Evaluating a new low-cost radiosonde system for use in adaptive sounding networks (and its implications) Michael Douglas, National Severe Storms Laboratory Norman, OK John Mejia, Desert Research Institute, Reno, Nevada (formerly at OU).
Evaluating a new low-cost radiosonde system for use in adaptive sounding networks(and its implications)Michael Douglas, National Severe Storms Laboratory Norman, OK John Mejia, Desert Research Institute, Reno, Nevada(formerly at OU)
Original MotivationMuch of my research has involved work with developing countries. These Weather Services usually cannot support dense radiosonde networks...How can these countries/regions carry out effective Numerical Weather Prediction activities?
NSSL Director’s Discretionary Funds allowed for the purchase of a new, low-cost (~$12K) radiosonde system this past year, along with some testing costs.Tests have been carried out in Albuquerque and Norman.
4 “AA” batteries
(info from Company brochure - claims to be “verified”)
Radiosondes ~ $175-$200 each in low quantity
Average of 7 soundings - Sippican RH is ~10% less; T difference less than .1˚C. Winds (GPS) identical.Get pdf of preliminary report from PACS-SONET web site (Google “PACS SONET”)
Note: too little attention
to wind details...
Can we design a cost-effectiveadaptive sounding network?
“Cost effective” implies benefits exceed costs! (Wx Forecasting is fundamentally an economic activity)
Thus, at least $300K to get started, then significant staff effort to keep running.
Initial start-up costs limit experimenting with
“sounding network design”
Ground stations must be inexpensive ($10K vrs $100K)
Network must be adaptive (say ~120 obs’s/year instead of 730 obs’s/yr)
Labor must be local, part-time (pay-by-observation), even at $100 per ob’ this is only ~$15K/year.
Balloon ascent rate (~5 m/s) requires ~30-60 minutes to profile troposphere - inadequate for storm-scale forecasting.
Time changes and practical limits of synchronizing launches may limit spatial density, perhaps 100 km spatial separation is a practical lower limit.
Point of diminishing return rapidly approaches as network density increases - depends on incremental benefits of add’l fcst skill (rarely quantified).
Radiosonde cost (function of quantity purchased)
~ $150 - $200 in low quantities depending on vendor
Balloons (size dependent ~$25)
Inflation gas (Helium is 3 times H2 cost but safer...)
~ $10 - $30 per balloon
Labor cost is controllable...to a point. Pay by observation is most economical. Lets assume $100 per observation for argument.
Can use ~$300 per observation as plausible (USA) cost...
for improving hurricane track forecasting
Red= routine obs’s, black = adaptive
23 sites across Caribbean Sea region for hurricane track/intensity forecasting
Set-up cost ~$500K
Annual operation for 60 obs’s/year per site
@$300/ob ~ $500K
How does this compare with other possible hurricane monitoring and forecast activities?(HRD in 2008 used ~1200 dropsondes and 39 research/operational P-3 flights; these total ~ $2M+)
Possible to “easily” reconfigure network for regional focus or evaluation of adaptive strategies (research potential)
Scaling things up a bit:Imagine adaptive network consisting of 100 additional sites across western North America (~4x current density)
Set-up cost ~ $2 M, annual cost for 120 obs’s/year per site @ $30K/site: $3 M How does this cost compare with other efforts to improve 12-72 hr fcsts over the central and eastern US?
(~60 sites shown)
Focus on critical weather forecasts downstream
Flexibility in deciding which stations operate on a daily basis
Should be great motivator for NWS forecasters - control over special sounding network (“Democratic” decision-making for go-days?)
Technology straightforward, little R&D required
Could be implemented quickly…
OSSE’s do cost $$$ (computer and research time) and are model and procedure dependent.
OSSE’s cannot evaluate any subjective use of additional soundings and improved analyses at the WFO’s.
Why has the current NWS raob network had the same density for the past ~ 50 years? Has it been OSSE-optimized? That is, is the current radiosonde network adjusted to just reach the point of diminishing returns? Not likely...
It may actually be less expensive, more convincing, and take considerably less time to to carry out operational trials than to carry out an OSSE.
... That the current radiosonde network should be replaced by an adaptive network... Daily obs’s are needed for many purposes...
Any adaptive sounding network should complement the current network and be focused on high impact weather events (however those are defined!)
This makes it much easier to justify the operational costs
Ought to be NWS...but.... could easily take a decade to program funds...
Universities could do it...but which ones...and why should they?
Many economic sectors might benefit and could easily fund it... but... why should they if someone else will?
NSF-type basic research activity lacks operational component to engage NWS...
Low initial cost is key to everything!
This may be most cost-effective means to increase short range forecast skill (to 72 hr or thereabouts) in many parts of world - including the USA.