The Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard Envisat (Environmental Satellite) globally measured the day and night limb emission from atmospheric constituents from July 2002 to April 2012, when contact to the satellite was lost. MIPAS spectra cover wavelengths from 4.3 to 15.6 µm with a resolution of 0.035 cm-1 (unapodized, full resolution) from 2002 to 2004 and 0.0625 cm-1 (unapodized, reduced resolution) onwards. MIPAS was in a Sun-synchronous orbit, with ascending/descending nodes at 10:00/22:00 LT. MIPAS almost continuously measured in its nominal (NOM) mode (6–68 km) but used special modes to expand its measurements to the mesosphere and lower thermosphere (MLT) during around ten 2–3 full-day campaigns in 2005 and 2006 and on a regular basis (every 10 days) starting in March 2007. These special modes of operation are the middle-atmosphere mode (MA; covering 18–102 km, in 3 km vertical steps), the upper-atmosphere mode (UA; covering 40–102 km, in 3 km steps, and 102–170 km, in 5 km steps) and the noctilucent-cloud mode (NLC; covering 39–102 km, in 3 km steps except at 78–87 km, where 1.5 km vertical steps were used; this mode was only used for 3-day campaigns in the solstices) .

The MA-, NLC- and UA-mode measurements are currently used to derive kinetic temperature, ozone, water vapor, methane, carbon monoxide, nitric oxide, nitrous oxide, nitrogen dioxide and ice volume density in the MLT. The retrieval of temperature and line-of-sight vertical pointing information (TLOS) is the first one in this chain, since TLOS is needed for all other retrievals. Thus, assuring a high-quality TLOS is essential. TLOS is retrieved from the CO2 atmospheric emission measured by MIPAS around 15 µm up to the lower thermosphere, which, in contrast to the retrievals from measurements in the NOM mode , needs the inclusion of a nonlocal thermodynamic equilibrium (non-LTE) model, since the atmospheric infrared emissions at those altitudes are generally affected by these effects . (GC2012 hereafter) documented the first release of temperatures in the MA, UA and NLC modes (vM11, where M=5, 6 and 7 stand for MA, UA and NLC, respectively). Those versions included measurements from 2005 to 2009. GC2012 made a comprehensive description of the retrieval setup and the mechanisms considered in the non-LTE model, and compared the results with measurements from other instruments. The spectra provided by the European Space Agency (ESA) used to generate that TLOS version were version 4.61/4.62.

MIPAS L1b spectra in the version 4.61/4.62 are not available for measurements made after 2009, but the updated version 5.02/5.06 is provided from then on. Changes from the former version to the latter in engineering altitude and in radiance, due to a new calibration, nonlinearity corrections of the detectors and a better treatment of the forward/reverse problem are significant. That implies that a uniform MIPAS data set covering all MIPAS MA, UA and NLC temperature measurements using vM11 is not possible. Fortunately, the spectra version 5.02/5.06 L1b was released for all measurements made by MIPAS during its lifetime. These two facts motivated us to generate a new version of TLOS using 5.02/5.06 spectra. Since the comparisons of temperature with other instruments in GC2012 showed systematic differences, we also modified the retrieval setup with the aim of addressing their causes.

We present for the first time a complete MIPAS reduced-resolution (January 2005–April 2012) MA/UA/NLC temperature data set in versions v521, v621 and v721 (vM21 hereafter). We describe the improvements introduced in these retrievals, their impact on MIPAS temperatures and the retrieved temperature fields in Sect. . In order to assess the quality of these new versions, we compare these temperatures with measurements from five satellite instruments and two lidars. A short summary of each of these instruments is presented in Sect. . Section  describes the results of the comparisons from 20 to 100 km, including a discussion on the differential behavior in the different modes of observations and in the two hemispheres. Section  summarizes our findings.

