douglas spangenberg 1 , patrick minnis 2 , michele l. nordeen 1 , sunny sun-mack 1
DESCRIPTION
Cloud Property Retrievals over the Arctic from the NASA A-Train Satellites Aqua, CloudSat and CALIPSO. Douglas Spangenberg 1 , Patrick Minnis 2 , Michele L. Nordeen 1 , Sunny Sun-Mack 1 and Q. Z. Trepte 1 1- Science Systems and Applications, Inc, Hampton, VA, USA - PowerPoint PPT PresentationTRANSCRIPT
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Cloud Property Retrievals over the Arctic from the NASA A-Train Satellites Aqua, CloudSat and CALIPSO
Douglas Spangenberg1, Patrick Minnis2,
Michele L. Nordeen1, Sunny Sun-Mack1
and Q. Z. Trepte1
1- Science Systems and Applications, Inc, Hampton, VA, USA
2- NASA Langley Research Center, Hampton, VA, USA
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
NASA A-Train Constellation
CloudSat (Radar) Aqua
(MODIS)
CALIPSO (Lidar)
0.5-2 min15 sec
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
North Pole A-Train Orbit Tracks: April 19, 2008
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
A-Train Satellites
Aqua:• Passive MODIS sensor•1km res pixels sub-sampled to 2 km for cloud property retrievals• Channels used for cloud detection, cloud property retrievals (NASA CERES algorithm): 0.65, 2.1, 1.38, 3.7, 6.7, 7.3, 8.5,11,12,13.3 m - Original Algo, Cloud Detection/Phase, Cloud-Top Altitude• Cloud Properties: Z,T, Phase, , LWP, IWP, Particle Size
CALIPSO: • Cloud-Aerosol lidar with 532, 1064 nm channels• 0.33-5.0 km horizontal res; 30, 60 m vertical res• Cloud properties: N layers, T, Z, Phase, , IWP• Lidar attenuates after =5; often can’t see to cloud base
CloudSat: • 94 GHz Cloud Profiling Radar• 2.5x1.4 km horizontal res; 240 m vertical res• Cloud properties: , LWC/LWP, IWC/IWP, Particle Size
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
A-Train Cloud Analysis, 22:25 UTC Apr 19, 2008R: 0.65 mG: 3.7-11 mB: 11 m
Aqua Cloud Phase Aqua Optical Depth
Aqua RGB Aqua 11m BT
A-Train
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
A-Train Cloud Analysis: 22:25 UTC Apr 19, 2008
CALIPSO VFM
CALIPSO Phase
A-Train
Aqua Cloud Phase
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
A-Train Cloud Analysis: 22:25 UTC Apr 19, 2008
CloudSat Reflectivity
CloudSat Ice Re
CloudSat IWC
Aqua 11m BT
A-Train
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
A-Train Cloud Analysis: 22:25 UTC Apr 19, 2008
CloudSat LWC
CloudSat Liq ReAqua Liquid Re
A-Train
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Aqua-MODIS Validation
• Compare CERES Aqua-MODIS cloud property retrievals to CloudSat/CALIPSO retrievals (passive vs active sensor retrievals)
• Results from April 2008 afternoon/daytime overpasses, 22-23:30 GMT
• ARM/ISDAC field experiment flight days
• Region: 60-80N; 130-180W
• Nearest 4 Aqua-MODIS pixels along CloudSat/CALIPSO track used
• CALIPSO & CloudSat data points matched to within 4 km, 4 min
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Aqua-MODIS Validation
Scene Type % Match NCloud 68 2968Clear 84 299Ice 64 (28) 998Liq/Mixed 92 (93) 572
Cloud Amount & Phase Matching between CALIPSO & Aqua:
Scene Type Amount (%)
N
All Clouds 89 3452Ice Clouds 68 2632Liq/Mix Clouds 21 817
CALIPSO Scene Types Sampled:
• Results valid for CALIPSO upper-most cloud layer
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Aqua-MODIS Validation
Cloud Top Height, CALIPSO vs Aqua:
CALIPSO mean: 5.24 kmAqua mean: 4.39 kmAqua bias: -0.85 km
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Aqua-MODIS Validation
Ice Crystal Effective Diameter, CloudSat vs Aqua:
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
New Aqua-MODIS Multilayer Cloud Property Retrievals
Aqua Optical Depth
Low-Level ZtopSL/UL Ztop
April 19 2008, 22:20 GMT
• Uses 13.3 m channel/CO2 slicing to detect multilayer clouds •, Re, T, Z, for low (liquid) layer• Can improve ice cloud detection by adjusting highest cloud top upward
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Summary & Future Work
• CALIPSO, CloudSat provide data for validating Aqua-MODIS cloud property retrievals on a continuous basis over remote Arctic/Antarctic. • A-Train data can be compared with cloud model data & retrievals from passive sensors on geo satellites (validation studies). • CALIPSO reported combinations of ice and liquid phase in low level Arctic clouds rather than reporting mixed phase.
• Problem in CloudSat data for clouds below ~1km, to hopefully be resolved.
• In-situ data obtained during field experiments will provide valuable data for validating CALIPSO/CloudSat retrievals (ISDAC/AK-Apr 2008).
4th PAN-GCSS Meeting/Polar Clouds Working Group
NASA Langley Research Center / Atmospheric Sciences
Toulouse, France 2-6 June 2008
Summary & Future Work
• Comparisons between Aqua passive sensor retrievals and active sensor retrievals of CALIPSO show good agreement for cloud amount, phase, height.
• Comparisons between Aqua and CloudSat , particle size, LWP/IWP showed larger discrepancy which needs to be resolved - Account for differences inherent in retrievals methods - Improve Aqua-MODIS retrieval techniques for polar clouds
• Multilayer Aqua-MODIS cloud algorithm should be able to provide improved retrievals for high ice clouds and low mixed/liq clouds.
• Web Pages for Information/Data Access:- CALIPSO: http://www-calipso.larc.nasa.gov/- CloudSat: http://cloudsat.atmos.colostate.edu/data/