PIANO (Penetration and Interruption of Alpine Foehn) - HOBO temperature and humidity logger data set

ABSTRACT This is the data set of 51 HOBO temperature and humidity loggers operated during the field campaign of the research project PIANO (Penetration and Interruption of Alpine Foehn) in the Inn Valley and Wipp Valley near Innsbruck, Austria, during fall and early winter 2017. The goal of the campaign was to study the erosion of cold air pools during south foehn and the associated foehn breakthrough at the valley floor in the vicinity of Innsbruck as well as the subsequent foehn breakdown. The campaign comprises seven Intensive Observation Periods (IOPs), more specifically six south foehn events (IOP 2 to IOP 7) and one west foehn (IOP 1). The HOBO data set does not only include the period of the PIANO field campaign but covers more than a year of data from mid July 2017 to mid November 2018. DATA SET DESCRIPTION 1. Spatial coverage and locations Measurements with the HOBO temperature and humidity loggers were collected during the PIANO field campaign in the greater Innsbruck area, Austria. Most of the loggers were operated at the valley floor on a roughly 1 x 1 km2 grid. A subset of these loggers was deployed along four slope profiles north, south, east and west of the city center. The northern, western and eastern profiles were located on the northern side of the Inn Valley. Of these, the western and eastern profiles were more shallow and reached to approximately 150 m above the valley floor. The southern profile reached to 300 m above the valley floor. The central northern profile extended up to the Nordkette ridge at Hafelekar (1700 m above valley floor). 2. Temporal coverage The PIANO field campaign took place during fall and early winter 2017. However, the HOBO data set is available for a longer period from mid July 2017 to mid November 2018. Due to malfunctions, not all loggers measured continuously during this period. Some loggers have longer data gaps of more than two months (see overview figure of HOBO data set). 3. Instrument details Sensor type and radiation shield Measurements were taken with 51 temperature and relative humidity loggers of type HOBO MX2302, manufactured by Onset Computer Corporation. The logger's external temperature and relative humidity sensors were protected from direct solar radiation by a naturally ventilated multi-plate radiation shield of type RS3-B, also manufactured by Onset. HOBO ID number and serial number The HOBO ID numbers H01 to H51 in the data files refer to the 51 locations where measurements were taken. GPS coordinates and heights of these locations are provided in the data files. Some of the loggers malfunctioned and needed to be replaced. For this reason, the data files also contain the serial numbers and the operation period of the loggers deployed at each location. Time and measurement interval Time in the data files is in UTC. All temperature and humidity values are instantaneous measurements. The measurement interval is 1 minute during the PIANO campaign in 2017 and 2 minutes from the beginning of January 2018 (see overview figure of HOBO data set). The change from 1 to 2 minutes became necessary to avoid memory overflow as a result of a decrease in the frequency of station visits for data downloading after the PIANO campaign. Regardless of this change, the complete time series in the data files exhibits a constant time interval of 1 minute, however, filled with NaNs if no measurement is available at a certain minute. Installation height The majority of HOBO sensors were deployed 4 m above ground level (AGL) on the northern side of street lamps and power or cable car pylons. Exceptions to the standardized installation height were made out of necessity at the southern profile (loggers H34, H35 and H37) and at the central northern profile (loggers H39, H41, H43 and H44). H35 was installed on a metal structure 10 to 20 m above a steep slope and H34 was installed on top of a ski jump tower, less than 1 m above the roof, but around 50 m AGL. H37, the highest station of the southern profile, was located on top of a flagpole at about 5 m AGL. For the northern profile the following HOBO loggers were mounted at 2 m AGL: H44 and H43 on a tree, H41 on a tent pole, and H39 on a lamp pole. Under very calm conditions and with a strong positive or negative radiation balance at the surface (e.g. during sunny days or clear nights), these differences in installation height could be influential. Measurement