Condign volumes 1 to 3

Read from the scan by GLM-OCR; expect the odd misread word.

# UNCLASSIFIED

UK RESTRICTED

## EARTH'S MAGNETIC FIELD IN THE UKADR

## INTRODUCTION

1. Earth's magnetic field has been briefly researched because of:

- The possible connection of field strength with UAP events.

- As a comparison with the magnetic field strengths used during the magnetic field experiments reported at Working Paper No 25.

## FIELD MEASUREMENTS

2. Over the period 1987-95 eight international stations, comprising a SubAuroral Magnetometer Network (SAMNET) monitored the changes every five seconds. Earth's internal magnetic field changes only slowly in direction and magnitude, but there are also magnetic effects due to the flow of charged particles in the upper reaches of the atmosphere (the ionosphere) and in space. Day plots have been taken every 1 second, since 1995. Each station records the magnetic field in three orthogonal directions. The stations cover the UK, Sweden, Norway, Finland and the Faroe Islands.

3. Field Intensity The magnetic field is calculated (in Nano Teslas) from the International Geomagnetic Reference Field (IGRF). The total intensity in the UK is 49,000 to 50,000 nT $ (1 \mathrm{n T} \equiv 1 \delta) $ . Changes in intensity are $ \sim 3 0 \mathrm{n T} $ per year. The horizontal component of the field is about 20,000 nT in Southern UK and 15,000 nT in Northern UK.

4. Field Angles The field inclination angle is $ \sim 7 0^{\circ} $ with typical changes of one to two minutes (of angle) per year. For epoch 1970 the declination angle is between -6 and -12 degrees, with changes of $ \sim 6 $ minutes of angle per year.

5. The North magnetic pole is migrating NW by 9km per year (79.1 $ ^{\circ} $ N 28.9 $ ^{\circ} $ E). For the chart shown at Figure 1, $ 1 \delta=1 0^{-5} $ Gauss. $ =1 0^{-9} \mathrm{T}=1 \mathrm{n T}. $ The plotted readings show no sudden or unexplained variations but rather a steady decline in magnetic intensity level over the 50 to $ 60^{\circ} \mathrm{N} $ lines of latitude straddling most of the UKADR.

6. Local Variations No information is available on small variations which may occur in specific locations. Particularly, no field peculiarities are present in the main plots to indicate the possibility of influencing geographical clustering of UAP reports.

## UNITED KINGDOM MAGNETIC SURVEY

7. Data gathered nationally by a network of 51 stations (survey points), established between 1985 and 1988, allow local (crustal) magnetic variations to be monitored $ ^{[1]} $ . Global models accurately represent the main part of the geomagnetic field, originating in the earth's core. At the surface there are perturbations caused by magnetised rocks and electric currents in the ionosphere and