Klemen Bergant

How reliable are thermal constants for insect development when estimated from laboratory experiments

The concept of thermal time, where a linear relationship between developmental rate (d) and environmental temperature (T) is assumed for plants and poikilothermic animals (∂ = a + b · T ; a is the intercept, b the slope, and ∂ the model estimate of d) (e.g., Bonhomme, 2000), has been widely used as an approximation of physiological time (Trudgill et al., 2005). This approach has been especially common in studies of insect development (e.g., Hon e k & Kocourek, 1990; Hone k, 1996), as temperature plays a major role in the course of their life. Although a linear approximation of the generally non-linear relationship between developmental rate and temperature (e.g., Briere & Pracros, 1998) is valid only within a limited range of temperatures, the simplicity of the thermal time approach makes it very valuable in practice. Thermal constants [lower developmental threshold (LDT) and sum of effective temperatures (SET)] can be estimated from the assumed linear relationship, usually determined from laboratory observations of insect development at different constant temperatures. The LDT, which is defined as the temperature at which the development of insect ceases (d = 0) (e.g., Jaro8 ik et al., 2004; Trudgill et al., 2005), can be estimated as LDT = − a/b. The SET, which is defined as the temperature difference above LTD when total development (d = 1) is reached in a single day (e.g., Jaro8 ik et al., 2004; Trudgill et al., 2005), can be estimated as SET = 1/b (Figure 1). Because the values d = 0 and d = 1, which determine LDT and SET, are extremes in developmental rates and therefore outside the range of values used for the development of the linear model, the estimation of thermal constants is a typical example of extrapolation. This stimulated us to investigate how uncertain the estimates of thermal constants actually are; we base our investigation on laboratory experiments, due to the extrapolation inherent to the computational procedure.

Scanning Mobile Lidar for Aerosol Tracking and Biological Aerosol Identification

We report on the development of a scanning mobile Mie-fluorescence lidar for the detection and identification of biological and non-biological aerosols in the lower troposphere. Our lidar system has the capability to perform azimuth and elevation angle scans with an angular resolution of 0.1° in both day-time and night-time conditions. As the transmitter, we use a solid state Nd:YAG laser with simultaneous emission of 8 ns light pulses at 1064 nm and 266 nm with a maximum repetition rate of 10 Hz. Scattered light is collected by a Newtonian telescope with a diameter of 300 mm. The receiver consists of three channels for the detection of elastic scattering signals at 1064 nm and 266 nm as well as the fluorescence signal of the amino-acid tryptophan intrinsic to biological substances with a local peak at 295 nm. An important benchmark of the system are the aerosol loading measurements pending the eruption of the Icelandic Eyjafjallajokull volcano on 14 April 2010. Experiments on 20 April 2010 showed an elevated aerosol layer at an altitude of 2500 m a.s.l., which was confirmed as a layer of volcanic ash by other experiments. We also present first two-dimensional measurements of aerosol loading in urban areas, which can be of assistance in locating the aerosol sources, their dispersal trajectories, and simulation results for tryptophan fluorescence signal from biological aerosols.

Application of the Ultraviolet Scanning Elastic Backscatter LiDAR for the Investigation of Aerosol Variability

In order to investigate the aerosol variability over the southwest region of Slovenia, an ultraviolet scanning elastic backscatter LiDAR was utilized to make the vertical scan for atmospheric probing. With the assumption of horizontal atmospheric homogeneity, aerosol optical variables were retrieved from the horizontal pixel data points of two-dimensional range-height-indicator (RHI) diagrams by using a multiangle retrieval method, in which optical depth is defined as the slope of the resulting linear function when height is kept constant. To make the data retrieval feasible and precise, a series of key procedures complemented the data processing, including construction of the RHI diagram, correction of Rayleigh scattering, assessment of horizontal atmospheric homogeneity and retrieval of aerosol optical variables. The measurement example demonstrated the feasibility of the ultraviolet scanning elastic backscatter LiDAR in the applications of the retrieval of aerosol extinction and determination of the atmospheric boundary layer height. Three months’ data combined with the modeling of air flow trajectories using Hybrid Single Particle Lagrangian Integrated Trajectory Model were analyzed to investigate aerosol variability. The average value of aerosol extinction with the presence of land-based air masses from the European continent was found to be two-times larger than that influenced by marine aerosols from the Mediterranean or Adriatic Sea.