SPIRE spectroscopy of the prototypical Orion Bar photodissociation region

<i>Aims. <i/>We present observations of the Orion Bar photodissociation region (PDR) obtained with the SPIRE instrument on-board <i>Herschel<i/>. <i>Methods. <i/>We obtained SPIRE Fourier-transform spectrometer (FTS) sparse sampled maps of the Orion bar.<i>Results. <i/>The FTS wavelength coverage and sensitivity allow us to detect a wealth of rotational lines of CO (and its isotopologues), fine structure lines of C and N<sup>+<sup/>, and emission lines from radicals and molecules such as CH<sup>+<sup/>, CH, H<sub>2<sub/>O or H<sub>2<sub/>S. For species detected from the ground, our estimates of the column densities agree with previously published values. The comparison between <sup>12<sup/>CO and <sup>13<sup/>CO maps shows particularly the effects of optical depth and excitation in the molecular cloud. The distribution of the <sup>12<sup/>CO and <sup>13<sup/>CO lines with upper energy levels indicates the presence of warm (~100–150 K) CO. This warm CO component is a significant fraction of the total molecular gas, confirming previous ground based studies.