National Data Buoy Center (NDBC) Data#

This notebook introduces National Data Buoy Center (NDBC) data with a focus on buoys in Southern Lake Michigan.

The NDBC provides both station metadata and station measurements. NDBC data, guides and documentation can be found on the NDBC web site.

The Standard Meteorological data includes:

  • WDIR   Wind direction

  • WSPD   Wind speed (m/s) averaged over an eight-minute period for buoys and a two-minute period for land stations.

  • GWS   Peak 5 or 8 second wind gusts speed (m/s).

  • WVHT   Significant wave height (m)

  • DPD   Dominant wave period (s)

  • APD   Average wave period (s)

  • PRES   Sea level pressure (hPa)

  • ATMP   Air temperature (Celsius)

  • WTMP   Water temperature (Celsius)

  • DEWP   Dewpoint

Solar Radiation data may include:

See the Measurement Description and Units link for more information.

The NDBC web interface (https://www.ndbc.noaa.gov/) which is linked in the image below, is a convenient way to identify stations.

NDC Screenshot

Southern Lake Michigan Buoys#

This list of Southern Lake Michigan Buoys was fine-tuned using the NDBC web interface above , five of these stations appear to be deactivated. The five digit station identifiers below are needed for API calls to return station data.

Identifier

Name/Location

Type

Owner

Measurements

KNSW3

Kenosha Light, Kenosha, WI

fixed

NWS

WDIR, WSPD, GST, PRES, ATMP

45187

Winthrop Harbor

buoy

UIUC

WDIR, WSPD, GST, WVHT, MWD, ATMP, WTMP

45186

Waukegan Buoy

buoy

UIUC

WDIR, WSPD, GST, WVHT, DPD, ATMP, WTMP

WHRI2

Waukegan Harbor, IL

fixed

NWS

WDIR, WSPD, GST, ATMP

45174

Wilmette Buoy

buoy

IL-IN Sea Grant

WDIR, WSPD, GST, WVHT, DPD, MWD, PRES, ATMP, WTMP, DEWP: ~~SRAD1~~

~~FSTI2~~

~~Foster Ave, Chicago, IL~~

fixed

~~CPD~~

ATMP data ends in 2021

OKSI2

Oak St., Chicago, IL

fixed

CPD

WDIR, WSPD, GST, ATMP: SRAD1

CHII2

Harrison-Dever Crib, Chicago, IL

fixed

GLERL

WDIR, WSPD, GST, ATMP, DEWP

~~45177~~

~~Ohio St. Beach, Chicago, IL~~

buoy

~~CPD~~

WVHT, DPD, WTMP, last data 2019

45198

Chicago Buoy

buoy

IN-IL Sea Grant

WDIR, WSPD, GST, WVHT, DPD, WMD, WTMP

CNII2

Northerly Isle, IL

fixed

NWS

WDIR, WSPD, GST, ATMP, DEWP

~~JAKI2~~

~~63rd St. Chicago, IL~~

fixed

~~CPD~~

data ends in 2022

CMTI2

Caulument Harbor, IL

fixed

NOAA

WDIR, WSPD, GST, PRES, ATMP, DEWP

BHRI3

Burns Harbor, IN

fixed

NWS

WDIR, WSPD, GST, PRES, ATMP

45170

Michigan City Buoy, IN

buoy

IL-IN Sea Grant

WDIR, WSPD, GST, WVHT, DPD, WMD, PRES, ATMP, DEWP: SRAD1

MCYI3

Michigan City Harbor Entrance

fixed

GLERL

WDIR, WSPD, GST, PRES, ATMP, DEWP

~~18CI3~~

~~Michigan City CG Station~~

fixed

~~USCG~~

last data 2015

45026

Cook Nuclear Plant Buoy, Stevensville, MI

buoy

Limno Tech

WDIR, WSPD, GST, WVHT, DPD, WMD, PRES, ATMP, WTMP, DEWP: ~~SRAD1~~

~~20CM4~~

~~ST. Joseph CG Station, MI~~

fixed

~~USCG~~

last data 2015

SJOM4

St. Joseph, MI

fixed

NWS

WDIR, WSPD, GST, PRES, ATMP

45168

South Haven Buoy, MI

buoy

Limno Tech

WDIR, WSPD, GST, WVHT, DPD, WMD, WTMP,DEWP

SVNM4

South Haven Light, MI

fixed

GLERL

WDIR, WSPD, GST, ATMP

Station’s with IDs in boldface collect data all year. This most of the fixed station.

