Update on HPWREN Real-time Santa Ana Weather Alerts

16 April 2018

An experimental update for real-time weather alerts, based on the original HPWREN implementation from 2004 (http://hpwren.ucsd.edu/news/041106.html), is now operating on a trial basis. This new version, which utilizes data from HPWREN and SDG&E weather stations, supports multiple profiles, including which sensor thresholds to use, which sensor subset to analyze (or "all"), and which email addresses to send the real-time alerts to. It currently analyzes data every few minutes from usually about 170 weather stations, with an ability to support many analysis profiles.

Image 1. Illustration of the sensor locations, based on an HPWREN real-time data sensor map focusing on Santa Ana wind events for Google Earth using both HPWREN and SDG&E meteorological sensor data. The tower colors are reflective of wind directions, ranging from red (60 degrees = Santa Ana direction) to blue (240 degrees = coastal winds). The tower heights are reflective of wind speed. A tower can be clicked for a real-time data display.

In its implementation, the system consists of two principal components on an HPWREN server, one that loads real-time sensor data into shared memory as it arrives via multicast from the data collectors, and a processing and analysis component, running every few minutes. The analyzer reads the data from shared memory, and then sequentially reads profile files, which contain the parameters for the interpretation and enumeration of the sensors to be used (or "all"). It currently considers only Relative Humidity, Wind Speed, and Wind Direction, as there are no remaining Fuel Moisture sensors in the system. As before, the default (profile 1) trigger behavior is:

Image 2

To avoid oscillations of the alert conditions, the clearing of an alert requires that:

All alerts also get currently cleared at 7 AM, resulting in reminders if the condition still persists. An email header file corresponding to a specific profile enumerates the email/SMS recipients for the alerts. An email alert may look like:

Date: Fri, 13 Apr 2018 21:28:01 -0700

From: HPWREN real-time weather data alerts ❬weatheralerts@hpwren.ucsd.edu❭

To: l2@hpwren.ucsd.edu

Subject: Santa Ana condition real-time weather sensor alert (1)

H-ML: RH=16 WD=51 WS=26 AT=46 20180413.212738 Mount Laguna (32.89,-116.42)

Sensor identifiers beginning with "H-" are HPWREN sensors, while those starting with "S-" are part of the SDG&E weather stations system. The other parameters in the email are Relative Humidity, Wind Direction, Wind Speed, Air Temperature, date.time stamp, sensor descriptive name, and sensor location. Image 1 illustrates the sensor locations in Google Earth, based on hpwren.ucsd.edu/KML/sensor-viz.kml. Image 2 shows an example multi-line page on a smart phone.

Please contact us via email or the HPWREN feedback form at http://hpwren.ucsd.edu/contactForm4.html if you are interested in the trial. Please consider that the default (all sensors) profile can easily generate more than a hundred emails/page per day during a substantial Santa Ana condition.

With many thanks to SDG&E for real-time access to their weather station data.