LA's Climate: Past, Present, and Future

Los Angeles Today 

(http://www.youtube.com/watch?feature=endscreen&v=uGcDed4xVD4)

Presently, Los Angeles experiences fairly consistent temperatures throughout the year due to its maritime location.  The precipitation is highest during the spring and winter months, and dry during the summer months.

(http://www.csun.edu/~klb27749/junk/spreadsheets/graphs-pdf.pdf)

While present day Los Angeles is on the coastline of the United States, in the past the city was underwater.  This makes it difficult to quite say what its climate was like, but we do know that an overall higher temperature was cause for such high water levels that submerged the city.

Earth 100 million years ago  

(http://www.ncdc.noaa.gov/paleo/ctl/cliscibeyond.html)

For the sake of this assignment, let's speculate what LA would have been like if it remained above ground.  100 million years ago there was overall higher temperatures, with ocean temperatures up to 27 degrees Fahrenheit higher than today's.  With a lower temperature gradient throughout the earth, ocean currents and winds were less powerful.  Los Angeles continues to be at about the same latitude, so the biggest effect would have been the increase in ocean temperature.  With an overall increase the climate would be comparable to a tropical climate. 

 

Los Angeles 100 Million Years from now

(http://www.youtube.com/watch?feature=endscreen&v=uGcDed4xVD4)

In the future, Los Angeles will return to its location underwater.  If it were not underwater, the impact of any shifting would not be as great as in some locations once again because of its maritime location and little change in latitude.  Although as seen before, the ocean temperatures do have an impact.  Where currently a year-round cool ocean breeze keeps a consistent temperature year round, the increase in ocean temperature would increase the city's temperature.

Should temperatures increase to as they were 100 million years ago.  We would see another humid and warm tropical-esque climate for Los Angeles (See climograph for 100 mya).  Of course, this is only if the city weren't entirely underwater.

Climate in Los Angeles compared to Springfield, MO

Looking at Springfield, Missouri gives a great contrast to the weather and climate in Los Angeles, California.

Springfield is in the mid latitude and is a land-locked area.  The absence of the offshore breeze allows for a greater variance in temperature throughout the year.  Where Los Angeles' latitude is is at 34°07′n, Springfield is at 37°13′n

(Weather.com)

According to the Köppen-Geiger Climate Classification, Springfield is in the category of Dfa or Humid Continental Climate.  Springfield experiences higher precipitation throughout the year than Los Angeles (noaa.gov). Springfield, MO averages more precipitation than Los Angeles, CA by 30.6in.

 

(Weather.com)

 

Springfield, MO experiences times of high temperatures, as well as very low temperatures.  They also have events such as ice storms and tornadoes.  There can be high winds due due to nearby valleys.

Overall, the main difference seen is that there is more consistent weather in California due to the coastal breeze and the variance in latitude.  Springfield experiences more extreme highs, lows, and natural events, as well as an increased amount of precipitation.

Climatology of Los Angeles

 Köppen-Geiger Climate Classification

Under the Köppen-Geiger Climate Classification the coastal areas are classified as Csb and the inland areas are Csa.  This means they experience a warm temperate climate with dry summers.  The coastal summers experience a warm summer, where inland experiences hot summers.

 

(www.schweizerbart.de/resources/downloads/paper_free/55034.pdf)

Climate Controls

 
Los Angeles' proximity to the Pacific Ocean has a great impact on the weather.  The onshore flow helps regulate the temperature where there is a fairly consistent temperature throughout the year.

As mentioned, the city is bounded by the Santa Monica Mountains to the north, with the San Gabriel Mountains bordering to the east. This has a great effect of the smog levels in Los Angeles. This problem is fed by the pollution of millions of daily commuters.

(losangeles.ourtiempo.com)

Climate Change

The average annual temperature of Los Angeles since 1921 has increased, but the change has been less dramatic since 2000. It is also difficult to accurately evaluate climate change on such large scales without knowing greater details.

 

(http://www.climatestations.com/los-angeles/)

Climate in Los Angeles compared to Lima, Peru

Both coastal cities on the Pacific Ocean, Lima and Los Angeles share many differences and similarities.

Although the seasons are variedbetween the north and south hemispheres, the temperatures in Los Angeles and Lima remain very steady and similar throughout their seasons.

(weather.com)

 Lima has a much lower precipitation rate due to the Andes Mountains. Los Angeles also experiences fairly low precipitation, but this is due to the dominance of the stable marine layer. Precipitation is rare between May and October and any rain that does occur is usually the result of isolated thunderstorms associated with subtropical moisture. During the remainder of the year the eastern Pacific high pressure ridge is displaced and Los Angeles finds itself on the southern margins of the northern hemisphere polar jet stream. With cold air aloft, the marine layer breaks down. Pacific storms, sometimes fed with subtropical moisture, often push cold fronts across California from northwest to southeast.(http://www.wrh.noaa.gov/lox/climate/climate_intro.php)

(weather.com)

 

Both Lima and Los Angeles experience weather due to maritime air masses, where both are influenced by polar air, Los Angeles is also greatly influenced by subtropical air.

Air Masses

 Los Angeles often experiences cool temperatures due to the onshore flow from the Pacific Ocean.

(image source : http://www.nc-climate.ncsu.edu/edu/k12/.breezes)

In Los Angeles upper air inversions develop because it is on the edge of the subtropical high pressure cell in the Pacific Ocean. Subsiding air from the high pressure cell is compressed by the increasing pressure of the surrounding air as it descends, so the air warms up as it subsides.  Combined with the cool air at ground level from onshore flow, there is also a general subsidence of warm air aloft. The inversion layer acts as a lid to prevent air at ground level from rising and dispersing.  The mountains inland also help trap the air.  

(image source: http://www.ec.gc.ca/air/default.asp?lang=En&n=AFF4D58F-1)

Any pollutants emitted build up in the trapped air.  The smog worsens in high temperatures and clears best with high winds.

 

(image source: http://www.huffingtonpost.com/2009/07/10/la-vows-to-be-coalfree-by_n_229832.html)

(http://daphne.palomar.edu/calenvironment/smog.htm) 

Geography of Los Angeles

Los Angeles, California is home to nearly 10 million people, making it the second largest city in the United States.  As the weather affects many people, the people have an effect on the weather.  Smog and air pollution collect in the coastal basin during times of little air movement, a common problem in the city.

The city is bounded by the Pacific Ocean to the west and south, carrying north to the Santa Monica Mountains, with the San Gabriel Mountains bordering to the east.  The temperatures in Los Angeles are mild throughout the year, due to the heavy influence of the warm, moist Pacific air.

(sources: U.S. Census Bureau, city-data.com)

Average Temperature and Precipitation

The annual average temperature for Los Angeles is 63.9°F with an average of 17 inches of precipitation annually.

Average Monthly Temperatures (°C)

 (source: weather.com)
Average Monthly Precipitation (mm)

  (source: weather.com)