Plots of minimum temperatures per hour; x-axis is day number for the year The horizontal line is at Temp = -8.5 C. Sometimes the temperature monitors produce bogus values of -40 to -50 C. Ignore these !

%META:FILEATTACHMENT{name="yplot_2008.gif" attr="" comment="January 2008 minimum temperatures" date="1204146768" path="yplot_2008.gif" size="39925" user="FrankGhigo" version="1.1"}% %META:FILEATTACHMENT{name="yplot_2007.gif" attr="" comment="Temperatures for 2007" date="1204146816" path="yplot_2007.gif" size="90575" user="FrankGhigo" version="1.1"}% %META:FILEATTACHMENT{name="yplot_2006.gif" attr="" comment="Temperatures for 2006" date="1204146840" path="yplot_2006.gif" size="75139" user="FrankGhigo" version="1.1"}% %META:FILEATTACHMENT{name="yplot_2005.gif" attr="" comment="Temperatures for 2005" date="1204146859" path="yplot_2005.gif" size="72735" user="FrankGhigo" version="1.1"}% %META:FILEATTACHMENT{name="mplot2004.gif" attr="" comment="Temperatures for 2004" date="1204148059" path="mplot2004.gif" size="91303" user="FrankGhigo" version="1.1"}% %META:FILEATTACHMENT{name="yplot_2003.gif" attr="" comment="Temperatures for 2003" date="1204148087" path="yplot_2003.gif" size="79919" user="FrankGhigo" version="1.1"}%

goes below 16 F ( -8.8 C), it seems worthwhile to compile some

goes to or below 16.5 F ( -8.6 C), it seems worthwhile to compile some

• The percent of files during each month in which the temperature goes below -8.5 C is tabulated below.

• These file minima are what is plotted versus day number for each year, below.
• The percentage of readings in which the temperature goes below -8.5 C is tabulated in the table.
• (there is usually a reading per second)

Note weather restrictions, described here.

%META:TOPICINFO{author="FrankGhigo" date="1204051500" format="1.0" version="1.1"}% %META:TOPICPARENT{name="Main.FrankGhigo"}%

Low Temperature Statistics for the GBT

Since we now have restricted azimuth slew speed when the temperature goes below 16 F ( -8.8 C), it seems worthwhile to compile some statistics about when and how often these low temperatures happen.

• The archived log data, samplers "TEMP_1" and "TEMP_2, from weather station 2 have been used.
• The minimum temperature in each FITS log file (about one file per hour usually) is noted.
• The percent of files during each month in which the temperature goes below -8.5 C is tabulated below.

Table: Percentage of time the temperature was below -8.5 C

Month / year:	_ 2003 _	_ 2004 _	_ 2005 _	_ 2006 _	_ 2007 _	_ 2008 _
JAN	43	38	21	--	15	25
FEB	12	14	10	9	42
MAR	5	3	10	3	3
APR	0	0	0	0	1
OCT	1	0	0.3	0	0
NOV	3	0.3	7	2	2
DEC	11	20	18	10	5

-- FrankGhigo - 26 Feb 2008