Presentation on theme: "Suggestions for upgrading the pilot balloon network in West Africa and elsewhere in the tropics Michael Douglas National Severe Storms Laboratory/NOAA."— Presentation transcript:
Suggestions for upgrading the pilot balloon network in West Africa and elsewhere in the tropics Michael Douglas National Severe Storms Laboratory/NOAA Norman, Oklahoma, USA (and Javier Murillo, Jose Galvez, John Mejia, CIMMS/Univ of Oklahoma) Good pibal site- Nouakchott, Mauritania
This talk is an outgrowth of our effort in 2006 to enhance the pilot balloon network in west Africa for NAMMA-2006.
Our previous experience in Latin America… Establishing pilot balloon stations in 10 countries, more than 60 sites, running for ~10 years. Other field experiments of ~ 1 month duration where from pilot balloon sites were operated. About 50,000 pilot balloon observations made. Extensive quality control efforts developed and data flow and display emphasized - to aid visualization by meteorological services. Google: “PACS-SONET” Also BAMS article Nov 2008
Our previous experience in Latin America… 10-year project to run climate monitoring network of pilot baslloon stations from Mexico to Argentina. Observations made at more than 60 sites, though most temporary. About 50,000 pilot balloon observations made. Extensive quality control efforts developed and data flow and display emphasized - to aid visualization by meteorological services. Google: “PACS-SONET” Also Bulletin of the AMS Nov 2008 article
Pibal observations involve simple materials and procedures…balloons are small and inexpensive, gas cylinders are usually readily available and portable. Inflation procedure is simple, yet accurate.
40-year old theodolites provides accurate observations… main limitation is observer skill) Smoke, dust, clouds limit tracking balloon
Advantages of pilot balloon observations Low cost relative to radiosondes (~ 5-10%) Low initial investment - new theodolite ~$8K new No permanent shelter or hydrogen generator needed for the small volumes of gas required No electricity needed, station easily relocatable if needed Relatively simple training needed - but lots of practice (observations can be done at any surface synoptic station)
NAME-2004 July Z at 500 mb (pibal winds at 5890 m ASL) blue are pilot balloon winds green are radiosondes
Pilot balloon site during NAME-2004 (desert site in Arizona) Good observers under favorable conditions can take excellent data!
Mean AM winds during 17 low-level jet events during SALLJEX-2003
NASA measurement campaign focused on tropical wave to storm transition and possible role of Saharan dust in this transition Our role: to strengthen the sounding network over West Africa by enhancing the pilot balloon network Approval in late April no time for prior site visits. Site visits took place from mid-July to mid-August NASA measurement campaign focused on tropical wave to storm transition and possible role of Saharan dust in this transition Our specific project: to strengthen the sounding network over West Africa by enhancing the pilot balloon network Approval in late April no time for prior site visits. NASA-AMMA 2006
Major problems during NAMMA set-up in West Africa ( our group visited 10 pibal sites in Guinea, Senegal, Mauritania and Mali…) Essentially no cylinder gas was available in West Africa - a major complication that prevented quickly solving gas shortages! Most field costs were much higher than we expected, complicating budgeting equipment (especially theodolites) in poor condition
GIP-3 gas generation cylinders…2 needed (minimum) at any sounding site. Each cylinder costs ~ $8,000. Many of these at some sites, but often in poor condition and not safe to use.
Hydrogen generation supplies come from France… slow logistical chain…via ship
One trained individual prepares the materials…not the observers
Pouring mix into cylinder…
Top of cylinder screwed on tightly (done quickly)
Some facilities we saw were abandoned many years ago…
Pilot balloon supplies in Dakar 40 gm balloons, candle, nozzle/weight, databook, pibal calculator
Wind calculation done with programmed calculator… advantage: fast. disadvantage: no quality-control capability - if bad data is typed in then bad winds will result without the observer knowing…
Quality control of raw pilot balloon data We installed special (free) software that displays raw angles and the observer corrects obvious errors. Corrected winds immediately recalculated and plotted. Nouadhibou, Mauritania
equipment (especially theodolites) in poor repair theodolites in poor condition Often no “high-power” telescope Bamako, before theodolite replacement
Fixed-height theodolite stand - inconvenient for most observers (adjustable height stand needed) Dangerous sharp corners and too-large a platform prevent using the gunsights to track balloons after launch and when balloon passes overhead “Gunsights” (too short) Small details are important
Better mount (smaller, rounded) and theodolite with longer gunsights (Ziguinchor, Senegal)
Many cylinders old or unusable… Dakar
Detecting problems not always easy…typical pilot balloon data should look like this… Nouakchott Aug 2-16,2006 Wave passage at 1500m Wave passage at 1500m Some high, some low soundings Due to clouds, dust…
A problem is suggested here… Mopti, Mali Sept 2006 note uniform heights - suggesting artificial termination of soundings after ~ 10 minutes.
Fundamental problem - little use of the observations Most African National Met Services focus on climate - not “weather”… Weather analysis and forecasting done mainly by ASECNA; little to no analysis and forecasting done by most NMS’s…
General suggestions for pilot balloon networks Sounding networks need close oversight at the regional level - Attention to detail needed everywhere. Solution to gas supply critical to success -compressed hydrogen cylinders distributed via road from one centralized port a possible solution for all West Africa sites. Continued use of local caustic soda generators is not ideal - other solutions possible. Surface observers are currently highly underutilized; could do much more with suitable training/education. Real-time display, monitoring, and analysis of these data are needed to generate interest in using them.
Suggestions… Make the relatively modest investment (compared with radiosonde network) to resurrect the pilot balloon network to function literally “better than ever”… which would require… –Adaptive observations - perhaps seasonally –Regional design of network - not national… –Solving gas, communications and quality control issues Other option is…
Have one organization finance and run the entire sounding network in the global tropics Network designed and overseen by scientific staff… Network optimized for global and regional NWP… Staff and logistics mostly independent of NMS’s…
More spatially-uniform network Potentially much more reliable - funding and labor independent of local govt’s. Minimize burden on geographically large, but poor countries. Advantages of a centrally-controlled sounding network
Problem is when a large-economy country is bordered by two geographically-large countries with small economies … Namibia and Botswana 2 million each South Africa 44 million
Should Nigeria pay for observations in neighboring countries? Should Senegal pay for observations in Mali, Guinea and Mauritania?
Summary Current pibal network in Africa in disrepair.. Pilot balloon networks can be useful in tropics but close oversight and attention to many details is essential. Oversight can either be internal to each country (difficult) or external - provided by international design and supervision…