WIGOS Pilot Project on
GRUAN Observing Practices and Governance
ITEM: 2.2


(Submitted by Dr John Nash on behalf of CIMO)



This document provides a proposed revision of the GRUAN Manual that aligns the document with CBS and CIMO’s vision for GRUAN, takes into account a WMO desire for the introduction of an operational component to GRUAN, and shapes the document overall for easier adaptation of parts of it for use as input to WMO’s WIGOS Manual and Guide.
The meeting is requested to consider this input as a CIMO contribution to revision of the GRUAN Manual.



Purpose of this Manual

This The GCOS Reference Upper Air Network (GRUAN) manual is designeddescribes standardized to ensure adequate uniformity in operating protocols, standardization in data reduction, meta-data collection, and data dissemination which shall be employed among participating sites and the GRUAN Lead Centre as it supportsin order for the goals of GRUAN to be achieved. These goals are agreed between and the mission of GCOS and WMO.. The primary goals of GRUANare to provide vertical profiles of reference measurements suitable for reliably detecting changes in global and regional climate on decadal time scales, initially for temperature and water vapour, with the aim of expanding to other essential climate variables in liaison with other existing scientific networks such as in Global Atmosphere Watch.The measurements will provide a calibrated reference standard for global satellite-based measurements of atmospheric essential climate variables, will be a reference standard for the measurements of the existing GCOS Upper Air network.fully characterize the properties of the atmospheric column, and ensure that potential gaps in satellite measurement programmes do not invalidate the long-term climate record.

The GRUAN manual establishes mandatory practices and operating protocols (distinguished by use of the words ‘must’ or ‘shall’) having the status of requirements in a technical resolution, which it is necessary that sites within GRUAN follow or implement. It defines the requirements for GRUAN site operations, including requirements on uncertainty and long-term stability. The manual also establishes recommended practices, procedures and specifications (distinguished by use of the words ‘should’ or ‘could’) which participating sites are urged to comply with, but which are not mandatory. In this way the manual establishes the operational philosophy under which GRUAN shall operate and informscurrent and future GRUAN sites of the expectedmodus operandifor GRUAN.

While it is not planned that this document becomes part of the WMO Technical Regulations, which would require its approval by the WMO Congress, its description as a ‘manual’ is consistent with the WMO nomenclature i.e. it is a document that provides higher level directives and indicates where underlying ‘guides’ provide more detailed and specific information.Relevant information from this manual will be incorporated inthe WMO Manual on the Gobal Observing System(WMO-No. 544) and the Guide on the Global Observing System(WMO-No.488). GRUAN Observing systems and operating practices will be referred to in the WMO Guide to Instruments and Methods of Observation (WMO-No.8) and this document will be linked to the relevant scientific documentation for the specialised scientific sounding systems. A GRUAN station may be a scientific observing site outside of the WMO operational Global Observing System, but the long term observational procedures shall follow the guidelines laid down in this GRUAN manual whether it is a purely scientific site or whether it is already part of the Global Observing System, and the WMO Manuals shall reference these practices. Therefore, rather than providing detailed specifications for various systems within GRUAN, t

The manualprovides defines higher level the principlesthat are intended to direct the development of the methods, techniques and processes needed to achieve the stated goals of GRUAN. The initial essential climate variables to addressed in detail have been temperature and water vapour, and the scope of GRUAN will be extended as resources permit to cover a wider range of essential climate variables in liaison with existing scientific networks.. In essence, the manual specifies what climate variables are to be observed and how those observations are to be made in order to meet the relevant observational requirements of the various end-user communities of GRUAN data products. Where possible, the document does providemore in-depth detail on specific methodologies , and these shall be appropriate for incorporation into or reference by existing WMO literature such as the WMOGuide to Meteorological Instrumentsand Methods of Observation.