accuracy and data correction According to the manufacturer’s specifications, the Onset HOBO MX2302 measures temperature and relative humidity (RH) externally with an accuracy of 0.2 K and 2.5 % RH (between 10 % and 90 % RH), respectively. The temperature sensor has a resolution of 0.04 K and drifts less than 0.01 K per year. The RH sensor has a resolution of 0.05 % and a drift of less than 1 % per year. The response times (to 90 % change) of temperature and RH are 5 and 4 minutes, respectively, for air moving 1 m s-1 and with the sensors mounted inside the RS3-B radiation shield. Before the measurement campaign, all HOBO loggers were mounted on the University of Innsbruck rooftop for comparison measurements. The observed differences in temperature between loggers were on the order of 0.2 K and, thus, comparable to the measurement accuracy. Therefore, no corrections have been applied to the data set provided here. 4. Data file structure File format Provided are data in netCDF format as well as overview figures in PNG format. Each netCDF file contains data of one month. File names contain date information. The following wildcard characters are used in the file example below: yyyy - year; mm - month. Data yyyymm_hobo.nc is a netCDF file that contains HOBO data of a specific month. A total of 17 files are provided for the period July 2017 to November 2018. Overview figures hobo_locations.png illustrates the locations of the HOBO loggers on a terrain map. hobo_overview_temperature.png illustrates the whole temperature data set. It is useful for assessing data availability and the change in the measurement interval from 1 to 2 minutes. hobo_overview_relative_humidity.png illustrates the whole relative humidity data set. It is useful for assessing data availability and the change in the measurement interval from 1 to 2 minutes. 5. Publications The HOBO data set is described and analyzed in Muschinski (2019) and Muschinski et al. (2020) with respect to the cold air pool structure in the Inn Valley during south foehn. The data set is also used in Rzehak (2018) and Schmitt (2018) to study Innsbruck's urban heat island in summer and winter, respectively. Furthermore, HOBO data is analyzed in two case studies of PIANO IOP 2 (Haid et al. 2020, Umek et al. 2021). 6. Contact Contact alexander.gohm (at) uibk.ac.at for any questions regarding the data set. 7. Acknowledgements The PIANO field campaign was supported by the Austrian Science Fund (FWF) and the Weiss Science Foundation under Grant P29746-N32, by KIT IMK-IFU, Austro Control GmbH, Zentralanstalt für Meteorologie und Geodynamik (ZAMG), the Hydrographic Service of Tyrol, Innsbrucker Kommunalbetriebe AG (IKB), Bergisel Betriebsgesellschaft m.b.H., Innsbrucker Nordkettenbahnen Betriebs GmbH, T-Mobile Austria GmbH, Unser Lagerhaus Warenhandelsgesellschaft, PEMA Immobilien GmbH, HTL Anichstraße, Hilton Innsbruck, TINETZ-Tiroler Netze GmbH, Land Tirol, and the communities Patsch and Völs. 8. References Haid, M., A. Gohm, L. Umek, H. C. Ward, T. Muschinski, L. Lehner, and M. W. Rotach, 2020: Foehn-cold pool interactions in the Inn Valley during PIANO IOP2. Quarterly Journal of the Royal Meteorological Society, 146, 1232–1263, https://doi.org/10.1002/qj.3735 Muschinski, T., 2019: Spatial heterogeneity of the pre-foehnic Inn Valley cold air pool and a relationship to Froude number: Observations from an array of temperature loggers during PIANO. Master's Thesis. Department of Atmospheric and Cryospheric Sciences, Unversity of Innsbruck, 101 pp., https://resolver.obvsg.at/urn:nbn:at:at-ubi:1-43559 Muschinsik, T., A. Gohm, M. Haid, L. Umek, and H. C. Ward, 2020: Spatial heterogeneity of the Inn Valley cold air pool during south foehn: Observations from an array of temperature loggers during PIANO. Meteorologische Zeitschrift, https://doi.org/10.1127/metz/2020/1043 Rzehak, S., 2018: Städtische Wärmeinsel in Innsbruck im Sommer. Bachelor Thesis, Department of Atmospheric and Cryospheric Sciences, Unversity of Innsbruck, 46 pp. Schmitt, P., 2018: Städtische Wärmeinsel in Innsbruck im Winter: Untersucht im Zeitraum Dezember 2017 bis Februar 2018. Bachelor Thesis, Department of Atmospheric and Cryospheric Sciences, Unversity of Innsbruck, 73 pp. Umek, L., A. Gohm, M. Haid, H. C. Ward, and M. W. Rotach, 2021: Large‐eddy simulation of foehn–cold pool interactions in the Inn Valley during PIANO IOP 2. Quarterly Journal of the Royal Meteorological Society, 147, 944–982, https://doi.org/10.1002/qj.3954