The retrieval of temperature, line-of-sight (LOS) altitude information and temperature horizontal (mainly latitudinal) gradients in versions vM21 is done from measurements of the CO2 atmospheric radiance at 15 µm for each MIPAS single limb scan. The scheme of the setup follows that described in detail for vM11 by GC2012, which in turn is an extension of the retrieval in the MIPAS NOM mode with the GRANADA non-LTE model described in . We note that vM21 uses the same microwindows as vM11 (see Table 1 in GC2012) and the same retrieval altitude grid (1 km below 50 km and 2 km above; we note that the forward calculations are performed using the finer grid (1 km) up to 88 km). The main upgrades introduced in the retrieval vM21 and their impact on the retrieved temperatures with respect to vM11 are as follows:

MIPAS L1b spectra: VM21 retrievals use calibrated spectra as supplied by ESA in version 5.02/5.06 (, and references therein). The effect on retrieved temperatures, compared to results using the previous 4.61/4.62 spectra, is smaller than 1–2 K below 90 km (when affected, that difference is generally positive) and temperature decreases above that altitude, exhibiting the maximum difference (in absolute value) at 95 km (-10 K). That occurs at all latitudes and in all seasons except for the summer at latitudes higher than 70∘. Under the latter conditions, the changes are more pronounced. The effect is there smaller than 1–2 K only below 75 km, the temperature increases by 4 K around 75 km and at the mesopause, and it decreases above that altitude, with the maximum change at 95 km (-15 K).

Other important aspects of the retrieval, including non-LTE collisional rate constants, are set as in the previous vM11 version (refer to GC2012 for more details) with some (minor) non-LTE updates as described in

Using this retrieval setup, we derived temperatures, line of sight and temperature horizontal gradients for all MIPAS MA, UA and NLC measurements in the optimized resolution, i.e., from January 2005 to April 2012. Figures , and show seasonal latitude–altitude zonal means of the retrieved temperatures for the MA, UA and NLC modes, respectively, the corresponding vertical resolutions and the difference with vM11 temperatures. The MA and UA modes cover the four seasons, which include measurements taken during December-January-February (DJF), March-April-May (MAM), June-July-August (JJA), and September-October-November (SON), and the NLC mode covers two seasons, which include measurements taken in January and July. The averages shown in these figures contain measurements extending only from 2005 to 2009, but they are representative of the complete period. This has been done for the sake of compatibility with vM11 averages, since the latter were done from 4.61/4.62 spectra, only available for 2005–2009. Our Fig.  left and central panels are thus directly comparable to those in Fig. 2 in GC2012.

The latitude–altitude temperature distributions behave similarly in the three modes of observation. The vertical resolution is, however, slightly (1–2 km) better in the NLC mode from 75 to 90 km, where it decreases with respect to the MA and UA mode due to the finer NLC-mode vertical sampling. The mesopause is also slightly colder, and the lower thermosphere slightly warmer, in the summers in the NLC mode. The higher vertical resolution in the 80–90 km region accounts for up to 3–4 K lower NLC temperatures (in the polar summer mesopause). The remaining differences exist because the NLC measurements are taken closer to the solstices whereas the MA and UA measurements are taken regularly through DJF or JJA, i.e., the summers in Fig.  show a more extreme scenario than in Figs.  and .

The vM21 estimated systematic and random temperature errors remain similar to those of versions vM11 (cf. Table 2 of GC2012). The sources of systematic errors considered are the uncertainties in non-LTE errors collisional rates, atomic oxygen abundance, CO2 abundance, CO2 spectroscopic properties (strength, position and width of spectral lines), gain calibration, instrument line shape and spectral shift (see further details on error sources included in GC2012). Systematic errors depend on latitude and season but are typically smaller than 1 K below 70 km, 3 K at 85 km and 10 K at 100 km. For summer high latitudes, these values are larger in the upper mesosphere and above, reaching 6 K in the mesopause (88 km) and 30 K at 100 km. The vM21 temperature random errors are mainly caused by the instrumental noise and are smaller than 0.5 K below the stratopause and 7 K at the mesopause. The vertical resolution is barely affected by the version used.

