# Presentation: 387674

## Future Trends in the Pan American Climate Studies Sounding Network (PACS-SONET)

**Michael W. Douglas, National Severe Storms Laboratory**** ****-**** ****Javier Murillo, CIMMS**** ****/**** ****University of Oklahom****a**
_**http**__**://www.nssl.noaa.gov/projects/pacs/**_

**SCOPE**
**The**** ****scope of PACS-SONET differ****s**** from many previous fi****e****ld progra****m****s in that****:**
**it has been expanded to a ****b****roader geographical region ****f****rom ****n****orthern Mexico to Paraguay.**
**it has a relatively long duration for a fiel****d**** program****.  ****Initially planned for 6 ****mo****nths, it has since been extended f****o****r a total of almost**** ****80 months.**
**communication of d****a****ta is in ****n****ear real****-****ti****m****e via Internet.**

**PILOT BALLOON OBSERVATIONS**
- Pilot balloon soundings, rather than radiosonde observations, have been made throughout the PACS-SONET life span. The main advantage of pilot balloon observations is that they are inexpensive. Typically, a 30-gram balloon launch, excluding labor costs, is only 5-10% that of a radionsonde launch. To date the project has generated more than 30,000 soundings. The graphic below shows the number of observations per month generated by the network from April 1997 to August 2003.

**Future Trends in the Pan American Climate Studies Sounding Network (PACS-SONET)**

**1.4. Extension of the PACS-SONET program**
**In late 1999 support was obtained for extension of the PACS-SONET program for an additional 3-year period. In addition to an extension in time, the network was expanded to a broader geographical region. Pilot balloon sites have been operating in ****Paraguay**** (2) and ****Bolivia**** (6). The primary objective of these additional observations was to describe the variability of the low-level flow east of the Andes and the circulation over the Bolivian altiplano. In ****Mexico****, 7 sites are being operated by the Mexican navy, including two in northwestern Mexico to improve the description of the low-level flow along the Gulf of California. In March 2001, one station was established in Venezuela at San Fernando de Apure, a location in the very flat llanos north of the Orinoco River. The figure at right shows the current PACS-SONET configuration and other stations that have been operational with financial or logistic support from the project.**

***The Pan American Climate Studies Sounding Network (PACS-SONET) is a ****** ******research activity funded by the NOAA’s Office of Global Programs******. ******I******t has ev******o******lved from****** ******a regional network of 6-month duration to a ******h******emis******p******he******r******ic activity that has been e******x******tended for a second****** ******3-ye******a******r period in 2003.***

**4****. ****TH****E FU****T****URE OF PACS-SONET**
**PACS-SONET ****h****as been extended for ****a ****second 3****-****year period, subject to a re-evaluation of the activity and  mor****e**** consensus-seeking on the part of the pro****j****ect.**** **
**A****s ****a**** first step ****t****ow****a****rds ****r****enewing the direction of the activity, a meeting has very recently been ****h****eld in  Paraguay in late ****A****ug****u****st 2003****.**** The meeting was intended to develop a con****sensus among each of the participating institutions as how to proceed to increase the effectiveness of the PACS-SONET. All participant countries and institutions were represented at the meeting. ****Preliminary conclusi****o****ns from the workshop indicate th****a****t future**** ****activities shou****l****d include****:**
**Radiosonde observations (PTU only****)**** ****a****t ****k****ey sites**** ****such as the Galapagos Islands****,**** Ecuador****.**** An ****o****ptical theodolite w****ou****ld be used to track the radiosonde in order to ****sa****ve funds b****y**** ****l****aunching inexpensive ****n****on-****G****PS sondes. Radiosonde observations are ****f****easible ****a****t locations were gas is generated****.**
**C****ontinue to support educ****a****tional activities to stimulate research with the data collected. Different options to better utilize the available funds w****e****r****e**** discussed ****d****uring the workshop.**
**Work  ****w****ith the participating institutions in**** ****designing ways to better qu****a****lity control the data.**
**E****stablishment of additional sites in Peru an****d**** Brazil with help from the national meteorological services. **
**The main benefit of t****h****e reunion of the country coordinators has been to create an awareness among the participants about the necessity of optimizing the available resources of the project to stimulate ****r****esearch and applied forecasting activities ****t****hroughout the region.  It was emphasized that PACS****-****SONET ****i****s not a m****a****jor source of resources f****o****r the countries involved, rather it can serve as a framework for the development of meteo****r****ological and climate activities in the region.**

