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The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tcd-8-5645-2014
© Author(s) 2014. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
06 Nov 2014
Review status
This discussion paper has been under review for the journal The Cryosphere (TC). The revised manuscript was not accepted.
Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya
R. J. Thayyen1 and A. P. Dimri2 1National Institute of Hydrology, Roorkee, Uttarakhand, India
2School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
Abstract. Moisture, temperature and precipitation interplay forced through the orographic processes sustains the Himalayan cryospheric system. However, factors controlling the Slope Environmental Lapse Rate (SELR) of temperature along the higher Himalayan mountain slopes across various glacio-hydrologic regimes remain as a key knowledge gap. Present study dwells on the orographic processes driving the moisture–temperature interplay in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya. Systematic data collection at three altitudes between 2540 and 3763 m a.s.l. in the Garhwal Himalaya (hereafter called monsoon regime) and between 3500 and 5600 m a.s.l. in the Ladakh Himalaya (herefater called cold-arid regime) revealed moistrue control on temperature distribution at temporal and spatial scales. Observed daily SELR of temperature ranges between 9.0 to 1.9 °C km−1 and 17.0 to 2.8 °C km−1 in the monsoon and cold-arid regimes respectively highlighting strong regional variability. Moisture influx to the region, either from Indian summer monsoon (ISM) or from Indian winter monsoon (IWM) forced lowering of SELR. This phenophena of "monsoon lowering" of SELR is due to the release latent heat of condensation from orographically focred lifted air parcel. Seasonal response of SELR in the monsoon regime is found to be closly linked with the variations in the local lifting condensation levels (LCL). Contrary to this, cold-arid system is characterised by the extremely high values of daily SELR upto 17 °C km−1 signifying the extremely arid conditions prevailing in summer. Distinctly lower SELR devoid of monsoon lowering at higher altitude sections of monsoon and cold-arid regimes suggests sustained wetter high altitude regimes. We have proposed a SELR model for both glacio-hydrological regimes demostrating with two sections each using a derivative of the Clausius–Clapeyron relationship by deriving monthly SELR indices. It has been proposed that the manifestations of presence or absence of moisture is the single most important factor determining the temperature distribution along the higher Himalayan slopes driven by the orographic forcings. This work also suggests that the arbitary use of temperature lapse rate to extrapolate temperature to the higher Himalaya is extremely untenable.

Citation: Thayyen, R. J. and Dimri, A. P.: Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya, The Cryosphere Discuss., 8, 5645-5686, doi:10.5194/tcd-8-5645-2014, 2014.
R. J. Thayyen and A. P. Dimri
R. J. Thayyen and A. P. Dimri

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Short summary
Slope environmental lapse rate of temperature in the monsoon and cold-arid regimes of the higher Himalaya is found to be varying between 9.0 to 1.9oC/km and 17.0 to 2.8oC/km respectively highlighting strong regional variability. Moisture availability/absence is found to be the key factor forcing the lapse rate variability. Present study also provided a modelling solution for estimating the lapse rate.Study suggests that the arbitrary use of lapse rate in the Himalaya is is extremely untenable
Slope environmental lapse rate of temperature in the monsoon and cold-arid regimes of the...
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