Z. P. Szewczyk GIST 25, 23-25 Oct. 2006 Recent Field Campaigns with CERES Instruments Z. Peter Szewczyk Kory J. Priestley Lou Smith Remote Sensing of Clouds

Z. P. SzewczykGIST 25, 23-25 Oct. 2006

Recent Field Campaigns with CERES Instruments

Z. Peter SzewczykKory J. Priestley

Lou Smith

Remote Sensing of Clouds and the Atmosphere XI, Stockholm, 09/11-14, 2006


Presentation Outline

• CERES mode for special observations• Planning tools under new restrictive rules• Field campaigns of 2006

– FM1/FM3 comparison– FM2/GERB1 comparison– AMMA support– SCALES support– True AT

• Summary


Clouds and the Earth’s Radiant Energy

System Instrument

CERES

• Narrow field-of-view (15x30km at nadir) scanning radiometer:

• Shortwave channel (0.3-5m),

• Total channel (0.3-100m),

• Window channel (8-12m)

• PFM on board TRMM (1998, failed 06/2000)

• FM1 & FM2 on board Terra (in service from 03/2000)

• FM3 & FM4 on board Aqua (from 06/2002, SW of FM4 is out )


Terra & Aqua orbits

Terra

Aqua

• Sun-synchronous, inclination angle 98.2o and 81.8o

• Equator crossing time: 10:30AM Terra and 1:30PM Aqua• about 15 minutes apart at nodes


CERES normal operation modes

• Cross-track (XT) Scan

• Rotational Azimuth Plane Scan (RAPS)

• Constant RAZ rate

• Ram direction restrictions

• Suspended due to degradation investigation


Scan mode for special operations

• In Programmable Azimuth Plane Scan (PAPS) mode, scanning plane orientation follows a prescribed schedule Step-wise changes of the azimuth angle

Time and angle changes depend on satellite position in an orbit

• New elevation profile due to ram direction restrictions• Increases sampling by orders of magnitude


CERES special operation tools • Objectives of special observations using PAPS:

Earth targets

Matching viewing geometry of other instruments

Sampling within required scan plane orientation

• Relative azimuth (RAZ) predictions (web-based)– Obtain 7-day satellite ground track file from Goddard– Compute scanner orientation for each scan (every 6.6s)– Generate daily RAZ prediction files for commanding

• Automated Command uploads– One-day sequences (ODS) formatted for a direct upload


Field campaigns of 2006

Summer of 2006:

• Terra-Aqua (FM1/FM3) comparison in June• CERES-GERB (FM2/GERB1) comparison in June• African Monsoon Multidisciplinary Analysis (AMMA)

in July • Ground validation for GERB2 and GERB1 at Valencia

Anchor Station (VAS) early August• True along-track (AT) scan every other Tuesday

starting on 08/22


Terra-Aqua comparisonCERES radiances belong to two-decade long Earth’s

radiation budget dataset

• Greenland is the most homogenous:

• FM1 and FM3 15 minutes apart

• Scans orthogonal to the solar plane

• Using short nadir scan profile to avoid ram directions

• Validation campaign:

• 06/05 – 06/30, 2006

• 600 orbital crossings of about 90 seconds each

• Significant amount of data for statistical analysis


FM1/FM3 scanning pattern

15:04 (GMT) on 06/05/2006 15:19 (GMT) on 06/05/2006


FM1 daily scanning

Filtered shortwave radiances on 06/05/2006

0 100 217Watts per square meter per steradian


FM2/GERB1 comparisonGERB radiances part of the ERB dataset

• Campaign around the summer solstice of 2006 CERES matches GERB viewing geometry (located at 6.5W)

FM2 on Terra in the PAPS mode for 25 days

4 daytime orbits per day for about 45 min scanning

Ram restrictions result in the Northern Hemisphere data only

The use of the short nadir scan profile doubles matched footprints


GERB measurements• Geo-stationary Earth Radiation Budget instrument

On board Meteosat-9 located at 6.5W in June

Array of 256 detectors covering the visible portion of the Earth

Short and long-wave radiation image every 15min.


FM2-GERB1 Pass at 9:44 (GMT) on 06/18/2006 Pass at 11:21 (GMT) on 06/18/2006


GERB ground validation

To validate GERB radiances with ground data

• Geo Earth Radiation Budget instrument with 256 detectors

• Valencia Anchor Station (VAS): 39.34oN and 1.17oW

• Of GERB pixel size (50x50 km) and quite homogenous

• Ground instrumentation by University of Valencia

• CERES measurements on July 31- August 6, 2006:

• FM2 on Terra – one or two passes per day

• about 2.5 minutes of data


FM2 daily scanning over VAS

Pass at 10:09 (GMT) on 08/01/2006 Pass at 11:47 (GMT) on 08/01/2006


African Monsoon Multidisciplinary Analysis

(AMMA)

To understand the impact of monsoons

• Niamey/Niger site: 13.47oN and 2.17oE

• Focus on clouds dynamics, air pollution

• CERES measurements in July (10th on) of 2006:

• FM2 on Terra

• One orbit per day for about 2.5 minutes


FM2 over Niamey (AMMA)

Command sequence at 10:51 (GMT) on 07/26/2006 Targeting the site


True along-track scan

To eliminate a spatial mismatch between nadir and oblique observations

• Original implementation:

• RAZ fixed, along the satellite velocity vector

• Earth’s rotation causes a wide swath of footprints

• New implementation:

• RAZ changes to account for the Earth’s rotation

• Significantly reduced spread of footprints


Footprints spread

swath shown on a 5º by 10º grid

• RAZ corrections: ±4º• about 80km mismatch between nadir and oblique (55º VZA) observations reduced to 3km


2006 campaign summary

Campaign Duration Orbits Amount of data

Terra/Aqua 07/05–07/30 350 900 min

FM2/GERB1 07/05–07/30 100 1100 min

VAS 07/31–08/06 11 30 min

AMMA 07/10–07/28 15 40 min

True AT 08/22, 09/05 28 700 min


Concluding remarks

• Busy summer of 2006 for CERES• Programmable Azimuth mode used for meeting data

collection goals• Planning tools reside on the website• Despite ram restrictions, large amount of data was

collected• Free service to the science communityhttp://asd-www.larc.nasa.gov/PAPS/cgi-bin/rygar.cgi

Documents

Z. P. Szewczyk GIST 25, 23-25 Oct. 2006 Recent Field Campaigns with CERES Instruments Z. Peter Szewczyk Kory J. Priestley Lou Smith Remote Sensing of Clouds