A Summary of The Tenth International TOVS Study Conference (ITSC X)

Boulder, Colorado 27 January - 2 February 1999


The Tenth International TOVS Study Conference - ITSC-X - was held in Boulder, Colorado, USA, from 27 January to 2 February 1999.  One hundred and thirty-four participants attended the Conference and provided scientific contributions.  Twenty-three countries, four international and many national organisations were represented: Australia, Austria, Brazil, Canada, China, the Czech Republic, Finland, France, Germany, Hungary, Italy, Japan, Republic of Korea, Mongolia, Netherlands, New Zealand, Norway, Russia, Spain, Sweden, Taiwan, the United Kingdom, the United States of America, ECMWF, EUMETSAT, WMO, the IRC, NASA and NESDIS.

The agenda for ITSC-X can be found in the ‘Report on the Tenth International TOVS Study Conference, Boulder, Colorado, 27 January - 2 February 1999’. Most of the meeting was occupied with scientific presentations on a range of issues: TOVS and ATOVS data characteristics and processing; the application of TOVS and ATOVS data in numerical weather prediction (NWP) and climate studies; preparations for Advanced Sounders; and relevant plans of operational satellite agencies and international issues.

Section 4 of the Report records the abstracts of all scientific contributions. The corresponding papers are published separately as the Technical Proceedings of The Tenth International TOVS Study Conference, ITSC-X, available through the Co-chairs of the International TOVS Working Group (ITWG).

Working Groups were formed to consider five of the main issues/areas identified prior to the Conference: ATOVS data access, processing and validation; TOVS and ATOVS in numerical weather prediction; TOVS and ATOVS in climate studies; advanced infrared sounders; and international issues and future systems. The Working Groups reviewed recent progress in these areas, made recommendations on key areas of concern and identified items for action. Working Group reviews and recommendations comprise Section 2 of the Report.

During the Conference, a session on Status Reports considered summaries of allied meetings and activities that had taken place since ITSC-IX. It also reviewed progress on the Action Items identified by ITSC-IX Working Groups. Many of these items formed the basis for further discussion by Working Groups at ITSC-X.

Several technical sub-groups met during ITSC-X to discuss developments and plans concerning specific software packages shared and in common use in TOVS and ATOVS processing centres. Brief reports on these sub-group meetings are recorded in Section 3 of the Report.

Overall, the meeting documented significant gains in many areas and noted areas for further activity. In particular, it noted that:

The conclusions and recommendations are summarised below.


As a result of the activities of the Working Groups and their reports to the Conference, the following  major conclusions and recommendations were adopted as a summary of the ITWG meeting at ITSC-X. More details and specific technical recommendations and actions are given in the Sub-Groups' full reports in Section 2 of the Report and the reports of the Technical Sub-Groups in Section 3 of the Report.

ATOVS data access, processing and validation

Issue Recommendation or action Person / group involved in recommendation or action
ATOVS data
Users should be informed of all significant changes to the ATOVS instrument by NESDIS via the ITWG list server E. Brown
AMSU-B A report on the AMSU-B problems should be compiled and distributed via the ITWG list server M. Chalfant
Software solutions to AMSU-B problems to be included in the AAPP P. Dibben and D. Klaes
A check should be performed on the consistency of the AAPP corrected radiances and the NESDIS global 1b dataset P. Dibben and P. Brunel
AVHRR/3 Further test periods with channel 3a 'on' should be considered, to allow a full scientific evaluation of the channel 3a data in the morning orbit NESDIS
Status of ATOVS
processing software
A document should be made available to the ITWG describing the scientific aspects of the NESDIS ATOVS processing A. Reale
Feedback on AAPP problems should be posted on the AAPP web page D. Klaes
A requirements document to be written for visualisation tools for IAPP ITWG members to
submit requirements
Dissemination of
ATOVS related 
In relation to instrument characteristics, a single web page should be provided at NESDIS to provide links to all relevant instrument data for ATOVS (including AMSU antenna patterns) and AVHRR T. Kleespies
Ancillary data files The new collocation dataset at NESDIS, the MDB, should be made available to the ITWG E. Brown
ATOVS case studies When requirements are confirmed and participant commitment affirmed, case study dates and areas should be defined and announced via the ITWG list server ITWG Co-chairs

