Since the summer of 1988 the North American surveillance network NLC CAN AM has been monitoring the climatological activity of the phenomenon known as noctilucent clouds (NLC). These mysterious night-time clouds only became visible at the end of the last century and are hence believed to be caused by environmental changes occurring at the surface of the Earth. In recent years there has been much speculation about and research regarding the origin of NLC, what they indeed portend about further environmental changes, and what changes may occur to the NLC themselves in the future.
NLC CAN AM in 1997 completed its tenth full season of concerted surveillance. The network consists now mostly of amateur observers, but many past participants were Canadian weather and flight service stations whose staff graciously conducted hourly sky checks for the clouds and duly recorded their observations on special report forms. The attendant body of data alone has been important in that it now gives the scientific community the opportunity to get a very accurate impression of NLC climatology in the 1980s and 1990s. Combined with the amateur data, the snapshot of NLC activity is even clearer. Over 50 000 individual observations have been logged since 1988, many of them from the above stations. A computer database from the first five years of NLC CAN AM observing, 1988 through to 1992, itself has nearly 40 000 observations.
The number of participating weather and flight service stations has steadily been dropping since 1993 due to station closures or reductions in operating hours and automation. In 1997 only five stations participated, and one of these stopped watching in mid season due to schedule reductions. The only participating station remaining that has also gathered hourly synoptic data in each of the previous nine seasons of NLC CAN AM surveillance is the La Ronge, Saskatchewan Flight Service Station.
Positioned at 55 degrees N latitude within the zone of highest summer incidence of NLC, La Ronge is in an ideal geographic position to monitor the phenomenon. Moreover, the quality of data received from this station has been exemplary. In my view, La Ronge can be considered a vital data point in present and future evaluations of NLC climatology, and for this reason, every attempt should be made to foster continued monitoring of NLC from La Ronge on an annual basis. The purpose of this report is to discuss ways of ensuring the continuation of surveillance.
As the current arrangement with Nav Canada regarding voluntary observations being conducted at the La Ronge Flight Service Station is most satisfactory, I propose first that the nature of present NLC recording there be preserved as long as possible. In a soon-to-be-composed proposal to Nav Canada requesting continued voluntary support by all Nav Canada stations currently participating in the NLC CAN AM programme, I will stress the importance of retaining the status quo at La Ronge and request that any changes to the station's operating schedule be relayed to NLC CAN AM as soon as possible so that measures to preserve NLC observing can be implemented. If the situation evolves whereby the continuous record at La Ronge is threatened, a number of alternate plans could be considered. They are listed by number below.
Options 1, 5, and 7 would require funds on a year-to-year basis in order to have observing continued. The source of these funds could be:
a) research grants from universities
b) grants from various levels of government
c) corporate and private donations, especially from businesses in northern Saskatchewan
d) NLC CAN AM
e) funds generated by the observers themselves.
Regarding (d), the NLC CAN AM network currently has no sources of revenue, so it would be difficult to come up with funds each summer to pay an observer. Regarding (e), perhaps it may be possible, for example, to have a hired observer pursue other revenue streams over the summer to aid the payment of herself/himself. Such streams may include:
i) the establishment of an interpretive kiosk in La Ronge highlighting NLC, aurorae, etc.
ii) the distribution of merchandise extolling NLC (N.B. NLC CAN AM currently possesses a cache of "NLC" postcards which are used in correspondence and which have been well-liked by those who have seen them).
La Ronge, though remote, is a tourism node, with the La Ronge Provincial Park nearby, so an interpretive setup may become a going concern in the summertime. Maybe the community itself could assist by declaring itself "The Noctilucent Cloud Capital of Canada".
Perhaps mention should be made of the observing regimen itself. Currently the La Ronge staff check for NLC starting on the night of May 21st and ending on the night of August 10th. Sky checks are made on-the-hour in conjunction with regular weather observations. The checks are done from 0500-0900 UT except for the period Aug 1-10th, when they are made from 0400-1000 UT. So the NLC "work week", though continuous and strictly nocturnal, is usually only 28 hours per week.
Lastly, the question of "why?" should be addressed. As with all kinds of other environmental monitoring, the task of keeping track of data is increasingly becoming the domain of automation. With NLC, monitoring by satellites, eg. the WINDII instrument aboard UARS, has been successful and suggests that keeping track of NLC on a long term basis could most efficiently be done by satellite. I agree with this assertion and frankly cannot proffer many convincing arguments to forego technological advancements in favour of the old-fashioned visual methods. My principal argument is that with La Ronge, we have a site, and a favourable one at that, that has been observing for a decade at a time when rapid changes in the upper atmosphere seem to be occurring. The best way to compare the future nature of NLC with that of the recent past is to retain the same monitoring methods that have been used. In this case, the surveillance happens to be simply visual recording.
I invite input from the parties to which this report is being sent on the feasibility of pursuing the above options presented, as well as views on the viability of the preservation of visual NLC monitoring at La Ronge, SK. I pledge the full support of NLC CAN AM to assist in any of the above endeavours, and, in the meantime, would be happy to keep all interested parties informed on the ongoing status of La Ronge.
Mark S. Zalcik Coordinator NLC CAN AM