (Ns), altocumulus (Ac), altostratus (As), deep convective (cumulonimbus), or high (cirrus and cirrostratus) clouds, based on different rules for hydrometeor vertical and horizontal scales, the maximum Ze measured by the CPR, indications of precipitation, and ancillary data including ECMWF predicted temperature profiles and surface topography height.

Primary Publication(s)

Sassen, K., and Z. Wang, (2008) Classifying clouds around the globe with the CloudSat radar: 1-year of results, Geophys. Res. Lett., 35, L04805, doi:10.1029/2007GL032591.

  • 2B-CLDCLASS P1_R05 (Current)
  • 2B-CLDCLASS P_R04

Process Description and Interface Control Document (PDICD)

PDICD (Rev. 1) (Updated May 17, 2019)
E09 Data Issues (Updated January 30, 2023)

Process Description and Interface Control Document (PDICD)

PDICD (Updated July 24, 2007)

Algorithm Specifications (for latest R05)

Geolocation Fields

Field Type Dimensions Units Valid Range Missing Missing Op. Factor Offset
Profile_time FLOAT32 nray seconds [0.0, 6000.0] 1.0 0.0
UTC_start FLOAT32 scalar seconds [0.0, 86400.0] 1.0 0.0
TAI_start FLOAT64 scalar seconds [0.0, 600000000.0] 1.0 0.0
Latitude FLOAT32 nray degrees [-90.0, 90.0] 1.0 0.0
Longitude FLOAT32 nray degrees [-180.0, 180.0] 1.0 0.0
Height INT16 nbin,nray 109 [-5000, 30000] -9999 == 1.0 0.0
Range_to_intercept FLOAT32 nray km [600.0, 800.0] 1.0 0.0
DEM_elevation INT16 nray meters [-9999, 8850] 9999 == 1.0 0.0
Vertical_binsize FLOAT32 scalar 109 -9999.0 == 1.0 0.0
Pitch_offset FLOAT32 scalar degrees [-90.0, 90.0] 1.0 0.0
Roll_offset FLOAT32 scalar degrees [-90.0, 90.0] 1.0 0.0

Data Fields

Field Type Dimensions Units Valid Range Missing Missing Op. Factor Offset
cloud_scenario INT16 nbin,nray none [0, 32767] 1.0 0.0
CloudLayerBase FLOAT32 ncloud,nray km [0, 20] 1.0 0.0
CloudLayerTop FLOAT32 ncloud,nray km [0, 30] 1.0 0.0
CloudLayerType INT16 ncloud,nray none [0, 9] 1.0 0.0
Data_quality UINT8 nray -- [0, -1] 1.0 0.0
Data_status UINT16 nray -- [0, -1] 1.0 0.0
Data_targetID UINT8 nray -- [0, -1] 1.0 0.0
RayStatus_validity UINT8 nray -- [0, -1] 1.0 0.0
Navigation_land_sea_flag UINT8 nray -- [1, 4] 1.0 0.0
Precip_flag INT8 nray [0, 9] 1.0 0.0
SST FLOAT32 nray deg C [-100.0, 100.0] -1000.0 == 1.0 0.0
Surface_wind FLOAT32 nray m/s [0.0, 200.0] -1000.0 == 1.0 0.0
CloudLayer INT16 nray none [0, 32767] 1.0 0.0

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