The vM21 temperature differences with respect to vM11 are important, particularly above 80 km (see Figs. –). The latitude–altitude distribution of the vM21–vM11 temperature difference remains almost invariant with mode in all seasons. The differences in each mode do not significantly vary with season at low latitudes (< 30∘), but they do at higher latitudes. Beyond 30∘ N/S, differences are larger during solstice than equinox and slightly larger above 80 km during JJA (or only July in NLC) than during DJF (or only January in NLC). The latter is explained by interhemispheric differences in the temperature itself. Temperatures during JJA show sharper structure (colder mesopauses and warmer lower thermospheres at all latitudes). In general, those translate into a larger sensitivity to some of the main changes introduced in vM21 retrievals: atomic oxygen, because of the larger non-LTE effects in more extreme atmospheres, or temperature horizontal gradient regularization, because of the larger gradients along the line of sight.

Overall, the effects of these new retrieval setups sum up to a 1–2 K increase right above the stratopause (maximum in the polar summers), mainly driven by the updated HITRAN spectral database, with a maximum in polar summers due to the additional effect of the MIPAS 5.02/5.06 L1b spectraversion. The effect of the spectral database modulated by that of the L1b spectra version is also the main reason for the increase in temperature (up to 2 K) around 75 km at all latitudes and the 1–2 K decrease around 80 km in the polar summer in the NLC mode. Other changes, like those of offset and temperature horizontal gradient regularizations, as well as apodization accuracy and a priori in the polar summer, also affect temperature below 80 km, but to a lesser extent.

The vM21 temperatures above 80 km and up to 102 km, in general, decrease with respect to vM11 at most latitudes and seasons (except around the summer high latitudes (> 60∘) mesopause; see below), with maximum (in absolute value) negative differences at the mesopause (-10 K around 95 km and slightly smaller in the Arctic winter). This decrease in temperature is mainly due to the 5.02/5.06 L1b spectra version, although effects from changes in (in this order) (i) the temperature horizontal gradient regularization (particularly at the mesopause at low latitudes), (ii) the atomic oxygen (particularly above the mesopause), (iii) the offset regularization and the apodization accuracy (particularly below the mesopause), and (iv) the carbon dioxide (in the polar winter) are not negligible (1–3 K, in absolute values).

The exception to that general behavior occurs at the summer high latitudes (> 60∘). The mesopause there, at lower altitude and temperature than in other latitudes and seasons, is 2–4 K warmer and 3–4 km lower in vM21, mainly due to the increase caused by the updated atomic oxygen, which is partially compensated for by a 2–3 K decrease caused by the improved offset and temperature horizontal gradient regularizations. As in other atmospheric conditions, the temperature in the summer high latitudes decreases by 4 K at 90 km, due to the combined effect of the changes in the L1b spectra, the temperature horizontal gradient regularization, the CO2 abundance and the offset regularization. However, the response to changes above 95 km is amplified due to the significantly larger temperature vertical gradient, which additionally leads to higher temperatures (which result in larger non-LTE effects), and the larger temperature gradients along the line of sight. When upgrading from vM11 to vM21, the temperature decrease around 100 km at high latitudes is -15 K in the austral summer and -20 K in the boreal summer, mainly due to the atomic oxygen and the L1b spectra version, but also to the temperature horizontal gradient regularization and the CO2 abundance (effects are larger than 3 K, in absolute values).

In order to assess the quality of the MIPAS temperatures derived using vM21 retrievals, we compare our results with close-to-simultaneous remote measurements from seven instruments. Besides the comparison with two lidars on the ground, we include five other satellite instruments that, together with MIPAS, provided temperature in the MLT on a regular basis over long periods (longer than 5 years) between January 2005, when the vM21 retrievals start, and April 2012, when MIPAS stopped operations.

