scholarly journals Shallow Temperature Lapse Rate Signified Elevation Dependent Warming in Different Treeline Environments in the Himalaya- Possible Implications to Treeline Vegetation

2021 ◽  
Author(s):  
Rajesh Joshi ◽  
Ninchhen Dolma Tamang ◽  
Surendra Pratap Singh
Keyword(s):  
Climate Models ◽  
Winter Season ◽  
Growing Season ◽  
Rate Of Change ◽  
Lapse Rate ◽  
High Temporal Resolution ◽  
Moisture Regime ◽  
Temperature Lapse Rate ◽  
The One ◽  
The Himalaya

Abstract There are emergent evidences that the rise in temperature in high altitude regions in comparison to low altitude of the Himalaya is more rapid than other parts of the World. This Elevation-dependent warming (EDW) can accelerate the rate of change in mountain ecosystems, including cryosphere, hydrology, biodiversity and socio-economic systems. In this paper, we present Temperature Lapse Rates (TLRs) from 20 stations for three treeline transects representing different climate regimes along the Himalayan arc. TLRs were calculated based on high temporal resolution data collected for two year (2017-18) from complex mountain terrain of treeline environment. The annual mean TLR increased with decreasing moisture, being markedly high at dry WH transect (-0.66℃/100 m) and lowest (-0.50℃/100 m) for moist EH transect. The One-Way ANOVA confirms that the TLR varied spatially, declining from West to East across the Himalayan arc, and significantly differ among seasons (F=3.2175; P = 0.03). The lowest mean TLRs were found during the winter season (EH: -0.46℃/100m; CH: -0.40℃/100m; WH: -0.31℃/100m). The monthly TLR varied within a narrow range (-0.49℃/100m to -0.54℃/100m) at EH transect, -0.24℃/100m to -0.68℃/100m at CH transect and from -0.26℃ to -0.90℃ at WH transect with lowest monthly TLR in December (-0.24 to -0.32℃/ 100m) for all three sites. Study shows moisture, snow albedo and reflectance play a key role as controlling factors on TLR in treeline environments. Higher growing season temperatures observed for treelines in Himalaya (8.4±1.8℃, 10.3±1.4℃, and 7.5±2.7℃) shows warmer treeline in Himalaya. The EDW may impact the dynamics of treeline, snow and moisture regime, surface energy balance, increased water stress, species distribution, and growing season of alpine vegetation in the Himalaya. The findings of the study could provide useful insight (ground-based) to re-parameterize the climate models over the Himalayan region. This study can facilitate improving interpolation of air temperature for ecological modeling studies in ungauged and the data-sparse regions, especially for the higher Himalaya where ground based station data are extremely scarce.

scholarly journals FORUM: Unique Far-Infrared Satellite Observations to Better Understand How Earth Radiates Energy to Space

2020 ◽  
Vol 101 (12) ◽  
pp. E2030-E2046 ◽  
Author(s):  
L. Palchetti ◽  
H. Brindley ◽  
R. Bantges ◽  
S. A. Buehler ◽  
C. Camy-Peyret ◽  
...  
Keyword(s):  
Climate Models ◽  
Longwave Radiation ◽  
Far Infrared ◽  
Lapse Rate ◽  
High Spectral Resolution ◽  
Critical Parameters ◽  
Temperature Lapse Rate ◽  
Stratospheric Water Vapor ◽  
Explorer Mission ◽  
Spectrally Resolved

