Gulf Surges, the Diurnal Cycle, and Convective Outflows as Revealed by the NCAR ISSs in NAMERichard H. Johnson, Peter J. Rogers, Paul E. Ciesielski, Brian D. McNoldy, and Richard K. Taft
Colorado State University
Acknowledgments: NSF, NOAA, NCAR ATD staff, and numerous students who worked at ISS sites
NCAR Integrated Sounding System (ISS)• Vaisala GPS sounding system• Enhanced surface observing
station• 915 MHz Doppler clear-air wind
profiling radar• Radio Acoustic Sounding System
(RASS)
• 3 ISSs used in NAME
• 1 GLASS sounding system ISS Trailer, Los Mochis
NAME SOUNDING NETWORK
PUERTO PEÑASCO
BAHIA KINO
LOS MOCHIS
LORETO
3 ISSs 1 GLASS
N GULFS1
(IOP2)
S2 (IOP3)
2004
May June July Aug Sep
PRECIPITABLE WATER (105-115°W)
(NCEP Operational Analysis)
HU
RR
JA
VIER
HU
RR
HO
WA
RD
TS B
LAS
(IOP10)
TS A
GA
THA
HU
RR
CEL
IA
HU
RR
DA
RB
Y
HU
RR
FR
AN
KTS
GEO
RG
ETTE
HU
RR
ISIS
Moisture surges
and tropical waves,
cyclones
BLAS
DARBY
FRANK
GEORGETTE
HOWARD
ISIS
JAVIER
CEN
TRA
L G
ULF
700-hPa V WIND (15-25°N)
Easterly Waves During NAME EOP
May
Jun
Jul
Aug
Sep
2004
CELIA
L
TROPICAL STORM BLAS
YUMA
●`
●MAZATLAN
Heat Low
1004
TS BLAS
QuikSCAT Winds
HURR JAVIER
HURR HOWARD
TS GEORGETTE
N GULF
S GULF
13 JULY
HURR DARBY?
HURR FRANK
V
BLAS
13 July 20040024-0824Z
LOS MOCHIS
BAHIA KINO
PUERTO PEÑASCO
●LOS MOCHIS ISS
MIDNIGHT NOON
SURGE
GUST FRONT
4-hPa rise
00 UTC
05 10 15 20
GUST FRONT
SURGE PEAK
km
● BAHIA KINO ISS
7 hPa rise, but over longer period
SURGE
3-hPa rise
NOONMIDNIGHT
PUERTO PEÑASCO ISS●
SURGE
GUST FRONTS
3.5-hPa rise
NOONMIDNIGHT
km
surge
(RASS shut down at night due to noise
impact on local populace)
4-hPa additional rise
SURGE CONTINUES NEXT DAY, PEAKING AT NIGHT
NOONMIDNIGHT
NOONMIDNIGHT
PRESSURE MAXIMUM, 8 hPa INCREASE OVER 2 DAYS
Puerto Peñasco Bahia Kino Los Mochis
Pressure rise signature progresses up the Gulf (8-10 h from Los Mochis to Puerto Peñasco)
20-25 m s-1 propagation speed!
Pressure signature and speed characteristic of an internal bore or mixed Kelvin wave–bore (e.g., Ralph et al. 2000)
7-8 hPa rise
Altair12/20 – 13/04Z
Puerto Peñasco13/12 – 13/18Z
●
● ●
●●
PEAK WINDS NEAR THE SURFACE IN
THE NORTH
…PEAK WINDS ELEVATED IN THE SOUTH
GULF-// WINDS
●●
● ●●
COOLING ASSOCIATED
WITH SURGES…
• PRINCIPALLY CONFINED BELOW 700 hPa• LASTS FOR 3-4 DAYS• ELEVATED IN S FOR FIRST SURGE
T
Rain moved northward
along coastal
plain and into AZ with
surge
24-h totals, 12-14 July
UTC NOONMIDNIGHT
EOP-MEAN LOW-LEVEL
WIND DIURNAL CYCLE
(7 JUL – 14 AUG)
PP
BK
LM
Strong low-level jet at PP, much weaker at BK, absent at LM (Douglas 1995)
Sea breezes
Puerto Penasco
Bahia Kino
Los Mochis Weak land
breezes, nocturnal offshore convection near S-Pol
S-POL RADAR
3 Aug2004
1000-1330UTC
NOAA-ETL PROFILER
Summary and Conclusions• ISSs successfully documented many aspects of NAM along Gulf of California, including characteristics of surges
• July 13 surge associated with TS BLAS, preceded by downdraft outflows from SMO convection
• Peak surge winds on 13 July descend from 1.2 km AGL at LM and BK, to near 700 m at PP, maximum wind 20 m s-1 at Puerto Penasco; convective outflows are shallower (peak winds near 300 m)
• Pressure rises 3-4 hPa over 8-10 h period of surge, followed by additional 4 hPa rise over next 1-2 days (2-3°C surface temperature drop); initial P-rise signal moved rapidly up Gulf (20-25 m s-1) internal bore, mixed Kelvin wave-bore? (awaiting more data)
Summary and Conclusions (cont)
• Surge on 13 July led to increased TPW and rainfall over southwestern US
• Diurnal cycle of PBL winds varies from south to north; prominent nocturnal LLJ in north, absent in south; prominent afternoon sea breezes at BK and LM; weak land breezes at BK and LM, coastal offshore convection near S-Pol
• Results are preliminary; further analysis awaits additional surface, pibal, and sounding data
(Ralph et al. 2000)
(Ralph et al. 2000)(Nuss et al. 2000)
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