Exploring the NDBC with Python#

# Import standard python libraries
import numpy as np            # Numerical Python: scientific 
import pandas as pd           # tabular data and timeseries package
import matplotlib.pyplot as plt
import datetime as dt 

Active stations#

Import a list of active stations directly from the NDBC as a Data Frame. NB, the five digit station identifiers in this list are lower case. The NBDC search engine is not case sensitive, but various NDBC filenames use both lower and uppercase station IDs.

active_st = pd.read_xml(path_or_buffer="https://www.ndbc.noaa.gov/activestations.xml")
print(active_st.shape)
(1341, 13)

Southern Lake Michigan Buoys#

Create a subset of South Lake Michigan buoys based on a geographical bounding box.

mask = ((active_st['lat'] > 41.5) & (active_st['lat'] < 42.6)  & (active_st['lon'] < -84.7) & (active_st['lon'] > -88))
slm_buoys = active_st.loc[mask]
print(slm_buoys.shape)
#display(slm_buoys)
(22, 13)

The code below removes columns which are not relevant for Lake Michigan. By inspection, some of the stations on the “active” list have not collected data in recent years, the code block below also removes those stattions.

slm_buoys = slm_buoys.drop(['seq','dart','waterquality','currents','pgm'],axis=1)

slm_buoys = (slm_buoys[(slm_buoys.id != "FSTI2") & (slm_buoys.id != "fsti2")]) #  Data collection ended in 2021
slm_buoys = slm_buoys[slm_buoys.id != "45177" ]                                #  Data collection ended in 2019
slm_buoys = slm_buoys[(slm_buoys.id != "JAKI2") & (slm_buoys.id != "jaki2") ]  #  Data collection ended in 2022
slm_buoys = slm_buoys[(slm_buoys.id != "18CI3") & (slm_buoys.id != "18ci3") ]  #  Data collection ended in 2015
slm_buoys = slm_buoys[(slm_buoys.id != "20CM4") & (slm_buoys.id != "20cm4")]   #  Data collection ended in 2015
slm_buoys.reset_index(inplace = True)
print(slm_buoys.shape)
slm_buoys.reset_index(drop=True,inplace=True)
display(slm_buoys)

slm_buoys.to_csv('slm_buoys.txt', header=None, index=None, sep=' ', mode='a')
station_list = slm_buoys['id'].tolist()
print(station_list)
(17, 9)
index id lat lon elev name owner type met
0 259 45026 41.982 -86.619 176.0 Cook Nuclear Plant Buoy, Stevensville, MI Limno Tech buoy y
1 289 45168 42.397 -86.331 177.0 South Haven Buoy, MI Limno Tech buoy n
2 290 45170 41.755 -86.968 177.0 Michigan City Buoy, IN Illinois-Indiana Sea Grant and Purdue Civil En... buoy n
3 294 45174 42.135 -87.655 176.0 Wilmette Buoy, IL Illinois-Indiana Sea Grant buoy n
4 303 45186 42.368 -87.795 176.0 Waukegan Buoy, IL University of Illinois at Urbana-Champaign buoy n
5 304 45187 42.491 -87.779 176.0 Winthrop Harbor Buoy, IL University of Illinois at Urbana-Champaign buoy n
6 309 45198 41.892 -87.563 176.0 Chicago Buoy Illinois-Indiana Sea Grant and Purdue Civil En... buoy n
7 654 bhri3 41.646 -87.147 180.0 Burns Harbor, IN NWS Central Region fixed y
8 703 chii2 41.916 -87.572 176.0 Harrison-Dever Crib, Chicago, IL GLERL fixed y
9 718 cmti2 41.730 -87.538 178.5 9087044 - Calumet Harbor, IL NOS fixed y
10 721 cnii2 41.856 -87.609 180.0 Northerly Isle, IL NWS Central Region fixed y
11 911 knsw3 42.589 -87.809 176.0 Kenosha Light, Kenosha, WI NWS Central Region fixed n
12 982 mcyi3 41.729 -86.912 176.0 Michigan City Harbor Entrance Light, Michigan ... GLERL fixed y
13 1069 oksi2 41.912 -87.624 179.0 Oak St., Chicago, IL Chicago Park District fixed y
14 1213 sjom4 42.098 -86.494 182.0 St. Joseph, MI NWS Central Region fixed y
15 1241 svnm4 42.401 -86.288 176.0 South Haven Light, South Haven, MI GLERL fixed y
16 1317 whri2 42.361 -87.813 180.0 Waukegan Harbor, IL NWS Central Region fixed y
['45026', '45168', '45170', '45174', '45186', '45187', '45198', 'bhri3', 'chii2', 'cmti2', 'cnii2', 'knsw3', 'mcyi3', 'oksi2', 'sjom4', 'svnm4', 'whri2']

