Rationale

1
RationaleTier 1
The principal rationale for a dense network of
soundings, profilers and radars in Tier 1,
together with rain gauges, is to describe and
understand the diurnal cycle of precipitation
and the structure of precipitation in the core
region of the NAMS and to better understand
regimes associated with intra-seasonal
variability, including the influences of surges,
jets, surface fluxes and topographic blocking.
These observations are critical for budget
studies and model validation.  
2
Objectives to which soundings, radars and
profilers contribute

• Observe and describe statistically the daily
  evolution of ordinary convective rainfall
• over the high Sierra Madre Occidental, the
  western and eastern slopes, the Gulf of
  California
• coastal plain, and the southern Gulf region.
•  
• Clarify the relationship of convection on east
  and west slopes of the Sierra Madre Occidental
• and water vapor transport from the Gulf of Mexico
  and the Gulf of California.
•  
• Observe and describe statistically the location
  and amplitude of organized mesoscale
• rainfall systems within the diurnal cycle.
•  
• Observe and diagnose the principal mechanisms
  that force or maintain mesoscale rainfall
• systems so that the effects of these may be
  adequately represented in models
• (e.g. convectively-generated cold pools, sea and
  land breeze fronts, microphysics, other
• diurnally-varying and/or topographically-influence
  d aspects).
•  
• Assist in the identification of local properties
  and processes associated with variability in
• the precipitation (e.g. anomalous surface latent
  or sensible heat fluxes, quasi-permanent
• convergence zones)
•  

3
Objectives-cont

• Observe the development and propagation of
  southerly surges and associated low-level jets
• in the Gulf of California in the broader regional
  context of tropical easterly waves and
• mid-latitude westerly trough passages.
•  
• Clarify the relationship of southerly surges/jets
  to the forcing, organization and northward
• propagation of convectively-generated
  precipitation.
•  
•  

4
Instrumentation and Design Constraints

• The plan is to maximize use of observing systems
  currently operated by the SMN and to augment
• these with research systems currently maintained
  by U.S. agencies. There are five SMN sounding
• sites in Tier 1 Guaymas, Mazatlan, Torreon,
  Chihuahua, and La Paz. There are four 5-cm
• Doppler radars in Tier 1 Obregon, Gusave, Cabo
  San Lucas, and Palmito.
• The sounding sites are presumed to be fully
  functional, so experimental design constraints
  mainly
• concern the frequency and scheduling of soundings
  and the provision of expendables as may be
• required. All of the radars are operational,
  however, none currently meet standards for
  systematic
• recording of calibrated 3-D reflectivity and
  velocity data required to address the scientific
• objectives.
•  
•  

