1. GCOS Reference Upper-Air Network Status Report Dian Seidel SPARC Temperature Trends Panel Meeting 19-21 July 2006 Abingdon

2. GCOS Implementation Plan (Oct. 2004) Adopted by UNFCCC Action A15 (AF10) Action: Complete implementation of GUAN, including infrastructure and data management. Who: National Meteorological Services operating GUAN stations in cooperation with GCOS Secretariat and WMO CBS. Time-Frame: Complete 2006. Performance Indicator: Percentage of data archived in WDC Asheville. Action A16 (AF14) Action: Specify and implement a Reference Network of high-altitude, high- quality radiosondes, including operational requirements and data management, archiving and analysis. Who: Parties’ National Meteorological Services and research agencies, in cooperation with AOPC and WMO CBS. Time-Frame: Specification and plan by 2005. Implementation completed by 2009. Performance Indicator: Plan published. Data management system in place. Network functioning. Data availability.

3. “Workshop to Define Climate Requirements for Upper-Air Observations” Boulder, 8-11 Feb. 2005 Briefed at March 2005 panel meeting Participants – mainly climate scientists Developed accuracy, precision, resolution, coverage, and long-term stability requirements for 27 variables (state, wind, trace gas, aerosol, radiation, cloud) Temperature identified as “Priority 1” variable; GCOS Essential Climate Variable, with requirements from surface to stratopause Developed “Cascade of Networks” concept www.oco.noaa.gov/docs/ua_workshopreport_v7.pdf

4. “Workshop on Reference Upper Air Observations for the Global Climate Observing System: Potential Technologies and Networks" Seattle 22-24 May 2006 Participants – mainly instrument and observing network scientists and managers Developed consensus on GRUAN concept and next steps Info at www.oco.noaa.gov/workshop2/

5. Key Climate Science Drivers for GRUAN Monitoring and detecting climate variability and change Understanding the vertical profile of temperature trends Understanding the climatology and variability of water vapor, particularly in the upper-troposphere and lower stratosphere Understanding and monitoring tropopause characteristics Understanding and monitoring the vertical profile of ozone, aerosols and other constituents Prediction of climate variations Reliable reanalyses of climate change Understanding climate mechanisms and improving climate models

6. Cascade of Upper-Air Observations Benchmark Network ~10 stations GCOS Reference Upper Air Network (GRUAN) 30-40 stations GCOS Upper Air Network (GUAN) 161 stations Comprehensive observing network All stations, observing systems, reanalyses etc. Spatial density Climate driven

7. Variable TemperatureWater VaporPressure Priority (1-4)111 Measurement Range 170-350 K0.1 ppm to 55 g/kg1 to 1100 hPa Vertical Range 0 km to stratopause0 to ~30 km0 km to stratopause Vertical Resolution 0.1 km (surface to ~30 km) 0.5 km (above ~30 km) 0.05 km (surface to 5 km) 0.1 km (5 to ~30 km) 0.1 hPa Precision0.2 K0.1 g/kg in lower troposphere 0.001 g/kg in upper troposphere 0.1 ppm stratosphere 0.1 hPa Accuracy0.1 K in troposphere 0.2 K in stratosphere 0.5 g/kg in lower troposphere 0.005 g/kg in upper troposphere 0.1 ppm stratosphere 0.1 hPa Long-Term Stability 0.05 K 11 1%0.1 hPa Comments 1 The signal over the satellite era is order 0.1-0.2K/decade (Section 2.1.1) so long-term stability needs to be order of magnitude smaller to avoid ambiguity. 1 Stability is given in percent, but note that accuracy and precision vary by orders of magnitude with height. Requirements for Meteorological State Variables

8. GCOS Reference Upper-Air Network GCOS → long-term global climate monitoring is a prime motivation. Not necessarily current GUAN stations. Would serves as a reference or anchor for observations from comprehensive network, including satellites. Would not provide global, spatially-representative coverage. Complementary to emerging GPS-RO observations that may serve as benchmark observations A world-wide network; broad international participation, following GRUAN criteria

9. Overarching Principles Adherence to GCOS Monitoring Principles –Employ high-quality, proven instrumentation (not a testbed) –Changes are minimized and managed –Metadata as important as data Oversight by dedicated GCOS scientific personnel –Real-time, proactive monitoring of the health of the network –Instrument mentor/project scientist (as in ARM) –Site manager/technician for site –Real-time and retrospective research component –Peer-reviewed publication of plans, activities, results Site coordination/collocation with other networks Close coordination with satellite community Establish, as far as possible, traceability to SI units Data management, archive, and analysis component (details later) Data freely and rapidly available

10. Strawman Station Selection Criteria Variety of climatic regimes, surface types (latitude, land/sea) Connection with involved scientific institute Mix of low and high altitude sites Start with a few stations, chosen based on existing observing program and readiness First group could include: (GUAN, BSRN) –ARM Sites (Trop. W. Pacific, S. Great Plains, N. Slope Alaska) –Lindenberg –Camborne –Payerne 3 –Boulder, Sodankyla, Costa Rica, Lauder (O 3 & water vapor continuity) Possible workshop to assess best procedures and configurations Next focus on sites with existing upper-air capabilities as candidates

11. Strawman Instrumentation Minimal Site (priority 1 variables) –Standard surface variables (wind, p, T, U) –Redundant/simultaneous balloon-borne observations of T, WV with different measurement techniques Ensuring continuity, and ability to make radiation corrections, of T data Ensuring dynamic range of WV data –Both pressure and GPS/radar height for redundancy –Ground-based GPS receiver Better Site (for closure of radiative calculations, priorities 1 and 2) –Surface radiation variables via BSRN –Microwave radiometer –IR radiometer (cloud obs, radiance computation check) Ideal Site – meets all stated requirements

12. Current Efforts Meeting report to be completed by end of summer and published as GCOS report GCOS/WCRP Atmospheric Observation Panel for Climate (AOPC) Working Group on Atmospheric Reference Observations (WG-ARO) –Chair, Adrian Simmons. Members, to be appointed soon –Draft Terms of Reference include: To work with relevant agencies and programmes to define and promote a global network for long-term atmospheric multi-variable reference observations that makes optimal use of existing and planned infrastructure To define a data management and dissemination structure to maximise the use of resulting data, and to promote their use in future climate monitoring activities To liaise with CGMS, the WMO Space Programme, CBS and CIMO on satellite and radiosonde calibration and validation issues, including reference instrumentation and metadata, especially through the Global Space-based Inter-Calibration System initiative Move this issue forward within GCOS and GEOSS Identify data center (possibly NCDC) Liaise with satellite community GRUAN discussions at CIMO (12/06) and CBS (11/06), WOAP (8/06), CGMS/COSPAR (11/06) meetings Reference radiosonde: NOAA FY2009 budget looks promising for initial activities

13. Opportunities for SPARC Input Make recommendations on temperature requirements, siting, observation protocols, instrumentation. Advocate for GRUAN within WCRP and GCOS. Support GCOS efforts. Help coordinate with stratospheric science community, NDACC, GAW, IGAC, …