Proposed Enhanced Observational Period and Intensive
Observing Periods for NAME 2004
Prepared by Art Douglas, Mike Douglas, Bob
Maddox
Given the various field and research activities associated with NAME,
it seems prudent to define a commonly agreed upon set of dates for the EOP
and IOPs. A number of platforms are anticipated to be in place prior to
the start of the field campaign and they include: portable and enhanced SMN
radar systems, a wind profiler network, a pibal network and lightning detection
system. Costs associated with these observing systems are not as heavily
dependent on the defined time line for the EOP and IOPs. However, due to
the high costs associated with field personnel, ship and flight time and
radiosonde measurements it is proposed to focus the EOP and IOPs relative
to the synoptic climatology and synoptic meteorology of the region.
For the EOP a start date of June 15 is suggested. Given that the mean
start date of the monsoon in southern Tier I (southern Sinaloa) is approximately
June 25 this would allow a 10 day ramp-up period prior to the anticipated
start of the monsoon. This mean start date is based on daily data from 12
foothill and coastal plain stations, 1951-2000. Slightly less than 50% of
the years show a monsoon start date by June 25. The proposed end date for
the EOP will be August 21
st. This date is based on a pronounced
mean decline in daily rainfall across Arizona and northern Sonora in association
with the southward retreat of the monsoon. MCS, easterly wave and gulf surge
activity are also far less common by late August across the northern portion
of Tier I. Relative to the SMN radiosonde activity, we anticipate being
able to move up or move back the start date for the 2
X
daily observations by one week given an early or late start to the monsoon.
A major reason for defining the period of the EOP and IOP is associated
with the costs for the extra radiosonde observations that will be conducted
at 7 SMN sites in Mexico. The SMN will be providing the balloons and hydrogen
for the observations and it is proposed that OGP-NAME will be providing the
radiosonde systems. Over the past two years in the SWG it has been proposed
that all SMN sites will shift from a once daily to a twice daily schedule.
NAME will provide the extra daily observation at each of the 7 northern
raob sites in Mexico: La Paz, Guaymas, Mazatlan, Chihuahua, Torreon, Zacatecas
and Monterrey.
On the US side of the border, it is proposed that NAME-OGP and the NWS support
taking 4 extra soundings per day, during IOPs, at the following stations:
San Diego, Las Vegas, Flagstaff, Tucson, Albuquerque, Del Rio, Midland and
Amarillo
The NAME Forecast Operations Center (FOC) in Tucson and Mexico City will
be central to decision-making relative to the IOPs and it is proposed that
20 IOP days will be identified within the EOP. During the IOP periods it
is proposed that 6 radiosonde observations per day be taken at the 7 SMN
sites in order to define the diurnal cycle of the monsoon system as it relates
to key synoptic features (e.g. backdoor cold fronts, cold core cut-off lows,
easterly waves, tropical storms, gulf surges and MCs). Additionally, these
proposed 6 daily observations will enhance efforts to evaluate the data from
the wind profilers that are planned to be co-located with four of the SMN
radiosonde sites in northwest Mexico (La Paz, Guaymas, Mazatlan and Chihuahua).
The 20 IOP days will be tagged to the key synoptic features that NAME
will try to investigate. In some cases (e.g. easterly waves, tropical cyclones,
cutoff lows and back door cold fronts), the FOC will be able to predict
these events 48 hours prior to their impact on the Tier 1 region of NAME.
This will provide for a period of enhanced observations leading up to these
more "predictable" events and a thus the evolution of the systems will be
captured across Tier I.
