Climate Stations Deployment

The currently used sensors are from Fine Offset Electronics and in Nature 40 identical in construction from froggit as the so-called DP series and from ecowitt with the original series identification GW-1000.

Currently 5 WiFi Hubs with 8 sensors and one base station each are connected via via LoRa radio. The base station is equipped with wind vector, precipitation irradiance and temperature/humidity sensors. The WiFi Hub in turn uses any accessible WLAN to pass on the data in this case via mobile network to a data server.

Sensor Specification

GW1000/DP1500 WiFi hub:

Frequency: 868Mhz
Air temperature range: -10°C to +60°C, resolution: 0.1°C, accuracy: +/- 1°C
Air humidity range: 10% - 99%, Resolution: 1%, accuracy: +/- 5%.
Air pressure range: 300-1100hPa, resolution: 0.1 hPa, accuracy: +/- 5hPa
Power supply: USB 5V

DP50 temperature/humidity sensor:

Frequency: 868Mhz
Air temperature range: -10°C to +60°C, resolution: 0.1.°C, accuracy: +/- 1°C
Air humidity range: 10% - 99%, resolution: 1%, accuracy: +/- 5%.
Transmission interval: 48 seconds
Power supply: 2 x 1.5V AA batteries

Base Unit:

Frequency: 868Mhz
Temperature range: -40°C to +60°C, accuracy: +/- 1°C
Air humidity range: 10% - 99%, accuracy: +/- 5%
Precipitation: range 0-9999mm, resolution +/- 0.25mm, accuracy: +/- 10%
Wind speed: 0-50m/s, accuracy: +/- 3.5 km/h or 10%
Wind speed/gust calculation every 16 s
Wind direction accuracy: +/- 1°
UVI: range: 0 - 15 index, UV accuracy: +/- 15%
Solar radiation: range 0 - 200k Lux, accuracy +/- 15%
Measuring interval outdoor unit: 16 seconds
Power supply: Outdoor unit: 2 x 1.5V AA batteries. The primary energy source is the solar panel. The batteries provide backup power when solar energy is limited.

Calibration Concept

The low budget sensors are usually lacking of a stable measurement quality. To obtain reliable micro climate data a two step calibration process is implemented. In a first step the measurements of all sensors will be statistically analysed to identify sensor which produce outliers. In a second step the sensors are calibrated against an operational running high price reference station in the field.

For the future a machine learning approach including the radiation, azimuth, temperature and humidity as predictors for the calibrated temperature as the response variable will be used as an rolling calibration tool.

Channel Assignment and and Station Coding

HubId	WeatherStationId	BaseID	CH01	CH02	CH03	CH04	CH05	CH06	CH07	CH08
GW100A-WIFI243E	E5C37C83C2C1EB2C 62BC8FC299D8E281	45	e0	20	49	c8	42	eb	20	bc
level		ground		l7	l6	l3		l4	l5
GW100A-WIFIF774	D3E7B46BC773DA5D 0D30F7B94570700F	cc	40	99	22	bb	d	db	5b	65
level		ground	tt	l7	l3	l2	l1	l5	l6	l4
GW100A-WIFIF824	64B95BE38E36DB75 ECE69E193C9CFD62	2f	33	ee	2d	c0	fd	f1	6e	7a
level		ground	l5	l2	l1	l3	l6	l4	tt	l7
GW100A-WIFIFB27	C90B7356EFDA99C5 584B057DA2363EDB	3e	3b	b8	e2	4d	89	d2	c3	d3
level		ground	l7	l4	l1	tt	l2	l3	l5	l6
GW100A-WIFIFC29	CC354E3266838432 3E5CB75B8D4A4722	7c	f	8f	92	9c	c	57	53	9d
level		ground	l7	l6	l1	tt	l4	l2	l3	l5

Pre-Calibration

The first calibration step is completed.

Calibration Step 1a — *Pre-calibration setup. Un-shielded Sensors (left), Setup of a radiation shield (middle), all sensors protected with a passive radiation shield (right)*

Calibration Step 1b — *Pre-calibration setup. Un-shielded Sensors (left), Setup of a radiation shield (middle), all sensors protected with a passive radiation shield (right)*

The 40+ sensors will be moved to the Campbell reference station in the Marburg Open Forest at the beginning of week 24, where calibration phase 2 will start.

Field Calibration

The current deployment situation of the Micro-Climate-Sensors is shown on the map below. Currently we are running in a calibration mode.

More data is available by clicking on the station.

Full-screen version of the map

The field calibration step is finished.

Calibration Step 2a — *The installation of the field experiment. Overall setup (left), Detail of the gw1000-sensorbox (middle), Passive radiation shield array (right)*

Calibration Step 2b — *The installation of the field experiment. Overall setup (left), Detail of the gw1000-sensorbox (middle), Passive radiation shield array (right)*

3D Tree Sensor Deployment

The equipping of the selected five core study trees with three-dimensionally distributed climate sensors is finished.

placeholder image 1 — Some temperature/humidity sensors on cst_00076. The holders of *cst_00071* will be extended soon to roughly 60 cm in order to measure the temperature and humidity inside the tree crown instead of the immediate stem climate.

3D Climate Data

The sensors are running in the Marburg Open Forest. The core study trees that are shown on the underneath map. For a convenient overview please have a look at the ecowitt dashboard (need account). For the following core study trees (cst see also map below) you will find live data in a two minutes resolution:

cst_0002 GW100A-WIFIF774
cst_0028 GW100A-WIFI243E
cst_0050 GW100A-WIFIFC29
cst_0051 GW100A-WIFIFB27
cst_0076 GW100A-WIFIF824

In additon the raw data stream is available via the sensingbiodiversity server.

Note: The calibration phase was completed on July 12 (2020). At this stage, the data have not been checked or validated in any way.

Map of 3D Climate Sensor Trees

Full-screen version of the map