Braun, Scott A.

da Silva, A.

Ferrare, R.

Kacenelenbogen, M.

Mace, G.

Petersen, W.

Redemann, J.

Stephens, G.

Waliser, D.

Winker, D.

English

NASA Technical Reports Server

ACCP Aerosols and Clouds, Convection & Precipitation Study
The NASA Decadal Survey Observing-
System Study for Aerosols and Clouds, 
Convection, and Precipitation (ACCP)
Scott Braun1, A. da Silva1, R. Ferrare2, M. Kacenelenbogen4, W. Petersen3, G. Stephens5, 
D. Waliser5, D. Winker2, G. Mace6, J. Redemann7
1) NASA Goddard Space Flight Center            2) NASA Langley Research Center
3) NASA Marshall Space Flight Center         4) NASA Ames Research Center
5) Jet Propulsion Laboratory      6) University of Utah
7) University of Oklahoma
AGU Session H21E – Space-based precipitation observations, estimation, and 
applications: A centennial Perspective
https://ntrs.nasa.gov/search.jsp?R=20200000890 2020-03-28T18:46:40+00:00Z
ACCP Aerosols and Clouds, Convection & Precipitation Study
ACCP Overview
The 2017 Decadal Survey (DS) recommended cost-capped missions with specified 
caps, creating challenge for team to envision new science but ensure an 
implementable observing system
Aerosols Clouds, Convection, and Precipitation
Observable 
Priorities
Aerosol properties, aerosol vertical 
profiles, and cloud properties to 
understand their effects on climate 
and air quality
Coupled cloud-precipitation state and 
dynamics for monitoring global 
hydrological cycle and understanding 
contributing processes including cloud 
feedback
Desired 
Observables
Backscatter lidar and multichannel, 
multi-angle/polarization imaging 
radiometer
Radar(s), with multi-frequency passive 
microwave and sub-mm radiometer
ACCP Aerosols and Clouds, Convection & Precipitation Study
Science Teams:
Science Impact Team (SIT) co-chaired by G. Mace, J. Redemann
Applications Impact Team (AIT) co-chaired by D. Kirschbaum, A. Omar
Science and Applications Leadership Team (SALT)
A. da Silva, S. Braun, G. Stephens, D. Waliser, R. Ferrare, D. 
Winker, W. Petersen, M. Kacenelenbogen, D. Kirschbaum, A. 
Omar
ACCP Study Organization Other teams:• Study Management 
Team
• Systems 
Engineering Team
• Value Framework 
Team
• Science Community 
Committee
ACCP Aerosols and Clouds, Convection & Precipitation Study
ACCP Science Objectives
4
High Cloud 
Feedback
Low Cloud 
Feedback
Convective Storm 
Systems
Cold Cloud & 
Precipitation
Aerosol Attribution
& Air Quality
Aerosol 
Redistribution
Aerosol Absorption, 
Direct &  Indirect 
Effects on Radiation
Mission Study on Aerosol and 
Clouds, Convection & Precipitation 
8  Science Objectives
Traceable  to the 2017 Decadal Survey (2)
ACCP Science
7 8
1
6
5
3
2
4
ACCP Aerosols and Clouds, Convection & Precipitation Study
1. WATER VAPOR + CLOUDS + PRECIPITATION + 
RADIATION
Previous / PoR measurements have not provided 
collocated measurements of clouds and precipitation; 
combined with PoR water vapor & radiation, these 
measurements are key to understanding:
• Low Cloud Climate Feedback
• High Cloud Climate Feedback
• Cloud and Precipitation Development 
• Atmospheric Water Cycle
Clouds Precipitation
e.g. , VIIRS, 
ABI, 
EarthCare, 
Field 
Observations
e.g., GPM,
EarthCare, 
Field 
Observations
ACCP 
Designated 
Observing 
System
Clouds, Convection and Precipitation
New Science 
Enabling 
Observations
Collocated Cloud 
Convection and 
Precipitation 
Observations H2O Vapor
e.g., IASI,
CrIS, Field 
Observations
2. VERTICAL MOTION IN CONVECTIVE STORMS
There are no global measurements of vertical motion 
inside convective storms; these are key to understanding:
• Storm Development & Life Cycle
• Hydration of the Upper Troposphere
• Precipitation Extremes
Program of Record (PoR)
3. HIGH LATITUDE CLOUDS AND SNOWFALL
Previous / PoR measurements provide inadequate 
information to constrain snowfall estimates. Relevant to:
• Polar Hydrometeorology
• Sea Ice and Ice Sheet Surface Mass Balance
e.g., CERES,
EarthCare
Radiation
Low and High Cloud Climate 
Feedbacks
Cloud, Storm and Precipitation 
Development and Lifecycles  
ACCP Aerosols and Clouds, Convection & Precipitation Study
1. 4D AEROSOL SAMPLING & LIFE CYCLE
Previous PoR measurements have not provided 
collocated temporal and vertical measurements of 
aerosol distribution and properties; key to understanding:
• Aerosol Sources and Transport 
• Aerosol Processing
• Aerosol Removal and Redistribution 
• Modeling and Forecast Skill
Aerosol
DIstribution
e.g. 
ABI,AHI
VIIRS
Lidar
Polarimeter
Aerosols
ACCP will 
augment the 
future Program 
of Record (PoR)
3. AEROSOL PROPERTIES
New and improved measurements of aerosol single 
scatter albedo and size to:
• Discriminate Anthropogenic and Natural Aerosols
• Improve Understanding of Aerosol Sources
• Evaluate Modeling and Air Quality
2. AEROSOL AMOUNT
Improved measurements of AOD, AAOD, and aerosol 