met: indicates whether the station has reported meteorological data in the past eight hours (y/n). Mosy buoy’s are recovered for winter and won’t report meteorological data in winter montsh.

Realtime Meteorological Data#

NDBC has separate file and directory structures for historic and realtime data (from the last 45 days). In particular, filenames for historic data use lower case station IDs while reatime data use upper case station IDs.

# Create a function to fetch and wrangle realtime data. Stdmet data is saved under the .txt extension.

def get_rt_data(stationid):
    
    url = 'https://www.ndbc.noaa.gov/data/realtime2/' + stationid.upper() + '.txt'
    df = pd.read_table(url,sep = "\s+")

    # Wrangle the Buoy Data
    units = df.loc[0]
    df.drop(df.index[0], inplace=True)
    
    # Set the column types
    df['#YY'] = df['#YY'].astype(int)
    df['MM'] = df['MM'].astype(int)
    df['DD'] = df['DD'].astype(int)
    df['hh'] = df['hh'].astype(int)
    df['mm'] = df['mm'].astype(int)
    if 'WDIR' in df.columns:
        df['WDIR'] = pd.to_numeric(df['WDIR'], errors='coerce')
    if 'WSPD' in df.columns:
        df['WSPD'] = pd.to_numeric(df['WSPD'], errors='coerce')
    if 'GST' in df.columns:
        df['GST'] = pd.to_numeric(df['GST'], errors='coerce')
    if 'WVHT' in df.columns:
        df['WVHT'] = pd.to_numeric(df['WVHT'], errors='coerce')
    if 'DPD' in df.columns:
        df['DPD'] = pd.to_numeric(df['DPD'], errors='coerce')
    if 'APD' in df.columns:
        df['APD'] = pd.to_numeric(df['APD'], errors='coerce')
    if 'MWD' in df.columns:
        df['MWD'] = pd.to_numeric(df['MWD'], errors='coerce')
    if 'PRES' in df.columns:
        df['PRES'] = pd.to_numeric(df['PRES'], errors='coerce')
    if 'ATMP' in df.columns:
        df['ATMP'] = pd.to_numeric(df['ATMP'], errors='coerce')
    if 'WTMP' in df.columns:
        df['WTMP'] = pd.to_numeric(df['WTMP'], errors='coerce')
    if 'DEWP' in df.columns:
        df['DEWP'] = pd.to_numeric(df['DEWP'], errors='coerce')
    if 'VIS' in df.columns:
        df['VIS'] = pd.to_numeric(df['VIS'], errors='coerce')
    if 'TIDE' in df.columns:
        df['TIDE'] = pd.to_numeric(df['TIDE'], errors='coerce')
    if 'PTDY' in df.columns:
        df['PTDY'] = pd.to_numeric(df['PTDY'], errors='coerce')

    df['datetime'] = pd.to_datetime(dict(year=df['#YY'], month=df.MM,  day = df.DD, hour=df.hh, minute=df.mm))
    df.set_index('datetime',inplace=True)
    return (df)

Realtime data for the Harrison-Dever Crib (CHII2)#

StationID = 'CHII2'
rtdf = get_rt_data(StationID)
StationName = slm_buoys.loc[slm_buoys['id'] == StationID.lower(),'name'].iloc[0]
print(StationName)
print(rtdf.head())
Harrison-Dever Crib, Chicago, IL
                      #YY  MM  DD  hh  mm   WDIR  WSPD   GST  WVHT  DPD  APD  \
datetime                                                                       
2024-11-23 07:20:00  2024  11  23   7  20  310.0   8.2  10.8   NaN  NaN  NaN   
2024-11-23 07:10:00  2024  11  23   7  10  310.0   7.7   9.8   NaN  NaN  NaN   
2024-11-23 07:00:00  2024  11  23   7   0  320.0   7.2   8.2   NaN  NaN  NaN   
2024-11-23 06:50:00  2024  11  23   6  50  310.0   7.2   8.8   NaN  NaN  NaN   
2024-11-23 06:40:00  2024  11  23   6  40  300.0   8.8   9.8   NaN  NaN  NaN   