AbstractThe outgoing longwave radiation (OLR) emitted to space is a fundamental component of the Earth’s energy budget. There are numerous, entangled physical processes that contribute to OLR and that are responsible for driving, and responding to, climate change. Spectrally resolved observations can disentangle these processes, but technical limitations have precluded accurate space-based spectral measurements covering the far infrared (FIR) from 100 to 667 cm−1 (wavelengths between 15 and 100 µm). The Earth’s FIR spectrum is thus essentially unmeasured even though at least half of the OLR arises from this spectral range. The region is strongly influenced by upper-tropospheric–lower-stratospheric water vapor, temperature lapse rate, ice cloud distribution, and microphysics, all critical parameters in the climate system that are highly variable and still poorly observed and understood. To cover this uncharted territory in Earth observations, the Far-Infrared Outgoing Radiation Understanding and Monitoring (FORUM) mission has recently been selected as ESA’s ninth Earth Explorer mission for launch in 2026. The primary goal of FORUM is to measure, with high absolute accuracy, the FIR component of the spectrally resolved OLR for the first time with high spectral resolution and radiometric accuracy. The mission will provide a benchmark dataset of global observations which will significantly enhance our understanding of key forcing and feedback processes of the Earth’s atmosphere to enable more stringent evaluation of climate models. This paper describes the motivation for the mission, highlighting the scientific advances that are expected from the new measurements.

Trend Analysis of Temperature Data for Narayani River Basin, Nepal

Sci ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 38
Author(s):  
Mohan Bahadur Chand ◽  
Bikas Chandra Bhattarai ◽  
Prashant Baral ◽  
Niraj Shankar Pradhananga
Keyword(s):  
Trend Analysis ◽  
River Basin ◽  
Global Climate ◽  
Monsoon Season ◽  
Statistical Significance ◽  
Winter Season ◽  
Temperature Data ◽  
Lapse Rate ◽  
Seasonal Trends ◽  
Temperature Lapse Rate

Study of spatiotemporal dynamics of temperature is vital to assess changes in climate, especially in the Himalayan region where livelihoods of billions of people living downstream depends on water coming from the melting of snow and glacier ice. To this end, temperature trend analysis is carried out in Narayani river basin, a major river basin of Nepal characterized by three climatic regions: tropical, subtropical and alpine. Temperature data from six stations located within the basin were analyzed. The elevation of these stations ranges from 460 to 3800 m a.s.l. and the time period of available temperature data ranges from 1960–2015. Multiple regression and empirical mode decomposition (EMD) methods were applied to fill in missing data and to detect trends. Annual as well as seasonal trends were analyzed and a Mann-Kendall test was employed to test the statistical significance of detected trends. Results indicate significant cooling trends before 1970s, and warming trends after 1970s in the majority of the stations. The warming trends range from 0.028 °C year−1 to 0.035 °C year−1 with a mean increasing trend of 0.03 °C year−1 after 1971. Seasonal trends show highest warming trends in the monsoon season followed by winter, pre-monsoon, and the post-monsoon season. However, difference in warming rates between different seasons was not significant. An average temperature lapse rate of −0.006 °C m−1 with the steepest value (−0.0064 °C m−1) in pre-monsoon season and least negative (−0.0052 °C m−1) in winter season was observed for this basin. A comparative analysis of the gap-filled data with freely available global climate datasets shows reasonable correlation thus confirming the suitability of the gap filling methods.

scholarly journals Coupling of climate models and ice sheet models by surface mass balance gradients: application to the Greenland Ice Sheet

2012 ◽  
Vol 6 (2) ◽  
pp. 255-272 ◽  
Author(s):  
M. M. Helsen ◽  
R. S. W. van de Wal ◽  
M. R. van den Broeke ◽  
W. J. van de Berg ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Lapse Rate ◽  
Surface Mass Balance ◽  
Surface Mass ◽  
Temperature Lapse Rate

Abstract. It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation from a climate model, and parameterizing the meltwater run-off as a function of temperature, which is often related to surface elevation (Hs). In this study, we propose a new strategy to calculate SMB, to allow a direct adjustment of SMB to a change in ice sheet topography and/or a change in climate forcing. This method is based on elevational gradients in the SMB field as computed by a regional climate model. Separate linear relations are derived for ablation and accumulation, using pairs of Hs and SMB within a minimum search radius. The continuously adjusting SMB forcing is consistent with climate model forcing fields, also for initially non-glaciated areas in the peripheral areas of an ice sheet. When applied to an asynchronous coupled ice sheet – climate model setup, this method circumvents traditional temperature lapse rate assumptions. Here we apply it to the Greenland Ice Sheet (GrIS). Experiments using both steady-state forcing and glacial-interglacial forcing result in realistic ice sheet reconstructions.