We determined the colocated measurements of each instrument and MIPAS measurements from January 2005 to April 2012 in its MA, UA and NLC modes of operation. The measurements in a colocated pair are taken at a maximum of 2 h and 1000 km apart. These criteria minimize differences coming from atmospheric variability without compromising the statistical significance of the comparisons. In order to optimize this balance, we have performed tests by increasing and decreasing both the spatial and temporal differences between the measurements. Decreasing the distance and the time difference between colocated pairs to 500 km and 1 h, respectively, barely changes the results. For a given pair, we use the averaging kernels and a priori of the coarser vertical resolution instrument to smooth the colocated profile of the finer-resolution one. That is, we smooth lidars' SABER, SOFIE, and OSIRIS profiles in their comparisons with MIPAS, and MIPAS in its comparison with MLS. Given their similar vertical resolution, we do not smooth MIPAS or ACE-FTS profiles in their comparison. We use altitude as the vertical coordinate for all comparisons except for those between MIPAS and MLS, for which we use pressure.

We calculated the temperature difference for each pair of profiles, and then their yearly averages for colocations within 20∘ wide latitude boxes for four periods: DJF, MAM, JJA and SON. We then calculated the mean for each season and latitude box. The spring averages encompass the measurements during MAM in the Northern Hemisphere (NH) and SON in the Southern Hemisphere (SH), autumn during SON in the NH and MAM in the SH, summer during JJA in the NH and DJF in the SH, and winter during DJF in the NH and JJA in the SH.

Figures – show the average seasonal differences for the four seasons in the MA mode and Figs.  and for summer and winter in the NLC mode. Note that, even if we determined the differences as a function of pressure in the MIPAS versus MLS comparison, we plot them as a function of MIPAS altitude for the sake of simplicity. Results for the comparisons of colocated measurements in the UA mode (see Supplement) are almost identical to those in the MA mode. The figures also include the estimated MIPAS temperature systematic errors and the number of coincidences for each season and latitude box. Using only MIPAS errors represents a pessimistic scenario because, strictly speaking, the temperature differences should be compared with the combined systematic errors for each instrument pair, which necessarily have larger values than the shading in the figures. Differences in temperatures of the stratopause (point in the temperature-altitude average profile with maximum temperature in the stratosphere and lower mesosphere region) and mesopause (point with minimum average temperature in the upper mesosphere and lower thermosphere region), even if they are located at different altitudes in each pair of instruments, are also plotted using symbols at their corresponding mean altitudes in MIPAS colocated profiles. When these symbols are exactly over the difference profiles, this indicates that the two instruments under consideration located the strato- and/or the mesopauses at the same altitude.

The understanding of atmospheric variable interhemispheric differences, commonly known as interhemispheric asymmetries, is an important topic that is currently often addressed in atmospheric studies. Studies based on differences are usually more reliable than those dealing with absolute values because the persistent (in time and/or place) systematic errors may cancel out. That is not the case if artificial spatial and temporal inhomogeneities in the measured atmospheric variables (which may be due to several aspects such as dependence of the retrievals on atmospheric conditions, dependence of the observations and/or inversions on the time or location, etc.) are present. A correct interpretation of interhemispheric asymmetries relies on the ability of the measurements to homogeneously reproduce the atmospheric state fields. Temperature interhemispheric asymmetries are widely used, for example, in polar mesospheric cloud studies , for which a differential behavior in the two hemispheres occurs.

Our goal here is to assess MIPAS's ability to measure temperature and altitude interhemispheric asymmetries, or, in other words, detect differences between NH and SH measurements not originated by the real atmospheric state. Note that the difference between instruments in hemispheric asymmetry of certain observable is equivalent to the hemispheric asymmetry in the observable difference between instruments. That is, the resulting differences in temperature interhemispheric asymmetry also reflect deviations between NH and SH MIPAS temperature differences with the other instruments.