**1. ****H****ISTORY AND EVOLUTION**
**1.****1****.  Original net****wo****rk**.
**The original P****A****CS-SONET ****c****onfiguration consisted of 12 pilot ballo****o****n stations****.**** The stations were ****e****stablished du****r****in****g**** March and A****p****ril of 199****7**** in Mexico****,**** Nicaragua, Costa Rica, Panama****,**** Colombia, Ecuador and Peru. The objectives of this network included****:**

**d****escribing the amplitude of the ****d****iurnal variation**** ****of the windfield at a number of sites.**
**D****etermining the ****c****irculation anomalies ****a****ssociated wit****h**** wet and dry spells over Central America.**
**Determining whether large differences existed between the NC****E****P reanalysis and observations in d****a****ta spar****s****e ****r****egions of the eastern tropical Paci****f****i****c****.**

**Fig. 1. Map showing the original station configuration during mid-1997.**

**1.2. Changes due to El Niño 1997-98**
**Due to the strong El Niño event of 1997-98, the observational plan was modified to extend the observational period at many stations through the end of October 1998 and establish additional stations in Ecuador and Peru to better sample conditions in the region of anticipated heavy rainfall. Due to financial reasons, some of the stations actually stopped in August 1998. Nonetheless, an unprecedented data set was obtained to describe the wind field associated with the developing El Niño.**

**1.3. Special Mesoscale Campaign in Bolivia**
**Pilot balloon observations were also made at Santa Cruz, Bolivia, as part of the special El Niño campaign. Although these were only made for 3 months they showed a strong and variable low-level jet at Santa Cruz, which had not been described from observations previously. These observations stimulated further observations from a more extensive network in Bolivia during 1999. The map at right shows the pilot balloon network in Bolivia during January-April 1999. **

**2. SC****I****ENTIFIC OBJECTIVES**
**The fundament****a****l over****a****ll objective of ****t****h****e**** pro****j****ect is to establish a long-term atmospheric sounding network for**** ****providing baseline measurement****s**** for real****-****time climate monitoring an****d**** for compari****s****on with model develop****m****ent**** ****activities over the PACS domain.**
***The fundamental scientific objective of****** PA******C******S-SONET****** is to determine both the annual cycle and****** ******interannual variability of the lower tropospheric windfield associated with the monsoon circulations over and around the Americas, with the aim of explaining the observed variability of precipitation over the land regions.***

**2.1****. Relevance to**** PACS**
**PACS-SONET observations**** provide the background ****f****ield to the**** s****pecialized field experiments****:**
_***North American Monsoon E***__***x***__***periment (NAM***__***E)***__*** 2004.***_** ****The ****observations at Puerto ****P****eñasco and Topolobampo in ****northwestern Mexico  are intended to ****help ****describe the ****lo****w****-level flow along the**** ****Gulf of Calif****o****rnia**** ****and will be of relevan****c****e for NAME.**
_***South American Low-le***__***v***__***el Jet Experiment (SALLJEX***__***)***__*** 200***__***2-***__***03.***_** The observat****i****ons a****t**** two sites in Paraguay and 6 sites in Bolivia served as t****h****e ra****m****p-up network for the upper-air compone****n****t of SALLJEX.**
_***E***__***PIC 2001***_**. The stations deployed from southern Mexico to northern Peru provided a context for field activities related to EPIC. **

**The impact of the additional observations can be appreciated from the figure and the quality of the data quickly assessed by comparing neighbor stations.**

**3****. ****PACS-SONET DELIVERABLE****S**
**3.1 Rea****l-time data collection.**
-  In addition to more observing sites, efforts have been made to make the network a real-time data collection and distribution activity. This required communications to be upgraded at many sites, and the development of procedures to ensure the flow of data to research institutions and to all interested forecasting institutions. The latter is accomplished mainly through the development of the project’s web page, in which the observations are made available in real time, in the form of both raw data and synoptic maps plotted** **at selected levels. The figure at right shows wind barbs from pilot balloon soundings (blue) at 3 sites in Bolivia and one in Asuncion, Paraguay, along with winds obtained from the regular radiosonde network (green).

**3.2 Climate monitoring**
**Several stations have been operating since 1997 and just now the time series is large enough to make crude estimations of the interannual varibility. The figures show monthly means of the meridional wind at San Cristobal, Galapagos for the months of May (a), July (b) and December (c). Southerly cross-equatorial flow at Galapagos is moderately strong in May and has a maximum in July-August-September. December shows the greatest interannual variability.****  **

**(a) May**

**(c) December**

**(b) July**