In general my interests cover a wide range of snow and glacier topics, from snow metamorphism to avalanches and glacier mass balance and glacier area and mass change in response to a warming climate. Methodologies include both in situ and satellite data. Current focus is on determining how much river discharge originates as melting seasonal snow and how much as melting glacier ice across High Asia, the CHARIS project. This distinction is important because while seasonal snow cover returns every year, albeit in varying amounts, glaciers disappear as a result of a warming climate—and that water source is totally lost for the current era.
Establishing a Collaborative Effort to Assess the Role of Glaciers and Seasonal Snow Cover in the Hydrology of the Mountains of High Asia -The USAID-funded CHARIS project: NSIDC.org/CHARIS
Across the five full basins of the CHARIS study (east-to-west, Brahmaputra, Ganges, Indus, Amu Darya, Syr Darya) the annual contribution to river discharge from melting glacier ice for the period 2010 to 2015 averages around 1%. However, the contribution from seasonal snow cover ranges from approximately 40% in the west (Indus, Amu Darya, Syr Darya) to approximately 30% for the Brahmaputra and 5% for the Ganges (see figure 1.) The remaining river discharge results from rainfall and ground water. Within the 3,000- to 6,000-meter elevation band the contribution of glacier ice slightly exceeds 1% in the east increasing to approximately 5% in the west. The contribution from seasonal snow cover within this elevation band ranges from approximately 65% to 75% in the Indus, Amu Darya, Syr Darya, and Brahmaputra to approximately 40% for the Ganges. Melt from glacier ice makes a significant contribution only during the months of June, July, and August. During these summer months in the Ganges and Brahmaputra the river discharge is dominated by monsoon rainfall. In summary, glacier melt water contributes greatest to river discharge in the countries considered most vulnerable to drought, for example Pakistan and Afghanistan, and therefore glacier melt serves as a buffer against drought following winters with less than normal snowfall combined with lack of summer rain. While slow glacier retreat is being observed in the east, glaciers appear to be more stable in the west (higher elevation and higher latitude than the east), and the seasonal snow cover does not show a statistically significant reduction over the past 15 years in the west.
The CHARIS project has established collaborative partnerships with 11 institutions in 8 countries (Bhutan, Nepal, India, Pakistan, Afghanistan, Kyrgyzstan, Tajikistan, Kazakhstan). These partnerships provide a two-fold benefit through both capacity building and sharing of in-situ field data with University of Colorado researchers. A total of 9 training workshops for partners have been conducted by CU staff over the past 5 years covering the topics of fundamental glaciology, digital elevation models (DEMs), geographic information systems (GIS), satellite data applications, mountain hydrology, water chemistry, snow cover and glacier mapping and melt modeling. These partnerships promote and facilitate the international cooperation required for successful cross-boundary water resources management on a regional, not just a national basis.
- Khan AL; Rittger K; Xian P; Katich JM; Armstrong RL; Kayastha RB; Dana JL; McKnight DM. (Sep 2020). Biofuel Burning Influences Refractory Black Carbon Concentrations in Seasonal Snow at Lower Elevations of the Dudh Koshi River Basin of Nepal. Frontiers in Earth Science , 8. 10.3389/feart.2020.00371
- Racoviteanu, AE; Rittger, K; Armstrong, R. (20-Sep 2019). An Automated Approach for Estimating Snowline Altitudes in the Karakoram and Eastern Himalaya From Remote Sensing. FRONTIERS IN EARTH SCIENCE, 7. 10.3389/feart.2019.00220
- Armstrong, RL; Rittger, K; Brodzik, MJ; Racoviteanu, A; Barrett, AP; Khalsa, SJS; Raup, B; Hill, AF; Khan, AL; Wilson, AM; Kayastha, RB; Fetterer, F; Armstrong, B. (2019). Runoff from glacier ice and seasonal snow in High Asia: separating melt water sources in river flow. REGIONAL ENVIRONMENTAL CHANGE, 19(5), 1249-1261. doi: 10.1007/s10113-018-1429-0
- Armstrong, RL; Rittger, K; Brodzik, MJ; Racoviteanu, A; Barrett, AP; Khalsa, SJS; Raup, B; Hill, AF; Khan, AL; Wilson, AM; Kayastha, RB; Fetterer, F; Armstrong, B. (JUN 2019). Runoff from glacier ice and seasonal snow in High Asia: separating melt water sources in river flow. REGIONAL ENVIRONMENTAL CHANGE, 19(5), 1249-1261. 10.1007/s10113-018-1429-0
