NBP-06	Weekly Report – 18-26 June 1999 - draft

During the second week of the Palmer LTER sea ice cruise we moved from the ice edge (first sea ice 
encountered about 66.5S (320.100) to medium thick first year ice at 69.5 (-220.100).  Sea ice extent is
relatively low in area and late in arriving this year.  

We began our 2nd week by transecting south carrying out periodic sea ice & sea bird observations and 
selected stations for CTD & 1m vertical net tows.  CTD stations were held at LTER grid stations (500.100, 
400.100,  320.100, 300.100, 280.100, 240.100, 200.100, 150.100, 100.100, 050.100, 000.100, -050.100, -
100.100, -160.100, -220.100). Water samples were collected at predetermined depths for a variety of 
chemical and micro-biological determinants.

Once into 10/10 pack ice three ice buoys were deployed for Dr. Hartmut Hellmer (Alfred-Wegener 
Institute, Bremerhaven):
#9363 deployed at 2221 U on 19 June at 68 51.48S, 77 07.91W
#9365 deployed at 0523 U on 20 June at 69 11.90S, 78 16.98W
#9357 deployed at 0810 U on 22 June at 68 38.38S, 78 25.29W
These buoys will be tracked via satellite for the duration of the winter to determine sea ice drift and 
divergence in this region of the Western Antarctic Peninsula.

Two sea ice stations, in thin to medium thick first year ice, were established during this period.  Ice Station 
#1 at –220.100 (69 25.39S, 79 28.49W) and Ice Station #2 at –100.100 (68 48.698S, 77 19.427W).  Science 
activity at each station included: 
snow/ice transects for snow depth, snow-ice interface temperature & ice thickness & freeboard; 
ice cores for physical analysis (temperature, salinity, delta18O & stratigraphy including beautiful thin 
sections by Jinro Ukita)
ice cores & ice “blocks” for chemical and biological measurements (PC, PN, PP, P-Si, DOC, DON, DOP,
inorganic nutrients, bacteria & phytoplankton biomass and potential activities) and photosynthetic pigment, 
total particulate carbon & nitrogen, inorganic nutrients, taxonomic composition and potential primary 
production.;
CTD (temperature, conductivity, depth, transmittance, O2, flourescence and water samples for LTER core 
measurements);
PRR (Profiling Reflectance Radiometer, Ed, Lu);
Spectral radiometer (light transmission through snow & ice;
frazil ice meter (absorption at 900 & 995 nm);
ROV (with PRR, transmissometer, fluorometer, temp & salinity);
1m net tows; 
diver observations beneath the ice & collection of krill larvae; and
sea bird observations & collection.

Ice Station #1(20,21 June) lasted two days and during this period a heavy swell developed and moved 
through the pack. Weather during this period was mild with light winds yet the storm passing thru the 
Drake passage 1000km to the north caused considerable disturbance within  this first year  (30-80 cm
thick) ice. 

Ice Station #2 (22-26 June) was established in thin first year ice (20-70 cm thick) with light (few cm)
snow cover.   We began and ended this station with high barometric pressure, low air temperatures
(-15C to –20C) and winds generally less than 5 knts.  A low pressure “storm” passed through during
this four-day period raising temperatures to a balmy –3.6C with winds between 10-15knts.  As a 
consequence we were able to record both in the physics and biology during both periods sea ice growth
and ablation.

We continue to receive excellent support from Captain Joe Borkowski and crew and MPC Karl Newyear 
and the rest of the ASA personnel.  The satellite imagery provided via John Booth at Palmer is giving an 
accurate spatial overview of sea ice within the area and has been especially helpful locating sites of various 
stages of sea ice.  The science teams continue to work as an integrated team and is very excited about our 
results to date.

Kindly note that the ASA-NBP email link will be disrupted from 1-4 July – during our next reporting 
period.

Ray Smith, Chief Scientist
NBP-06 Palmer LTER Sea Ice Cruise