# Isoprene Emissions, Oxidation Chemistry and Environmental Impacts
## 6 Measurements of Isoprene and Model Validation
\begin{table}
\begin{tabular}{l l l l l l} \hline \hline
**Location** & **Time** & **Lat, Lon** & **Measurement Technique** & \
\begin{tabular}{l} **Measured Isoprene** \\ **Mixing Ratio (ppb)** \\ \end{tabular} &
\begin{tabular}{l} **Modeled Isoprene** \\ **Mixing Ratio (ppb)** \\ \end{tabular} \\ \hline Guangdong, China \(-1000\) m [134] & Annual & \(23,112\) & GC-MS & \(0.76\pm 0.50\) & \(0.27\) \\ \hline Hong Kong \(-507\) m [135] & Jun-Jul & \(22,114\) & GC-FID & \(1.03\pm 0.03\) & \(0.66\) \\ \hline Lin’an Station, China \(-130\) m [136] & Apr-May & \(30,120\) & GC-MS/FID & \(0.55\pm 0.52\) & \(0.37\) \\ \hline Jianfeng Mountain, China \(-820\) m [136] & Apr-May & \(18,108\) & GC-MS/FID & \(0.40\pm 0.39\) & \(0.39\) \\ \hline Tengchong Mountain, China \(-1960\) m [136] & Apr-May & \(24,98\) & GC-MS/FID & \(0.08\pm 0.16\) & \(0.14\) \\ \hline Tengyue Town, China \(-1660\) m [136] & Apr-May & \(25,98\) & GC-MS/FID & \(0.13\pm 0.06\) & \(0.06\) \\ \hline Tai O, Hong Kong \(-80\) m [137] & Annual & \(22,114\) & GC-MS/FID & \(0.37\pm 0.16\) & \(0.27\) \\ \hline Mt. Tai \(-152\) m [138] & Jun-Jul & \(36,117\) & GC-ATS/FID & \(0.15\pm 0.18\) \({}^{*}\) & \(0.01\) \\ \hline Tibet, China \(-386\) m [139] & Jul-Aug & \(36,101\) & GC-FID/CD/MS & \(0.13\pm 0.29\) \({}^{*}\) & \(0.01\) \\ \hline France \(-650\) m [140] & Jun & \(43,5\) & PIR-MS & \(2.09\) & \(0.11\) \\ \hline Bosco Fontana Nature Reserve, Italy [141] & Jun-Jul & \(45,10\) & PIR-MS & \(1.07\pm 0.80\) \({}^{*}\) & \(0.09\) \\ \hline Montsensory, Barcelona, Spain \(-720\) m [142] & Jul-Aug & \(41,2\) & PIR-MS & \(0.43\) & \(0.17\) \\ \hline Ocean: Cape Town to Crocer Island [143] & Dec & \(-35\) to \(-47,18\) to \(51\) & GC-PID & \(0.033\) \({}^{*}\) & \(0.0002\) \\ \hline Ocean: Hobart to Putra Arenas [143] & Jan-Feb & \(-43\) to \(-72,2\) & GC-PID & \(0.047\) \({}^{*}\) & \(0.002\) \\ \hline Ocean: Punta Arenas to Cape Town [143] & Mar & \(-34\) to \(-46\) & GC-PID & \(0.038\) \({}^{*}\) & \(0.032\) \\ \hline \hline \end{tabular} Note: The values are reported as daytime average mixing ratios except the values with \({}^{*}\), which are daily average mixing ratios. The sampling heights (where available) are also shown in the six description.  
\end{table} 
Table 2: _Cont._The isoprene mixing ratios in the Amazonian ecoreg are comparatively higher than in any other region and show an enormous variation depending on site, height, and season (Table 2). The measured isoprene mixing ratios in the Amazon follow a clear diel pattern as a function of light and temperature [117; 119; 120]. Compared with the dry season, a factor of two to three reduction in isoprene mixing ratios was observed at the Amazon forest during the wet season due to fluctuations in light, temperature, and leaf area index [117; 119; 121]. The isoprene measurements in the tropical savanna atmosphere [123; 124] showed the higher mixing ratios in woodland savanna and large vegetation compared with grassland savanna and low vegetation. A seasonal cycle with lower mixing ratios of isoprene during the dry season was observed due to a lower physiological activity of the vegetation compared with the wet season [123; 124]. The first airborne isoprene measurements over the tropical rainforest of Surinam by [PERSON] et al. [125] showed that the mixing ratios of isoprene increase strongly with the time of day and distance from the coast in accordance with ground-level emissions during the daytime. Measurements of isoprene within a Southeast Asian tropical rainforest by [PERSON] et al. [127] showed good agreement between surface and aircraft measurements of boundary layer isoprene levels above this natural rainforest, suggesting that, at least for the region studied, ground-level observations could be treated as broadly representative of isoprene emissions for that region. [PERSON] et al. [141], [PERSON] et al. [142], and [PERSON] et al. [140] observed high isoprene mixing ratios at Bosco Fontana Nature Reserve, a mixed oak and hornbeam forest in northern Italy, and an elevated (720 m a.s.l.)