Table of Contents

Purpose of this Manual

Table of Contents

Executive Summary


1.1.GRUAN heritage

1.2.The purpose of GRUAN

1.3.Organisation and design of GRUAN

1.4.Implementation of GRUAN

1.5.Links to partner networks

1.6.Link to satellite-based measurement programmes



2.2.The concept of a reference measurement

2.3.Managing Change


3.1Estimating measurement uncertainty

3.2Reporting measurement uncertainty

3.3Reducing measurement uncertainty

3.4Reducing operational uncertainty

3.5Validating measurement uncertainty


4.1Justification and context for Essential Climate Variables

4.2Priority 1 ECVs

4.3Moving beyond priority 1 variables



5.2Mandatory Operating Protocols

5.3Criteria for Assessing Added Value

5.4The Assessment and Certification Process

5.5Site Auditing


6.1Instrument selection

6.2Measurement redundancy

6.3Surface measurements

6.4Upper-air measurements

6.5Instrument co-location

6.6Calibration, validation and maintenance


7.1Guiding principles

7.2Measurement scheduling

7.3Operation and maintenance, quality standards


8.1Overview of GRUAN data flow

8.2GRUAN data policy

8.3Collation of meta-data

8.4Data format

8.5Data submission

8.6Data dissemination

8.7Data archiving

8.8Quality control at the instrument/site level




Appendix A – Expanded details on additional GRUAN Essential Climate Variables


Executive Summary

The executive summary as it currently stands is excessively long. It will be condensed in subsequent versions of the manual.

The development and current operation of the GRUAN network is described by a number of distinct but often overlapping documents, including GCOS-112, GCOS-121, GCOS-134, GCOS-140, web-based material, reports from GRUAN task teams and papers published in the international peer reviewed literature. The purpose of this manual is not to supersede that documentation. It is also not the purpose of this manual to provide authoritative, comprehensive information in GRUAN – that will continue to be provided through the GRUAN body of literature as a whole. Rather, tThe purpose of this manual is to provide a vehicle for communicatingcomprehensive documentation of information and documenting messages important essential to the ongoing operation of GRUAN but which may not find a natural home elsewhere in the GRUAN body of documentation..Therefore, this document is neither complete nor comprehensive in its coverage of GRUAN. The high level messages emerging from this GRUAN manual are summarized in this executive summary.

  1. The purpose of GRUAN

The purpose of GRUAN shall be to:

1.1.i)Provide vertical profiles of reference measurements of temperature and water vapour suitable for reliably detecting changes in global and regional climate, on multi-decadal time scales,for all climatically distinct regions of the globe, acting as a reference to the stability of the observations provided by the operational GCOS .Upper Air Network.

ii)Provide a calibrated reference standard for global satellite-based measurements of atmospheric essential climate variables., starting with temperature and water vapour.

i)iii)Measure sufficient additional atmospheric and surface variables, necessary to allow satisfactory simulation of the radiances observed by satellite sounding systems, at as many stations as possible..

ii)Fully characterize the properties of the atmospheric column.

1.2.iv)Ensure that any interruptions in satellite-based measurement programmes donot invalidate the long-term climate data record..

GRUAN should also provide observations in real-time for incorporation in meteorological analysis, provided this is not detrimental to achieving the primary purposes of the network, as defined above.


iv)In the context of other WMO observing systems, GRUAN shall effectively be the climate reference backbone of the existing global operational upper-air network.2

Organisation and design of GRUAN

2.1The GRUAN reference network will operate under the joint governance of GCOS and WMO.

2.2Working oversight of the network will be performed by the GCOS Working group on Atmospheric Reference Observations, incorporating representatives at working level from WMO.

2.3A GRUAN Lead Centre agreed by GCOS and WMO, will be responsible for integrating best practices into GRUAN operations, managing the network systems, including data management.

2.4GRUAN sites shall use a designated system of methods, techniques and facilities, implemented for making and archiving best quality upper air observations on a global scale. At any site, this system will not be changed without permission from the GRUAN Lead Centre.