scholarly journals Modeling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon glacio-hydrological regime of the Himalaya

2016 ◽  
Author(s):  
Renoj J. Thayyen ◽  
Ashok P. Dimri
Keyword(s):  
Hydrological Regime ◽  
Atmospheric Model ◽  
Lapse Rate ◽  
Temperature Lapse Rate ◽  
Annual Variations ◽  
Temperature And Precipitation ◽  
Factors Influencing ◽  
Hydrologic Regimes ◽  
Himalayan Mountain ◽  
The Himalaya

Abstract. Moisture, temperature and precipitation interplay forced through the orographic processes sustain and regulate the Himalayan cryospheric system. However, factors influencing the Slope Environmental Lapse Rate (SELR) of temperature along the Himalayan mountain slopes and an appropriate modeling solution remains a key knowledge gap. Present study evaulates the SELR variations in the monsoon regime of the Himalaya and proposes a modeling solution for the valley scale SELR assessment. SELR of selected station pairs in the Sutlej and Beas basins ranging between 662 m a.s.l. to 3130 m a.s.l. and that of Garhwal Himalaya ranging between 2540 m a.s.l. and 3763 m a.s.l. were assessed in this study. Study suggests moisture- temperature interplay is forcing the seasonal as well as elevation depended variability of SELR. SELR constrianed to the nival- glacier regime is found to be comparable with the saturated adiabatic lapse rate (SALR) and lower than the valley scale SELR. Moisture influx to the region, during Indian summer monsoon (ISM) is found to be lowering the seasonal valley scale SELR to SALR levels during July and August months. Highest valley scale SELR was observed in the months of April, May and June, which susequently lowered to the SALR level with the influx of monsoon moisture. This seasonal variability of SELR is found to be closly linked with the variations in the local lifting condensation levels (LCL). Inter-annual variations in SELR of the nival-glacier regime is found to be significant while that of the valley scale SELR is more stable. Hence, it is proposed to use the valley scale SELR for glacier melt/runoff studies. We propose a simple model for deriving the valley scale SELR of monsoon regime using a derivative of the Clausius–Clapeyron relationship. SELR modeling solution is achieved by deriving separate monthly SELR indices from one of the station pairs in the Beas basin from 1986–1990 and sucessfully applied for other select station pairs in Sutlej and Garhwal basins as well as for different time periods. This work emphasis that the arbitary use of temperature lapse rate is extremely untenable in the Himalayan region and significant further research is required to build data and concepts for a comphrehensive atmospheric model valid across the glacio-hydrologic regimes of the Himalaya.

Trend Analysis of Temperature Data for Narayani River Basin, Nepal

Sci ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 49
Author(s):  
Mohan Bahadur Chand ◽  
Bikas Chandra Bhattarai ◽  
Niraj Shankar Pradhananga ◽  
Prashant Baral
Keyword(s):  
Trend Analysis ◽  
River Basin ◽  
Global Climate ◽  
Monsoon Season ◽  
Statistical Significance ◽  
Winter Season ◽  
Temperature Data ◽  
Lapse Rate ◽  
Seasonal Trends ◽  
Temperature Lapse Rate