                     MWD  PRES  ATMP  WTMP  DEWP  VIS  PTDY  TIDE  
datetime                                                           
2024-11-23 07:20:00  NaN   NaN   6.5   NaN   4.6  NaN   NaN   NaN  
2024-11-23 07:10:00  NaN   NaN   6.7   NaN   5.1  NaN   NaN   NaN  
2024-11-23 07:00:00  NaN   NaN   6.6   NaN   4.8  NaN   NaN   NaN  
2024-11-23 06:50:00  NaN   NaN   6.7   NaN   4.7  NaN   NaN   NaN  
2024-11-23 06:40:00  NaN   NaN   6.8   NaN   4.9  NaN   NaN   NaN  
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors

pad = 1.05
my_ytick_labels=['N','E','S','W','N']

fig, (ax1, ax2, ax3) = plt.subplots(3, 1, figsize=(14, 12))
#fig.suptitle(StationName,y=0.99)
fig.suptitle(StationName + " (" + StationID + ")",y=0.95)

ax1b = ax1.twinx()
ax2b = ax2.twinx()
ax3b = ax3.twinx()

ax1.grid(True)
ax1.axis([rtdf.first_valid_index(),rtdf.last_valid_index(),0,360])
major_angle_ticks = np.arange(0,361,90)
ax1.set_yticks(major_angle_ticks)
ax1b.set_yticks(major_angle_ticks)
ax1.plot(rtdf.index, rtdf['WDIR'], 
         color='indigo',
         linestyle='none',
         marker='o',
         markersize=1,
         linewidth=1)
ax1.set_ylabel('Wind Direction')
ax1b.set_yticks(ticks=major_angle_ticks,labels=my_ytick_labels)
#ax1.set_xlabel('Time (UTC)')
ax1.set_title('Wind Direction Timeseries')

# Wind speed, gust, direction
ax2.axis([rtdf.first_valid_index(),rtdf.last_valid_index(),0,rtdf['GST'].max()])
ax2b.axis([rtdf.first_valid_index(),rtdf.last_valid_index(),0,1.9438*rtdf['GST'].max()])
ax2.plot(rtdf.index, rtdf['GST'], 
         color='saddlebrown',  
         linewidth=0.5,
         linestyle='--',
         label='GST')
ax2.plot(rtdf.index, rtdf['WSPD'], 
         color='darkorange',
          linewidth=0.5,
          label='WSPD')
ax2.set_ylabel('Wind Speed [m/s]')
ax2b.set_ylabel('Wind Speed [kn]')
ax2.legend(loc='upper right')

# Temperature

ax3.axis([rtdf.first_valid_index(),rtdf.last_valid_index(),rtdf['DEWP'].min(),rtdf['ATMP'].max()+5/9])
ax3b.axis([rtdf.first_valid_index(),rtdf.last_valid_index(),rtdf['DEWP'].min()*9/5+32,9*rtdf['ATMP'].max()/5 +32+1])
ax3.plot(rtdf.index, rtdf['DEWP'],  
         linewidth=0.5,
         color='black',
         label='DEWP')
ax3.plot(rtdf.index, rtdf['ATMP'], 
         linewidth=0.2,
         color='cornflowerblue',
         label='ATMP')
ax3.set_ylabel('Temperature [degC]')
ax3b.set_ylabel('Temperature [degF]')
ax3.legend(loc='upper right')

plt.savefig('realtime.pdf')
plt.show()
../../_images/0b60a073d0978c63ff3521143d810bf3d93883536b1101c9e7a70e5e8e8154cf.png

Distribution of Wind Speeds

import matplotlib.pyplot as plt
bins = np.linspace(start=0,stop=rtdf["GST"].max(),num=25)  # return evenly spaced numbers over an interval
plt.hist(rtdf["GST"],bins, alpha=0.5, label="Gusts",color='orange',edgecolor='darkorange',align='right')
plt.hist(rtdf["WSPD"],bins, alpha=0.5, label="Wind Speed",color='blue',edgecolor='darkblue',align='right')
plt.legend(loc='upper right')
plt.xlabel('Speed (m/s)')
plt.ylabel('Frequency')
plt.title('Frequency of Wind Speeds (' + StationID + ')')
plt.show()
../../_images/82e25504c34f214092129a717e2fc4f8cd20da5705b85efef212caeab736ba37.png