2.5GRUAN network operations will incorporate an assurance programme to validate the stability and uncertainty of the measurements, agreed with WG-ARO, and managed in detail, by the GRUAN Lead centre

2.6GRUAN shall also be responsive to the latest technological and scientific progress in measurement techniques and observational climate requirements. Development work can continue at a site until mature and validated, when it could be introduced into GRUAN operations with the agreement of the GRUAN Lead centre.

i)GRUAN shall be organized as part of GCOS, and advised by the WMO Commission for Basic Systems and the WMO Commission for Instruments and Methods of Observation.

GRUAN shall be constituted as a coordinated system of methods, techniques and facilities, implemented at GRUAN sites, for making upper air observations on a global scale.

GRUAN shall be designed as a flexible and developing network capable of continuous improvement, responsive to the latest technological and scientific progress in measurement techniques, and in accordance with changing requirements for observational data.

iv)Sites comprising GRUAN shall be guided directly by a GRUAN Lead Centre designated by WMO.

v)The Lead Centre shall be responsible for implementing GRUAN operational protocols at network sites, for managing various systems that apply to GRUAN as a whole, and for collecting and integrating best practices across the network.

3.Implementation of GRUAN

GRUAN task teams shall contribute to the governance and operation of GRUAN. 3.1 The implementation of GRUAN shall be guided by the Working Group on Atmospheric Reference observations (WG-ARO)


Specific issues in support of network design and other decisions shall be performed by GRUAN task teams shall support theas agreed by WG-ARO . and the Lead Centre in implementing GRUAN by considering specific issues in support of decision making, andThese will entrain ing operational and other relevant expertise in support of GRUAN.

3.3 A GRUAN Analysis Team for Network Design and Operations Research (GATNDOR) shall undertake focused, short-term research to address specific topics identified by the the WG-ARO. The work will be conducted in coordination with other relevant GRUAN task teams.

3.4The WG-ARO shall agree on the appropriate method of establishing standard operational procedures for observing systems within GRUAN. This could be a new task team, an instrument mentor, or an existing instrument team within other associated WMO projects/ operational groups.

As new measurement systems become operational within GRUAN, the WG-ARO shall give consideration to the establishment of a task team/instrument mentor to facilitate the implementation of standard operating procedures for the new system across the whol network.

x)3.5 The GRUAN Lead Centre shall identify sites where instrument operators need training, and organise cost-efficient training courses for the network at appropriate locations, as advised by the appropriate task team/instrument mentor,, together with other GRUAN sites where the required expertise is available, shall act as centres of excellence for certain instruments and shall conduct targeted training programmes for instrument operators across the network to encourage uniformity of instrument operation between sites.

A GRUAN Analysis Team for Network Design and Operations Research (GATNDOR) shall undertake focused, short-term research to address specific topics identified by the GRUAN science, the WG-ARO, and the Lead Centre.

GATNDOR activities shall be coordinated with the GRUAN task teams and with national GCOS programmes when appropriate.

xiii)3.6All activities associated with the implementation of GRUAN shall be the responsibility of the countries hosting GRUAN sites and should, as far as possible, be met through national funding.

  1. Partner networks
  2. GRUAN shall not operate in isolation of existing networks but shall collaborate and liaise with existing networks to leverage skills and expertise available from those networks, avoid undue duplication of effort, and ensure that GRUAN data products are tailored to best meet the needs of partner networks.

4.2The WG-ARO shall establish work in close coordination between GRUAN andwith the governing bodies of partner networks, with respect to the development of GRUAN operations.. the GRUAN sites where GRUAN operations coincide with other network operations. Specifically,the WG-ARO shall then identify WG members as liaisonsmethods of improving liaison with partner networks to ensure close communication between GRUAN and those networks. , particularly at expert team level.

4.3In addition contact with expert teams from existing networks shall be made by WG-ARO, GRUAN task teams, and GATNDOR to support GRUAN operations.