## 摘要
本数据集包含51台HOBO温湿度记录仪（HOBO temperature and humidity loggers）的观测数据，这些设备部署于2017年秋季至初冬期间，在奥地利因斯布鲁克附近的因河谷（Inn Valley）与维普河谷（Wipp Valley）开展的PIANO（阿尔卑斯焚风穿透与阻断，Penetration and Interruption of Alpine Foehn）研究项目野外试验中运行。本次野外试验的研究目标为探究南风焚风过程中冷空气池的消散、因斯布鲁克附近河谷地面处伴随的焚风突破现象，以及后续的焚风消散过程。本次试验共设置7个强化观测期（Intensive Observation Periods，IOPs），其中6次为南风焚风事件（IOP 2至IOP 7），1次为西风焚风事件（IOP 1）。本HOBO数据集不仅涵盖PIANO野外试验时段，还包含2017年7月中旬至2018年11月中旬共计一年以上的观测数据。

## 数据集描述
1. 空间覆盖范围与测点位置
本次HOBO温湿度记录仪的观测数据采集于奥地利因斯布鲁克大都市区的PIANO野外试验期间。大部分记录仪布设于河谷地面，遵循近似1km×1km的网格布局。其中部分记录仪沿城市中心北、南、东、西四个方向的坡面剖面布设。北、西、东三面的剖面均位于因河谷北侧，其中西、东剖面坡度较缓，布设高度最高至河谷地面以上约150m；南剖面的布设高度最高至河谷地面以上300m；中部北剖面则延伸至哈费莱卡尔（Hafelekar）的诺德克特（Nordkette）山脊，海拔为河谷地面以上1700m。

2. 时间覆盖范围
PIANO野外试验的实施时段为2017年秋季至初冬，但本HOBO数据集的覆盖时段更长，为2017年7月中旬至2018年11月中旬。由于部分记录仪出现故障，并非所有设备在该时段内均实现连续观测，部分记录仪存在超过两个月的长时间数据缺失（详见HOBO数据集概览图）。

3. 仪器详情
### 传感器类型与辐射屏蔽装置
本次观测采用Onset Computer Corporation生产的HOBO MX2302型温湿度记录仪，共计51台。记录仪外置的温度与相对湿度传感器搭载Onset公司生产的RS3-B型自然通风多板辐射屏蔽罩，以避免太阳直射对传感器的干扰。

### HOBO编号与序列号
数据文件中的HOBO编号H01至H51对应51个观测测点，数据文件中已提供各测点的GPS坐标与海拔高度。部分记录仪因故障需要更换，因此数据文件中同时包含各测点所部署记录仪的序列号与运行时段。

### 时间与观测间隔
数据文件中的时间采用协调世界时（UTC）格式，所有温度与湿度数据均为瞬时观测值。2017年PIANO试验期间的观测间隔为1分钟，2018年1月1日起调整为2分钟（详见HOBO数据集概览图）。调整观测间隔的原因是PIANO试验结束后，野外站点的数据下载频次降低，为避免存储溢出而进行的设置变更。尽管如此，数据文件中的完整时间序列仍采用固定1分钟的时间步长，若某一分钟无有效观测数据，则以NaN（非数值）填充。

### 安装高度
大部分HOBO传感器安装于路灯、电力杆塔或缆车塔架的北侧，离地高度（AGL，Above Ground Level）为4m。南剖面（记录仪H34、H35、H37）与中部北剖面（记录仪H39、H41、H43、H44）的安装高度未遵循该标准，具体情况如下：H35安装于陡坡上方10~20m处的金属结构上；H34安装于跳台滑雪塔顶部，距屋顶不足1m，但离地高度约为50m；H37作为南剖面的最高测点，安装于旗杆顶部，离地高度约5m。北剖面的部分记录仪安装高度为2m AGL：H44与H43安装于树木上，H41安装于帐篷杆上，H39安装于灯杆上。在极端静稳且地表辐射平衡极强的条件下（如晴朗白天或晴朗夜间），此类安装高度的差异可能对观测结果产生影响。

### 观测精度与数据校正
根据厂商技术规格，Onset HOBO MX2302外置式温湿度传感器的测量精度分别为0.2K（温度）与2.5%RH（相对湿度，测量范围10%~90%RH）。温度传感器的分辨率为0.04K，年漂移量小于0.01K；相对湿度传感器的分辨率为0.05%，年漂移量小于1%。当风速为1m/s且传感器搭载RS3-B辐射屏蔽罩时，温度与相对湿度传感器的90%响应时间分别为5分钟与4分钟。本次观测试验前，所有HOBO记录仪均部署于因斯布鲁克大学校顶进行对比观测，记录仪间的温度观测差异约为0.2K，与仪器测量精度相当，因此本数据集未进行任何校正处理。

