Developing GPM Ground Validation Using System Engineering Principles

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Developing GPM Ground Validation Using System
Engineering Principles

• V. Chandrasekar
• Colorado State University
• CSU-CHILL Radar Facility
• Fort Collins, CO-80523

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Introduction

• Development of the Ground Validation (GV) system
  from System Engineering principles enables, a
  top down flow of requirements into the GV
  system
• GPM mission goals will provide the driver for the
  GV system

3

• Introduction

• The GPM system is being developed within based
  on system engineering principles
  
• Ground validation is one of the key elements of
  the system engineering principles for the GPM
  system
  
• Validation can be seen either as a subsystem of
  the GPM system or an important system
  engineering process for the GPM
  

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• Introduction

• Development process of GPM-GV system should
  include
  
• Definition of exact functions to be performed
• Examination of the ability to perform the system
  function
  
• Development of a GPM-GV system architecture and
  define the hierarchy of subsystems
  
• Definition of procedures that can be used to test
  the functionality
  
• System integration
• Demonstrating required performance and operation
  of the system throughout its life, including
  maintenance, and upgrades

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Overall structure of GPM-GV system
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• Features of GPM-GV Systems

• System function definition( Example)
• Validating and assisting GPM in quantifying
  space-time variation in rainfall, relationship
  between rain microphysics/mixed phase
  depth/melting layer/DSD properties
• Purpose is to answer
• What are the primary microphysical contributors
  to satellite algorithm precipitation retrieval
  errors and how do they vary as a function of
  meteorological regime ( From the draft GV white
  paper )

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• Features of GPM-GV Systems

• System function definition( Example)
• Validating and assisting GPM in accurate,
  precise, frequent, and globally distributed
  measurements of instantaneous rainrate
  
• Validating and assisting GPM in error
  characterization of precipitation retrievals
  
• Validating and assisting GPM in frequent sampling
  and complete continental coverage of high
  resolution rainfall measurements
  
• Purpose is to answer How can GPM be effectively
  used for hydrometerological applications?
  
• To what extent GPM can be used to
  enhance the national precipitation observing
  network?

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• Features of GPM-GV Systems

• GV system control System control include
• Timing, schedule and location and any sequence
  definition of GPM-GV operation
  
• Risk management

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• Features of GPM-GV Systems

• CommunicationThe communication aspects of the GV
  system
  
• Establishes the protocols of who communicates
  with who
  
• Is there inter-site, inter-process communication?
  
  
• Protocols as to GV system communications with GPM
  satellite algorithm system, as well as
  communication between GV sites and hierarchy of
  subsystems are established here
• Data communication is a very important part of
  communication. Data communication should be
  bidirectional, both from the GPM system to GV
  system and the reverse.

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• Features of GPM-GV Systems

• GV system inputs
• In the case of GPM-GV this is expected to be an
  open system, in the classic definition, the GV
  can be taking inputs across its boundaries from
  non-GPM sources also such as local and regional
  forecasts, to decide on the mode of operation.

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• Life Cycle of the GPM-GV system

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• Life Cycle of the GPM-GV system

• The life cycle of the GPM/GV system includes the
  following phases
  
• Establish the requirements ( Important Step )
• Define the GPM/GV system
• Design The first three phases occur nearly
  simultaneously through iteration. Presently
  GPM-GV is at this level of lifecycle

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• Life Cycle of the GPM-GV system

• Deployment Testing and system level validation of
  the GV systems, such as calibration of the
  sensors, testing communication, control and
  process ( very important)
• Commissioning
• Operation and maintenance

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• Requirement Development Users

• Users of the GV system include, the main GPM
  system, the scientific community and the GPM-GV
  site scientists. A user is anyone who plays role
  in any stage of the life cycle and not just the
  end user
• Some users identified here
• GPM algorithm developers
• GPM-GV site managers
• GPM-GV algorithm scientists
• GPM mission researchers
• Outreach end users
• GPM-GV Instrument developers
• GPM-GV system managers 

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• Requirement Development Users
• Function Requirements

• Special constraints
• They may include ensuring coverage to, say
  continental, ocean and mountainous regions
  
• These may also include ensuring measurements of
  rain and snow regions
  
• Interface requirement of GPM-GV with the rest of
  GPM. This will ensure that the role of GPM-GV in
  issues such as algorithm development are made
  part of the system design process
• Ease of use access Used to define data access,
  communication again being able to trace to system
  goals
  
• Life cycle This requirement may specify when the
  GPM-GV sites may need to start operating
  

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• GPM-GV System Architecture

• Establishing the architecture is perhaps the most
  important process in addition to establishing
  requirements, in development of the GPM-GV
  system
• The architecture building is typically a
  visionary and very creative process, that ensures
  all the future changes can be implemented without
  fundamentally breaking the architecture
• The architectural design creates the form of
  the GPM-GV system

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• GPM-GV System Architecture

• There are few important features that must be
  envisioned in the GPM-GV system architecture
  
• Integration of heterogeneous remote sensor and
  in-situ data from around the globe
  
• Incorporation of information theoretic principles
  in distinguishing and assimilating multi-sensor
  environments as an example, information from a
  single rain gage in an isolated area may be much
  more important than information from a similar
  gage co-located with disdrometers, and radars
• Developing a strategy how the subsystems should
  interact
  
• ( thereby defining the communication
  architecture)
  
• Modularity for upgrade
• Reliability and risk
• Ability to develop hierarchical design

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• GPM-GV System Architecture

Hierarchical development of the GPM-GV system
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• GPM-GV System Architecture

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• GPM-GV System Architecture

• The GPM-GV sites can be seen as vertical
  integration sites across the thrust areas
  
• Such a cross discipline integration will be
  an important job of the GV site ( that
  encompasses, all three parts ) manager
  
• This process also defines a GV site that
  should perhaps do at least few of the parts
  

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• GPM-GV System Architecture

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• GPM-GV System Architecture

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• Decomposition Partitioning of GPM-GV System

• Decomposition or partitioning of the GPM-GV
  system is important to develop interfaces and
  simplify
  
• Several models are available to partition
• Geographic region
• Another alternative is by type of sensing, such
  as radars, gages and disdrometers

• Risk Management

• One of the important contributions of system
  engineering is to provide a methodology to assess
  and minimize risk
  
• Various risks possible within GV
• Technical Obsolescence (example GV system
  communicating such that an expensive proprietary
  system is needed by all users to download and
  analyze the data )
• Data loss (Lack of back up strategy at super
  sites)

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• System Integration Testing

• System integration is the inverse process of
  System Design
  
• System design, proceeds by hierarchical
  decomposition, whereas system integration pulls
  the pieces together
  
• This will be an important aspect of International
  GPM-GV. The integrated GPM-GV unit must operate
  as a cohesive unit delivering the emerging
  functionality of GPM-GV
• This is likely to be an important challenge
  because of globally diverse data sets. This is
  THE BIGGEST CHALLENGE to this community