Where possible, GRUAN shall identify, adopt, and extend if necessary, tools and methodologies that have been developed in existing networks that can serve the needs of GRUAN. In particular, data QA/QC procedures developed in existing networks shall, where suitable, be adopted in GRUAN. Where networks are working towards QA/QC procedures, GRUAN should partner with these networks to develop systems that meet the operational requirements of both parties. Where GRUAN develops QA/QC techniques that are superior to those used elsewhere, those techniques shall be shared with partner networks.

iv)4.4The GRUAN Lead Centre shall facilitate identify methods of access to measurement database from partner networks to enable cross-calibration with GRUAN measurements and to quantitatively link GRUAN measurements to similar measurements made within partner networks.

v)4.5The WG-ARO shall establish close connections to the satellite communityrelevant satellite technical programmes, such as GSICS.. Because GRUAN measurements are likely to serve a wide range of end-users within the satellite measurement community, WG-ARO members shall be assigned to liaise with key clients within the satellite communityto ensure that GRUAN data products are tailored, where possible, to best meet the needs of this community.

vi)4.6GRUAN shall be operated in such a way that homogeneity of measurements across the network will ensure that any significant site specific differences between GRUAN data and those from satellite-based instruments result from spatial biases in those systems andare not in from the GRUAN data products.

vii)4.7GRUAN shall provide a reference-standard that will serve as a common baseline for splicing satellite-based measurement time series to create CDRs.

viii)4.8GRUAN shall collaborate with the WMO SCOPE-CM programme to generate CDRs of upper air ECVs and in this way contribute to Action C10 defined in the GCOS implementation plan (GCOS-92) viz. 'Ensure continuity and over-lap of key satellite sensors ...undertaking reprocessing of all data relevant to climate for inclusion in integrated climate analyses and reanalyses'.

4.9The WG-ARO shall establish maintain active links to with the following partner networks:


4.8.2GAW (Global Atmospheric Watch

4.8.3NDACC (Network for the Detection of Atmospheric Composition Change)

4.8.4 SHADOZ (Southern Hemisphere Additional Ozonesondes)

4.8.5 ARM (Atmospheric Radiation Measurement) Programme

4.8.6 BSRN (Baseline Station Radiation Network)

3.ix. (AErosol RObotic NETwork)

BSRN (Baseline Station Radiation Network)

GAW (Global Atmospheric Watch)

SHADOZ (Southern Hemisphere Additional Ozonesondes)

AERONET (AErosol RObotic NETwork)

3.ix.6.ARM (Atmospheric Radiation Measurement) Programme

NMS (National Meteorological Services)

Reanalyses Centres

4.5Reference measurements and managing change

i)5.8All GRUAN measurements systems shall make reference quality measurements, i.e that, at a minimum, the observations are tied to an internationally accepted traceable standard, that the uncertainty on the measurement (including corrections) has been determined, and that the entire measurement procedure and set of processing algorithms are properly documented and accessible.

ii)5.9For GRUAN measurement systems making vertically resolved measurements, measurement uncertainties shall also be vertically resolved such that each measurement in a profile shall be treated as a single measurement result requiring both the measurement and its uncertainty.

iii)5.10The methods bywhich the measurements are obtained and the data productsderivedshall be reproducible at any timein the futuredocumented for future reference..Meta-data shall be archived that describe how the measurements weremade, which corrections were applied, what changes occurred during the observation and post-observationperiods to the instruments and the data reduction algorithms.

iv)5.11GRUAN shall operate in a way such that changes in instrumentation, changes in operating procedures, changes in data processing algorithms and changes in operators do not introduce unidentified temporal or spatial discontinuities or biases into GRUAN data products.

v)5.12When changing instrument types, operating procedures, or data processing algorithms, GRUAN shall develop the necessary proceduresthe old and new measurement systems shall be operated simultaneously for a sufficient period of time to fully characterize any systematic biases between the old and new measurement systems so that corrections can be made to the historical data to maintain a long-term homogeneous measurement series. The length of overlapprocedures used shall be informed by robust scientific investigations including a detailed understanding of the error limitations of the instrumentation in use..