TOVS/ATOVS data in climate studies

Stratospheric retrievals In support of Pathfinder activities, document the characteristics of current and past IR sounding channels and recommend necessary characteristics for future instruments. Pathfinder Working Group Co-chairs
Pathfinder activities Agencies encouraged to continue low-cost, efficient dissemination of data from future instruments, including METOP, NPOESS and ATOVS NESDIS and EUMETSAT
Continuance of support for Pathfinder activities into the AMSU and HIRS/3 era and beyond, to establish the longest possible data record for climate research
ERA-15 and ERA-40 Radiance monitoring statistics should be retained in electronic form for the VTPR and TOVS radiances R. Saunders and G. Kelly
Reports to be provided on the characteristics of the filters flown on early satellites R. Saunders
Pathfinder and reanalysis activities Advocacy of a program to intercompare existing climate data sets (e.g. Pathfinder Path A, B, P; Spencer & Christy's MSU 2R, MSU 4; NCEP & ECMWF reanalyses) especially from the point of view of global and regional interannual variability and trends ITWG
ATOVS - AMSR Offer to AMSR team of ITWG expertise in calibration and validation of satellite-based sounders such as AMSU, as well as in the selection of additional sounding channels targeted towards climate monitoring Co-chairs
Calibration, validation and continuity Information on radiance bias corrections and forward model tuning should be documented and made available to the community.  Specifically, information is needed on: radiance bias corrections; QC and rejection statistics; use of input data J. Bates, J. Susskind,
N. Scott and R. Saunders
A standard climatological radiosonde data set should be assembled
Radiance biases from reanalysis and Pathfinder projects should be intercompared
Additional work on TOVS calibration should be undertaken to establish consensus and reconcile differences ITWG
Future infrared sounding instruments should observe radiances covering the same spectral bands as HIRS to ensure that its data record will be continued for as long as possible Satellite agencies
General action items Provide input to the Intergovernmental Panel on Climate Change's Third Assessment Report ITWG Co-Chairs/ Working Group Co-chairs

The use of TOVS/ATOVS in data assimilation /numerical weather prediction (DA/NWP)

Evaluation and use of TOVS/ATOVS in DA/NWP Exchange of monitoring results should continue; also, each center to be encouraged to develop their own web page on which to post results. A master document to be developed on the ITWG site linking all web pages C. Chouinard and B. Harris
The so-called 'one observation experiment' should be posted on the web page of each center C. Chouinard & E. Andersson to coordinate
Forward modelling Strong support should be given to further improve the modelling of the radiative transfer problem. Specifically, close attention should be given to: surface emissivity modelling; improved LBL models; improved specification of instrument characteristics; improved fast RTM through larger dependent data bases and gradient comparisons of LBL and fast RTM models ITWG
Future platforms and real-time access to data WMO/NESDIS/EUMETSAT should develop a communication system with sufficient bandwidth to allow real-time data transfers from current and future platforms.  Also, the development of a common format (e.g. BUFR) is strongly encouraged WMO/NESDIS/
NESDIS/EUMETSAT should further develop and publicise procedures for handling real-time data requests for external users NESDIS/
Sufficient resources should be allocated in relation to future satellite programs to ensure proper use of the data at NWP and DA centers NWP and DA centers
A web-based list of information and software available for exchange should be developed; the exchange of expertise should be encouraged through short-term visits NWP and DA centers/ ITWG/ C. Chouniard

