Regional scale sounding network enhancement

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Regional scale sounding network enhancement

• Michael Douglas, NSSL

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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.

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• 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.

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

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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)
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• 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.

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Special heat low network5 low desert sites, very
cloud freeseemingly over-sampled, but strong
horizontal gradients in mean justify it...
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Mean 700 mb winds (m/s) for 18 day
period...justify dense low-desert network
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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

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Measurements strategies...

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

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Data dissemination plan...

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

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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 IOPs
• Trade-offs between sampling anomalous versus
  special events...?
• Costs relatively low, can do both routinely,
  labor may be main limitation for IOPs

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Expected coordination with data assimilation /
modeling groups...

• Suspect they will seek both data and comparisons
  with basic analyses...

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May June July August Sept October IOP-obs's tota
l obs's HEAT LOW COMPONENT Nee
dles, 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
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What sites do we eliminate?
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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?