N-ICE2015 surface and under-ice spectral shortwave radiation data

This data set contains spectral shortwave radiation data (incident, reflected and transmitted) from two different sites: time-series from a fixed site on Floe 3 and 4, so called "supersite", and from point measurements from a "refrozen lead" during drift of Floe 3. #### Supersite Downwelling and upwelling spectral SW radiation above and below ice, spectral SW albedo and transmittance, at one location on Floe 3 and 4. Measured with Ramses ACC-VIS radiometers (350-900 nm) and processed to 15 min averages. Dataset contains one file for Floe 3 (incident, reflected and transmitted (right below ice)) and one for Floe 4 (incident, reflected, transmitted (right below ice) and transmitted at 10 m depth in the water) in Netcdf format. In both cases installed at a location with thick snow and ice, for respective Floe. To keep the sites undisturbed for the period of measurement no information on snow or ice thickness exist beyond the time of deployment. Initial conditions. Floe 3: snow depth 40 cm, ice thickness 130 cm. Floe 4: snow depth 15-20 cm, ice thickness 120 cm. #### Refrozen lead Incident and transmitted spectral irradiance from transects on a refrozen lead. Sensors: Trios RAMSES ACC-VIS Wavelength range: 320-900nm NOTE! Do not fully trust data for wavelengths below 350nm, the sensors are less accurate here. Dataset has one file for measurements conducted with snow cover intact, and for some dates measurements were also made after snow had been removed (bareice). - RefrozenLead_bareice_Trios-1.6.nc - RefrozenLead_Trios-1.6.nc #### Groups The transect consisted of five repeated locations across a refrozen lead next to R/V Lance. The groups in the files are called p1 through p5, where p1 is the location closest to Lance, and p5 is farthest away from Lance. The transect was repeated 11 times between 12 May and 3 June 2015.(See [Kauko et al. 2017](https://doi.org/10.1002/2016JG003626)) Variables - wl: Wavelength [nm] - inc: Incident irradiance [W m^(-2) nm^(-1)] - trans: Transmitted irradiance [W m^(-2) nm^(-1)] - time: Time in UTC (N x 6 matrix, columns are year, month, day, hour, minute, second) - lat, lon: Position of Lance (i.e. not exact position of measurement) - expday: Julian day of 2015 when transect was sampled Processing Spectra where the tilt of the under-ice sensor was >5 degrees along either x- or y-axes have been discarded.本数据集包含两类不同观测站点的短波光谱辐射数据（涵盖入射、反射与透射辐射）：其一为浮冰3号（Floe 3）与浮冰4号（Floe 4）上固定监测点位（即所谓‘超级站点（supersite）’）的时序观测数据，其二为浮冰3号漂移期间于‘再冻结冰间水道（refrozen lead）’开展的单点测量数据。 ### 超级站点（supersite） 在浮冰3号与浮冰4号的一处固定点位，开展了冰上与冰下的下行、上行短波光谱辐射，短波光谱反照率以及透射率的测量。本次测量使用Ramses ACC-VIS辐射计（Ramses ACC-VIS radiometers），光谱覆盖范围为350~900 nm，所有数据已处理为15分钟平均的时序结果。 本数据集包含两个NetCDF格式文件：其一对应浮冰3号，包含入射、反射以及冰下紧邻位置的透射辐射数据；其二对应浮冰4号，包含入射、反射、冰下紧邻位置的透射辐射，以及水下10米深度处的透射辐射数据。两处监测点位均对应积雪与海冰较厚的区域，以匹配对应浮冰的环境特征。为保障测量期间站点不受干扰，除部署时的初始条件外，未记录后续的积雪或海冰厚度数据。初始条件如下：浮冰3号：积雪深度40 cm，海冰厚度130 cm；浮冰4号：积雪深度15~20 cm，海冰厚度120 cm。 ### 再冻结冰间水道（refrozen lead） 包含于再冻结冰间水道断面上获取的入射与透射光谱辐照度数据。使用的传感器为Trios RAMSES ACC-VIS，光谱覆盖范围为320~900 nm。注意：请勿完全采信波长低于350 nm的观测数据，该波段范围内传感器精度较低。 本数据集包含两个NetCDF格式文件：分别为积雪覆盖完整时的测量数据，以及部分日期移除积雪后的裸冰工况测量数据： - RefrozenLead_bareice_Trios-1.6.nc - RefrozenLead_Trios-1.6.nc ### 分组（Groups） 本次观测断面沿紧邻R/V Lance科考船的再冻结冰间水道布设，包含5个重复点位，文件中的分组命名为p1至p5，其中p1为最靠近R/V Lance的点位，p5为距离最远的点位。该观测断面于2015年5月12日至6月3日期间重复开展了11次采样（详见[Kauko等，2017](https://doi.org/10.1002/2016JG003626)）。 ### 变量说明 - wl：波长，单位为纳米（nm） - inc：入射辐照度，单位为W·m⁻²·nm⁻¹ - trans：透射辐照度，单位为W·m⁻²·nm⁻¹ - time：采用UTC（协调世界时）的时间戳（N×6矩阵，各列依次为年、月、日、时、分、秒） - lat, lon：R/V Lance的位置（并非测量点位的精确坐标） - expday：采样断面对应的2015年儒略日 ### 数据处理 当冰下传感器沿x轴或y轴的倾斜角度大于5°时，对应的光谱数据已被剔除。