Abstract
Band-shaped precipitation systems are frequently observed as back-building (BB) types with most convective cells successively initiating on the upwind side. Usually, nearly neutral stratifications of moist static energy (h*) are observed in the convection areas, whereas conditionally unstable stratifications remain in the surroundings. To understand the difference in features between these two areas and the frequent occurrence of the BB type, heating, whose types are (i) a point source, (ii) an infinitely extending line, and (iii) a line with an end, is prescribed in environmental fields with uniform zonal wind (U*) and damping (γ*), and the linear responses of buoyancy are studied. The response fields for heating types (ii) and (iii) are obtained by applying a solution of buoyancy for (i) heating. Here it is assumed that the neutralization of h* occurs by temperature adjustment with a deviation having an intensity of ΔT*. In the U*= γ*=0 case, the temperature deviations are ΔT*/2 at most in the influence region far from the end, because two oppositely propagating gravity waves are induced for the response. This solution corresponds to response one on the Cartesian coordinate system. It is concluded that the neutralization of h* in the convection areas and its response in the surroundings induce the different stratifications, maintaining the conditionally unstable stratifications in the surroundings even though intense precipitation occurs. In the U*≠0 cases, frequent formations of the BB types are anticipated as one possibility, because the influence of the response on the upwind side of precipitation is small, and new convection is likely to occur.