extinction profiles to advance understanding of:
• Aerosol Direct Radiative Effects at TOA & Surface 
• Air Quality
• Aerosol Atmospheric Heating & Hydrologic Sensitivity
e.g. 
3MI
PACE
Trace Gases
Aerosol 
Properties
e.g. 
Trop-OMI
TEMPO
Aerosol DOProgram of Record (PoR)
Vertical Profiles
Enhanced properties
New
Science 
Enabling 
Observations
ACCP Aerosols and Clouds, Convection & Precipitation Study
Cloud
Formation
Links between ‘A’ & ‘CCP’
H2O Vapor
Aerosols are fundamental to the 
formation of clouds and precipitation, 
and thus relevant to all CCP objectives.  
Precipitation
DevelopmentAerosols
I. Aerosol Effects on Cloud 
Microphysics and Precip
III. Aerosol Processing, Removal and 
Redistribution by Cloud
Removal
Redistribution
Precipitation removes aerosols, convection and 
storms loft and redistribute aerosols
Chemical processing of aerosol occurs within 
cloud droplets
These aerosol impacts on clouds and 
precip lead to impacts on radiation, 
thus further linking Aerosol and CCP 
objectives.  
II. Aerosol Indirect 
Radiative Effects
ACCP Aerosols and Clouds, Convection & Precipitation Study
ACCP Constraints
• Cost-capped observing system
• Define minimum and enhanced desired capabilities, not threshold 
and baseline requirements
• Instruments will be selected from existing capabilities rather than 
designed to desired science capabilities
• Must be of sufficiently high technical readiness (TRL6) by mission preliminary 
design review
• Finding an observing system that meets objectives is ultimately 
dependent on knowledge of available capabilities (Instrument 
Library)
ACCP Aerosols and Clouds, Convection & Precipitation Study
ACCP Architecture Study
Radar
Lidar
Radio.
Polar.
Architecture Components:
• Instruments
• Spacecraft buses
• Ground systems
• Launch vehicles
• Mission operations
• Suborbital observations/GV
• Science team
Study instrument library includes a broad 
range of capabilities:
• Radars include W, Ka, Ku bands, 
Doppler and non-Doppler, scanning and 
nadir only
• Radiometers include cross-track and 
conically scanning, frequencies ranging 
from 10 to 883 GHz
• Lidars include 2 and 3 frequencies, 
backscatter and HSRL 
• Polarimeters include varying channels 
(5 to hyperspectral) and angles (5 to 
255)
• Spectrometers include VIS, NIR, SWIR, 
LWIR, TIR
ACCP Aerosols and Clouds, Convection & Precipitation Study
The ACWs generated ~32 architectures 
including
• Single- and dual- medium-to-large 
satellites
• Smallsat (<180 kg) systems
• Hybrid small/large satellite systems
• Constellations of cubesats
• Impacts of international contributions
Architecture Construction 
Workshops (ACWs)
Polar orbit solutions
Inclined orbit additions
ACCP Aerosols and Clouds, Convection & Precipitation Study
ACW General Findings
In
cr
ea
si
ng
 R
el
at
iv
e 
Co
st
In
cr
ea
sin
g R
el
at
ive
 C
os
t
Increasing Science Benefit
Potentially Implementable Range
Results for first 18 architecturesRelative costs and 
qualitative science 
benefit scores
ACCP Aerosols and Clouds, Convection & Precipitation Study
Dual-satellite, dual-orbit architecture with:
Polar satellite:
• W, Ka-band Doppler radars, swath of 12.5 km at Ka
• Radiometer with 118, 183 GHz, and several sub-mm 
channels
• Dual-wavelength lidar, HSRL @ 532 nm
• Thin ice cloud spectrometer (contributed)
• 60-angle polarimeter 
GPM-orbit satellite:
• W, Ka-band Doppler radars, swath of 12.5 km at Ka
• Radiometers with 183/325/670 GHz
• Smallsat dual-wavelength backscatter lidar
• 60-angle polarimeter 
Collaborative Design Center Study #1 & #2
CDC#2 breaks up this architecture into smaller 
components. Instead of 2 satellites, broken up 
into 4 (two per orbit).
ACCP Aerosols and Clouds, Convection & Precipitation Study
Value Framework Scoring
Key parameters for assigning a 
science benefit score include 
the utility of geophysical 
variables for achieving the 
science objectives and the 
quality of the geophysical 
variables that are derived from 
each architecture. 
The value framework will allow 
for a fairly objective cost-
benefit assessment of the 
architectures considered within 
the observing system study.
An illustrative example of value framework scoring
ACCP Aerosols and Clouds, Convection & Precipitation Study
Study Summary
• Next CDC is in March and will consider JAXA Ku Doppler 
radar
• Three more CDC possible after March CDC
• March and June 2020: Suborbital workshops
• 2021: Modeling workshop possible to look at integration of 
observations with Earth System Models
• Earliest possible launch likely in 2029, likely in two phases 
due to expected budget profile


The NASA Decadal Survey Observing-System Study for Aerosols and Clouds,Convection, and Precipitation (ACCP)

The NASA Decadal Survey Observing-System Study for Aerosols and Clouds,Convection, and Precipitation (ACCP)

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