CloudSat DPC
  • Quicklooks
  • Orders
    New Order Cart & Past Orders SFTP Access FAQs
  • Data Products
    Overview
    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)
  • Resources
    CloudSat/CALIPSO Distance Footprints Software Tools Orbital Elements (TLEs)
  • Publications
  • Contact
  • Questions?
    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

2C-PRECIP-COLUMN

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

Captioned Figure 1
An example plot comparing reflectivity from 2B-GEOPROF with rain rate from 2C-PRECIP-COLUMN.

The objective of the algorithm is to determine the presence of surface precipitation, and quantify the intensity, based on CloudSat Profiling Radar (CPR) observations. The algorithm makes use of the radar reflectivity near the surface of the earth and an estimate of path integrated attenuation (PIA) determined from the surface reflection characteristics to determine precipitation occurrence (over all surface types) and intensity (over water surfaces).

Changes/Updates in Algorithm Version P_R05

  • This product now primarily focuses on precipitation incidence. A side effect is that some variables have been renamed; Precip_rate becomes Diagnostic_precip_rate, and so on.
  • The convective and stratiform retrievals have been rebuilt from the ground-up, and now share a largely unified code base. New lookup tables of precipitation rate and path integrated attenuation have been built using Robin Hogan’s Time-Dependent Two-Stream model of multiple scattering (Hogan and Battaglia 2008). Improvements have also been made that should result in better simulation of the CloudSat radar’s antenna beam pattern.
  • A new method of determining PIA, using local observations of the clear sky surface, is used when available. This significantly reduces uncertainty in PIA, especially over the ocean surface (see Section 2.1.1).
  • PIA is now reported everywhere it can be calculated, including for non-raining profiles. It is reported (experimentally) over non-water surfaces.
  • Various bug fixes.

(For more details, see the 2C-PRECIP-COLUMN P_R05 Process Description and Interface Control Document (PDICD).)

Primary Publication(s)

Haynes, J. M., T. S. L'Ecuyer, G. L. Stephens, S. D. Miller, C. Mitrescu, N. B. Wood, and S. Tanelli, (2009) Rainfall retrieval over the ocean with spaceborne W-band radar, J. Geophys. Res., 114, D00A22, doi:10.1029/2008JD009973.

  • 2C-PRECIP-COLUMN P1_R05 (Current)
  • 2C-PRECIP-COLUMN P2_R04

Process Description and Interface Control Document (PDICD)

2C-PRECIP-COLUMN P1_R05 PDICD (Rev. 1) (Updated January 26, 2018)
E09 Data Issues (Updated January 30, 2023)

Process Description and Interface Control Document (PDICD)

2C-PRECIP-COLUMN P2_R04 PDICD (Updated January 24, 2013)

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
DEM_elevation INT16 nray meters [-9999, 8850] 9999 == 1.0 0.0

Data Fields

Field Type Dimensions Units Valid Range Missing Missing Op. Factor Offset
unused INT8 scalar 45 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
Status_flag INT8 nray [0, 21] 1.0 0.0
Conv_strat_flag INT16 nray [-3, 3] -1000 == 1.0 0.0
PIA_hydrometeor FLOAT32 nray dB [-100.0, 100.0] -1000.0 == 1.0 0.0
PIA_near_surface FLOAT32 nray dB [-100.0, 100.0] -1000.0 == 1.0 0.0
PIA_uncertainty FLOAT32 nray dB [0.0, 100.0] -1000.0 == 1.0 0.0
Sigma_zero FLOAT32 nray dB [-100.0, 100.0] -1000.0 == 1.0 0.0
Near_surface_reflectivity FLOAT32 nray dBZe [-100.0, 100.0] -1000.0 1.0 0.0
Frozen_precip_height FLOAT32 nray km [0.0, 20.0] -1000.0 == 1.0 0.0
Rain_top_height FLOAT32 nray km [0.0, 20.0] -1000.0 == 1.0 0.0
Melted_fraction FLOAT32 nray [0.0, 1.0] -1000.0 == 1.0 0.0
Lowest_sig_layer_top FLOAT32 nray km [0.0, 20.0] -1000.0 == 1.0 0.0
Highest_sig_layer_top FLOAT32 nray km [0.0, 20.0] -1000.0 == 1.0 0.0
Cloud_flag INT8 nray [0, 9] 1.0 0.0
Surface_type INT8 nray [0, 9] 1.0 0.0
Freezing_level FLOAT32 nray km [0.0, 10.0] -1000.0 == 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
Diagnostic_precip_rate FLOAT32 nray mm/h [-40.0, 40.0] -1000.0 == 1.0 0.0
Diagnostic_precip_rate_min FLOAT32 nray mm/h [-40.0, 40.0] -1000.0 == 1.0 0.0
Diagnostic_precip_rate_max FLOAT32 nray mm/h [-40.0, 40.0] -1000.0 == 1.0 0.0
Diagnostic_precip_rate_no_ms FLOAT32 nray mm/h [-40.0, 40.0] -1000.0 == 1.0 0.0
Diagnostic_retrieval_info INT8 nray [0, 51] 1.0 0.0
Diagnostic_retrieval_type INT8 nray [0, 9] 1.0 0.0
Diagnostic_SRT INT8 nray [0, 9] 1.0 0.0
Diagnostic_PIA_method INT8 nray [1, 9] 1.0 0.0
Diagnostic_PIA_hydrometeor_ws FLOAT32 nray dB [-100.0, 100.0] -1000.0 == 1.0 0.0
Diagnostic_PIA_uncertainty_ws FLOAT32 nray dB [0.0, 100.0] -1000.0 == 1.0 0.0
Experimental_land_PIA FLOAT32 nray dB [-100.0, 100.0] -1000.0 == 1.0 0.0
Experimental_land_PIA_uncertainty FLOAT32 nray dB [0.0, 100.0] -1000.0 == 1.0 0.0

© 2025, CloudSat DPC