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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: 19 September 2023 (Day 262) 15:26:30

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

1B-CPR

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

1B-CPR measures the backscattered power as a function of distance from the radar. The backscattered power is sampled every ~240 m; there are 125 range bins, for a total window of 30 km. The raw, Level 0 data is converted to calibrated Level 1B data using pre-launch and in-flight calibration measurements.

Primary Publication(s)

Tanelli, S.; Durden, S.L.; Im, E.; Pak, K.S.; Reinke, D.G.; Partain, P.; Haynes, J.M.; Marchand, R.T., CloudSat's Cloud Profiling Radar After Two Years in Orbit: Performance, Calibration, and Processing, Geoscience and Remote Sensing, IEEE Transactions on, vol.46, no.11, pp.3560,3573, Nov. 2008 doi: 10.1109/TGRS.2008.2002030

  • 1B-CPR P_R05 (Current)
  • 1B-CPR P_R04

Process Description and Interface Control Document (PDICD)

E09 Data Issues (Updated January 30, 2023)
PDICD (Updated September 14, 2017)

Process Description and Interface Control Document (PDICD)

Data Issues (Updated October 17, 2007)
PDICD (Updated June 27, 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
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
DEM_geoid_anomaly FLOAT32 nray km [-1.10e-01, 9.00e-02] 1.0 0.0
Range_to_first_bin FLOAT32 nray meters [650000.0, 740000.0] -9999.0 == 1.0 0.0
RayHeader_RangeBinSize FLOAT32 scalar meters [2.40e+02, 2.40e+02] -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
NoiseFloorPowers FLOAT32 nbin,nray 87 [1.00e-15, 2.00e-14] -9999.0 == 1.0 0.0
ReceivedEchoPowers FLOAT32 nbin,nray 87 [1.00e-15, 1.00e-06] -9999.0 == 1.0 0.0
FlatSurfaceClutter FLOAT32 nbin,nray 87 1.00e-30 == 1.0 0.0
Data_quality UINT8 nray -- [0, 255] 1.0 0.0
Data_status UINT16 nray -- [0, 65535] 1.0 0.0
Data_targetID UINT8 nray -- [0, 255] 1.0 0.0
Navigation_land_sea_flag UINT8 nray -- [1, 4] 1.0 0.0
RayHeader_lambda FLOAT32 scalar meters [3.19e-03, 3.19e-03] 1.0 0.0
RayHeader_SpatAvg FLOAT32 scalar seconds [1.60e-01, 4.80e-01] -9999.0 == 1.0 0.0
RayHeader_CalVers FLOAT32 scalar -- [0.0, 5.0] 1.0 0.0
RayStatus_validity UINT8 nray -- [0, 255] 1.0 0.0
RayStatus_PRI UINT8 nray 1.6 microsec [140, 208] 0 == 1.0 0.0
RayStatus_pulseWidth UINT8 nray microsec [3, 3] 0 == 1.0 0.0
RayStatus_pulsesTx INT16 nray -- [580, 678] 0 == 1.0 0.0
RayStatus_antennaNoise FLOAT32 nray mW 1.0 0.0
TransmitPower FLOAT32 nray 87 [700.0, 2100.0] -9999.0 == 1.0 0.0
TransmitPower_Avg FLOAT32 scalar 87 [700.0, 2100.0] -9999.0 == 1.0 0.0
RadarCoefficient FLOAT32 nray m^(-3) [1.00e-02, 1.00e-01] -9999.0 == 1.0 0.0
Sigma-Zero INT16 nray dB*100 [-1000, 4000] -9999 == 1.0 0.0
SurfaceBinNumber UINT8 nray -- [82, 125] 255 == 1.0 0.0
SurfaceClutter_Index FLOAT32 nray 99.0 == 1.0 0.0
SurfaceBinNumber_Fraction FLOAT32 nray -99.0 == 1.0 0.0

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