SWAMP-90/EMVER-93 Material

The purpose of this link is to provide unpublished (or not widely known) material that may be relevant to NAME preparations. Much of this material relates to three previous field activities in the NAME region. The first was a 1990 field experiment called SWAMP (Southwest Area Monsoon Project) that involved P-3 flights, radiosonde measurements and a network of about 10 pilot balloon stations (all but one in Mexico). The second project, carried out in 1993, was called either SWAMP-93 (US side) or EMVER-93 (Mexican side) and involved roughly similar measurement programs (minus the P-3). Finally, a shorter 2 week program was carried out in 1995 at Puerto Penasco, Mexicali, and at some US sites in Arizona. Some figures have been taken from the papers:

Douglas, M.W., A. Valdez, and R. Garcia, 1998: Diurnal Variation and horizontal extent of the Low Level Jet over the northern Gulf of California. Mon. Wea. Rev., 126, pp 2017-2025.

Douglas, M.W., and S. Li, 1996: Diurnal Variation of the Lower-tropospheric flow over the Arizona Low Desert from SWAMP-1993 observations. Mon. Wea. Rev., 124, 1211-1224.

Douglas, M.W., and J.C. Leal, 2003: Summertime surges over the Gulf of California: Aspects of their climatology, mean structure, and evolution from radiosonde, NCEP reanalysis, and rainfall data. Weather and Forecasting, 18, pp55-74.

The purpose of the each item more specifically is:

Juan Carlos’s precipitable water figures. These are based on 11-years of July and August radiosonde data, except for short periods of raob data at La Paz and at Puerto Peñasco.

NAME participants should understand this is the type of info that comes strictly from monthly mean radiosonde sounding info (11 year averages).

Moisture flux analyses, based on mean winds (over the layer) and mean moisture values over the layers.

Moisture flux analyses show the mean moisture flux based on 11 years of radiosonde data from July and August (averaged together). Relatively few years of data from La Paz and Puerto Penasco. Note the areas where there are greater uncertainty, and how these uncertainties depend on the available data. The units of moisture flux are m g s-1 kg-1.

Gordon Dean’s (retired FSU) streamline anaylses based on 1990 SWAMP data. These analyses should be perused for continuity of synoptic and large mesoscale features, such as propagating cyclonic and anticyclonic eddies over the southern Gulf of California. Also, perusers should evaluate what upper-air sounding network is needed to specify the details they desire on synoptic-seasonal time scales.

Very few people have ever seen synoptic charts of the NAME domain with data as dense as during the SWAMP and EMVER experiments. Despite the limitations of these analyses they are presented to show the characteristic synoptic variability that might be expected during NAME. The adequacy (or inadequacy) of the sounding network for describing the evolution of the synoptic-scale flow should be considered from these analyses. The main objective in presenting these maps is to suggest the relative contribution of different observations over the NAME domain to the overall analysis.

Some nomenclature peculiar to Gordon’s analyses:

Since pilot balloon data was 3-4 times daily, some off-time observations are written next to the station, but not plotted (to convince the reader of the continuity inherent in the analyses). "N.R" means "no report" — the observation was not made at this time for some reason and "S.R." means "short-run" meaning the pilot balloon was not tracked to this level.

As a general comment, despite the seeming-doubtfulness of many of the small vortices shown in these analyses, the reader is challenged to produce different analyses that show better continuity of the features.

1993 Heat low paper figures

1995 two-weeks August means: Two weeks of 8-times daily obs’s (pibal) and 2X daily radiosondes at Puerto Peñasco and twice-daily obs’s at Mexicali, MX and observations at some special US sites (Phoenix, Ajo) were used to produce 2-week mean maps at different levels to show the mean conditions during the experiment as a context for the 8-times daily Peñasco observations. Note the strong anticyclonic circulation (both shear and curvature vorticity) about the Arizona low desert. This is the same feature seen on individual maps (see "Arizona heat low example" folder).

Arizona heat low example: These are data plots (wind only) from a mix of radiosonde (green) and pilot balloon (blue) observations. The maximum in anticyclonic vorticity near 700 mb is evident; this is near the level where the thermal gradient becomes weak between the air over the northern Gulf and the air over the low desert of Arizona. How many observations are needed to accurately estimate the daily evolution of the heat low strength?

Tezopaco mean wind profiles: Tezopaco was a inland observation site (about 100km east of Guaymas) during the 1993 EMVER experiment. It was chosen because it lies in relatively low(430m asl) flattish terrain, along the presumed inflow to the region of maximum convection observed in satellite composites in NW Mexico. Tethered balloon soundings, a few radiosonde launches, and many pibals were made over an approximately 2 month period.

The mean U profiles show the diurnal variation of flow towards the mountains… A deep afternoon inflow is present…

Tethersonde profiles show the passage of a gulf surge on August 12th; the major temperature profile changes occurred in less than 2 hours.

EMVER 93 Metadata

EMVER 93 synoptic maps: Maps have been prepared from the EMVER-1993 pilot balloon and radiosonde data sets to show the synoptic flow at selected levels over northwestern Mexico - over a region corresponding roughly to the NAME TIER 1 domain. These maps, at the 300m, 600m, 900m, 1200m, 1500m (~850mb), 3000m (~700mb),and 6000m (~500mb) levels, are arranged to be looped to show the continuity(or lack of continuity) of the daily flow patterns. Pilot balloon observations (green) also give the speed (kts) and direction of the observation. Radiosonde observations also show temperature (red) and dewpoint (light green).
Again, the purpose of preparing these plots is to provide an idea of the variability of the flow that might be expected on a daily basis during the warm season over the NAME Tier 1 domain, its vertical variation, and to help visualize the observational density that may be required to describe it to acceptable accuracy.