We compare the temperature and altitude interhemispheric asymmetries measured by MIPAS in the stratopause and the mesopause with those from the other five satellites. In order to avoid sampling effects (in location and/or time) as much as possible, we determined the interhemispheric asymmetries for each instrument from the set of colocated measurements. We also used the full season colocation set instead of selected periods, which assures a large number of colocations for all instruments in each hemisphere (plus a North and South Pole coverage by SABER, which alternates their observation every 2 months) and thus a representative result. Nevertheless, it is important to note that this approach implies that the absolute interhemispheric asymmetries derived using only the colocation sets (written below for the case of MIPAS) instead of each instrument complete data set do not coincide necessarily with the mean seasonal interhemispheric asymmetries measured by each of those instruments. This is precisely due to the limitation imposed by the different temporal and spatial distributions of the colocations along a season and a latitude box for each instrument pair.

Figure  shows the difference between MIPAS average NH–SH asymmetries and those from colocated measurements from the other instruments in the stratopause and the mesopause, for the summer and winter seasons and at 70–90∘ and 50–70∘ latitudes. The x axes show the differences between instruments in the temperature asymmetry and the y axes show the differences between instruments in the altitude asymmetry. In those plots we represent the absolute values of the asymmetry differences and assign a negative sign only when MIPAS asymmetry has the opposite sign to that from the other instrument (that is, if MIPAS measured a higher temperature in one hemisphere but the other instrument measured it in the other hemisphere). In other words, a positive/negative value indicates an agreement/disagreement in the sign of the asymmetry.

During summer, MIPAS stratopause temperature and altitude NH–SH asymmetries averaged for all colocation sets are -3 ± 2 K and 0 ± 0.3 km, respectively, for 70–90∘, and -4 ± 1 K and 0 ± 0.5 km, respectively, for 50–70∘. The differences between MIPAS and the other instruments summer stratopause temperature NH–SH asymmetry are smaller than 1 K for both latitude boxes. It is worth noting that, in several cases, that value is significantly smaller than the corresponding absolute difference between the stratopause temperature measured by each instrument, as shown in Fig. . The difference in the MIPAS summer stratopause altitude NH–SH asymmetry from the other instruments is smaller than 1.5 km and within MIPAS vertical resolution at the corresponding altitude. MIPAS winter stratopause temperature and altitude NH–SH asymmetries averaged for all colocation sets are -16 ± 5 K and 1 ± 2 km, respectively, for 70–90∘, and -6 ± 3 K and -2 ± 2 km, respectively, for 50–70∘ (note that long periods after NH sudden stratospheric warnings, when the stratopause temperature significantly decreases, are included). MIPAS comparisons with MLS, SABER and SOFIE for winter stratopause temperature and altitude interhemispheric asymmetries are very good (smaller than 1 K and 2 km, respectively) both at 70–90∘ and 50–70∘ latitudes, but there is a 4 K deviation with respect to the asymmetry measured by ACE-FTS at 70–90∘. All instruments detect the same sign for the stratopause temperature hemispheric differences.

MIPAS summer mesopause temperature and altitude NH–SH asymmetries averaged for all colocation sets are -9 ± 4 K and 0.5 ± 1 km, respectively, for 70–90∘, and -6 ± 7 K and -0.5 ± 1 km, respectively, for 50–70∘. We note that a large standard deviation does not denote a large error of the anomaly measured by MIPAS but a wide spread due to the different periods in a season and/or locations in a latitude box of each set of MIPAS colocations with each instrument. Differences between MIPAS summer mesopause temperature and altitude NH–SH asymmetries and the corresponding asymmetries measured by the other instruments are smaller than 2 K and 2 km, respectively, except for the comparison with OSIRIS at 50–70∘ and MLS. That 2 K temperature asymmetry difference is significantly smaller than the corresponding temperature absolute difference between the instruments at the mesopause (see Fig. ). MLS exhibits a persistent deviation in its temperature hemispheric asymmetry of 10 K (70–90∘) and 15 K (50–70∘). The negative sign shown in the plot additionally indicates that MLS temperature interhemispheric asymmetry has a different sign from those of all other instruments (in particular, MLS NH summer mesopause is warmer than in the SH, opposite to the behavior measured by the other instruments). OSIRIS temperature NH–SH asymmetry difference from the other instruments is also large (7 K) at 50–70∘ latitudes, but has the same sign.

