# Presentation: 154705

## Developing GPM Ground Validation  Using System Engineering Principles

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

## 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

## 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

_**Introduction**_

## 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

_**Introduction**_

## Overall structure of GPM-GV system

## 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 )

## 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?*

## 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

## Features of GPM-GV Systems

**Communication**:The 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.

_**Features of GPM-GV Systems**_

## 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.

## Life Cycle of the GPM-GV system 

## 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

## 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

## 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

## Requirement Development & Users

- 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

_**Requirement Development & Users**_
**Function Requirements**

## 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

## 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

## GPM-GV System Architecture

- Hierarchical development of the GPM-GV system

_**GPM-GV System Architecture**_

## GPM-GV System Architecture

## GPM-GV System Architecture

-  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

_**GPM-GV System Architecture**_

## GPM-GV System Architecture

_**GPM-GV System Architecture**_

## GPM-GV System Architecture

## 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

- 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)

_**Risk Management**_

## 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