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Regional scale sounding network enhancement

This study aims to improve estimation of moisture fluxes and enhance observation networks to understand variability in moisture sources, tropical waves, and quasi-permanent heat low. The study includes additional moisture flux sites, increased spatial density of wind soundings, and a special heat low network.

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Regional scale sounding network enhancement

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  1. Regional scale sounding network enhancement Michael Douglas, NSSL

  2. Objectives of the activity • Although there are many possible topics for research related to moisture flux variability over the NAME domain this study will focus on three. Each of these topics require a network of special observations to provide a reliable answer. These topics are, together with their rationale: • 1) Improve estimation of moisture fluxes from the eastern Pacific Ocean into the NAME Tier 1 domain (Gulf of California and surroundings). This is needed to determine the relative importance of local (Gulf of California evaporation) versus remote (eastern Pacific) moisture sources in the precipitation over the NAME Tier 1 domain and to determine if variations in precipitation over the Tier 1 domain are linked to variations in moisture flux into the region from the eastern Pacific. • 2) Improve the description of tropical wave variability over central Mexico and south of the Gulf of California. Increasing the spatial density of wind soundings will provide a more accurate depiction of the strength and structure of westward propagating waves that are believed to be the primary forcing for the so-called "gulf surges", which are associated with major variations in the northward moisture flux over Tier 1; • and • 3) improve the description of variations of the quasi-permanent heat low observed over the southwestern desert of the US and northwestern Mexico. Fluctuations in the intensity of the heat low contribute to variations in the pressure gradient along the Gulf of California and thus the up-Gulf moisture transport.

  3. 1) Improve estimation of moisture fluxes from the eastern Pacific Ocean into the NAME Tier 1 domain. This is needed to determine the relative importance of local (Gulf of California evaporation) versus remote (eastern Pacific) moisture sources in producing observed variations in precipitation over the Tier 1 domain.

  4. Moisture flux supplemental sites(only one radiosonde site)

  5. 2) Improve description of tropical wave variability over central Mexico and south of the Gulf of California. Increasing the spatial density of wind soundings will provide a more accurate depiction of westward propagating waves that are believed to be the primary forcing for "gulf surges", which are associated with major variations in the northward moisture flux over Tier 1.

  6. Westward propagating wave associated with composite surge at 600 mb (NCEP reanalyses)(observations north of Mexico City, over high interior plateau needed to help specify wave structure)

  7. 3) improve description of the quasi-permanent heat low observed over the southwestern desert of the US and northwestern Mexico. Fluctuations in heat low intensity contribute to variations in the pressure gradient along the Gulf of California and thus the up-Gulf moisture transport.

  8. Special heat low network5 low desert sites, very cloud freeseemingly over-sampled, but strong horizontal gradients in mean justify it...

  9. Mean 700 mb winds (m/s) for 18 day period...justify dense low-desert network

  10. Platform description: • Pilot balloon observations will be made at ~22 new sites • Optical theodolites (1-2 persons required for observation, average duration 30-50 minutes; computer/internet required to process/send info in real-time) • 20 balloons (30gm) per standard gas cylinder (~6 cubic m) • Can be made almost anywhere, if communications no concern • Radiosonde observations will be made at several high priority sites: • West coast site of Baja California • Torreon region (not resolved yet how to do this) • Possibly Puerto Peñasco (when ISS not present) • Note: these radiosonde systems are thermo only; winds come from optical theodolite tracking unless other system can be arranged

  11. Measurements strategies... • Most soundings will be routine, predetermined, at synoptic times. • Some sites will, during the EOP, be capable of more frequent observations.

  12. Data dissemination plan... • After post-processing the data will be distributed to JOSS. • About 6 months required to process data...

  13. Field coordination requirements • IOP coordination: • How will we participate in coordination? • One representative will help at Tucson ops center... • Will we need to coordinate with ship/aircraft and other systems? • Not really. • How will the sounding network be coordinated to satisfy budget study objectives and also sample special events? • Will function routinely, except for IOP’s • Trade-offs between sampling anomalous versus special events...? • Costs relatively low, can do both routinely, labor may be main limitation for IOP’s

  14. Expected coordination with data assimilation / modeling groups... • Suspect they will seek both data and comparisons with basic analyses...

  15. May June July August Sept October IOP-obs's total obs's HEAT LOW COMPONENT Needles, CA 15 60 90 90 60 15 30 360 Lordsburg, NM 15 60 90 90 60 15 30 360Tempe, AZ 15 60 90 90 60 15 30 360Mexicali 15 60 90 90 60 15 30 360Benjamin Hill 15 60 90 90 60 15 30 360Mohawk, AZ 15 60 90 90 60 15 30 360MOISTURE FLUX COMPONENTPeñasco (add'l to SONET) 0 0 60 60 0 0 60 180Cataviã, BC 15 60 90 90 60 15 0 330Bahia Tortugas, BC 15 60 90 90 60 15 0 330Isla Guadalupe, BC 15 60 60 60 60 15 0 270Cd. Constitucion, BCS 15 60 120 120 60 15 30 420La Paz, BCS 15 60 120 120 60 15 30 420S. Jose d. Cabo, BCS 15 60 120 120 60 15 30 420Isla Socorro, COL 15 60 60 60 60 15 0 270Isla Clarion, COL 15 60 90 90 60 15 0 330Isla Maria Madre, NAY 15 60 90 90 60 15 0 330TROPICAL WAVE SPECIFICATION Alpine, TX 15 60 60 60 60 15 30 300N. Casas Grandes, CH 15 60 90 90 60 15 0 330Jimenez, CH 15 60 90 90 60 15 0 330Torreon, DUR 15 60 90 90 60 15 0 330Matehuala, SLP 15 60 90 90 60 15 0 330Ocampo, COA 15 60 90 90 60 15 0 330Durango, DUR 15 60 90 90 60 15 0 330Zapopan, JAL 15 60 60 60 60 15 0 270 345 1380 2100 2100 1380 345 360 8010

  16. What sites do we eliminate?

  17. Training workshop for observers prior to field phase... • March-April time frame… students and other participants to be involved in the field program activities • Several days of lectures to give background to participants, then field training activities. • Site in northwestern Mexico, possibly one near Xalapa?

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