1. GLOBAL CLIMATE OBSERVING SYSTEM- REQUIREMENTS AND REALITIES OF PROVIDING OVERLAPPING RADIOSONDE FLIGHT SERIES DATA FOR LONG TERM CLIMATE CONTINUITY Carl A. Bower, Jr. NOAA National Weather Service TECO 2006 World Meteorological Organization Geneva, Switzerland Carl A. Bower, Jr. NOAA National Weather Service TECO 2006 World Meteorological Organization Geneva, Switzerland

2. GCOS Upper-air Network Composition and Issues 163 GUAN sites in WMO Regions 6 Radiosonde Manufacturers 67 Countries make up GUAN 40% of GUAN network launches one or fewer radiosondes per day Recommended overlapping flight series is costly On-going changes in the GUAN –Radiosonde changes –Algorithm changes –Provider changes

3. Radiosonde Vendors GUAN Sites by WMO Region

4. GCOS Continuity Recommendations Maintain historical data series for long-term climate trends analysis GUAN sites to use one radiosonde type for as long as feasible Overlapping flight series of the old radiosonde and the new radiosonde if change is required –At selected representative sites –One-year overlap Comparison data used to formulate bias transfer functions for application to new data Maintain historical data series for long-term climate trends analysis GUAN sites to use one radiosonde type for as long as feasible Overlapping flight series of the old radiosonde and the new radiosonde if change is required –At selected representative sites –One-year overlap Comparison data used to formulate bias transfer functions for application to new data

5. NWS Policy on Data Continuity NWS recognizes importance of long-term climate records stability NWS policy is to: –To conduct intercomparison studies as new instruments are introduced to the network –To determine transfer functions between old and new sensors –To determine differences at representative locations Differences related to sensor change Differences related to spatial separation Implementation not started—GUAN sites not impacted NWS recognizes importance of long-term climate records stability NWS policy is to: –To conduct intercomparison studies as new instruments are introduced to the network –To determine transfer functions between old and new sensors –To determine differences at representative locations Differences related to sensor change Differences related to spatial separation Implementation not started—GUAN sites not impacted

6. The Realities of Providing Overlapping Flight Series Data for NWS GUAN Sites 17 National Weather Service GUAN sites Sites cover –Equatorial tropics –Mid latitudes –Arctic US climate community designated all NWS GUAN as continuity sites NWS replacing all sites with GPS-based systems All sites continuity is not affordable nor necessary 17 National Weather Service GUAN sites Sites cover –Equatorial tropics –Mid latitudes –Arctic US climate community designated all NWS GUAN as continuity sites NWS replacing all sites with GPS-based systems All sites continuity is not affordable nor necessary

7. Selecting Representative GUAN Sites for Continuity Flights Weatherhead determined temperature trends per decade from 40-year period of record Nine stations selected from 3 different regions in United States Means and standard deviations by pressure level are different between stations within a region Trends appear to be regional but are remarkably similar within a region Weatherhead determined temperature trends per decade from 40-year period of record Nine stations selected from 3 different regions in United States Means and standard deviations by pressure level are different between stations within a region Trends appear to be regional but are remarkably similar within a region

8. Major North American Air Mass types Weatherhead’s upper air data trend similarity analysis was impetus to down select climate continuity from 17 sites Results were consistent with air-mass source regions NWS network impacted by 6 major air mass regions No more than 5 to 8 sites for test Weatherhead’s upper air data trend similarity analysis was impetus to down select climate continuity from 17 sites Results were consistent with air-mass source regions NWS network impacted by 6 major air mass regions No more than 5 to 8 sites for test

9. NWS GUAN Sites with Air Mass Areas defining overarching characteristics Petersen grouped NWS GUAN sites into climate regions. Seven regions identified for GUAN locations Regions include tropical, maritime polar, Artic and continental polar stations One representative site selected for each region Petersen grouped NWS GUAN sites into climate regions. Seven regions identified for GUAN locations Regions include tropical, maritime polar, Artic and continental polar stations One representative site selected for each region

10. Radiosonde Functional Comparison Flights Up to one year of radiosonde comparison flights –Minimum 200 flights for four season sites –Minimum of 100 flights for two season sites –Day and night flights Change of radiosonde types, sensor suites or transfer equations Representative locations selected based on climate regions Determine bias transfer functions Up to one year of radiosonde comparison flights –Minimum 200 flights for four season sites –Minimum of 100 flights for two season sites –Day and night flights Change of radiosonde types, sensor suites or transfer equations Representative locations selected based on climate regions Determine bias transfer functions

11. The Realities of Providing Overlapping Flight Series Data for International GUAN Sites Nash recognized the difficulty for International sites to conduct overlapping continuity flight series –67 countries –Numerous radiosonde types –Rapid evolution of new radiosondes and replacement of old radiosondes –Lack of overlapping flights for new Vaisala sondes, Modem sondes, Sippican sondes etc Proposed to Expert Team that RICs could possibly perform series Proposed funding be procured and ground systems be placed at RICs Nash recognized the difficulty for International sites to conduct overlapping continuity flight series –67 countries –Numerous radiosonde types –Rapid evolution of new radiosondes and replacement of old radiosondes –Lack of overlapping flights for new Vaisala sondes, Modem sondes, Sippican sondes etc Proposed to Expert Team that RICs could possibly perform series Proposed funding be procured and ground systems be placed at RICs

12. World Meteorological Organization Regional Instrumentation Centers RegionLocation 1 AfricaOran, Algeria Cairo, Egypt Nairobi, Kenya Gaborone, Botswana 2 AsiaBeijing, China Tsukuba, Japan 3 South AmericaMeteorological Laboratory and Workshop of the National Meteorological Service of Argentina 4 North and Central America Mt Washington, New Hampshire The Caribbean Meteorological Institute of Barbados RMTC, San Jose, Costa Rica 5 Southwest Pacific Melbourne, Australia (Regional Radiation Center) 6 EuropeService des equipments et des techniques instrumentals de la meteorology, Trappes, France

13. RIC Site Expansion Required Some global areas not represented by RICs Region VI lacks RIC Arctic representation required Most GUAN sites are or will be flying new radiosondes without having overlapping studies at representative locations Some global areas not represented by RICs Region VI lacks RIC Arctic representation required Most GUAN sites are or will be flying new radiosondes without having overlapping studies at representative locations

14. Radiosonde Vendors GUAN Sites by WMO Region

15. Conclusions 1-year overlapping flight series is hard to satisfy: –Continuous changes in technology impact long term continuity –Fewer sites still large task with 6 different radiosonde providers Many countries/Regions cannot afford cost of continuity RICs may have potential if funded by climate programs –Issues with representative spatial measurements –More and different sites required –Require redundant ground stations for overlapping flight series No known flight series performed: – RS80/RS92 –Vaisala/Modem –Individual country modernization 1-year overlapping flight series is hard to satisfy: –Continuous changes in technology impact long term continuity –Fewer sites still large task with 6 different radiosonde providers Many countries/Regions cannot afford cost of continuity RICs may have potential if funded by climate programs –Issues with representative spatial measurements –More and different sites required –Require redundant ground stations for overlapping flight series No known flight series performed: – RS80/RS92 –Vaisala/Modem –Individual country modernization