Spatial and temporal variations of stable isotopes in precipitation in midlatitude coastal regions

Abstract

Spatial and temporal variations of the isotopic composition of precipitation were investigated to better understand their controlling factors. Precipitation was collected from six locations in Hokkaido, Japan, and event-based analyses were conducted for a period from March 2010 to February 2013. Relatively low δ values and a high d-excess for annual averages were observed at three sites located along the Japan Sea compared to the three sites at Pacific Ocean side.Lower δ values in spring and fall and higher d-excess in winter were observed for the region along the Japan Sea. In total, 264 precipitation events were identified. Precipitation originated predominantly from low-pressure system (LPS) events, which were classified as northwest (LPS-NW) and southeast (LPS-SE) events according to the routes of the low-pressure center, that passed northwest and southeast of Hokkaido, respectively. LPS-SE events showed lower δ 18 O than LPS-NW events, which is attributable to the lower δ 18 O of water vapor resulting from heavy rainfalls in the upstream region of the LPS air mass trajectories over the Pacific Ocean. This phenomenon observed in Hokkaido can be found in other midlatitude coastal regions and applied for hydrological, atmospheric, and paleoclimate studies. A characteristic spatial pattern was found in LPS-NW events, in which lower δ 18 O was observed on the Japan Sea side than on the Pacific Ocean side in each season. This is likely due to the location of the sampling sites and their distance from the LPS: Precipitation with lower δ 18 O in the region along the Japan Sea occurs in a well-developed cloud system near the low-pressure center in cold and warm sectors of LPS, whereas precipitation with higher δ 18 O on the Pacific side mainly occurs in a warm sector away from the low-pressure center. Air mass from the north does not always cause low δ in precipitation, and the precipitation process in the upstream region is another important factor controlling the isotopic composition of precipitation, other than the local temperature and precipitation amount. KEYWORDS air mass trajectory, atmospheric water vapor, Hokkaido, precipitation event, route of low-pressure system, stable isotopes of water

A Lacustrine Biomarker Record From Rebun Island Reveals a Warm Summer Climate in Northern Japan During the Early Middle Holocene Due to a Stronger North Pacific High

“…This is equivalent to the formula δD 5.12 . The MAT at the study site is 6.4°C (1981-2010; Japan Meteorological Agency, https://weather.time-j.net/ Stations/JP/teshio) and the mean annual δD at Teshio 80 km southeast of the sampling site is −69.6‰ (2010-2014Li et al, 2017). These values are consistent with the relationship described above.…”

“…In winter, the westerly wind axis shifts south, a cold and dry air mass occupies the study site, the δD of precipitated water is lighter, and the d-excess is higher. The higher d-excess in winter is attributed to kinetic fractionation during the evaporation process in the Sea of Japan under a large humidity deficit and a strong temperature contrast in the air-sea surface interface (Sugimoto et al, 1988;Li et al, 2017).…”

Water age in stormwater management ponds and stormwater management pond‐treated catchments

“…Samples taken during an event or within 48 hr of the end of an event (the last record of ≥1‐mm hourly rain or when winter air temperatures returned to 0°C after exceeding 2°C) were classified as “event samples,” and all others were classified as “baseflow samples.” Accordingly, 25% of our samples were event samples and 75% baseflow samples. Composite rain samples were collected using a stationary funnel with a polyethylene vessel that is modified with a long thin venting tube to avoid evaporation (Li, Sugimoto, & Ueta, ), whereas composite snowmelt was collected using a melt‐pan with the dimensions of 20‐cm wide, 30‐cm long, and 10‐cm tall, following the design outlined in Tekeli, Sorman, Sensoy, and Şorman (). Upon collection, samples were stored in 20‐ml high‐density polyethylene scintillation vials with conical polyseal caps to reduce airspace, wrapped in parafilm, and stored in a dark cool place to minimize evaporation (Anderson et al, ; Garvelmann et al, ; Kanduč, Mori, Kocman, Stibilj, & Grassa, ; Li et al, ; Tetzlaff et al, ).…”

“…Composite rain samples were collected using a stationary funnel with a polyethylene vessel that is modified with a long thin venting tube to avoid evaporation (Li, Sugimoto, & Ueta, ), whereas composite snowmelt was collected using a melt‐pan with the dimensions of 20‐cm wide, 30‐cm long, and 10‐cm tall, following the design outlined in Tekeli, Sorman, Sensoy, and Şorman (). Upon collection, samples were stored in 20‐ml high‐density polyethylene scintillation vials with conical polyseal caps to reduce airspace, wrapped in parafilm, and stored in a dark cool place to minimize evaporation (Anderson et al, ; Garvelmann et al, ; Kanduč, Mori, Kocman, Stibilj, & Grassa, ; Li et al, ; Tetzlaff et al, ). All samples were tested for δ 18 O and δ 2 H. Samples were analysed at the University of Manitoba, the University of Toronto Scarborough, and Carleton University.…”

Spatial and temporal distributions of stable isotopes in precipitation over Thailand

“…Precipitation is an important part of the hydrologic cycle, as it is the predominant source of water to land. Correspondingly, understanding how the stable isotopic composition of precipitation is controlled by its formation (Genereux & Hooper, 1998) and knowledge of the spatio‐temporal variations in stable hydrogen and oxygen isotopic ratios of precipitation (δ 2 H and δ 18 O) are equally important in the field of isotope hydrology (Bedaso et al, 2020; Lemma et al, 2020; Li et al, 2017; Sun et al, 2016). Stable isotopes play a significant role in observing, reconstructing, and understanding past and present climatic conditions (Jiao et al, 2020; Rozanski et al, 1997; Xia et al, 2020).…”