About

The Sandy Bay Weather Station is located at Sandy Bay, Port Charles on the Coromandel Peninsula. It is operated by David Goodwin (email: first name @zx.net.nz). The weather station in use is a Vantage Pro2 Plus from Davis Instruments. The cabled version is being used due to both cost (half the price) and ease of maintenance (no backup battery to replace every few years). It started logging data at 5:55pm on the 5th of April 2015. On the 10th of September 2016 a more accurate temperature and humidity sensor was installed: ±0.3°C and ±2% across the entire measurement range (the old one was ±0.5°C and ±3% when above -7°C and below 90% humidity).

Current conditions are updated on this website at a rate of up to one update every 2.5 seconds depending on how often wind, etc, is changing. This data takes up to half a second to travel from Sandy Bay to Hamilton, Hamilton to California and then from California to your web browser. The data used in graphs and records tables is updated every five minutes.

The camera has been operating since 9:35am on the 1st of January 2016 and, after a fairly large software upgrade, became available on this website at 11am on the 5th of Feburary 2016. Images for every day from the start of 2016 (aside from 18-29 Jan due to a software glitch) are available - just navigate to the appropriate month and day starting from the "This Year" link at the top of the page.

Data Quality

The weather station is located at the northern end of the beach which limits its wind exposure a little. It also means that it falls in the shadow of the nearby hills at around 2:30pm (in april) which you can see in the UV and Solar graphs as a sudden drop in the afternoon.

In early-mid june 2016 the rain gauge was blocked which caused rain to be reported at the wrong time and at times under-reported (in cases where rainfall was heavy enough to overflow the funnel). The funnel was allowed to drain through the rain gauge at 9pm on the 1st of July causing a large amount of rainfall to be registered at that time.

A worn anemometer bearing was replaced on the 3rd of August 2019. The worn bearing will have probably been affecting readings (especially at low wind speeds) since at least December 2018.

From march 2019 the rain gauge appeared to be giving unusually low readings. It was unblocked in April but appeared to block up again quite soon after. It was unblocked again properly on the 3rd of August. These blockages will have caused the unusually low rainfall readings from March to August.

Starting late March/early April 2021 humidity readings started rarely going above 80% which seems wrong. By november the readings were more obviously bad with humidity occasionally climbing rapidly to 100% for a short period (on the 15th it jumped from from 82% to 100% in the space of 5-10 minutes). On the 19th of November the sensor was replaced with a spare

On the 4th of October the UPS providing backup power failed. This coincided with a covid-19 lockdown which prevented any intervention until the 19th of November. As a result no data was logged between 01:05 on 4 October and 21:30 on 10 November.

Setup Notes

The weather station is connected to Raspberry Pi 2 Model B - a small very low power computer computer with a quad core 900MHz ARM Cortex-A7 processor and 1GB of RAM running a variant of Debian GNU/Linux (Raspbian). To avoid problems caused by surprisingly frequent power disruptions its connected to an APC Back-UPS Pro 550 UPS which can keep everything going for > 2 hours without mains power. For an internet connection it uses a Sierra Wireless AirCard USB 306 GSM Modem with a 12 element Yagi antenna from Tennatron Industries (sold via Trademe) pointed towards Great Barrier Island.

The software in use, zxweather, was written specifically for running weather.zx.net.nz and handles collecting data from the weather station, transmitting it to a server on the Internet via an efficient binary protocol (3G data is expensive!) and producing this website.

Camera

The webcam (TestCam) is currently a prototype to see if its worth having images on this site. So for now its just a cheap Ubiquiti AirCam outdoor security camera. The original image resolution is 1280x720 but the camera applies fairly heavy compression which leaves quite a lot of artifacts in the image. To hide the artifacts and the slightly out-of-focus nature of the images they're scaled down to 640x320 before they're uploaded here. The resizing doesn't really result in any significant loss in detail as the compression applied by the camera has already thrown all that away. Perhaps someday a better (much more expensive) camera will be installed if this experiment goes well.

For traffic cost reasons its not possible to provide a live feed from the camera here. So one picture is uploaded every hour from sunrise until sunset (as detected by the stations solar & UV sensors).

It also currently produces a time-lapse video every day running from a little bit before civil dawn to a little bit after civil dusk (calculated based on date and location). These videos are produced at a rate of one photo per minute squeezing an hour of real time into two seconds of video. They're uploaded automatically every evening about 10-20 minutes after civil dusk and appear in the image section alongside the regular photos. Proper production deployment of video support throughout zxweather was on the 27th of November 2016 with a handful of videos produced with some prototype software from late October. The first few videos can be seen here.

Starting from 24 January 2017 a photo is saved every day at 10am. At the end of the year all of these photos are assembled into a video covering the time from 24 January 2017 at a rate of 10 days per second. The videos produced so far are:

The latest image for this camera is always available from http://weather.zx.net.nz/data/sb/images/test/latest/full. For a thumbnail, use http://weather.zx.net.nz/data/sb/images/test/latest/thumbnail

Other Notes


Some icons are Copyright © Yusuke Kamiyamane. All rights reserved. Licensed under the Creative Commons Attribution 3.0 license. Some icons are from Glyph Icons and are available under the Creative Commons Attribution 3.0 license.