Advanced IR sounder Working Group

Importance of GEO satellite
advanced infrared sounders
Encouragement should be given to national space agencies to implement advanced infrared sounding capabilities on future GEO satellites WMO
A detailed study of regional user requirements for advanced infrared sounder data should be undertaken Geostationary satellite
data providers
A program should be established to train regional users on the use of GEO wind and sounder data in nowcasting
Use of new technology
for improving spatial
resolution of soundings>
National space agencies should investigate the use of large focal plane array technology for enhancing the spatial resolution and clear air sampling capabilities of advanced infrared sounders Space Agencies
Cloud scene airborne measurement data sets and analysis methods should be established to provide a common basis for assessing sounder performance
An immediate study of the installation of HIRS/4 aboard NOAA/M should be undertaken, to provide an earlier opportunity to evaluate and benefit from the effects of reduced IFOV size NOAA
New spectral
Investigations should be undertaken into including far infrared wavelengths (15 - 1000 Ám) in future advanced infrared sounders Space agencies
Use of advanced
infrared sounder
data in NWP
Further work be undertaken to establish the best method(s) for extracting information from advanced infrared sounder data for NWP
Additional research should be undertaken to improve the efficiency of ground processing systems in using advanced infrared data for operational soundings
The facility should be created to make global AIRS data available in near-real-time to the international operational weather forecasting community NOAA/ NASA
Fast model
Recommended steps to increase the impact of fast models: establish & quantify potential error sources; review and improve ground calibration procedures; improve use of essential spacecraft information; support programs to define and correct errors in spectral parameters; support efforts to validate rapid algorithm performance; standardise vertical spacing of LBL calculations NOAA/NASA/
Data compression
Detailed study of lossy data compression techniques for advanced infrared sounders should be undertaken. Performance of lossy compressions should be evaluated and largest errors documented and transmitted to users Space agencies
Airborne and
ground truth
validation studies
Airborne measurement campaigns, covering a wide range of climatological and meteorological conditions, should be conducted and should employ well calibrated in situ and ground-based sensors
Radiance assimilation and retrieval assimilation Data producers should provide the NWP community with error covariance matrices of both radiances and retrievals NOAA,
and JMA
Climate applications of
Advanced Infrared
Detailed studies of advanced infrared sounders should be carried out to document and assess the utility of these instruments for providing accurate data products for climate studies Space agencies
Other uses of Advanced
Infrared Sounders in NWP
Detailed study should be undertaken of the performance and assimilation of Advanced Infrared Soundings over land.  In addition, development and distribution of an accurate, high resolution surface characterisation should take place NOAA and EUMETSAT
Other uses of Advanced 
Infrared Sounders in
atmospheric chemisry
Detailed study should be undertaken of the uses of advanced infrared sounders in atmospheric chemistry ITWG

International issues and future systems

satellite coordination
CGMS should consider cooordination of polar-orbiting equator crossing times to optimise satellite utilisation CGMS
sounder deployment
NASA should consider placing the NPP sounder in a PM orbit NASA
Relations with SOAT The USA Integrated Programme Office should be informed that ITWG is ready to participate on the Sounder Operational Algorithm Team when requested ITWG Co-chairs
Frequency protection >CGMS should consider means to provide for well-resourced activities towards the protection of frequency allocations CGMS
Relations with CBS OPAG IOS should consider a mechanism, similar to that between ITWG and CBS WGSAT, for providing guidance and assistance between ITWG and OPAG IOS OPAG IOS
Co-chairs of ITWG should develop an ITWG process to provide guidance and assistance to the OPAG IOS ITWG Co-chairs
with GOSSP
The Chairman of the GOSSP should be informed of ITWG's willingness to provide guidance, assistance and expertise with the expectation that a mechanism, similar to that between WMO and ITWG be developed
Status of the GTS WMO should inform meetings of the ITWG of the latest status and plans for improvements to the GTS WMO/ D. Hinsman
NPOESS Environmental
Data Records
The NPOESS IPO should include radiance products as part of the suite of NPOESS EDRs, as a matter of urgency NPOESS IPO
Direct readout of
NASA should consider support for activities with the ITWG community towards the establishment of direct readout software packages for AIRS (and MODIS) allowing timely use of the data for operations and research NASA
Real-time AIRS
and MODIS data
ITWG encourages provision, by NASA and NESDIS, of near real-time data from AIRS (and MODIS). NASA and NESDIS