1. 1 Some in situ data matters considered by AOPC From the Progress Report: “Developed Countries have improved many of their climate observation capabilities, but national reports suggest little progress in ensuring long-term continuity for several important observing systems. Developing Countries have made only limited progress in filling gaps in their in situ observing networks, with some evidence of decline in some regions, and capacity building support remains small in relation to needs. Both operational and research networks and systems, established principally for other purposes, are increasingly responsive to climate needs including the need for timely data exchange.”

2. 2 From the revised IP: Continued attention to baseline and reference networks Increased emphasis on: –comprehensive surface networks, for data on extremes and impacts/adaptation –urban measurements –high-resolution surface reanalysis for gap-filling –co-located measurements for the atmospheric and terrestrial domains Some specific amended or new actions call for: –transmission of hourly SYNOPs and monthly CLIMATs from full network –more transmission of hourly precip and radar-derived precip products –improved surface radiation measurement and data transmission –provision of BUFR-encoded radiosonde observations –exchange of data from ground-based GPS receivers –network development s for atmospheric composition

3. 3 At its last meeting, AOPC: reviewed as usual the status of observing networks, availability of historic data, and efforts of the Lead Centres and Secretariat; identified a number of matters requiring attention, including: – global exchange of snow-depth data in SYNOP reports – more prompt generation of World Weather Records – inclusion of additional ECV observations in these records – addition of sunshine data to CLIMAT messages – transition to use of BUFR encoding – GTS routeing of CLIMAT messages reviewed the progress of the GRUAN and welcomed: – potential US funding of ARM sites to be part of the network – JMA’s offer of Tateno as a GRUAN station – development of an Implementation Plan – designation of GRUAN as a pilot project of WIGOS welcomed improvements in GPCC gauge-based gridded datasets

4. 4 And since last meeting of AOPC: Large improvement in quality of radiosonde data for India In November 2009, all GUAN Stations in Africa reported for the first time in several years.

5. 5 What is GRUAN? Reference Upper-Air Network for ground based climate observation of the free atmosphere in the frame of GCOS Currently largely an abstract concept - to be implemented within the next years Eventually ~30 - 40 sites across the globe (currently 15) Serving to constrain and calibrate data from more spatially- comprehensive global observing systems (inc. satellites) Providing long-term, high-quality climate records of upper-air variables („GCOS essential variables”) – Upper-air temperature (including MSU radiances) – Water vapour – Wind speed and direction – Cloud properties – Earth radiation budget (including solar irradiance) – Others

6. 6 GRUAN aims to  Provide long-term, high quality upper-air climate records, with complete estimates of measurement accuracy  Fully characterize the properties of the atmospheric column and their changes  Constrain and adjust data from more spatially comprehensive global observing systems (including satellites and current radiosonde networks)  Ensure that potential gaps in satellite programs do not invalidate the long-term climate record  Building on, and augmenting, existing WMO networks, e.g. GUAN Cascade of Networks

7. 7 Key scientific questions to be addressed by the GRUAN Characterization of changes in temperature, humidity, and wind, using current operational radiosonde capabilities Understanding the climatology and variability of water vapour, particularly in the UTLS, as well as changes in the hydrological cycle Understanding and monitoring tropopause characteristics Understanding the vertical profile of temperature trends Bringing closure to the Earth’s radiation budget and balance Understanding climate processes and improving climate models

8. 8 Milestones achieved so far Designation of a GRUAN Lead Centre at the Lindenberg Observatory (Germany) Definition of major requirements for reference observations and what will constitute a formal GRUAN measurement Appointment of initial GRUAN stations Publication of the GRUAN Implementation Plan 2009-2013 (GCOS-134) Annual Implementation- Coordination Meetings Appointment of Task Teams First GRUAN-quality data expected in 2010

9. 9 2 nd Implementation-Coordination Meeting (ICM-2), March 2010 Designation of Task Teams: Team 1: Radiosondes Team 2: GPS-PW Team 3: Measurement schedules and associated site requirements Team 4: Site assessment, expansion and certification Team 5: Ancillary measurements GRUAN Science Team Site Team