HMP155 & sensor response time effect on measurement error

Its worth noting that the temperature time constant listed for the HMP155 is at a hefty 3 m/s airflow speed as shown in the photo from its manual. Thus the HMP155 temperature time constant converted to still air will, unfortunately, be significantly higher and hence the HMP155 temperature measurement error due to fluctuating air temperature will NOT be per WMO recommended guidelines as specified in the WMO – The CIMO Guide – Guide to Meteorological Instruments and Methods of Observation, 2014 Edition updated in 2017.

Due to the slow time response of this temperature sensor, an air temperature fluctuation of 2 °C over a period of 2 minutes in 3 m/s airflow will show a measurement error of 0.29 °C (at 3 m/s air speed) on top of the basic sensor accuracy/uncertainty.

Flow obstruction caused by a radiation shield will significantly increase this error for low wind speeds. Despite the status quo, it will be very hard to justify the HMP155’s use for precision climatic measurement. In 1 m/s air, the time constant can rise to 35 seconds and in 0.5 m/s air to 49 seconds, thus producing errors over 0.5 °C due to only the sensor’s slow response time.

• To reduce most air temperature errors due to sensor response time below 0.2 °C a sensor time constant of 13 seconds is required for air speeds of <1 m/s.

• To reduce the errors below 0.1 °C a τ63.2 % time constant of 7 seconds is required for air speeds of <1 m/s.

• The above values were calculated using the online Web calculator at the following link:

  • Influence of sensor response time (τ 63.2%) on climatic temperature measurements

• Below results were calculated using the Web calculator for sensor step response at this link:

  • Calculation of sensor stabilization time for climatic temperature measurements with heated humidity sensors

MeteoHelix® weather station watching over the international Pohoda music festival

The Pohoda music festival weather will not only be monitored by the SHMU but also by the ultra-precise MeteoHelix® IoT Pro weather station connected to the international Sigfox wireless network operated by SimpleCell Slovakia. Being the only micro-weather station capable of providing accurate meteorological data in all climates and weather conditions, the MeteoHelix and its about to be released MeteoWind® Compact IoT are perfectly suited for monitoring crowded and vandalism-prone places such as music festivals and inner cities.

With heat indexes climbing every year, it is important for music festival officials to have accurate data on air temperature and humidity and also on the intensity of solar irradiation to prevent heat strokes and other heat-induced emergencies.

For detailed weather information including weather forecast for the next 24 hrs at the Pohoda music festival, please see the following link:

• https://preview.allmeteo.com/#/ws/1891019 (login to allMETEO.com may be required)

The simple math of climate change

Global warming & climate change is a simple balance between the increase in greenhouse gas emissions and the ability of natural processes to absorb them.

Global Temperature Change = Green House Gas Emissions - ( Natural Plant Life - Agricultural Land Use )

• As Quantity of Green House Gases increases, global temperatures rise. ⇧

• As Natural Plant Life increases, CO2 is absorbed and global warming decreases. ⇩

• As Agricultural Land Use increases at the expense of Natural Plant Life, less CO2 is absorbed and global temperatures increase. ⇧

Increases in CO2 in the atmosphere help promote plant life growth to quickly absorb excess CO2 and return our planet’s climate into balance. As agricultural land use expands, natural pant life areas are converted into agricultural land through the destruction of natural vegetation.

Agricultural land takes up about 37 % of earth’s surface. Since growing seasons last only a few months and crops are harvested just at the peak of their CO2 absorption capabilities, agricultural land absorbs CO2 only a small part of each year. This simple fact creates a large decrease in CO2 absorption capability compared to land with natural vegetation which absorbs CO2 year round.

While the contribution of agricultural equipment to CO2 and equivalent emissions is currently less than 10 % of the total worldwide CO2 emissions (see chart), its contribution to the reduction of natural vegetation has not been accounted for.

Since 1960, both green house emissions and reduction in natural plant life due to expansion of agricultural land are both upsetting the energy balance of our ecosystems in the direction of global warming as shown below:

• CO2 concentrations have increased from 317 to 409 ppm by 30 % ⇧

• Agricultural land use has increased from 1.38 billion to 1.58 billion by 15 % ⇧, leading to a decrease world wide in natural vegetation.

Can recision agriculture solve global warming?

Precision agriculture has been around for years, though no one knew how to name it. Since the invention of the personal weather station with a tipping-bucket rain gauge by RainWise Inc., farmers have had access to somewhat accurate local meteorological data, yet not many knew how to take full advantage of it. With the advances in computing power, agricultural equipment and data processing techniques, higher precision data becomes more valuable to take full advantage of the possible increases in farming efficiency. This, in combination with the looming Internet-of-Things technological revolution, has lead to the reinvention of the personal weather station as a professional quality instrument by BARANI DESIGN Technologies. Its MeteoHelix® micro-weather stations are able to produce meteorological data of higher quality than most current climatological networks (3), in excess of World Meteorological Organization (WMO) requirements, for a fraction of the price of the most popular RainWise and Davis personal weather stations.

Since farming is highly dependent on weather, farming decision making is dependent on good meteorological data quality. New farming efficiency gains through high-quality meteorological and soil data can significantly increase crop yields. If sensor and data affordability is maintained not at the expense of data quality with the goal of reversing global warning, as with the MeteoHelix® weather stations, increases in crop yields will allow for a reduction in global agricultural land use. Reduction in global agricultural land use leading to expansion of natural vegetation areas will offset higher CO2 emissions even while our world population and emissions expand. The climate change equation will be moved closer to balance again.