OVERVIEW

This page was designed and executed by Leslie Rosenfeld and Todd Anderson of the Oceanography Department at the Naval Postgraduate School (NPS), and Yi Chao and Peggy Li of the ROMS Group of the Jet Propulsion Laboratory (JPL), as part of the NOAA-funded Center for Integrated Marine Technology (CIMT), a NOAA-funded pilot observing system project.  The COAMPS^® model wind product is provided by Jim Doyle of Naval Research Laboratory in Monterey. For more information about the national coastal ocean observing system, go to the Ocean.US and NOAA Coastal Services Center web sites.  To learn more about the ocean observing system in central and northern California go the Central and Northern California Coastal Ocean Observing System (CeNCOOS) web site.

OBSERVATIONS

M0 Buoy

Granite Canyon Weather Station

The over-water winds shown on this page are measured by anemometers mounted 3 to 5 meters (about 10 to 16 feet) above the sea surface on moored surface buoys.  M0, M1, and M2 are maintained by the Monterey Bay Aquarium Research Institute (MBARI).  46042 is maintained by the National Data Buoy Center (NDBC), which is part of the National Oceanic and Atmospheric Administration (NOAA).  The coastal winds are measured by anemometers generally mounted between 10 to 20 meters (33 to 66 feet) above the land surface and are maintained by a variety of institutions (Table 1).  The data are transmitted in near real-time and, except for one station, collected by Dick Lind of the NPS Meteorology Department.  In very light winds, the wind speed may be recorded as zero.  In these "light and variable winds", the direction is meaningless, so is not plotted.

 

Why are some data missing?

All wind measurements on a given image were made within ± 30 minutes of the time shown.  Data are transmitted by telephone or packet radio.  Failures in power, instrumentation and/or communications can cause data drop-outs.

A number of other oceanographic and meteorological variables are measured at these sites.  These data can be seen at the following web sites: NDBC Buoy# 46042; Monterey Moorings; Weather Stations around Monterey Bay; Moss Landing Weather Station.

MODEL

The model simulated wind at 10 meters above the sea level is used here. The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS^TM), developed and run by the Naval Research Laboratory in Monterey, CA, is the numerical model used for the wind nowcasts and forecasts.  The numerical model is a set of mathematical equations, representing the physical behavior of the atmosphere, that have been programmed into a computer.  The model has an update cycle of 12 hours.  That is, every 12 hours (at 0000 and 1200 Universal Time, formerly known as Greenwich Mean Time) the model takes all the available, irregularly spaced, observations for that hour (including some of those shown on this web page) and interpolates them, together with a previous model forecast, to produce fields (in this case wind velocity) on an evenly spaced grid.  That is called the analysis – or nowcast.  The model then projects the fields forward in time for 48 hours – that is called the forecast.  The latest model nowcasts and forecasts are normally downloaded and incorporated into the wind product displays at 0300 and 1500 Pacific Standard Time every day. The nowcast we get at 0300 is for the 0000 GMT (or 4PM Pacific Time of the previous day) and the one we get at 1500 is the nowcast for the 1200 GMT (or 4AM Pacific Time). Therefore, there is a 11 hour delay of the COAMPS model output. The implementation of the model used here (provided by Jim Doyle) has very fine spatial resolution (3 km) in an area including the coastal ocean from Pt. Conception to Cape Mendocino.  For clarity, the graphics on this website show only every other wind vector, corresponding to 6 km spatial resolution. Models of this type, as opposed to say global atmospheric models, include physics and detailed terrain that make it possible to realistically simulate the complex atmospheric features found in the nearshore zone.

Why does the model sometimes disagree with the data?

The physics governing the atmosphere are very complex, and the equations used to simulate its behavior are only approximations to what actually happens in nature.  Numerical models are improving all the time, but still have to make educated guesses about how to include some of the processes that affect the atmosphere.  One example of this is that as the size of surface waves in the ocean change, they cause different amounts of drag (or friction) on the atmosphere, thus affecting the wind speed.  Since the wind speed affects the size of the surface waves, there is a feedback loop between the ocean and atmosphere.  This is parameterized inexactly in the model.

Monterey Bay Climate and Weather

Annual cycle

Monterey Bay experiences a mediterranean type climate with cool summers and moderate winters.  Rainfall averages 19 inches per year and falls almost exclusively between October and May.  The seasonal shift between the dry spring/summer period and the wet fall/winter period is governed by the position of the northern hemisphere storm track and of the North Pacific high pressure system.  This seasonal shift also governs the prevailing winds.  In the winter, frequent storms pass through the area resulting in strong winds with variable direction.  The spring transition, in March or April, marks the beginning of several months of predominantly strong winds from the northwest.  These are intermittently interrupted by periods of several days duration when the wind slackens and may come out of the west or south.  In particular, a phenomenon known as a southerly surge will suddenly reverse the wind direction from blowing out of the northwest to coming out of the south, as it propagates northward along the coast.  The fall transition typically occurs in September and is a time of calm winds and sunny weather before the onset of the winter storms, usually in November.  There can be significant year-to-year changes to the "typical" annual cycle, some of it associated with the El Nino – Southern Oscillation (ENSO) cycle and/or the Pacific Decadal Oscillation (PDO).

Microclimates

Due to the proximity of the ocean and coastal mountains (hills), there is considerable variation in the weather over short distances in the Monterey Bay region.  For instance, frequently in the summer Pebble Beach will be foggy, while Carmel Valley is experiencing bright sunshine.  Often you will see distinct differences in the wind speed and direction over the Bay.  For example, when the winds are out of the northwest, the northern part of the Bay will be sheltered and will experience light winds, while the winds in the southern part of the Bay are stronger, and even stronger yet outside the Bay to the west.

Seabreeze

Due to daytime heating, the wind varies in speed and direction over the course of the 24-hour day.  The acceleration of winds directed down the Salinas Valley in the late morning and afternoon is particularly evident on sunny days, and can be seen in the animations.  You will see this effect most pronounced inside the Bay, with less diurnal variation as you go further offshore.

You can learn more about the climatology and meteorology of Monterey Bay at http://www.mbnms.nos.noaa.gov/sitechar/clim.html

ACKNOWLEDGEMENTS

Starting in 2002, the Coastal Observation Technology System (COTS) project funded CIMT to develop one of several demonstrations of regional coastal ocean observing / modeling systems. CIMT is funded under NOAA award #NA16OC2936 July 2002 to July 2005, and appreciates the help and support of the COTS program. CIMT partners Leslie Rosenfeld, Yi Chao, Peggy Li, Todd Anderson, Rondi Robison, and Steve Lonhart participated in the development of this product and they would like to thank Jim Doyle (Naval Research Laboratory, Monterey), Dick Lind, Chuck Wash, and Wendell Nuss (Meteorology Department, Naval Postgraduate School) for their considerable help. They also extend a special thanks to recreational kayakers, parasailers and Kayak Connection for their input and suggestions on this wind speed and direction product.