Preliminary Cruise Report – Meteorological Measurements

R/V Professor Khromov

Pusan, Korea to Otaru, Japan

July 22 – September 28, 1999

R. Limeburner and R. Beardsley, Woods Hole Oceanographic Institute

Alexey Sherebinin and Igor Filippov, Far Eastern Regional Hydromet Research Institute, Vladivostok

Purpose

The objectives of the meteorological component of the 1999 summer hydrographic cruise on the R/V Professor Khromov to the Sea of Japan were to make high quality shipboard measurements of wind speed and direction, barometric pressure, relative humidity, air temperature, sea surface temperature, short wave radiation, long wave radiation and precipitation. GPS positions were also recorded every 10-minutes to determine the ship’s speed during the cruise. The meteorological equipment was left on the ship during the September 1999 cruise to the Sea of Okhotsk and Figure 1 shows the combined cruise tracks from the WHOI GPS data.

Figure 1. The cruise track of the R/V Professor Khromov during the summer 1999 hydrographic cruises to the Sea of Japan and Sea of Okhotsk.

The meteorological equipment was shipped to Korea in July 1999 and the instruments were then mounted on the Russian ship in Pusan. This report describes the instruments used during the cruise and the data collected. R. Limeburner from the Woods Hole Oceanographic Institute (WHOI) installed the meteorological instruments on the ship in Pusan, Korea and Alexey Sherebinin and Igor Filippov from the Far Eastern Regional Hydromet Research Institute, Vladivostok assisted in the installation.

Log

The R/V Professor Khromov arrived in Otaru, Japan September 28, 1999 to unload hydrographic equipment and personnel from the Scripps Institute of Oceanography (SIO) and meteorological instruments from WHOI. Time words from the meteorological instruments were first checked when reading the data in Otaru. Table 1 below summarizes the time drift of each sensor.

Instrument	Sampling in Minutes	Number Records	Clock 9/28/99	UTC 9/28/99	Difference in seconds
GPS	10	10081	na	na	na
Wind	1	1706	05:10:36	05:14:21	-225
Rel. Hum/Temp	1	1706	04:47:02	05:53:22	+3920
Baro. Pressure	1	1705	02:20:56	02:20:12	+46
LW Radiation	1	1707	05:10:07	05:09:27	+40
SW Radiation	1	1707	03:20:52	03:20:07	+45
Sea Surf. Temp	1	1706?	05:21:11	05:18:29	+162
Precipitation	1	1704	02:30:39	02:33:26	+13

Table 1. Instrument status observed during recovery 9/28/99 in Otaru, Japan.

GPS Data

The raw GPS data (10087 positions) was recorded every 10 minutes during the cruises and this raw data was stored in file gpssep28.raw. There were 48 locations with flagged bad data. These errors were generally due to locally poor reception and were bracketed by good position data and so the bad points were replaced by linearly interpolated data. A time gap of about 22 hours was observed when the ship was tied up in Vladivostok 8/25/99 and this time and position data were linearly interpolated to 10 minute intervals.

The GPS receiver also had a malfunction with the year, month and day words after August 21, 1999 when a rollover in the GPS system occurred. The hour, minute, second, latitude and longitude appeared to be correctly recorded. The GPS data recorded before and after this transition in the GPS system is shown below.

1999/08/21,23/34/24,+43.501,+139.960

1999/08/21,23/44/00,+43.499,+140.002

1999/08/21,23/54/40,+43.498,+140.039

9999/99/99,99/99/99,+99.999,+999.999

9999/99/99,99/99/99,+99.999,+999.999

1981/01/152,00/27/24,+43.491,+140.170

1981/01/152,00/35/02,+43.489,+140.200

1981/01/152,00/44/32,+43.486,+140.238

1981/01/152,00/54/50,+43.481,+140.277

The sequential hour, minute, and second data recorded after 8/22/99 enabled a simple correction to the bad year, month and day data. .

The recorded 10-minute GPS sampling found in the file japangps.mat was not sampled at exactly 10-minute intervals since it takes a varying duration of time to receive the GPS signal. The edited raw data was first linearly interpolated to a 10-minute sampling interval (start 7/10/99 0000 and stop 9/28/99 0000). A decimal year day was then calculated with 1/1/99 0000 as day 0. Velocities (m/s) were calculated using a central difference method and the data was stored in a Matlab array named z10 in the file gps10min.mat. The data format is decimal year day, longitude, latitude, u (m/s), v (m/s). Figure 1 shows the resulting cruise track and Figure 2 summarizes the interpolated u and v ship velocities.

Figure 2. Ship velocity calculated from the corrected GPS data.

A summary of the GPS ship velocity data is shown in Figure 3. This data will be used to correct the wind speed and direction measured by the WHOI meteorological recorder.

Figure 3. Khromov ship speed from the WHOI 10 minute interpolated GPS data showing a stick plot (top), speed (middle) and east (blue m/s) and north (green m/s) speeds.

Wind Data

A summary of the measured wind including ship speed is shown below.

The raw wind data sampled every minute can be found in the Matlab5 file japanwnd.mat. Array data is u, v (m/sec the wind vector is toward), jd is the julian day, start is the start time, stop is the stop time.

The wind recorder direction was calibrated in the port of Otaru 9/28/99 from 0400 to 0500 UTC by fixing the sensor vane pointed aft, to starboard, forward and to port for about 5 minutes in each direction. The calibration was done while the instrument was mounted at the top of the ship’s mast. The Khromov’s heading at the Otaru dock was 165° magnetic with a magnetic variation of 9° W.

Date	Time UTC	Vane Direction	Wind Direction	Recorded Wind Direction Mag.	Corrected Wind Direction True
9/28/99	0425	345	165
9/28/99	0430	255	75
9/28/99	0435	165	345
9/28/99	0440	75	255

Table 2. Wind direction calibration in Otaru, Japan.

Barometric Pressure

The raw barometric pressure data sampled every minute can be found in the Matlab5 file japanbpr.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Long Wave Radiation

The raw long wave radiation data sampled every minute can be found in the Matlab5 file japanlwr.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Short Wave Radiation

The raw short wave radiation data sampled every minute can be found in the Matlab5 file japanswr.mat Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Sea Surface Temperature

The raw sea surface temperature data sampled every minute can be found in the Matlab5 file japansst.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Relative Humidity

The raw relative humidity data sampled every minute can be found in the Matlab5 file japareh.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Air Temperature

The raw air temperature data sampled every minute can be found in the Matlab5 file japanart.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Precipitation

The raw precipitation data sampled every minute can be found in the Matlab5 file japanprc.mat. Array data is z, jd is the julian day, start is the start time, stop is the stop time.

Winter 2000 Cruise Preparation

The brackets for the met sensors were left on the ship in Otaru, Japan. The 2 yellow wood boxes containing tools and spare met batteries were shipped to SIO with the hydrographic equipment. These boxes can stay at SIO and be shipped back to Pusan in January 2000 with the SIO equipment The met sensors were shipped back to WHOI via air freight.

Acknowledgements

The successful installation of the meteorological recorders was dependant on the knowledgeable support of Alexey Sherebinin and Igor Filippov of the Far Eastern Regional Hydromet Research Institute, Vladivostok. Lynne Talley (SIO) also provided excellent coordination of the meteorological installation with the Russian scientists and ship’s officers.