GCOS Reference Upper-Air Network Status Report

1. GCOS Reference Upper-Air NetworkStatus 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. Climate driven Spatial density 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. Cascade of Upper-Air Observations

7. 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 • Boulder, Sodankyla, Costa Rica, Lauder (O3 & 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, …