4. 数据文件结构
### 文件格式
数据集包含netCDF格式的观测数据与PNG格式的概览图。每个netCDF文件对应一个月的观测数据，文件名包含日期信息，示例中使用通配符表示：yyyy为年份，mm为月份。文件名为`yyyymm_hobo.nc`的netCDF文件包含对应月份的HOBO观测数据，2017年7月至2018年11月期间共计提供17个数据文件。

### 概览图说明
`hobo_locations.png`：展示HOBO记录仪在地形图上的测点位置；
`hobo_overview_temperature.png`：展示完整的温度数据集，可用于评估数据可用性与观测间隔从1分钟调整为2分钟的时间节点；
`hobo_overview_relative_humidity.png`：展示完整的相对湿度数据集，可用于评估数据可用性与观测间隔调整的时间节点。

5. 相关文献
本HOBO数据集已在Muschinski（2019）与Muschinski等人（2020）的研究中被描述与分析，用于探究南风焚风过程中因河谷的冷空气池结构特征。此外，Rzehak（2018）与Schmitt（2018）分别利用该数据集研究了因斯布鲁克夏季与冬季的城市热岛效应。另有两项针对PIANO IOP 2的案例研究（Haid等人2020，Umek等人2021）也使用了本HOBO观测数据。

6. 联系方式
若对本数据集有任何疑问，请联系alexander.gohm (at) uibk.ac.at。

7. 致谢
PIANO野外试验得到了奥地利科学基金（FWF）与魏斯科学基金会（Grant P29746-N32）的资助，同时感谢KIT IMK-IFU、Austro Control GmbH、奥地利中央气象与地球动力学研究所（Zentralanstalt für Meteorologie und Geodynamik，ZAMG）、蒂罗尔州水文局、因斯布鲁克市政公用事业公司（Innsbrucker Kommunalbetriebe AG，IKB）、Bergisel Betriebsgesellschaft m.b.H.、因斯布鲁克诺德克特缆车运营有限公司、奥地利T-Mobile有限公司、Unser Lagerhaus Warenhandelsgesellschaft、PEMA Immobilien GmbH、HTL阿尼希施特拉塞分校、因斯布鲁克希尔顿酒店、TINETZ-Tiroler Netze GmbH、蒂罗尔州政府以及帕奇（Patsch）与弗尔斯（Völs）社区的支持。

8. 参考文献
Haid, M., A. Gohm, L. Umek, H. C. Ward, T. Muschinski, L. Lehner, and M. W. Rotach, 2020: Foehn-cold pool interactions in the Inn Valley during PIANO IOP2. *Quarterly Journal of the Royal Meteorological Society*, 146, 1232–1263, https://doi.org/10.1002/qj.3735
Muschinski, T., 2019: Spatial heterogeneity of the pre-foehnic Inn Valley cold air pool and a relationship to Froude number: Observations from an array of temperature loggers during PIANO. Master's Thesis. Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, 101 pp., https://resolver.obvsg.at/urn:nbn:at:at-ubi:1-43559
Muschinski, T., A. Gohm, M. Haid, L. Umek, and H. C. Ward, 2020: Spatial heterogeneity of the Inn Valley cold air pool during south foehn: Observations from an array of temperature loggers during PIANO. *Meteorologische Zeitschrift*, https://doi.org/10.1127/metz/2020/1043
Rzehak, S., 2018: Städtische Wärmeinsel in Innsbruck im Sommer. Bachelor Thesis, Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, 46 pp.
Schmitt, P., 2018: Städtische Wärmeinsel in Innsbruck im Winter: Untersucht im Zeitraum Dezember 2017 bis Februar 2018. Bachelor Thesis, Department of Atmospheric and Cryospheric Sciences, University of Innsbruck, 73 pp.
Umek, L., A. Gohm, M. Haid, H. C. Ward, and M. W. Rotach, 2021: Large‐eddy simulation of foehn–cold pool interactions in the Inn Valley during PIANO IOP 2. *Quarterly Journal of the Royal Meteorological Society*, 147, 944–982, https://doi.org/10.1002/qj.3954