Xiangqian Wu and Mitch GoldbergNOAA/NESDIS Center for Satellite Applications and Research (STAR)

P1.16 GLOBAL SPACE-BASED INTER-CALIBRATION SYSTEM (GSICS)

Introduction

The Global Space-based Inter-Calibration System (GSICS) is a WMO-sponsored collaboration among national and international agencies that manage operational environmental satellites (CMA, CNES, EUMETSAT, JMA, KMA, NESDIS, and WMO), with support from universities (UW/SSEC) and other organizations (NASA, NIST). GSICS has been primarily motivated by the increasingly demanding users, due to both the sophistication of the traditional applications such as numerical weather prediction (NWP) and the expansion to the new applications such as climate monitoring. GSICS is also motivated by the rapidly growing global observing system in terms of the number and diversity of the sensors. The goal of the GSICS is to enhance satellite instrument calibration and satellite data validation. These are critical components of the Global Earth Observation System of Systems (GEOSS).

Review

Calibration (CEOS Definition)The process of quantitatively defining the system responses to known, controlled signal inputs

Space-based Inter-CalibrationThe quantitative analysis of responses by multiple space-borne instruments to common signal inputs

Spatially co-located, Temporally concurrent, Geometrically aligned, Spectrally matched

GSICS is led by its Executive Panel, with advisory support from GSICS Research Working Group (GRWG) and GSICS Data Working Group (GDWG). Most work is routinely performed at GSICS Processing and Research Centers (GPRC) at each member site, in collaboration with national space or standard agency and universities (Calibration Support Segment, CSS). These activities are coordinated through GSICS Coordination Center (GCC).

ReviewExisting

Area or nadir or both

GSICSPixel anywhereSave all and down select later

WhyIs mean bias all we care?

Implementation

Common AlgorithmStart with a reasonable version that

can be used as referenceImprove over time and by consensus

In each cycle, developer offersAlgorithm (logics, threshold)Pseudo code (detailed spec)Actual codeDataResults

NESDIS is developing Version 1 with GRWG-I recommendations

MemberExecutive

PanelResearch WG Data WG

CMA N. Lu P. Zhang Z. Rong

CNES D. Renaut P. Henry

EUMETSAT J. Schmetz M. König V. Gätner*

JMA T. Kurino Y. Tahara T. Matsumoto

KMA M. Ou S. Chung

NOAA M. Goldberg* X. Wu* B. Barkstrom

WMOJ. Lafeuille (Secretary)

Two types of orbitLow Earth Orbiting (LEO) and Geostationary (GEO)

R. Iacovazzi

J. Lafeuille

Cao

Tobin et al

Schmetz et al

GRWG-I, 22-23 JAN 2007, NESDIS

Identified GEO-GEO inter-calibration as near term priority, even though it’s long been widely used

Issues:Different instruments on different orbitsAttribute radiance differences to calibration uncertaintyCo-locations not uniquely determined by orbit intersection

Opportunity:Hyperspectral instruments (AIRS & IASI)

StrategyFocused on AIRS vs. GEO imagerReviewed existing algorithmsOutlined the strategy for GSICS algorithm

Four components of GSICSGEO-GEO, LEO-LEO, Sensors on common platform, GEO-LEO

GRWG-II and GDWG-I, 12-14 JUN 2007, EUMETSAT

Gunshor et al König et al

Tahara

Doelling et al

SummaryGSICS is a WMO-sponsored international collaboration. It is motivated by both user requirements and new challenges and opportunities of technology. Its goal is to enhance satellite instrument calibration and satellite data validation, which are critical components of the GEOSS.

The GSICS has four major components. The LEO-LEO inter-calibration based on Simultaneous Nadir Overpass (SNO) is mature. The GEO-GEO and common platform inter-calibration promise many opportunities and challenges in future. The GEO-LEO inter-calibration is the near term priority of GSICS.

After reviewing the existing algorithms and the GSICS requirements, the GSICS GEO-LEO algorithm strategy and implementation were outlined in GRWG-I and revised in GRWG-II. The Executive Panel has been providing timely guidance, and the GDWG made valuable contributions at its first meeting. The preliminary results from a prototype algorithm confirm that the strategy is feasible and the results will be valuable.

Reviewed the progress since GRWG-IWeb site & NewsletterTest data, algorithm, code, and results

Revised Data distribution

NESDIS distribute subsets of data for individual GEOEUMETSAT distribute similar IASI data

Some thresholds values

Data managementContent, format, file name of archive

Reviewed existing algorithms for GEO-LEO inter-calibration of solar bands

R. Iacovazzi