A JUNE MONSOON

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• A JUNE MONSOON?
• David L. Mitchell1, Dorothea Ivanova1 and David
  Gochis2
• Desert Research Institute, Reno, Nevada
• 2. National Center for Atmospheric Research,
  Boulder, Colorado

Acknowledgment We thank the people at
NOAA/NESDIS, CIMSS at Univ. Madison, Wisc., the
Navel Research Laboratory in Monterey and UNiSYS
for hosting their products on the internet
regarding satellite SSTs, total precipitable
water, rainfall amounts and wind fields.
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Mean rainfall rates for the AZNM region for N. GC
SST intervals of 0.5oC based on five June-August
seasons.
AZNM region cumulative normalized rainfall for
periods having N. GC SSTs indicated SST. Time
is implicit with increasing SSTs.
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7 July 2002 at 00 UTC, Total Precip. Water (TPW)
9 July 2002 at 00 UTC, TPW
11 July 2002 at 00 UTC, TPW
2.4oC increase in N. GC SST over 2 days, reaching
29.8oC.
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2002 AZ Monsoon Onset Period
11 July 2002 at 00 UTC. 24 hour
rainfall accumulation
15 July 2002 at 00 UTC. 24 hour
rainfall accumulation
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Hypothesis Development MM5 Modeling of the
1999 Arizona Monsoon Onset
SST Evolution along the NW coast of Mexico
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SST Dependence of Vertical Mixing Over the
Northern Gulf
Cross-Section A-B Potential temperature
Northern gulf SST 26 oC SST below N. GC 28 oC
Northern gulf SST 30 oC SST below N. GC 30 oC
5 AM LST, day 3
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Cross-Section C-D Water vapor mixing ratio
Northern gulf SST 29 oC SST below N. GC 30 oC
Northern gulf SST 30 oC SST below N. GC 30 oC
5 AM LST, day 3
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N. GC 26oC 28oC otherwise
N. GC 29oC 30oC otherwise
N. GC. 30oC 30oC otherwise
Sensitivity of CAPE (Convective Available
Potential Energy) to GC sea surface temperatures.
Simulation time 54 h 11 pm LST. Yellow
1300 J/kg (CAPE) Orange 2100 J/kg Red
2900 J/kg Brown 3700 J/kg
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Dependence of CIN on GC SST
5 AM MST Day 3
5 PM MST Day 3
26/28 oC 29/30 oC
30/30 oC
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Conceptual Model of Moisture Advection Dependence
on SST
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Comparison of modeled and observed normalized
rainfall rates for AZNM region ,
for modeled conditions in conformity with
hypothesis
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Examples of NAME Soundings over the GC August
Cruise
3 km
2.5 km
Altitude
10
0
30
0
10
30
20
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Temperature, Dewpoint, deg. C
Temperature, Dewpoint, deg. C
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A June Monsoon?
Blended SSMI/TRMM experimental rainfall estimates
from NRL, Monterey
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SST TPW
NG 24.2 oC
NG 26.7 oC
16 June 2005
20 June 2005
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Wind fields suggest Gulf of Calif. moisture source
5 pm MST June 20th, 850 mb
5 pm MST June 20th, 700 mb
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June monsoon summary
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Food for Thought
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What will happen next?
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SUMMARY
1. MM5 simulations suggest that the marine
boundary layer in the Gulf of California (GC)
may be sensitive to GC SSTs. This MBL may act as
a moisture source for monsoon rainfall over
AZ. 2. The moisture source for the June period
of scattered thundershowers affecting AZ, the
Great Basin and Colorado appears to be the GC.
This same pattern is common during the monsoon
season. 3. Soundings over the GC during NAME
are consistent with MM5 soundings. 4.
Observations of SST, TPW, winds and rainfall
during the June monsoon of 2005 appear
consistent with the hypothesis developed from the
MM5 study. 5. Since the GC appears to be
warming at a rate of about 1.4 oC over the last
20 years, it is important to understand the role
that GC SSTs play in monsoon dynamics.