Get data from nearby stations for comparison

StationID2 = 'OKSI2'
StationID3 = 'CNII2'

StationName2 = slm_buoys.loc[slm_buoys['id'] == StationID2.lower(),'name'].iloc[0]
StationName3 = slm_buoys.loc[slm_buoys['id'] == StationID3.lower(),'name'].iloc[0]

station2_df = get_rt_data('OKSI2')
station3_df = get_rt_data('CNII2')

The windroses below show a prominent windshadow for the Oak St. station.

from windrose import WindroseAxes

fig, (ax1, ax2, ax3) = plt.subplots(1, ncols=3, figsize=(15, 5), subplot_kw ={'projection': 'windrose'})
fig.suptitle("Windroses from Three Nearby Stations",y=1.1)

fig.add_axes(ax1)
ax1.bar(rtdf["WDIR"], rtdf['WSPD'], normed=True, opening=0.8, edgecolor="white")
ax1.set_legend(units="m/s")
ax1.set_title(StationName + " (" + StationID + ")",y=1.1)

fig.add_axes(ax2)
ax2.bar(station2_df["WDIR"], station2_df['WSPD'], normed=True, opening=0.8, edgecolor="white")
ax2.set_legend(units="m/s")
ax2.set_title(StationName2 + " (" + StationID2 + ")",y=1.1)

#ax3 = WindroseAxes.from_ax()
ax3.bar(station3_df["WDIR"], station3_df['WSPD'], normed=True, opening=0.8, edgecolor="white")
ax3.set_legend(units="m/s")
ax3.set_title(StationName3 + " (" + StationID3 +")",y=1.1)

plt.tight_layout()
plt.show()
../../_images/59ca9fa5268520401a4590ac74763437223b693655ad6d6cdeba0ce69fb36706.png

Historial NDBC Data#

The top level directory or historical ndbc data is https://www.ndbc.noaa.gov/data/historical/. Standard meteoroligical data (smet) if found in the directory https://www.ndbc.noaa.gov/data/historical/stdmet/, while standard radiation data is found in https://www.ndbc.noaa.gov/data/historical/srad/

Unlike reatime data, the filenames for historic data contain station IDs in lower case. The data is stored in separate files for each year.

https://www.ndbc.noaa.gov/view_text_file.php?filename=chii2h2023.txt.gz&dir=data/historical/stdmet/ https://www.ndbc.noaa.gov/data/historical/stdmet/chii2h2023.txt.gz

def get_hdata(station,year):

    url = 'https://www.ndbc.noaa.gov/data/historical/stdmet/' + station.lower() + 'h' + str(year) + '.txt.gz'
    df = pd.read_table(url,sep = "\s+",compression='gzip',low_memory=False)
    # Wrangle the Buoy Data
    units = df.loc[0]
    df.drop(df.index[0], inplace=True)
    # Set the column types
    df['#YY'] = df['#YY'].astype(int)
    df['MM'] = df['MM'].astype(int)
    df['DD'] = df['DD'].astype(int)
    df['hh'] = df['hh'].astype(int)
    df['mm'] = df['mm'].astype(int)
    if 'WDIR' in df.columns:
        df['WDIR'] = pd.to_numeric(df['WDIR'], errors='coerce')
    if 'WSPD' in df.columns:
        df['WSPD'] = pd.to_numeric(df['WSPD'], errors='coerce')
    if 'GST' in df.columns:
        df['GST'] = pd.to_numeric(df['GST'], errors='coerce')
    if 'WVHT' in df.columns:
        df['WVHT'] = pd.to_numeric(df['WVHT'], errors='coerce')
    if 'DPD' in df.columns:
        df['DPD'] = pd.to_numeric(df['DPD'], errors='coerce')
    if 'APD' in df.columns:
        df['APD'] = pd.to_numeric(df['APD'], errors='coerce')
    if 'MWD' in df.columns:
        df['MWD'] = pd.to_numeric(df['MWD'], errors='coerce')
    if 'PRES' in df.columns:
        df['PRES'] = pd.to_numeric(df['PRES'], errors='coerce')
    if 'ATMP' in df.columns:
        df['ATMP'] = pd.to_numeric(df['ATMP'], errors='coerce')
    if 'WTMP' in df.columns:
        df['WTMP'] = pd.to_numeric(df['WTMP'], errors='coerce')
    if 'DEWP' in df.columns:
        df['DEWP'] = pd.to_numeric(df['DEWP'], errors='coerce')
    if 'VIS' in df.columns:
        df['VIS'] = pd.to_numeric(df['VIS'], errors='coerce')
    if 'TIDE' in df.columns:
        df['TIDE'] = pd.to_numeric(df['TIDE'], errors='coerce')
    if 'PTDY' in df.columns:
        df['PTDY'] = pd.to_numeric(df['PTDY'], errors='coerce')

