1. Site classifications, definitions, and updates to Landnet
K. Thome
NASA
WGCV Plenary # 44
EUMETSAT, Darmstadt, Germany
August 28-31, 2018

2. Historical Background - Need for Global, Integrated Network of Calibration Sites
User communities were increasingly relying on information products from multiple satellite sensors
Better calibration should result from more post launch calibration, involving standardized measurement protocols, instrumentation, and processing
Field measurements are resource-intensive activities
Less expensive complementary approaches should provide more frequent calibration updates and enable the monitoring of sensor performance trends, even without surface measurements

3. Historical Background The effort led to the concept of a web-based test- site catalog - Landnet

4. Historical Background
Effort was made to:
Agree scope of Test site definition
Identify characteristics of sensors which can benefit from test sites
Agree desirable list of site characteristics/descriptors
Define key “classification characteristics” (discriminators) per application
First pass review to classify real sites
Discussion on implementation, maintenance, review
Resulting catalog
Provided a list of prime candidate terrestrial targets for consideration as benchmark sites for the post-launch radiometric calibration of space-based optical sensors
Online test site catalog provided public Web site access
Incompleteness of available information on prime test sites indicated more coordination and documentation were needed

5. Historical Background
Future Plan for Landnet was:
Refine the selection of recommended primary sites
Establish traceability chain for primary site data
Gather complete site characterization data and information
Acquire and archive imagery of all primary sites –this was done well
Define core measurements (eg. Instruments)
Develop online calibration data access infrastructure – came close
Develop guidelines and establish endorsements mechanisms for meeting calibration standards
Endorse and advocate compliance with calibration standards
Difficulties encountered achieving all of these plans
Never clearly defined a mechanism to update the site list

6. More history – At WGCV-42 we discussed what to do with Landnet
Improve definitions of the purpose of Landnet
Opted to try and use the RadCalNet Admission Panel to help evaluate Landnet status on a yearly basis
Identify sites that are no longer active
Yearly to site administrator receives no response
No published results within a three-year period
Evaluate proposals from sites wanting to be added to LandNet
Five years of demonstrated use for a single application or sensor
Use of site for a minimum of three sensors, one of which provides globally-available products

7. CEOS activities since WGCV-42 point toward including other factors in how we address Landnet
Original Landnet sites are now not useful for the community
Users want sites with more widely available data collected on more regular schedules
Sites with multiple applications preferred by satellite sensor teams
Push for interoperable and analysis ready data sets is increasing the importance of test sites
Numbers of sites and uses continues to expand and maintaining a comprehensive and current list may not be feasible at WGCV level
Concept of a test site is changing
Not necessarily a well defined geographic location
May not be in the same location over time
Cross-calibration techniques are defining sites based on joint acquisitions

8. Propose a WGCV Test Site list
Supersite discussion between LPV and IVOS after WGCV-43 shows that there are common features to test sites allowing a single site collecting many of the sites
Create a website entry point at WGCV level that lists several key WGCV test sites
General purpose description of how site is used, its location, and links to more detail
Sites would be representative of types and purposes for cal/val
Content would be aimed towards data product users, project managers, satellite conops teams
Links would point cal/val experts to information more suitable to their interests
Crude example shown on following page

9. Established traceability chain Online calibration data access
WGCV test sites are used for activities ranging from sensor calibration to data product validation. The table below lists a range of representative sites currently in use that meet key features of WGCV test sties:
Established traceability chain
Online calibration data access
Compliance with calibration standards
Each of WGCV’s subgroups maintains a list of sites meeting the above and specific to each group’s activities. Detailed descriptions of the sites, measurements at the sites, and access to data archives can be found at the links in the table.
Test site label
Center coordin ate
Key site propertties
Primary purpose
Secondary purposes
More detailed description
Railroad Valley
38.5 N W
High reflectance bare soil surface at high elevation, low aerosol loading
Radiometric calibration
Surface reflectance validation

10. Raises multiple questions
Does WGCV push the responsibility of maintaining a website list of test sites to the subgroups?
Would hierarchy of a WGCV website be test site centric or application centric? Table listed by test site names or by usage?
Does WGCV wish to continue Landnet or reboot/restart the concept within a broader WGCV test site concept?
Path forward should lead to a revised test site list by WGCV-45 regardless of what path we choose
Is there a clear next step to continue moving this effort forward?
Responsible party?
Priority of test site list versus other WGCV/subgroup web updates