From updated module outline

Temp/Precip/Extreme Weather

Graphics: (1-2 total)•Historical and projected temperature increase for San Diego County•Graphic showing how daily rainfall accumulations and frequency have changed historically and how they will change projected to 2050. •GHG emissions graphs: historical and projected

Hi Emily – Nilmini provided me with the module outlines on Friday. These seem like a good way to organize what we have been working on for SD2050 graphics. The first module seems most relevant to what we can provide – the Temp/Precip/Extreme Weather module. So I’ve started there.

First – historical temperature for San Diego countyWe went through the global historical climatology network which provides daily data at thousands of sites around the world. Included in this data set is the well-known cooperative observer network. Also included are airport and military sites. We picked 26 sites in the greater San Diego county region that had a) long records (at least 40 years) and b) data for maximum temperature, minimum temperature and precipitation. The next slide shows those sites.

The 26 sites are shown here with a large circle and site name. The color in the circle indicates the elevation of the site (in meters; see color bar). You can see we have sites that are not in the county but may provide a long-enough record to be of general information of relevance to the county. These sites represent our coastal area, our high elevation area and our desert region.

This is a repeat of the previous image without the site names – the names tend to clutter up the slide but may be useful for reference later (when you are wondering exactly where is Eagle Mountain?).

Now that we’ve identified these sites as having reasonable record lengths we investigate to see what the data quality is really like at these sites. We are looking to see if sites have periods of missing data or have values that seem too big or too small. We’re also looking at trends. Do we see the temperature increasing rapidly or decreasing rapidly? Do we see precipitation take a sharp decline or a sharp increase? How do the temperature and precipitation vary from year to year? Does that look reasonable? A site where the temperature doesn’t change very much would be suspect – even more so for precipitation. We know we see quite a bit of variation from year to year in our region.

Our first looks are at annual average temperature; from this we will eliminate some of the 26 sites that we think don’t have a reasonable record. The average temperature is made from the max and min temperatures. We required a year to have at least 345 valid days of observations to be shown here. Of the sites shown here Cuyamaca is pretty good (not much missing). Chula Vista is not bad but the missing data in the 2000s are bothersome.

Eagle Mountain and El Centro have pretty good records. Too much missing data at El Capitan Dam and Elsinore.

The Hayfield Pumping Plant and Imperial records seem to be reasonable; some late 2010ish data missing at Imperial otherwise a good long record.

Palomar looks a bit spotty. Palm Springs and Riverside are not bad – more out of our area but both show an interesting warming (but some missing data problems after 2000).

Santa Ana looks good with trend similar to Palm Springs and Riverside. We really want to use San Diego Lindbergh. We know that a majority of the audience will understand where this is and what the “weather” is like there.

Since we know we probably want to use Lindbergh let’s take a closer look. The record is solid (no missing data; that is a big plus). We see a “jump” in the late 70s but notice from the y-axis this is not that much of a change; we see a similar but not so dramatic drop in the early 1980s. The overall trend is very slight.

Tempting to use Miramar or North Island but missing data after 2000 is troublesome. Long Beach is interesting and may provide some good comparison with Lindbergh (as another coastal site).

Based on just looking at average temperature we’re narrowing down what graphics we are showing next. We have graphics for all 26 sites (if there is interest in a particular site that is not shown we can quickly provide that; all graphics will go to Nilmini and Elizabeth for their database). Let’s focus a bit more on 8 sites: 3 coastal (San Diego Lindbergh, Newport Beach Harbor, Long Beach), 1 mountain (Cuyamaca), 1 inland (Riverside) and 3 desert (Imperial, El Centro, Eagle Mountain).

These plots look at the annual average max temperature at our 8 select sites. These records all seem reasonable. These is not a strong trend except for Cuyamaca which seems to be warming.