    df['datetime'] = pd.to_datetime(dict(year=df['#YY'], month=df.MM,  day = df.DD, hour=df.hh, minute=df.mm))
    df.set_index('datetime',inplace=True)

# NDBC uses these numeric values to indicate no data was taken
    
    df['WVHT'] = df['WVHT'].replace({99.00: np.nan})
    df['DPD'] = df['DPD'].replace({99.00: np.nan})
    df['APD'] = df['APD'].replace({99.00: np.nan})
    df['MWD'] = df['MWD'].replace({999: np.nan})
    df['PRES'] = df['PRES'].replace({9999.0: np.nan})
    df['WTMP'] = df['WTMP'].replace({999.0: np.nan})
    df['VIS'] = df['VIS'].replace({99.0: np.nan})
    df['TIDE'] = df['TIDE'].replace({99.0: np.nan})
    
    return (df)
df = get_hdata('45174',2023) # Wilmette Buoy
StationName = slm_buoys.loc[slm_buoys['id'] == '45174','name'].iloc[0]
print(StationName)
print(df.head())
Wilmette Buoy, IL
                      #YY  MM  DD  hh  mm  WDIR  WSPD   GST  WVHT   DPD  APD  \
datetime                                                                       
2023-05-01 00:00:00  2023   5   1   0   0   291   8.4  11.3  0.65  3.04  NaN   
2023-05-01 00:10:00  2023   5   1   0  10   293   8.4  11.1  0.70  3.06  NaN   
2023-05-01 00:20:00  2023   5   1   0  20   295   8.1  11.2  0.75  3.12  NaN   
2023-05-01 00:30:00  2023   5   1   0  30   299   7.6   9.3  0.77  3.12  NaN   
2023-05-01 00:40:00  2023   5   1   0  40   294   7.4  10.6  0.76  3.14  NaN   

                       MWD   PRES  ATMP  WTMP  DEWP  VIS  TIDE  
datetime                                                        
2023-05-01 00:00:00  326.0  995.6   6.1   6.8   2.9  NaN   NaN  
2023-05-01 00:10:00  328.0  995.7   6.1   6.8   4.0  NaN   NaN  
2023-05-01 00:20:00  322.0  995.7   6.1   6.8   3.2  NaN   NaN  
2023-05-01 00:30:00  179.0  995.7   6.0   6.8   3.4  NaN   NaN  
2023-05-01 00:40:00  335.0  995.7   5.9   6.8   3.4  NaN   NaN  
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors

pad = 1.05
my_ytick_labels=['N','E','S','W','N']

fig, (ax1, ax2, ax3, ax4) = plt.subplots(4, 1, figsize=(14, 12), constrained_layout=True)
fig.suptitle(StationName + " (45174)",y=1.02)

ax1b = ax1.twinx()
ax2b = ax2.twinx()
ax3b = ax3.twinx()
ax4b = ax4.twinx()

ax1.grid(True)
ax1.axis([df.first_valid_index(),df.last_valid_index(),0,360])
major_angle_ticks = np.arange(0,361,90)
ax1.set_yticks(major_angle_ticks)
ax1b.set_yticks(major_angle_ticks)
ax1.plot(df.index, df['WDIR'], 
         color='indigo',
         linestyle='none',
         marker='o',
         markersize=1,
         linewidth=1)
ax1.set_ylabel('Wind Direction')
ax1b.set_yticks(ticks=major_angle_ticks,labels=my_ytick_labels)
#ax1.set_xlabel('Time (UTC)')
ax1.set_title('Wind Direction Timeseries')