- Khan, AL, S Wagner, R Jaffe, P Xian, M Williams, R Armstrong and D McKnight. (28-Jun 2017). Dissolved black carbon in the global cryosphere: Concentrations and chemical signatures. GEOPHYSICAL RESEARCH LETTERS, 44(12), 6226-6234. 10.1002/2017GL073485
- Wilson, AM, S Gladfelter, MW Williams, S Shahi, P Baral, R Armstrong and A Racoviteanu. (MAY 2017). High Asia: The International Dynamics of Climate Change and Water Security. JOURNAL OF ASIAN STUDIES, 76(2), 457-480. 10.1017/S0021911817000092
- Normatov, PI, R Armstrong and IS Normatov. (SEP 2016). Variations in hydrological parameters of the Zeravshan River and its tributaries depending on meteorological conditions. RUSSIAN METEOROLOGY AND HYDROLOGY, 41(9), 657-661. 10.3103/S1068373916090090
- Severskiy, I, E Vilesov, R Armstrong, A Kokarev, L Kogutenko, Z Usmanova, V Morozova and B Raup. (2016). Changes in glaciation of the Balkhash-Alakol basin, central Asia, over recent decades. ANNALS OF GLACIOLOGY, 57(71), 382-394. 10.3189/2016AoG71A575
- Eakins, BW, ML Bohan, AA Armstrong, M Westington, J Jencks, E Lim, SJ McLean and RR Warnken. (MAR-APR 2015). NOAAs Role in Defining the US Extended Continental Shelf. MARINE TECHNOLOGY SOCIETY JOURNAL, 49(2), 204-210. 10.4031/MTSJ.49.2.17
- Racoviteanu, AE, R Armstrong and MW Williams. (SEP 2013). Evaluation of an ice ablation model to estimate the contribution of melting glacier ice to annual discharge in the Nepal Himalaya. WATER RESOURCES RESEARCH, 49(9), 5117-5133. 10.1002/wrcr.20370
- Painter, TH, MJ Brodzik, A Racoviteanu and R Armstrong. (24-Oct 2012). Automated mapping of Earth's annual minimum exposed snow and ice with MODIS. GEOPHYSICAL RESEARCH LETTERS, 39. 10.1029/2012GL053340
- Racoviteanu, AE, F Paul, B Raup, SJS Khalsa and R Armstrong. (2009). Challenges and recommendations in mapping of glacier parameters from space: results of the 2008 Global Land Ice Measurements from Space (GLIMS) workshop, Boulder, Colorado, USA. ANNALS OF GLACIOLOGY, 50(53), 53-69. 10.3189/172756410790595804
- Savoie, MH, RL Armstrong, MJ Brodzik and JR Wang. (15-Dec 2009). Atmospheric corrections for improved satellite passive microwave snow cover retrievals over the Tibet Plateau. REMOTE SENSING OF ENVIRONMENT, 113(12), 2661-2669. 10.1016/j.rse.2009.08.006
- Tedesco, M, M Brodzik, R Armstrong, M Savoie and J Ramage. (5-Nov 2009). Pan arctic terrestrial snowmelt trends (1979-2008) from spaceborne passive microwave data and correlation with the Arctic Oscillation. GEOPHYSICAL RESEARCH LETTERS, 36. 10.1029/2009GL039672
- Elder, K, D Cline, GE Liston and R Armstrong. (FEB 2009). NASA Cold Land Processes Experiment (CLPX 2002/03): Field Measurements of Snowpack Properties and Soil Moisture. JOURNAL OF HYDROMETEOROLOGY, 10(1), 320-329. 10.1175/2008JHM877.1
- Yang, DQ, YY Zhao, R Armstrong and D Robinson. (1-Jan 2009). Yukon River streamflow response to seasonal snow cover changes. HYDROLOGICAL PROCESSES, 23(1), 109-121. 10.1002/hyp.7216
- Beedle, MJ, M Dyurgerov, W Tangborn, SJS Khalsa, C Helm, B Raup, R Armstrong and RG Barry. (2008). Improving estimation of glacier volume change: a GLIMS case study of Bering Glacier System, Alaska. CRYOSPHERE, 2(1), 33-51. 10.5194/tc-2-33-2008
- Davis, RE, TH Painter, D Cline, R Armstrong, T Haran, K McDonald, R Forster and K Elder. (DEC 2008). NASA Cold Land Processes Experiment (CLPX 2002/03): Spaceborne Remote Sensing. JOURNAL OF HYDROMETEOROLOGY, 9(6), 1427-1433. 10.1175/2008JHM926.1
- Donlon, C, I Robinson, KS Casey, J Vazquez-Cuervo, E Armstrong, O Arino, C Gentemann, D May, P LeBorgne, J Piolle, I Barton, H Beggs, DJS Poulter, CJ Merchant, A Bingham, S Heinz, A Harris, G Wick, B Emery, P Minnett, R Evans, D Llewellyn-Jones, C Mutlow, RW Reynolds, H Kawamura and N Rayner. (AUG 2007). The global ocean data assimilation experiment high-resolution sea surface temperature pilot project. BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY, 88(8), 1197-1213. 10.1175/BAMS-88-8-1197
- Yang, DQ, YY Zhao, R Armstrong, D Robinson and MJ Brodzik. (11-May 2007). Streamflow response to seasonal snow cover mass changes over large Siberian watersheds. JOURNAL OF GEOPHYSICAL RESEARCH-EARTH SURFACE, 112(F2). 10.1029/2006JF000518
- Raup, B, A Racoviteanu, SJS Khalsa, C Helm, R Armstrong and Y Arnaud. (MAR 2007). The GLIMS geospatial glacier database: A new tool for studying glacier change. GLOBAL AND PLANETARY CHANGE, 56(2-Jan), 101-110. 10.1016/j.gloplacha.2006.07.018
- Jefferies, SM, SW McIntosh, JD Armstrong, TJ Bogdan, A Cacciani and B Fleck. (10-Sep 2006). Magnetoacoustic portals and the basal heating of the solar chromosphere. ASTROPHYSICAL JOURNAL, 648(2), L151-L155.
