Hi Gregory,

I figger that the climate zone in which you make these observations is of imperial importance with respect to the frequency of sea breezes. Moreover, the sea breeze must originate from the temperature difference between the sea surface temperature (SST) and the land surface temperature (LST), where LST > SST is a boundary condition, which makes or breaks the occurrence of a sea breeze.

Hence at the European West coast sea breezes occur most frequently during spring and summer, when LST is regularly > SST after sunrise and Southwestern to Western winds are sheer completely absent.

So how about the US East coast? what are the boundary conditions there Gregory?

Cheers,

Frank

It is when set is greater than land temp. Most sea breezes from 28-45 deg on the east coast of the us occur from april-aug; but it is unique to the Port as some rivers run colder. I have graphed the sea breezes for 28 ports along the coast for 13+ yrs and see more. Acting in Jan and Feb than any other month.

Below I am providing hodographs for 5 recent days for SSI (April in Spring). SST is cold (66-68F) and daytime air temperatures on land range from 59-79F. I chose a few events with little or no apparent synoptic forcing. In these cases, winds do not swing to the east until after temperatures are above 70 (as expected). As soon as the winds go east, in all cases, the temperature begins to drop (presumably cool water). However, in all cases the late afternoon hours are cooler than the water temperatures (and also cooler than the early morning hours). Interesting observation, but what is confusing is:

After sunrise on April 1, 2, and 11 winds back to the southeast while April 3 and 10 the winds veer to the southeast. In the absence of synoptic forcing, I would expect a veer in all these cases. Yet, I often see backing in the first few months of the year.

In the attached files, I did note that if high tide occured during the peak daylight hours, then the the winds flipped to the east later. Cold water in the back bay (to the southwest) could initiate the sea breeze as a more southwesterly phenomena. Nevertheless, Spring is an interesting time for weather with respect to many scales.

Hi Gregory,

In Indian coastal zone, the phenomenal behaviour of land and sea breeze is common if it is not disturbed by any meso-scale weather phenomena or synoptic SW-monsoon period . So possibility of daytime cold air advection or nighttime warm air advection through any meso-, sub-synoptic-, or synoptic-scale airmass behaviour can not be ruled out but it must be proven with geo-spatial data or information.

Regards,

Rina.

thanks. I did look at the Synoptic wx maps, but indeed they do not show minor phenomena. perhaps there is some slight forcing from the synoptic scale that is less apparent.

When meeting some conditions, sea-breeze may occur. But the synoptic wind is strong enough or observation position is not suitable, sea-breeze may be not detected.

So the frequency of sea breezes can not be decided by the observation.

I apreciate your response. I agree with what you say, but not completely with your last statement. As a lifelong sailor, I believe I can determine a sea breeze by observation. Being a human observer of the collective events might even be better than reviewing the weather station data while blind of the many visual and sensual clues in the environment.

Furenberg et al. 2002 found a list of criteria to filter out synoptic and other effects. They found that the some procedures applied by other researchers over filtered in their sea breezes on Sardinia Island. Unfortunately, they also had mountain/valley effects on Sardinia that is too hare to filter out. I applied the several filters to data collected at weather stations along the east coast of the US (western atlantic) and found some filters to be redundant. For example, a review of the 850 mB map filtered out many of the same synoptic events as just filtering out days with high surface winds or days when wind originated from the sea prior to sunrise. For a given year (8760 hourly observations), I found that cloud cover, temperature tendency, and pre-sunrise wind speeds to filter out all, but less than 200 hours of the remaining synoptic-scale events.

I conclude that observation to include: wind speeds, wind direction, cloud cover, temperature, time of day, and pressure tendency is high enough to identify the majority of sea breezes or modified sea breezes.

we got a basic knowledge about the onset of sea breeze using a water tank.

Yuan Renmin, Sun Jianning, Luo Tao, Wu Xuping, 2013. Scaling Characteristics of the Developing Sea Breezes Simulated in a Water Tank. Boundary Layer Meteorology, 148:455-478.