Tag Archives: Air temperature

RFc package: FetchClimate Client for R

Today my RFc package was accepted and published on CRAN.

With this package you can right now fetch the following environmental parameters

  • absolute air humidity
  • air temperature
  • elevation
  • diurnal temperature rate
  • frost days frequency
  • wed days frequency
  • potential evapotranspiration
  • precipitation rate
  • relative humidity
  • soil moisture
  • sunshine fraction
  • water vapour pressure
  • wind speed

The parameters above can be fetched for the point set of for the geo grid specified.

The original service providing data is collaborative project of Microsoft Research Cambridge and Information Technologies in Science lab where I currently work.

Toradex Oak sensors on FreeBSD

As the world moves toward the Internet of Things there are lots of cheap environmental sensors available at the market.
When it just started several years ago I spotted the Toradex company that sells embedded devices. I caught sight of the sensors series called Toradex Oak sensors. The Toradex supplied Microsoft Robotics Studio libraries for them which was right enough for my student project. So I ordered two.

Now I’m building the monitoring system for a summer house based on Raspberry PI. And these sensors made by Toradex suits well for gathering environmental data.
The official site provides a sample of using the sensors on linux. But I have a FreeBSD.
So I started to think about constructing a simple solution to gather the data on BSD.

The sensors identify themselves as HID devices. After short investigation I found that FreeBSD provides usbhidctl utility to communicate with HID. That looked promising as it did not require linux emulation. With a single command we are able to fetch all the immediate values from the sensor!

Another task was data storage engine. My colleague Eugene suggested me using collectd or statsd to organize storage. Both of them appeared to be able to store the data and to stream the data to remote host for further storage. I decided to use collecd as it is in C so my Rapberry PI box will have minimal package set.

Finally I ended up with the script that is invoked by collectd. The script enumerates HID USB devices, finds Toradex sensors, gets the values from them, applies proper units transformation and returns the data as the string compatible with collectd.

I share it here. So you can download it, modify and extend for your needs.

Open the post to access downloads.

GHCN v3 in SQL

The Global Historical Climatology Network-Monthly (GHCN-M) dataset by NCDC is particularly important data set if your research deals with climate data. It is widely accepted. Its major advantage is quality control and a variety of data sources combined together. I used it several times as reference data for validation of calculated climate surfaces. It is also great for uncertainty assessment of climate interpolation methods.

But it is distributed as text files of specific format only. And you will have to write a parser to fetch the data.

This week I decided to load the GHCNv3 into MySQL to make it flexible for fetching. I can fetch different subsets of the data into CSV files just with composing a proper select query. That made a significant speed up in experiments with interpolation techniques.

I share these SQL scripts to enable others researchers to load GHCN v3 into their own SQL servers. You can restore GHCN at your server and perform requests to it. Just download the script, execute it. And you are able to get the data you need. Fast :)

The scripts do not contain CREATE DATABASE statements. Thus create an empty database by hand and then execute the proper script.