Details

Autor(en) / Beteiligte

• Knight, J.H
• Kluitenberg, G.J

Titel

Simplified computational approach for dual-probe heat-pulse method

Ist Teil von

• Soil Science Society of America journal, 2004-03, Vol.68 (2), p.447-449

Ort / Verlag

Johnson Space Center: Soil Science Society of America

Erscheinungsjahr

2004

Link zum Volltext

Quelle

MEDLINE

Beschreibungen/Notizen

• Two equations are currently available for estimating soil volumetric heat capacity (rhoc) with the dual-probe heat-pulse (DPHP) method. One is simple but gives only approximate results because it assumes that the DPHP sensor releases an impulse of heat instantaneously. The other explicitly accounts for the finite duration of heating and gives exact results. Unfortunately, the equation that gives exact results involves the exponential integral function, which is not available in most computer spreadsheet software packages or data logger function libraries. In this note we introduce an approximation of the exact equation that contains only simple algebraic functions. The approximation consists of the first five terms of a Taylor series, which are written as a telescoped polynomial for computational purposes. For most applications of the DPHP method, the polynomial approximation gives estimates of rhoc that are at least an order of magnitude more accurate than estimates obtained from the simple equation based on instantaneous heating.