Major network expansion


7 sites have officially announced their intention to join GRUAN. We are very pleased to welcome the following candidate sites:

● Moscow (Russia)
● Singapore
● Darwin, Alice Springs, Melbourne, and Macquarie Island (Australia)
● Davis (Antarctica; operated by BOM, Australia)

For the current status of the network please have a look on our webpage.

The fourth certificated GRUAN site: Lauder, NZ


The NIWA-operated Atmospheric Research Laboratory in Lauder, NZ as the fourth certificated GRUAN site was dignified by Newspaper, Radio and TV.

Pre-launch procedures for RS92 soundings


Attached is a document describing the requirements for GRUAN station regarding the pre-launch procedures for routine soundings with Vaisala RS92 radiosondes.  In order to obtain high data quality, ensure long term stability,  and to make sure that measurement uncertainties are within the ranges that are reported in the product files, it is important that some ground checks are made before launch in the way described in this document and that the meta-data are reported to the GRUAN lead centre.

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Inventory of GRUAN Sites – First Version


On our GRUAN homepage a first version of a site inventory (description) is available now. It is very much appreciated if all GRUAN site managers could examine their site page(s) and advice me (per comment or email) of bugs or gaps which have slipped in.

Very welcome are any feedbacks about structure, layout and/or information content of the site pages. And of course you can write a comment with your opinion and wishes.

FAQ-07: Do all GRUAN stations need to have identical instrumentation?


No. GRUAN stations will have a variety of instrumentation and observational platforms. The GRUAN challenge will be to homogenize the observations of this diverse set of instruments to establish a consistent data set that can be used for climate research, satellite validation and the characterization of the atmospheric column. However, to achieve homogeneity of observations between different stations identical treatment of observations is a must. This means that observational data have to be analysed to the same detailed level and that uncertainty estimations have to be done consistently across all stations. To verify that observations and uncertainty estimates at different sites using different instrumentation leads to consistent results frequent intercomparisons of these instruments are required. This may be achieved either in dedicated intercomparison campaigns at dedicated sites or routine intercomparisons as part of the observational program.

FAQ-13: What are the implications if a station does not launch twice daily sondes as “desired” in the GRUAN requirements, but, 00/12 UT production sondes are launched at a “near-by” operational site?


Issues related to the non-co-location of different observing systems are currently being studied and depend critically on the horizontal distance as well as the local geography. Another important aspect is whether a non co-located routine sounding site is able to modify or amend current routine observations. Additional ground checks or more extensive meta data collection may be required to satisfy the needs of GRUAN. Thus it is important to understand the level of co-operation or control that a GRUAN site has over a non co-located radiosonde site. The critical question will be, whether it is possible to establish and verify measurement uncertainties for the routine sonde operations and whether it will be possible to compare these results in a quantitative fashion with remote sensing or special sonde operations at the core GRUAN site. If a quantitative connection between two non co-located sites cannot be established, their combined use may be limited.

FAQ-17: What are best practices at a GRUAN site?


Best practices at a GRUAN site aim at obtaining long term climate reference observations and reference observations for validation of other sensors. This requires operational best practices as well as best practices for instruments and data analysis. Establishing measurement uncertainties will be an important element of best practices. This implies that any instrument that is being used needs to be characterized to the best possible extent. For example, ground checks for sounding equipment are highly recommended for each parameter independent from a manufacturers ground check. This will ensure that possible and unexpected instrumental biases may be identified before launch. Instrument preparation needs to be standardized as much as possible to reduce any possible observer influence.

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