A fast Fourier transform was applied to fit the geomagnetic diurnal variation. Fitting results showed that when the polynomial degree was greater than 160, the residual error was close to 0 nT. White noise is the main component of the residual error when the polynomial degree was greater than 160, so this method was adopted to calculate the background noise of the geomagnetic field. Spectrum analysis further demonstrated the necessity to remove background noise from geomagnetic data.

To improve microwave satellite and airborne observation products in forest environments, a precise and reliable estimation of the permittivity of trees is required. We developed a probe suitable to measure the permittivity of tree trunks at L band in the field. The system is easily transportable in the field, low energy consuming, operational at low temperatures and weatherproof. The permittivity of seven tree species in both frozen and thawed states was measured, showing important contrast.

The main purpose of this paper is to introduce a receiver system for the synchronous acquisition of multiple electromagnetic signals in transient electromagnetic prospecting to achieve multiparameter and multichannel synchronous reception. The reliability, practicability, and data validity of the receiver were verified by different kinds of testing. It can be used for the reception of pseudorandom signals and distributed 3-D data, which can improve geophysical exploration efficiency.

A DTS system, using fibre-optic cables as a temperature sensor, measured surface and subsurface temperatures at a boreal forest underlain by permafrost in the interior of Alaska for 2 years every 30 min at 0.5-metre intervals along 2.7 km to monitor the daily and seasonal temperature changes, whose temperature ranges between −40 ºC in winter and 30 ºC in summer. This instrumentation illustrated characteristics of temperature variations and snow pack dynamics under different land cover types.

This BPNN approach with two alarms was well suited, and it was not necessary to consider the problems of characterising the wave phases and pre-processing, as stated previously. Furthermore, BPNN is a mature technology, which is expected to develop rapidly in the future, and does not require complex hardware. Determining an initial location and magnitude of the event was not necessary for this technique. An existing seismic monitoring network can be used.

TanSat is a key satellite mission in the Chinese Earth Observation program and is designed to measure the global atmospheric column-averaged dry-air CO₂ mole fraction. Several critical aspects of the spectrometer, including the spectral resolution, spectral dispersion, and the instrument line shape function of each channel were evaluated. The instrument line shape function of the spectrometer is notably symmetrical and perfectly consistent across all channels in the three bands.

In this study, a high-precision distributed wireless microseismic acquisition system has been designed for oil and gas exploration. The system design, which was based on the ADS1274 chip manufactured by TI, made full use of the four channels of the chip to collect vibration signals in three directions and one electrical signal, respectively. Furthermore, the acquisition system used GPS and WIFI technologies to achieve distributed wireless acquisition.