- Tedesco, M, EJ Kim, D Cline, T Graf, T Koike, R Armstrong, MJ Brodzik and J Hardy. (15-Mar 2006). Comparison of local scale measured and modelled brightness temperatures and snow parameters from the CLPX 2003 by means of a dense medium radiative transfer theory model. HYDROLOGICAL PROCESSES, 20(4), 657-672. 10.1002/hyp.6129
- Foster, J, R Kelly, A Rango, R Armstrong, EF Erbe, C Pooley and WP Wergin. (JUL-AUG 2006). Use of low-temperature scanning electron microscopy to compare and characterize three classes of snow cover. SCANNING, 28(4), 191-203. 10.1002/sca.4950280401
- Chang, ATC, REJ Kelly, EG Josberger, RL Armstrong, JL Foster and NM Mognard. (FEB 2005). Analysis of ground-measured and passive-microwave-derived snow depth variations in midwinter across the northern Great Plains. JOURNAL OF HYDROMETEOROLOGY, 6(1), 20-33. 10.1175/JHM-405.1
- Zhang, T, RL Armstrong and J Smith. (13-Nov 2003). Investigation of the near-surface soil freeze-thaw cycle in the contiguous United States: Algorithm development and validation. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 108(D22). 10.1029/2003JD003530
- Oelke, C, TJ Zhang, MC Serreze and RL Armstrong. (29-May 2003). Regional-scale modeling of soil freeze/thaw over the Arctic drainage basin. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES, 108(D10). 10.1029/2002JD002722
- Armstrong, RL and MJ Brodzik. (2002). Hemispheric-scale comparison and evaluation of passive-microwave snow algorithms. ANNALS OF GLACIOLOGY, VOL 34, 2002, 34, 38-44. 10.3189/172756402781817428
- Frei, A, RL Armstrong, MP Clark and MC Serreze. (JUN 2002). Catskill mountain water resources: Vulnerability, hydroclimatology, and climate-change sensitivity. ANNALS OF THE ASSOCIATION OF AMERICAN GEOGRAPHERS, 92(2), 203-224. 10.1111/1467-8306.00287
- Zhang, T and RL Armstrong. (1-Mar 2001). Soil freeze/thaw cycles over snow-free land detected by passive microwave remote sensing. GEOPHYSICAL RESEARCH LETTERS, 28(5), 763-766. 10.1029/2000GL011952
- Armstrong, RL and MJ Brodzik. (1-Oct 2001). Recent Northern Hemisphere snow extent: A comparison of data derived from visible and microwave satellite sensors. GEOPHYSICAL RESEARCH LETTERS, 28(19), 3673-3676. 10.1029/2000GL012556
- Tait, AB, DK Hall, JL Foster and RL Armstrong. (APR 2000). Utilizing multiple datasets for snow-cover mapping. REMOTE SENSING OF ENVIRONMENT, 72(1), 111-126. 10.1016/S0034-4257(99)00099-1
- Serreze, MC, MP Clark, RL Armstrong, DA McGinnis and RS Pulwarty. (JUL 1999). Characteristics of the western United States snowpack from snowpack telemetry (SNOTEL) data. WATER RESOURCES RESEARCH, 35(7), 2145-2160. 10.1029/1999WR900090
- Meier, MF, R Armstrong and MB Dyurgerov. (1997). Annual net balance of north cascade glaciers, 1984-94 - Comment. JOURNAL OF GLACIOLOGY, 43(143), 192-193.
- ARMSTRONG, RL and MJ BRODZIK. (1995). AN EARTH-GRIDDED SSM/I DATA SET FOR CRYOSPHERIC STUDIES AND GLOBAL CHANGE MONITORING. SATELLITE MONITORING OF THE EARTHS SURFACE AND ATMOSPHERE, 16(10), 155-163. 10.1016/0273-1177(95)00397-W
- Barry, RG, JM Fallot and RL Armstrong. (DEC 1995). Twentieth-century variability in snow-cover conditions and approaches to detecting and monitoring changes: Status and prospects. PROGRESS IN PHYSICAL GEOGRAPHY, 19(4), 520-532. 10.1177/030913339501900405
- MCCLUNG, DM and RL ARMSTRONG. (1993). TEMPERATE GLACIER TIME RESPONSE FROM FIELD DATA. JOURNAL OF GLACIOLOGY, 39(132), 323-326. 10.3189/S0022143000015987
- BARRY, RG and RL ARMSTRONG. (FEB 1990). GLACIOLOGY. GEOTIMES, 35(2), 58-59.
- BARRY, RG and RL ARMSTRONG. (SEP 1987). SNOW COVER DATA MANAGEMENT - THE ROLE OF WDC-A FOR GLACIOLOGY. HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES, 32(3), 281-295. 10.1080/02626668709491189