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We use coordinated observations with the Interface Region ImagingSpectrograph (IRIS) and the Swedish 1-m Solar Telescope (SST) to identify thedisk counterpart of type II spicules in upper-chromospheric and transitionregion (TR) diagnostics. These disk counterparts were earlier identifiedthrough short-lived asymmetries in chromospheric spectral lines: rapid blue- orred-shifted excursions (RBEs or RREs). We find clear signatures of RBEs andRREs in Mg II h & k, often with excursions of the central h3 and k3 absorptionfeatures in concert with asymmetries in co-temporal and co-spatial H-alphaspectral profiles. We find spectral signatures for RBEs and RREs in C II 1335and 1336 A and Si IV 1394 and 1403 A spectral lines and interpret this as asign that type II spicules are heated to at least TR temperatures, supportingother recent work. These C II and Si IV spectral signals are weaker for asmaller network region than for more extended network regions in our data. Anumber of bright features around extended network regions observed in IRISslit-jaw imagery SJI 1330 and 1400, recently identified as network jets, can beclearly connected to H-alpha RBEs and/or RREs in our coordinated data. Wespeculate that at least part of the diffuse halo around network regions in theIRIS SJI 1330 and 1400 images can be attributed to type II spicules withinsufficient opacity in the C II and Si IV lines to stand out as singlefeatures in these passbands.

Heating signatures in the disk counterparts of solar spicules in IRIS observations