MIPAS winter mesopause temperature and altitude NH–SH asymmetries averaged for all colocation sets are 5 ± 5 K and 1 ± 0.4 km, respectively, for 70–90∘, and 8 ± 4 K and 1 ± 1 km, respectively, for 50–70∘. The comparisons of interhemispheric asymmetries in the winter mesopause are more variable. MIPAS NH–SH temperature asymmetry difference with SABER at 70–90∘ is only 1 K, and both instruments show the same sign. MIPAS and SABER winter temperature asymmetries at these latitudes are reversed with respect to the other instruments (see negative sign in Fig. ). MIPAS temperature asymmetry differences are 7 K (SOFIE), 10 K (MLS) and 13 K (ACE-FTS); note that these values coincide with the hemispheric asymmetries in MIPAS temperature differences with those instruments. The winter comparisons improve in general at 50–70∘, where MIPAS temperature asymmetry has the same sign as ACE-FTS, MLS and SABER and is 2–4 K larger. The temperature asymmetries they all measure there have opposite sign to that measured by SOFIE. MIPAS and SOFIE temperature asymmetry difference is 5 K. The MIPAS altitude NH–SH asymmetry in winter is within 2 km of those measured by the other instruments except ACE-FTS (4 km and different sign).

We present vM21 MIPAS temperatures, the latest version of temperatures retrieved in the 20–102 km altitude range from the MA, UA and NLC modes, which measured the carbon dioxide emissions in the 15 µm region from January 2005 to April 2012. This version introduces the following updates with respect to the previous vM11: the HITRAN 2008 spectroscopic database; a climatology of atomic oxygen and carbon dioxide from WACCM-SD; a version of ESA-calibrated L1b spectra (5.02/5.06); and improvement in technical aspects of the retrieval setup, such as temperature gradient along the line-of-sight regularization, offset regularization, apodization accuracy, a priori, correction of CO2 non-LTE populations along the line of sight, H2O and O3 joint fit, and field-of-view radiance calculations.

The vM21 temperature, as compared to vM11, increases, on average, by 1–2 K in the stratopause and 0–2 K around 75 km, mainly due to effects from the version of the spectroscopic database and L1b spectra, although effects from changes in the offset and temperature horizontal gradient regularizations at all latitudes, and also those in the apodization accuracy and the a priori in the polar summer, are not negligible.

Except for the summer high latitudes, vM21 temperatures from 80 to 100 km are smaller than in vM11, with a maximum 15 K decrease at the mesopause, mainly due to the L1b spectra version, and with smaller effects caused by (in this order) the upgraded temperature horizontal gradient regularization, the atomic oxygen abundance, the offset regularization, the apodization accuracy and the carbon dioxide concentration. In the summer high latitudes, the mesopause is 2–4 K warmer than in vM11, primarily due to the atomic oxygen but partially compensated for by the effect of the improved offset and temperature horizontal gradient regularizations. Temperature at 90 km decreases by 4 K due to the spectra version, the temperature horizontal gradient and offset regularizations, and the CO2 abundance. Although the causes for the temperature changes above 95 km are the same as at other latitudes, their effects are amplified in the polar summer and temperature decreases by up to 20 K at 100 km.

The vM21 changes in temperature correct the main biases found from the lower stratosphere to the lower thermosphere in the comparisons of the previous temperatures (vM11) with other instruments, except around the mesopause during the high-latitude summers. Indeed, comparisons of the vM21 temperatures with measurements from ACE-FTS, MLS, OSIRIS, SABER, SOFIE and the two Rayleigh lidars at Mauna Loa and Table Mountain show, in general, significantly smaller differences (note that new versions are also used for ACE-FTS, MLS and SABER).

