Solar activity will peak during 2000, according to the newsletter, GPS for Air and Space Power. The increased solar activity could have an adverse effect on GPS users. Solar activity generates substantial electromagnetic atmospheric effect on radio signals passing though the earth's ionosphere, which can not only reduce the accuracy of GPS/WAAS receiver range calculations, but also can result in a complete loss of lock on a satellite. In the worst case, lock on could be lost with enough satellites so as to make determination of position difficult. The effect is expected to have a greater impact around the magnetic equator and polar cap regions, but the total impact on GPS is unknown.