Study of spatiotemporal dynamics of temperature is vital to assess changes in climate, especially in the Himalayan region where livelihoods of billions of people living downstream depends on water coming from the melting of snow and glacier ice. To this end, temperature trend analysis is carried out in Narayani river basin, a major river basin of Nepal characterized by three climatic regions: tropical, subtropical and alpine. Temperature data from six stations located within the basin were analyzed. The elevation of these stations ranges from 460 to 3800 m a.s.l. and the time period of available temperature data ranges from 1960–2015. Multiple regression and empirical mode decomposition (EMD) methods were applied to fill in missing data and to detect trends. Annual as well as seasonal trends were analyzed and a Mann-Kendall test was employed to test the statistical significance of detected trends. Results indicate significant cooling trends before 1970s, and warming trends after 1970s in the majority of the stations. The warming trends range from 0.028 ∘C year−1 to 0.035 ∘C year−1 with a mean increasing trend of 0.03 ∘C year−1 after 1971. Seasonal trends show highest warming trends in the monsoon season followed by winter, pre-monsoon, and the post-monsoon season. However, difference in warming rates between different seasons was not significant. An average temperature lapse rate of −0.006 ∘C m−1 with the steepest value (−0.0064 ∘C m−1) in pre-monsoon season and least negative (−0.0052 ∘C m−1) in winter season was observed for this basin. A comparative analysis of the gap-filled data with freely available global climate datasets show reasonable correlation thus confirming the suitability of the gap filling methods.

scholarly journals Understanding Growth Dynamics and Yield Prediction of Sorghum Using High Temporal Resolution UAV Imagery Time Series and Machine Learning

2021 ◽  
Vol 13 (9) ◽  
pp. 1763
Author(s):  
Sebastian Varela ◽  
Taylor Pederson ◽  
Carl J. Bernacchi ◽  
Andrew D. B. Leakey
Keyword(s):  
Time Series ◽  
Temporal Resolution ◽  
Germplasm Collection ◽  
Growth Dynamics ◽  
Ground Cover ◽  
Growing Season ◽  
Rate Of Change ◽  
High Temporal Resolution ◽  
Biotic Stresses ◽  
Spline Fitting

Unmanned aerial vehicles (UAV) carrying multispectral cameras are increasingly being used for high-throughput phenotyping (HTP) of above-ground traits of crops to study genetic diversity, resource use efficiency and responses to abiotic or biotic stresses. There is significant unexplored potential for repeated data collection through a field season to reveal information on the rates of growth and provide predictions of the final yield. Generating such information early in the season would create opportunities for more efficient in-depth phenotyping and germplasm selection. This study tested the use of high-resolution time-series imagery (5 or 10 sampling dates) to understand the relationships between growth dynamics, temporal resolution and end-of-season above-ground biomass (AGB) in 869 diverse accessions of highly productive (mean AGB = 23.4 Mg/Ha), photoperiod sensitive sorghum. Canopy surface height (CSM), ground cover (GC), and five common spectral indices were considered as features of the crop phenotype. Spline curve fitting was used to integrate data from single flights into continuous time courses. Random Forest was used to predict end-of-season AGB from aerial imagery, and to identify the most informative variables driving predictions. Improved prediction of end-of-season AGB (RMSE reduction of 0.24 Mg/Ha) was achieved earlier in the growing season (10 to 20 days) by leveraging early- and mid-season measurement of the rate of change of geometric and spectral features. Early in the season, dynamic traits describing the rates of change of CSM and GC predicted end-of-season AGB best. Late in the season, CSM on a given date was the most influential predictor of end-of-season AGB. The power to predict end-of-season AGB was greatest at 50 days after planting, accounting for 63% of variance across this very diverse germplasm collection with modest error (RMSE 1.8 Mg/ha). End-of-season AGB could be predicted equally well when spline fitting was performed on data collected from five flights versus 10 flights over the growing season. This demonstrates a more valuable and efficient approach to using UAVs for HTP, while also proposing strategies to add further value.

scholarly journals Trend Analysis of Temperature Data for the Narayani River Basin, Nepal

Sci ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 1
Author(s):  
Mohan Bahadur Chand ◽  
Bikas Chandra Bhattarai ◽  
Niraj Shankar Pradhananga ◽  
Prashant Baral
Keyword(s):  
Trend Analysis ◽  
River Basin ◽  
Global Climate ◽  
Monsoon Season ◽  
Statistical Significance ◽  
Winter Season ◽  
Temperature Data ◽  
Lapse Rate ◽  
Seasonal Trends ◽  
Temperature Lapse Rate