The MLO and TMF lidar measurements and MIPAS vM21 temperatures are generally within 1 K below 60 km and within 2–3 K from 60 to 80 km. Systematic exceptions occur in the winters around 45 km in the comparisons over TMF, where MIPAS temperatures are 3 K lower; in both equinoxes around 70 km over MLO, where MIPAS temperatures are 4 K lower; and in the summers above 70 km over MLO and around 80 km over TMF, where MIPAS temperatures are up to 4–5 K lower and higher, respectively.

MIPAS and ACE-FTS comparisons are very good, except in the summer. Their temperatures are within 1–2 K below 80 km and 2–4 K above 80 km in spring, autumn and winter (except for a narrow region around 80 km in the spring at 50–70∘). In the summer, MIPAS (and the rest of the instruments) on average measures a 3 K (5 K) warmer stratopause and a more than 15 K (20 K) colder mesopause.

The comparisons with MLS are good in the stratosphere, but MLS exhibits a colder upper stratosphere and lower temperatures than MIPAS (and the other instruments) at 55–75 km (0–5 K) and at the mesopause (3–10 K). MLS also differs from the other instruments in the temperature interhemispheric asymmetry because, in contrast to them, it measures a (significantly) colder summer mesopause in the Southern Hemisphere.

The differences between MIPAS and OSIRIS below 85 km are smaller than 2 K in spring, and 4 K in autumn and summer, with MIPAS temperatures being colder. Differences at 85–90 km are generally larger and reach 10 K in the summer high latitudes (mesopause) or 7 K (right below the mesopause) in other conditions. The difference at 95 km is reduced to 2–4 K.

Comparisons with SABER are remarkably good, bringing differences smaller than 2 K at all altitudes and seasons, except for high-latitude summers above 65 km. That means that average MIPAS-SABER differences between previous versions have been eliminated or significantly reduced in most conditions. The only exception occurs during the polar summer, when they are 3–4 K at 65–80 km (MIPAS colder) and 5–7 K around the mesopause (MIPAS warmer).

MIPAS and SOFIE differences are smaller than 2 K in the stratosphere. SOFIE stratopause is generally 3 K colder than MIPAS and, in general, the other instruments. Their temperatures in the mesosphere are within 1–3 K, MIPAS being generally colder. Except for autumn, MIPAS mesopause is 3–5 K colder than SOFIE.

Overall, MIPAS vM21 temperature comparisons exhibit typical (with a few specific exceptions) differences smaller than 1 K below 50 km and smaller than 2 K at 50–80 km in spring, autumn and winter at all latitudes, and summer at low to midlatitudes. Differences between MIPAS and the other instruments in the summer high latitudes are typically smaller than 1 K below 50 km, smaller than 2 K at 50–65 km and 5 K at 65–80 km. The differences in the mid-mesosphere are generally negative. MIPAS mesopause temperature lies within the range of the other measurements. It is generally within 4 K, except in the high-latitude summers, when it is within 10 K. The polar summer comparisons with SABER, MLS and OSIRIS point to a too warm MIPAS mesopause, whereas those with ACE-FTS and SOFIE to a too cold mesopause. The agreement in the lower thermosphere is typically better than 5 K, except for high latitudes during spring and summer, when MIPAS usually exhibits larger vertical gradients.

Despite sometimes larger differences between the temperatures measured by each instrument that sometimes exist, the comparisons of the interhemispheric temperature anomalies determined from the colocated observations indicate that MIPAS provides summer and winter stratopause and summer mesopause anomalies generally within 2 K of the other instrument measurements. The winter mesopause anomaly is generally within 4–5 K. This is not the case for the mesopause temperature anomaly comparison with MLS during summer and polar winter, SOFIE during the winter, and ACE-FTS in the polar winter, which even observe anomalies of opposite sign.