M01_corrected_nitrate_csv

Various nitrate sensors including the SUNA V1, SUNA V2 and ISUS (Sea-Bird Scientific) were deployed on NERACOOS Buoy M (Latitude: 43° 29.44'N and Longitude: 67° 52.79'W) from June 23, 2013 to March 23, 2021. This time period corresponds to University of Maine buoy deployments M0124, M0125, M0126, M0127, M0129, and M130 (http://gyre.umeoce.maine.edu/data/gomoos/buoy/html/M01.html). These sensors were placed at the surface, 1m, 50m, 100m, 150m and 250m and programmed to collect nitrate measurements six times per day (0045, 0445, 0845, 1245, 1645 and 2045 GMT) over a fixed sampling window of 30 seconds at approximately 1.4 readings per second. The number of sensors and their depths varied for each deployment depending on the number of available sensors. Five measurements recorded in the middle of the 30 second data stream were transmitted back to the University of Maine Physical Oceanography Group via cell phone. The mean concentration and standard deviation were calculated for each specific sampling time. If the standard deviation for a mean was greater than 2µM, the values were eliminated. Surviving data were then quality controlled (QCed) by removing outliers assessed as values less than -0.5µM and greater than 30µM. Whenever possible at the time of buoy deployment and recovery, a standard CTD cast was conducted with a carousel water sampler equipped with Niskin bottles. Ground truth water samples were collected at the same depth as the nitrate sensors. These samples were analyzed for nitrate concentrations at the University of Maine using a Bran Luebbe AA3 Autoanalyzer and standard techniques. Ground truth corrections were added or subtracted as an offset only if the difference between the nitrate concentration of the water sample collected and the mean nitrate sensor reading at approximately the same time was greater than 2 µM. Upon recovery of the instruments, the data was processed using the software provided by Sea-Bird (UCI.com) and compared with the real-time measurements as a check for accuracy. In the event that the sensor was not able to transmit in real-time, the processed data was QCed. Please contact David Townsend, [e-mail], University of Maine, School of Marine Sciences if you have any questions.
cdm_data_type=Point
Conventions=COARDS, CF-1.6, ACDD-1.3
defaultGraphQuery=time,Nitrate_umol&time%3E=max(time)-7days&depth=50&.draw=lines&.color=0x000000
Easternmost_Easting=-67.8798
featureType=Point
geospatial_lat_max=43.491
geospatial_lat_min=43.4907
geospatial_lat_units=degrees_north
geospatial_lon_max=-67.8798
geospatial_lon_min=-67.88
geospatial_lon_units=degrees_east
geospatial_vertical_max=250.0
geospatial_vertical_min=1.0
geospatial_vertical_positive=down
geospatial_vertical_units=m
infoUrl=http://www.neracoos.org/nutrientobservatory
institution=University of Maine School of Marine Sciences
keywords_vocabulary=GCMD Science Keywords
neracoos_data_provider=UMO
Northernmost_Northing=43.491
sourceUrl=(local files)
Southernmost_Northing=43.4907
standard_name_vocabulary=CF Standard Name Table v29
subsetVariables=Year, depth
testOutOfDate=now-121days
time_coverage_end=2021-03-24T00:45:00Z
time_coverage_start=2013-06-23T16:45:00Z
Westernmost_Easting=-67.88

多种硝酸盐传感器，包括SUNA V1、SUNA V2及ISUS（Sea-Bird Scientific）型传感器，自2013年6月23日至2021年3月23日期间，部署于NERACOOS浮标M（纬度：43°29.44'N，经度：67°52.79'W）上。此时间段对应于缅因大学浮标部署M0124、M0125、M0126、M0127、M0129及M130（http://gyre.umeoce.maine.edu/data/gomoos/buoy/html/M01.html）。这些传感器分别置于水面、1米、50米、100米、150米和250米处，并编程以每日六次（0045、0445、0845、1245、1645和2045 GMT）收集硝酸盐测量数据，在固定采样窗口内（30秒）以每秒约1.4次读数的频率进行。每个部署中传感器的数量和深度根据可用传感器的数量而有所不同。在30秒数据流中记录的五个测量值通过手机传输至缅因大学物理海洋学组。针对每个特定采样时间，计算了平均浓度和标准差。若平均浓度的标准差超过2µM，则相关值将被剔除。经过筛选的存活数据随后进行质量控制（QC），通过移除评估为小于-0.5µM和大于30µM的异常值。在浮标部署和回收期间，尽可能进行标准CTD抛射，配备Niskin瓶的水样采集器。地面真值水样在硝酸盐传感器相同深度处采集。这些样品在缅因大学使用Bran Luebbe AA3自动分析仪及标准方法进行分析，以测定硝酸盐浓度。仅当采集的水样硝酸盐浓度与同一时间点硝酸盐传感器的平均读数之差超过2µM时，才对地面真值进行修正。仪器回收后，使用Sea-Bird（UCI.com）提供的软件处理数据，并与实时测量结果进行比对，以验证准确性。若传感器无法实时传输，则对处理后的数据进行质量控制。如有任何疑问，请联系缅因大学海洋科学学院David Townsend博士，邮箱：[e-mail]。