# Wind speed, gust, direction
ax2.axis([df.first_valid_index(),df.last_valid_index(),0,df['GST'].max()])
ax2b.axis([df.first_valid_index(),df.last_valid_index(),0,1.9438*df['GST'].max()])

ax2.plot(df.index, df['GST'], 
         color='saddlebrown',  
         linewidth=0.5,
         linestyle='--',
         label='GST')
ax2.plot(df.index, df['WSPD'], 
         color='darkorange',
          linewidth=0.5,
          label='WSPD')

ax2.set_title('Windspeed and Gusts')
ax2.set_ylabel('Wind Speed [m/s]')
ax2b.set_ylabel('Wind Speed [kn]')
ax2.legend(loc='upper right')


# Water temperature

ax3.axis([df.first_valid_index(),df.last_valid_index(),df['DEWP'].min(),pad*df['ATMP'].max()])
ax3b.axis([df.first_valid_index(),df.last_valid_index(),32,pad*9*df['ATMP'].max()/5 +32])
ax3.plot(df.index, df['DEWP'],  
         linewidth=0.5,
         color='black',
         label='DEWP')
ax3.plot(df.index, df['WTMP'],  
         linewidth=1.2,
         color='teal',
         label='WTMP')
ax3.plot(df.index, df['ATMP'], 
         linewidth=0.2,
         color='cornflowerblue',
         label='ATMP')
ax3.set_ylabel('Temperature [degC]')
ax3b.set_ylabel('Temperature [degF]')
ax3.legend(loc='upper right')
ax3.set_title('Air and Water Temperature')

ax4.axis( [df.first_valid_index(),df.last_valid_index(),0,pad*df['WVHT'].max()])
ax4b.axis([df.first_valid_index(),df.last_valid_index(),0,pad*3.28*df['WVHT'].max()])
ax4.plot(df.index, df['WVHT'],  
         linewidth=1.5,
         color='teal',
         label='WVHT')
ax4.set_ylabel('Wave Height [m]')
ax4b.set_ylabel('Wave Height [ft]')
ax4.legend(loc='upper right')
ax4.set_xlabel('Time (UTC)')

#plt.savefig('images/buoyplots.pdf')
plt.show()
../../_images/f759eeaecca7bbaa7a206795544ac63f6b060ade1f40437ab867b8865823f6d5.png
# From the example scripts in https://windrose.readthedocs.io/en/latest/usage.html

from windrose import WindroseAxes, plot_windrose
import seaborn as sns

def plot_windrose_subplots(data, *, direction, var, color=None, **kwargs):
    """wrapper function to create subplots per axis"""
    ax = plt.gca()
    ax = WindroseAxes.from_ax(ax=ax)
    plot_windrose(direction_or_df=data[direction], var=data[var], ax=ax, **kwargs)

df = df.rename(columns={'MM': 'month'})

g = sns.FacetGrid(
    data=df,
    # the column name for each level a subplot should be created
    col="month",
    # place a maximum of 3 plots per row
    col_wrap=3,
    subplot_kws={"projection": "windrose"},
    sharex=False,
    sharey=False,
    despine=False,
    height=3.5,
)

g.map_dataframe(
    plot_windrose_subplots,
    direction="WDIR",
    var="WSPD",
    normed=True,
    # manually set bins, so they match for each subplot
    bins=(0.1, 1, 2, 3, 4, 5),
    calm_limit=0.1,
    kind="bar",
)

# make the subplots easier to compare, by having the same y-axis range
y_ticks = range(0, 17, 4)
for ax in g.axes:
    ax.set_legend(
        title="$m \cdot s^{-1}$", bbox_to_anchor=(1.15, -0.1), loc="lower right"
    )
    ax.set_rgrids(y_ticks, y_ticks)

# adjust the spacing between the subplots to have sufficient space between plots
plt.subplots_adjust(wspace=-0.2)
plt.suptitle(StationName + " (45174)",y=1.02)
Text(0.5, 1.02, 'Wilmette Buoy, IL (45174)')
../../_images/09d6899eabb6ae9367bc4c967f9e1912e9d0feade71bd10e2fe2f5ca66d67c8c.png