5
Instruments/Sites
UHF wind profilers (some with Radio-Acoustic
Sounding System (RASS) capabilities) provide
winds through 6 km plus virtual temperature
soundings to 2 km. NOAA/AL and ETL. Virtual
Integrated Sounding Systems, VISS (co-located SMN
sounding UHF profiler) NCAR Integrated
Sounding Systems, ISS, (UHF profiler RASS
rawinsonde) ISS and VISS will provide continuous
wind profiles in the low-to-mid troposphere along
with full tropospheric thermodynamic and wind
soundings. SMN 5 cm Doppler radars A 10 cm
Doppler-polarimetric radar (NASA N-POL, NCAR
S-POL) providing rainfall estimates, structure
of convection, airflow patterns The Ron Brown
shipboard platform (VISS, 5 cm Doppler
radar) Crtitical GofC location for surges.    
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Integrated Sounding Systems
Seatainer-packaged UHF Doppler wind
profiler ( 0.17km agl) Radio-Acoustic Tv
profiler (0.2 2 km agl) GPS rawinsonde
sounding system automated surface met
obs Applicable to regional analyses, breezes,
surges, cold pools, gravity waves, etc.
Soundings, gt 2/day event-based
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NCAR S-pol radar
10 cm Doppler, polarimetric radar Highly
portable, six 20 ft. seatainers Diesel generator
powered Easy set up Peak power 1 Mw 1 degree
beamwidth antenna Suite of Doppler and
polarimetric variables Doppler measurements,
polarimetric-based rainfall maps, hydrometeor
identification Internet ready Deployment costs
through NSF deployment pool for
NSF-supported research
8
NASA N-pol radar
10 cm Doppler, polarimetric radar Highly
portable, four 20 ft. seatainers Diesel generator
powered Easy set up Peak power 50 kw 1.4 degree
beamwidth antenna Suite of Doppler and
polarimetric variables Internet ready Leverage
NAME for TRMM and GPM validation studiesNASA
funding
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10
Rationale for Experimental Design
Concentration of observations in the southern
Gulf region is based on the climatology of
rainfall, the apparent geographical origin of
surge events, and diurnal tendency in this
region for rainfall to propagate westward, down
the SMO slopes, onto the coastal plain and into
the GoC itself. A set of continuous, high
resolution and reliable deep tropospheric
precipitation, wind and thermodynamic
measurements utilizing radar, profiler and
sounding observations over the southern one half
of the SMO and GoC are critical to the proper
initialization and validation of both regional
and cloud resolving numerical models. The
co-location of RAOB and profilers will minimize
uncertainties in the significance of data from
each individual observing system and increase
the quantitative applications of both.
Observations over the GoC channel, including SST
and interfacial fluxes, are also critically
important.    
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Deployment Issues
 
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Schedule
Perform SMA radar modifications and training
(spring 2003).   Install and conduct limited
operation of 3 UHF profilers (June-July 2003)
and routine operations of modified SMA radars
(June- Sept 2003).   Evaluation of UHF and SMA
radar data, (Fall-winter, 2003-4)   Installation
of ISSs, UHF profilers for VISS sites, and 10 cm
radar (spring 2004)   Field phase a
six-to-eight week operation (July-August) of ISSs
and VISS sites (sounding frequency _at_ six per day
during IOPs, twice per day otherwise, average
4/day) 24/7 operations of polarimetric radar.
50 day operation for the R/V Brown.   Conduct QC
and archival of sounding, profiling and radar
data continually throughout and immediately
following operational periods ( UCAR/JOSS,
NCAR/ATD, NOAA/AL/ETL, as appropriate).  
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Deployment Issues
Services Provided by NCAR/ATD 4 Integrated
Sounding Systems operated for 4 months on the
mainland 800 K (Average of 4 sondes per day,
60 days)  S-POL Doppler-Polarimetric radar
operated for 2-3 months 500 K Upgrades,
calibrations and staff training for all four SMN
radars 200 K Eligible for NSF
Field Deployment Pool funds Science Overview
Document due at NSF in December 2002   Services
Provided by NOAA/ETL and/or AL 3 UHF profilers
operated for 2 months in 2003 TBD 6 UHF
profilers operated for 4 months in 2004
TBD  
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R/V Ronald H. Brown

• Instruments
• Radar (Scanning C-band Doppler Vertically
  pointing Ka-band Doppler)
• Rawinsonde
• 915 MHz wind profiler
• DIAL/Mini-MOPA LIDAR
• Multi-spectral radiometers
• Air-sea flux system
• Meteorological observation (T,RH, P), rain gauges
  and ceilometer
• Oceanographic measurements including SST, CTD and
  ADCP

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Ronald Brown Sounding-Derived Winds and ?w During
EPIC
Zonal Wind
Meridional Wind

• Soundings launched 6X/day from 11 September-1
  October 2001
• Passage of 3 Easterly Waves (V and U wind
  signatures).
• Peak instability/lightning 0-2 days prior to
  trough passage

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Convective Structure Filtered Echo Height
Distributions vs. Time
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Distribution of 30 dBZ Echo Tops During EPIC

• Mean and mode of echo top distribution is flat
• Tail of distribution (most intense convection)
  extends to greatest height near 02 L