The study of spatiotemporal variation in temperature is vital to assess changes in climate, especially in the Himalayan region, where the livelihoods of billions of people living downstream depends on water coming from the melting of snow and glacier ice. To this end, temperature trend analysis is carried out in the Narayani River basin, a major river basin of Nepal, characterized by three climatic regions: tropical, subtropical and alpine. Temperature data from six stations located within the basin were analyzed. The elevation of these stations ranges from 460 to 3800 m a.s.l. and the time period of available temperature data ranges from 1960–2015. Multiple regression and empirical mode decomposition (EMD) methods were applied to fill in missing data and to detect trends. Annual as well as seasonal trends were analyzed and a Mann–Kendall test was employed to test the statistical significance of detected trends. The results indicate significant cooling trends before 1970s, and warming trends after 1970s in the majority of the stations. The warming trends range from 0.028 to 0.035 °C year−1 with a mean increasing trend of 0.03 °C year−1 after 1971. Seasonal trends show the highest warming trends in the monsoon season, followed by winter and the premonsoon and postmonsoon season. However, the difference in warming rates between different seasons was not significant. An average temperature lapse rate of −0.006 °C m−1 with the steepest value (−0.0064 °C m−1) in the premonsoon season and the least negative (−0.0052 °C m−1) in the winter season was observed for this basin. A comparative analysis of the gap-filled data with freely available global climate dataset show reasonable correlation, thus confirming the suitability of the gap filling methods.

scholarly journals Towards direct coupling of regional climate models and ice sheet models by mass balance gradients: application to the Greenland Ice Sheet

2011 ◽  
Vol 5 (4) ◽  
pp. 2115-2157 ◽  
Author(s):  
M. M. Helsen ◽  
R. S. W. van de Wal ◽  
M. R. van den Broeke ◽  
W. J. van de Berg ◽  
J. Oerlemans
Keyword(s):  
Mass Balance ◽  
Climate Models ◽  
Climate Model ◽  
Regional Climate ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Regional Climate Models ◽  
Lapse Rate ◽  
Surface Mass ◽  
Temperature Lapse Rate

Abstract. It is notoriously difficult to couple surface mass balance (SMB) results from climate models to the changing geometry of an ice sheet model. This problem is traditionally avoided by using only accumulation fields from a climate model, and deriving SMB by parameterizing the run-off as a function of temperature, which is often related to surface elevation. In this study, a new parameterization of SMB is presented, designed for use in ice dynamical models to allow a direct adjustment of SMB as a result of a change in elevation (Hs) or a change in climate forcing. This method is based on spatial gradients in the present-day SMB field as computed by a regional climate model. Separate linear relations are derived for ablation and accumulation regimes, using only those pairs of Hs an SMB that are found within a minimum search radius. This approach enables a dynamic SMB forcing of ice sheet models, also for initially non-glaciated areas in the peripheral areas of an ice sheet, and circumvents traditional temperature lapse rate assumptions. The method is applied to the Greenland Ice Sheet (GrIS). Model experiments using both steady-state forcing and more realistic glacial-interglacial forcing result in ice sheet reconstructions and behavior that compare favorably with present-day observations of ice thickness.

scholarly journals Factors controlling Slope Environmental Lapse Rate (SELR) of temperature in the monsoon and cold-arid glacio-hydrological regimes of the Himalaya

2014 ◽  
Vol 8 (6) ◽  
pp. 5645-5686 ◽  
Author(s):  
R. J. Thayyen ◽  
A. P. Dimri
Keyword(s):  
Temperature Distribution ◽  
Spatial Scales ◽  
Lapse Rate ◽  
Regional Variability ◽  
Temperature Lapse Rate ◽  
Temperature And Precipitation ◽  
Ladakh Himalaya ◽  
Temperature Ranges ◽  
The Himalaya ◽  
Hydrological Regimes

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.

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