Historical Radiation Data

def get_hrdata(station,year):
    
    url = 'https://www.ndbc.noaa.gov/data/historical/srad/' + station.lower() + 'r' + str(year) + '.txt.gz'
    print(url)
    df = pd.read_table(url,sep = "\s+",compression='gzip',low_memory=False)
  
    # Wrangle the Buoy Data
    units = df.loc[0]
    df.drop(df.index[0], inplace=True)
    # Set the column types
    df['#YY'] = df['#YY'].astype(int)
    df['MM'] = df['MM'].astype(int)
    df['DD'] = df['DD'].astype(int)
    df['hh'] = df['hh'].astype(int)
    df['mm'] = df['mm'].astype(int)
    if 'SRAD1' in df.columns:
        df['SRAD1'] = pd.to_numeric(df['SRAD1'], errors='coerce')
    if 'SWRAD' in df.columns:
        df['SWRAD'] = pd.to_numeric(df['SWRAD'], errors='coerce')
    if 'LWRAD' in df.columns:
        df['LWRAD'] = pd.to_numeric(df['LWRAD'], errors='coerce')

    df['datetime'] = pd.to_datetime(dict(year=df['#YY'], month=df.MM,  day = df.DD, hour=df.hh, minute=df.mm))
    df.set_index('datetime',inplace=True)

# NDBC uses these numerical values to indicate that no data was taken

    df['SRAD1'] = df['SRAD1'].replace({9999.0: np.nan})
    df['SWRAD'] = df['SWRAD'].replace({9999.0: np.nan})
    df['LWRAD'] = df['LWRAD'].replace({9999.0: np.nan})
    
    return (df)
df = get_hrdata('OKSI2',2023) 
StationName = slm_buoys.loc[slm_buoys['id'] == 'oksi2','name'].iloc[0]
print(StationName)
print(df.head())
https://www.ndbc.noaa.gov/data/historical/srad/oksi2r2023.txt.gz
Oak St., Chicago, IL
                      #YY  MM  DD  hh  mm  SRAD1  SWRAD  LWRAD
datetime                                                      
2023-01-01 00:00:00  2023   1   1   0   0    2.0    NaN    NaN
2023-01-01 01:00:00  2023   1   1   1   0    2.0    NaN    NaN
2023-01-01 02:00:00  2023   1   1   2   0    2.0    NaN    NaN
2023-01-01 03:00:00  2023   1   1   3   0    2.0    NaN    NaN
2023-01-01 04:00:00  2023   1   1   4   0    2.0    NaN    NaN
import matplotlib.pyplot as plt
import matplotlib.colors as mcolors

pad = 1.01

fig, ax1 = plt.subplots(1, 1, figsize=(14, 12), constrained_layout=True)
fig.suptitle(StationName + " (OKSI2)",y=1.02)

ax1.grid(True)
ax1.axis([df.first_valid_index(),df.last_valid_index(),0,pad*df['SRAD1'].max()])
ax1.plot(df.index, df['SRAD1'], 
         color=mcolors.CSS4_COLORS['darkorange'],
         linestyle='none',
         marker='o',
         markersize=2,
         linewidth=1)
ax1.set_ylabel('Solar Radiation (W/m${}^2$)')
ax1.set_xlabel('Time (UTC)')
ax1.set_title('Solar Radiation')

plt.show()
../../_images/aa907c0f26cab3f9e54515392abc44eb98872de72983df45b9cbd279b6f037e8.png

Python APIs for the NDBC#

Thare are several python packages that serve as APIs for the NBDC including:

  • Siphon a collection of Python utilities for downloading data from remote data services. These unidata packages have good search functions. Data retrieval currently seems to be implemented only for realtime data. Unidata is a UCAR community program. See also

  • ndbc-api, this Github also contains Example Notebook. ndbc-api also has a PyPi Repository. The station search methods in ndbc_api return very incomplete results. In particular, as of February 2024, the stations() method currently returns 146 out of 1323 stations, and nearest_station() method seems restricted to that subset. The ndbc_api methods which access station data and metadata seem to work for the complete set of buoy’s provided you have the five digit station identifier. Those methods are.

    • station() which returns station metadata

    • available_realtime() which can return data from the last 45 days

    • available_historical() which returns older data.

  • NDBC A pacakge to simplify to retrieval and parsing of NOAA NDBC data.

  • seebuoy Easily access real time and historical data from the National Data Buoy Center.